A fatigue-resistant arc-shaped damping element, its manufacturing method and application

Abstract

This invention relates to a fatigue-resistant arc-shaped damping element, its manufacturing method, and its application. The element is made of austenitic steel and has a rectangular cross-section fan-shaped ring with pin holes at both ends. The yield strength of the austenitic steel is not less than 250 MPa. Under periodic alternating tensile-compression elasto-plastic deformation, strain-induced ε-martensite phase transformation and reversible transformation between austenite and ε-martensite occur within the austenitic steel. Under conditions of 1% strain amplitude, -1 strain ratio, and a loading frequency of 0.1–0.2 Hz, the fatigue life of the austenitic steel is not less than 3000 cycles. The ratio of the width of the arc-shaped damping element to the radius of its central arc surface is between 1 / 10 and 1 / 3, and the central angle corresponding to the central arc surface between the pin holes at both ends is between 180° and 215°. The design damping displacement of the fatigue-resistant arc-shaped damping element is not less than 0.4 times the center distance between the pin holes at both ends of the arc-shaped damping element. The fatigue-resistant arc-shaped damping element of this invention has the characteristics of small size, simple manufacturing method, and good tensile-compressive load-bearing symmetry.

Description

Technical Field

[0001] This invention belongs to the field of seismic engineering technology, and in particular relates to a fatigue-resistant arc-shaped damping element, its manufacturing method, and its application. Background Technology

[0002] Tough metals have good plastic deformation capacity and exhibit excellent hysteresis characteristics (i.e., plastic energy dissipation characteristics) under repeated loading, and are therefore used to manufacture different types of metal energy dissipation shock absorbers.

[0003] In bridge vibration control, C-type and E-type steel dampers are installed between the superstructure and substructure of the bridge to provide tensile restraint and dissipate external vibration energy. Currently, the metal materials used to manufacture bridge dampers are typically low-yield-point steel and high-yield-strength carbon structural steel (such as Q355B). Both of these steels are ferritic steels; under alternating loads, fatigue damage usually begins and propagates earlier from stress and strain concentration points, lodged slip zones, and dislocation cellular structures within the ferritic steel material, ultimately leading to fatigue failure and a low fatigue life. Furthermore, as the strength of ferritic steel increases, its fatigue life during repeated plastic deformation typically decreases accordingly. Therefore, steel dampers made from the aforementioned ferritic steel materials often fail to meet fatigue resistance requirements under certain operating conditions.

[0004] In bridge structures, the installation of dampers is often influenced by available space. For example, in high-intensity seismic zones, there are significant displacement requirements for dampers, necessitating the design of larger ferritic steel dampers to meet the demands of damping displacement and force. However, bridge structures are often constrained by the space between the pier top and the beam bottom, making it impossible to design and use existing ferritic steel dampers, or their spatial layout is inflexible. Therefore, when using steel dampers to achieve energy dissipation and vibration reduction, reducing the size of the steel dampers helps to enhance the flexibility of their installation and use.

[0005] Given the low fatigue life of ferritic steel, existing C-shaped steel dampers used in bridge bearings are usually designed with a variable rectangular cross-section structure, that is, the cross-sectional area gradually increases from both ends of the C-shaped steel to the middle. The purpose is to improve the uniformity of stress and strain distribution on the damper during plastic deformation (reduce stress concentration and material fatigue damage at the edge of the steel damper cross-section) and appropriately improve the fatigue life of the damper. However, this variable cross-section structure design has the following disadvantages: (1) Variable rectangular cross-section C-shaped steel dampers are usually made by cutting steel plates, and the utilization rate of steel plate material is often less than 50%; and, as the size of the steel damper increases, the utilization rate of steel plate material will be even lower. The low material utilization rate leads to the high manufacturing cost of existing variable cross-section C-shaped steel dampers. (2) As the damping displacement increases, the asymmetry of the fatigue deformation hysteresis curve increases. During large-displacement fatigue deformation, the tensile and compressive damping forces provided by the variable cross-section C-shaped steel damper exhibit significant asymmetry (typically, the tensile damping force is significantly greater than the compressive damping force), thus failing to meet the design requirements for allowable damping force deviation, and resulting in a lower degree of fullness in the deformation hysteresis curve. Increasing the planar dimensions of the variable cross-section C-shaped steel can reduce the asymmetry in damping force tension and compression; however, this increases the yield displacement of the steel damper, reduces its effectiveness in dissipating external vibration energy, and the reciprocating deformation capacity of large-size steel dampers is not effectively utilized.

[0006] In summary, given the aforementioned unfavorable properties of existing C-type steel dampers, there is an urgent need to develop C-type steel dampers that can provide greater damping force, have superior fatigue performance, a simple and compact structure (which is conducive to the miniaturization and lightweighting of steel dampers), low manufacturing cost, and good tensile and compressive bearing symmetry. These dampers can then be applied to bridge bearings to achieve the functions of tensile limiting and energy dissipation and vibration reduction. Summary of the Invention

[0007] Based on the current situation that C-shaped steel dampers in the prior art can simultaneously achieve large damping force, excellent fatigue performance, low manufacturing cost, and good tensile and compressive load symmetry, the present invention provides a fatigue-resistant arc-shaped damping element in the first aspect, a manufacturing method of the above-mentioned fatigue-resistant arc-shaped damping element in the second aspect, and an application of the above-mentioned fatigue-resistant arc-shaped damping element in the third aspect.

[0008] The arc-shaped damping element provided by this invention has advantages such as superior fatigue performance, simple and compact structure, low manufacturing cost, good tensile and compressive load symmetry, and the ability to provide large damping force.

[0009] The objective of this invention can be achieved through the following technical solutions.

[0010] The first aspect of the present invention provides a fatigue-resistant arc-shaped damping element.

[0011] A fatigue-resistant arc-shaped damping element is made of austenitic steel and has a geometric shape of a sector-shaped ring with a rectangular cross-section and pin holes at both ends.

[0012] The austenitic steel has a yield strength of not less than 250 MPa and a fracture elongation of not less than 40%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1, and the loading frequency is 0.1 to 0.2 Hz, the fatigue life of the austenitic steel is not less than 3000 cycles.

[0013] The microstructure of the austenitic steel consists of metastable austenite, thermally induced ε-martensite with a volume fraction not exceeding 10%, and carbides with a volume fraction not exceeding 2%. During tensile or compressive elastoplastic deformation, the metastable austenitic structure of the austenitic steel undergoes ε-martensite transformation under strain, while α′-martensite transformation is suppressed. During periodic alternating tensile-compressive elastoplastic deformation, a reversible phase transformation between austenite and strain-induced ε-martensite occurs within the austenitic steel.

[0014] In the geometry of the fatigue-resistant arc-shaped damping element, the ratio of the width b of the arc-shaped damping element to the radius r of its central arc surface is between 1 / 10 and 1 / 3; the central angle 360°-θ corresponding to the central arc surface between the pin holes at both ends is between 180° and 215°; and the diameter of the pin hole is 0.4 to 0.6 times the width b of the damping element.

[0015] Based on the above selection of austenitic steel material and geometric design, the design damping displacement of the fatigue-resistant arc-shaped damping element is not less than 0.4 times the center distance L of the pin holes at both ends of the arc-shaped damping element. Under this design damping displacement condition, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element can complete at least 25 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%. Subsequently, under the condition of 1.2 times the design damping displacement, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element can continue to complete at least 3 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%.

[0016] In this invention, the central arc surface of the arc-shaped damping element is defined as a fan-shaped surface that is equidistant from the inner and outer edge surfaces of the arc-shaped damping element; the width of the arc-shaped damping element is defined as the distance between the inner and outer edge surfaces of the damping element along the radial direction of the aforementioned fan-shaped surface.

[0017] In this invention, the design damping displacement, damping force, and damping force symmetry of the arc-shaped damping element are defined as follows.

[0018] The design damping displacement refers to the maximum allowable tensile displacement (also the maximum compressive displacement) of the arc-shaped damping element under cyclic tensile and compressive deformation. Furthermore, under this maximum tensile (or compressive) displacement condition, with a loading frequency not lower than 0.01 Hz, the arc-shaped damping element can complete at least 25 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%. Subsequently, under 1.2 times the design damping displacement condition, with a loading frequency not lower than 0.01 Hz, the arc-shaped damping element can continue to complete at least 3 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%. Damping displacement refers to the tensile (or compressive) displacement of the arc-shaped damping element when it undergoes cyclic tensile and compressive deformation to absorb and dissipate external vibration energy. Damping force refers to the tensile load and compressive load borne by the arc-shaped damping element when it undergoes tensile and compressive deformation to absorb and dissipate external vibration energy. Damping force symmetry refers to the degree of closeness between the tensile load and the compressive load borne by the arc-shaped damping element under a certain damping displacement condition. It is expressed by the relative difference (=(tensile load-compressive load) / average value of tensile load and compressive load). A small relative difference between the two indicates good damping force symmetry, and vice versa.

[0019] This invention specifies that the material of the fatigue-resistant arc-shaped damping element is austenitic steel. The microstructure of the austenitic steel consists of metastable austenite, thermally induced ε-martensite with a volume fraction not exceeding 10%, and carbides with a volume fraction not exceeding 2%. This microstructural characteristic promotes strain-induced formation of lamellar ε-martensite with a single variant under tensile-compressive alternating loads, avoids strong interaction between thermally induced ε-martensite and strain-induced ε-martensite in the original matrix, thereby promoting reversible phase transformation between austenite and strain-induced ε-martensite, reducing the formation of internal defects in austenitic steel, and delaying fatigue crack propagation. This results in excellent low-cycle fatigue performance and cumulative plastic deformation capacity of the austenitic steel, thus enhancing the low-cycle fatigue performance and cumulative plastic deformation capacity of the arc-shaped damping element. The carbides distributed in the austenitic matrix help increase the strength of the austenitic steel and improve the damping force provided by the damping element. Furthermore, this invention limits the α′ martensitic transformation of metastable austenite within austenitic steel during tensile or compressive elastoplastic deformation. This is because when metastable austenite undergoes excessive α′ martensitic transformation under plastic strain, deformation localization easily occurs within the material, leading to a sharp decline in the low-cycle fatigue performance of austenitic steel and damping components. This invention strictly limits the microstructure of austenitic steel to ensure that austenitic steel and damping components can withstand large-strain fatigue deformation without premature fatigue failure.

[0020] The present invention specifies that the yield strength of austenitic steel is not less than 250 MPa and the elongation at break is not less than 40%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1 and the loading frequency is 0.1 to 0.2 Hz, the fatigue life of austenitic steel is not less than 3000 cycles. The main purpose of limiting the mechanical properties of austenitic steel is to ensure that the material has high strength, good plastic deformation capacity, and fatigue performance, so that the arc-shaped damping element can provide a large damping force and have the following large design damping displacement and fatigue performance: the design damping displacement is not less than 0.4 times the center distance of the pin holes at both ends of the arc-shaped damping element; under this design damping displacement condition, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element can complete at least 25 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%; thereafter, under the condition of 1.2 times the design damping displacement, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element can continue to complete at least 3 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%.

[0021] The arc-shaped damping element of this invention has a structural feature of a uniform rectangular cross-section. Compared with an arc-shaped damping element with a variable rectangular cross-section and the same central arc radius and thickness, the uniform rectangular cross-section arc-shaped damping element can provide greater damping force when its width is similar to the maximum width of the variable rectangular cross-section arc-shaped damping element (i.e., the width of the arc-shaped middle section of the variable rectangular cross-section damping element). Furthermore, compared with the variable rectangular cross-section arc-shaped damping element, the uniform rectangular cross-section arc-shaped damping element exhibits better symmetry of damping force at large damping displacements. Moreover, unlike the variable rectangular cross-section arc-shaped damping element, the uniform rectangular cross-section arc-shaped damping element is easier to manufacture through bending and forming methods, thus significantly reducing the manufacturing cost of the arc-shaped damping element.

[0022] In this invention, the ratio (b / r) of the width b of the arc-shaped damping element to the radius r of its central arc surface is specified as being between 1 / 10 and 1 / 3, and the central angle (360° - θ) corresponding to the central arc surface between the pin holes at both ends is between 180° and 215°. When the ratio (b / r) of the width of the arc-shaped damping element to the radius of its central arc surface is less than 1 / 10, the plastic deformation and load-bearing capacity of the damping element are small, and the excellent fatigue resistance of the austenitic steel material of the damping element cannot be fully utilized. When the ratio of the width of the arc-shaped damping element to the radius of its central arc surface, b / r, is greater than 1 / 3, the plastic deformation in the middle section and its vicinity is relatively large. This will result in the following: under the target design damping displacement (≥ 0.4 times the center distance L between the pin holes at both ends of the damping element), the damping element cannot complete 25 cycles of alternating tensile-compressive elastoplastic deformation with a damping force attenuation of less than 15%; or, the damping element cannot simultaneously meet the requirements of 25 cycles of fatigue deformation under the target design damping displacement and 3 cycles of fatigue deformation under 1.2 times the target design damping displacement. Therefore, this invention limits the ratio of the width of the arc-shaped damping element to the radius of its central arc surface, b / r, to between 1 / 10 and 1 / 3. Furthermore, when the central angle (360°–θ) corresponding to the central arc surface between the pin holes at both ends of the arc-shaped damping element is less than 180°, the damping force symmetry of the damping element is poor under large damping displacement. When the central angle (360°–θ) corresponding to the central arc surface between the pin holes at both ends of the arc-shaped damping element is greater than 215°, due to the limited center distance between the pin holes at both ends, the arc-shaped damping element cannot fully utilize its deformation energy dissipation function, and correspondingly, the structural dimensions of such a damping element are overly redundant. Therefore, this invention limits the central angle (360°–θ) corresponding to the central arc surface between the pin holes at both ends of the arc-shaped damping element to between 180° and 215°.

[0023] Compared with existing variable cross-section arc-shaped damping elements, the arc-shaped damping element with a constant rectangular cross-section of the present invention has the following advantages:

[0024] 1) Small radius of the central arc surface. Because it is made of austenitic steel with excellent fatigue performance (the material's fatigue performance is significantly better than that of ferritic low-yield-point steel and high-strength carbon structural steel used in existing damping elements), the damping element of this invention can withstand larger periodic cyclic elasto-plastic deformation strain and more cycles of cyclic elasto-plastic deformation. For the same design damping displacement, the radius of the central arc surface of the arc-shaped damping element of this invention can be more than 15% smaller than that of existing arc-shaped damping elements. This means the planar dimensions of the arc-shaped damping element of this invention can be significantly reduced, thereby achieving miniaturization and weight reduction of the damping element, saving installation space. Furthermore, reducing the radius of the central arc surface of the damping element can increase plastic deformation strain and damping force, reduce yield displacement, and make the fatigue deformation hysteresis curve fuller.

[0025] 2) The width of the arc-shaped damping element can be increased. As the width of the damping element increases, the deformation strain it withstands also increases. Similarly, because austenitic steel can withstand greater periodic reciprocating plastic deformation strain, for the same central arc radius, the width of the arc-shaped damping element of this invention can be larger than that of existing arc-shaped damping elements. Increasing the width of the damping element helps to increase the damping force, reduce the yield displacement, and increase the fullness of the hysteresis curve. It should be noted that although the width of the damping element is increased, miniaturization and weight reduction of the damping element can still be achieved due to the significant reduction in its central arc radius.

[0026] 3) Greater Damping Force. The austenitic steel material of the arc-shaped damping element of this invention is prone to ε-martensitic transformation and (incomplete) stacking fault proliferation during strain fatigue deformation, resulting in a significantly higher degree of work hardening than existing ferritic steels. When the yield strengths of the materials are similar, the damping force provided by the austenitic steel arc-shaped damping element of this invention is higher than that provided by existing ferritic steel damping elements. Therefore, from a material performance perspective, the damping force depends not only on the yield strength of the material but also on the degree of (cyclic) work hardening. In this invention, both the austenitic steel material and the reduced planar geometry contribute to improving the damping force of the damping element.

[0027] 4) The equirectangular cross-section structure of the arc-shaped damping element helps to improve the symmetry of the damping force and the fullness of the deformation hysteresis curve. Although the variable cross-section feature can make the stress and strain distribution on the arc-shaped damping element better uniform during deformation, the equirectangular cross-section feature can make the damping force provided by the arc-shaped damping element at large damping displacement more symmetrical and the deformation hysteresis curve fuller.

[0028] 5) The equal rectangular cross-section structure of the arc-shaped damping element reduces the manufacturing cost of the damping element. The equal rectangular cross-section arc-shaped damping element of the present invention is manufactured by bending and forming method, and the material utilization rate is close to 100%; in comparison, existing variable cross-section arc-shaped damping elements are obtained by cutting steel plates, and the material utilization rate is usually less than 50%. Therefore, the manufacturing cost of the damping element of the present invention is significantly reduced.

[0029] In one embodiment of the present invention, the mass percentage of the chemical composition of the austenitic steel is defined as follows: C ≤ 0.20%, 3.4% ≤ Si ≤ 6.0%, 24.0% ≤ Mn ≤ 34.0%, Al ≤ 2.0%, Ni ≤ 5.0%, P ≤ 0.12%, Ti ≤ 1.0%, Nb ≤ 1.0%, V ≤ 1.0%, with the remainder being Fe and unavoidable impurity elements. Specifically, the mass percentage of Ni and Al elements must satisfy Al + 0.4Ni ≤ 2.8%; and the mass percentage of Ti, Nb, and V elements must satisfy the following relationship: Ti + Nb + V ≤ 1.0%.

[0030] Austenitic steels meeting the above compositional requirements must also possess the following microstructural characteristics: the microstructure comprises metastable austenite, thermally induced ε-martensite with a volume fraction not exceeding 10%, and carbides with a volume fraction not exceeding 2%. Furthermore, the metastable austenite undergoes a reversible ε-martensite transformation under tensile-compressive alternating loads, while the α′-martensite transformation is suppressed, thus giving austenitic steel excellent low-cycle fatigue properties. Additionally, the carbide particles distributed within the austenitic matrix contribute to improving the strength of the austenitic steel.

[0031] In addition, among the above components, when the mass percentage of Al content exceeds 1%, austenitic steel has good atmospheric corrosion resistance (its corrosion weight loss rate is less than 0.38 times that of Q355B structural steel).

[0032] Without altering the basic microstructure characteristics, the chemical composition of austenitic steel may also contain small amounts of Cr and Cu elements; the present invention specifies that the mass percentages of Cr and Cu elements are ≤2% and ≤2%, respectively.

[0033] When the alloy composition and microstructure characteristics described above are present, the yield strength of austenitic steel is not less than 250 MPa and the elongation at break is not less than 40%; when the strain amplitude of the periodic alternating tensile-compression deformation is 1%, the strain ratio is -1 and the loading frequency is 0.1 to 0.2 Hz, the fatigue life of austenitic steel is not less than 3000 cycles.

[0034] The fatigue-resistant arc-shaped damping element described in this invention also includes the common C-shaped steel damper (also known as a C-shaped steel damping unit).

[0035] A second aspect of the present invention provides a method for manufacturing the above-mentioned fatigue-resistant arc-shaped damping element.

[0036] Fatigue-resistant arc-shaped damping elements are manufactured by bending forming using a bending forming device.

[0037] In one embodiment of the invention, the bending forming apparatus may include one adjustable adjusting roller and two fixed driving rollers; the center of the adjusting roller is located on the perpendicular bisector of the line connecting the centers of the two driving rollers, and the center of the adjusting roller can move along this perpendicular bisector toward the driving roller. During the bending forming process, the adjusting roller and the driving rollers rotate.

[0038] The manufacturing method of the fatigue-resistant arc-shaped damping element includes the following steps:

[0039] 1) Bending and forming

[0040] A sector ring is made of austenitic steel material with a uniform rectangular cross section by bending forming method. The ratio (b / r) of the width b of the sector ring to the radius r of the central arc surface of the sector ring is between 1 / 10 and 1 / 3, and the central angle corresponding to the central arc surface of the sector ring is not less than 180°.

[0041] 2) Machining the pin hole

[0042] Pin holes are machined at both ends of the sector ring. The central angle 360° - θ corresponding to the center arc surface between the two pin holes is between 180° and 215°. The diameter of the pin hole is 0.4 to 0.6 times the width b of the sector ring.

[0043] 3) Annealing treatment

[0044] The fan-shaped ring (i.e. arc-shaped element) with pin holes at both ends is kept at 750-1100℃ for 0.5-10 hours. After the heat preservation is completed, it is air-cooled to room temperature to obtain a fatigue-resistant arc-shaped damping element.

[0045] In step 1), the austenitic steel material with a uniform rectangular cross-section can be an austenitic steel forging or austenitic steel hot-rolled plate; and after the austenitic steel material with a uniform rectangular cross-section is annealed at 750–1100℃ for 0.5–10 hours, it needs to have the following mechanical and microstructural characteristics:

[0046] Mechanically, the yield strength of austenitic steel is not less than 250 MPa, and the elongation at break is not less than 40%. When the strain amplitude of periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1, and the loading frequency is 0.1–0.2 Hz, the fatigue life of the austenitic steel is not less than 3000 cycles. Microstructurally, the austenitic steel consists of metastable austenite, thermally induced ε-martensite with a volume fraction not exceeding 10%, and carbides with a volume fraction not exceeding 2%. During tensile or compressive elastoplastic deformation, the metastable austenite structure of the austenitic steel undergoes an ε-martensite phase transformation under strain, while the α′-martensite phase transformation is suppressed. During periodic alternating tensile-compression elastoplastic deformation, a reversible phase transformation between austenite and strain-induced ε-martensite occurs within the austenitic steel.

[0047] The austenitic steel forgings or hot-rolled sheets may not inherently possess the microstructure and properties after annealing. The forgings or hot-rolled sheets are bent into fan-shaped rings, then annealed to become damping elements. The damping elements are then made of materials with the aforementioned defined properties and microstructure.

[0048] Bending is performed on austenitic steel forgings or hot-rolled sheets. Generally, bending does not significantly alter the microstructure and properties of the forgings or hot-rolled sheets. However, if the forgings or hot-rolled sheets are bent without annealing, they may not achieve the specified microstructure and properties. Similarly, unannealed damping components may also fail to meet the specified microstructure and properties.

[0049] Therefore, the present invention specifies that: (1) when the austenitic steel material (i.e., forgings or hot-rolled plates) with a uniform rectangular cross-section is annealed at a temperature of 750–1100°C for 0.5–10 h, it can achieve the specified microstructure and properties to ensure that the material of the damping element can achieve the specified microstructure and properties. (2) after the austenitic steel material (i.e., forgings or hot-rolled plates) with a uniform rectangular cross-section is bent and formed, it is then annealed at a temperature of 750–1100°C for 0.5–10 h to achieve the specified microstructure and properties, so that the material of the damping element can achieve the specified microstructure and properties.

[0050] In step 1), before bending and forming, the preparation method of the austenitic steel material with a rectangular cross-section (i.e., austenitic steel forgings or hot-rolled plates) includes: (1) smelting and casting the austenitic steel material according to the composition ratio of the austenitic steel material to obtain a billet of austenitic steel material. (2) forging the billet of austenitic steel material into forgings or hot-rolling the billet into hot-rolled plates. In the forging process, the billet is heated at 1000-1250℃ and held for 1-6 hours; the billet is forged into forgings, the forging deformation pass temperature is ≥800℃, and the ratio of the cross-sectional area of ​​the billet before and after forging is ≥1.5. In the hot rolling process, the billet is heated at 1000-1250℃ and held for 1-6 hours; the billet is hot-rolled into hot-rolled plates, the hot rolling deformation is ≥40%, and the final rolling temperature is ≥800℃.

[0051] Before bending and forming, the austenitic steel material with a uniform rectangular cross-section (i.e., austenitic steel forgings or hot-rolled plates) does not require any annealing treatment.

[0052] The bending forming method described in step 1) includes the following implementation steps:

[0053] 1.1) The austenitic steel material is placed between the adjusting roller and the drive roller of the bending forming device, so that the austenitic steel material is in close contact with the adjusting roller and the drive roller;

[0054] 1.2) Move the adjusting roller to reduce the relative distance between the adjusting roller and the drive roller, drive the drive roller and the adjusting roller, so that the austenitic steel material is bent and deformed by passing through the drive roller and the adjusting roller; when the austenitic steel material is bent and deformed to one end, stop driving the adjusting roller and the drive roller.

[0055] 1.3) Continue moving the adjusting roller to further reduce the relative distance between the adjusting roller and the drive roller, change the rotation direction of the drive roller and the adjusting roller to drive the drive roller and the adjusting roller in the opposite direction, so that the austenitic steel material passes through the drive roller and the adjusting roller in the opposite direction and undergoes further bending deformation; when the austenitic steel material is bent and deformed to its other end, stop driving the drive roller and the adjusting roller.

[0056] 1.4) Repeat steps 1.2) and 1.3) to bend and deform the austenitic steel material into a sector ring until the radius of the central arc surface of the sector ring reaches the specified value r. Then, remove the sector ring from the bending forming device.

[0057] In step 1), the bending forming process of the austenitic steel material is carried out in a temperature range of room temperature to 250°C.

[0058] The rationale for the manufacturing method of the fatigue-resistant arc-shaped damping element described in this invention is as follows:

[0059] (1) Bending and forming

[0060] In this invention, the austenitic steel material used for bending can be an austenitic steel forging or austenitic steel hot-rolled sheet. To ensure that the final arc-shaped damping element possesses the specified mechanical and fatigue properties, the microstructure and properties of the selected austenitic steel forging or hot-rolled sheet are specified as follows:

[0061] After the austenitic steel forgings or hot-rolled plates are annealed at 750–1100℃ for 0.5–10 hours, they should have the following mechanical and microstructural characteristics: mechanically, the yield strength of the austenitic steel should be not less than 250 MPa and the elongation at break should be not less than 40%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1, and the loading frequency is 0.1–0.2 Hz, the fatigue life of the austenitic steel material should be not less than 3000 cycles. In terms of microstructure, the microstructure of austenitic steel consists of metastable austenite, thermally induced ε-martensite with a volume fraction not exceeding 10%, and carbides with a volume fraction not exceeding 2%. During tensile or compressive elastoplastic deformation, the metastable austenite microstructure of the austenitic steel material undergoes ε-martensite phase transformation under strain, while α′-martensite phase transformation is suppressed. During periodic alternating tensile-compressive elastoplastic deformation, a reversible phase transformation between austenite and strain-induced ε-martensite occurs within the austenitic steel material.

[0062] Because austenitic steel forgings or hot-rolled sheets possess excellent plasticity and toughness before annealing, they can be directly bent at room temperature. For austenitic steel forgings or rolled materials with small bending radii and large thickness (corresponding to small radius and large width of the central arc surface of the arc-shaped damping element), the austenitic steel forgings or rolled materials can be heated before each bending pass to facilitate the smooth implementation of the bending process, but the heating temperature should not exceed 250℃.

[0063] Before bending deformation begins, the austenitic steel material (i.e., austenitic steel forgings or hot-rolled plates) is in close contact with the adjusting roller and the drive roller. When the adjusting roller is pressed down by a certain displacement while the adjusting roller and the drive roller are not rotating, the austenitic steel material undergoes elastoplastic deformation at and near the contact point with the adjusting roller. When the adjusting roller and the drive roller rotate, the austenitic steel material continuously undergoes elastoplastic deformation at the aforementioned contact point, thereby bending the austenitic steel material. When the austenitic steel material is bent to one end, the adjusting roller is further pressed down and the rotation direction of the adjusting roller and the drive roller is adjusted to the opposite direction, so that the austenitic steel material undergoes repeated bending deformation, ultimately obtaining a sector-shaped ring with a central arc radius of a specified value r. Here, the central arc radius r of the sector-shaped ring is closely related to the following parameters: the radius r1 of the adjusting roller, the radius r2 of the drive roller, the center distance s of the drive roller, the downward pressure δ of the adjusting roller, and the thickness t of the austenitic steel material between the adjusting roller and the drive roller (which, after bending, becomes the width b of the sector-shaped ring and the arc-shaped damping element). The radius r of the central arc surface of the sector ring is approximately And its minimum value is not less than Or r1.

[0064] (2) Machining the pin hole

[0065] After bending and forming, pin holes are machined at both ends of the sector ring. The diameter of the pin holes is generally 0.4 to 0.6 times the width of the sector ring. The central angle 360° - θ corresponding to the central arc surface between the pin holes at both ends of the sector ring is between 180° and 215°.

[0066] (3) Annealing heat treatment

[0067] The fan-shaped ring with pin holes at both ends is annealed to complete the entire manufacturing process of the arc-shaped damping element. In this invention, the annealing soaking temperature is 750–1100℃, and the soaking time is 0.5–10 hours. The purpose of this process is to eliminate the deformation structure formed in the austenitic steel material during manufacturing (forging or hot rolling) and bending processes, and to achieve microstructural control of the material to obtain the target microstructure. The annealing process conditions of this invention are closely related to the alloy composition of the austenitic steel material. When the soaking temperature is below 750℃, the deformation structure cannot be fully eliminated, and the large number of dislocation entanglements in the austenitic steel matrix will interact with the strain-induced ε-martensite formed during alternating loads, thereby inhibiting the reversible phase transformation between austenite and ε-martensite. When the soaking temperature is above 1100℃, the austenite grains in the austenitic steel matrix are excessively coarse, which will also impair the low-cycle fatigue life at room temperature. Therefore, this invention controls the soaking temperature of the annealing heat treatment to be 750–1100℃. In the annealing process, the soaking time can be adjusted by appropriately changing the soaking temperature. If the holding time is too long, it will affect the production efficiency. Therefore, the present invention controls the soaking time to not exceed 10 hours.

[0068] This invention uses austenitic steel material and employs bending forming and annealing heat treatment processes to manufacture fatigue-resistant arc-shaped damping elements. The arc-shaped damping element has the structural characteristics of a sector-shaped ring with a uniform rectangular cross-section. The ratio of the width b of the arc-shaped damping element to the radius r of its central arc surface is between 1 / 10 and 1 / 3, and the central angle 360° – θ corresponding to the central arc surface between the pin holes at both ends is between 180° and 215°. Based on the aforementioned austenitic steel material selection, bending forming method, and annealing heat treatment process, the design damping displacement of the fatigue-resistant arc-shaped damping element is not less than 0.4 times the center distance L of the pin holes at both ends of the arc-shaped damping element. Under this design damping displacement condition, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element can complete at least 25 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%. Subsequently, under the condition of 1.2 times the design damping displacement, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element can continue to complete at least 3 cycles of periodic alternating tensile-compression elastoplastic deformation with a damping force attenuation of less than 15%.

[0069] The third aspect of the present invention provides the application of the above-mentioned fatigue-resistant arc-shaped damping element.

[0070] The fatigue-resistant arc-shaped damping element can be used individually or in combination. When used in combination, the arc-shaped damping elements are stacked together to form a damping unit group, which is connected together by pins passing through pin holes at both ends. Alternatively, the arc-shaped damping elements or damping unit groups can be used in pairs, meaning that under damping displacement, one arc-shaped damping element or damping unit group is under tension while the other is under compression.

[0071] The fatigue-resistant arc-shaped damping element is connected to the bridge bearing via a connector, serving to limit tension and dissipate external vibration energy. The arc-shaped damping element is connected to the connector via a pin at the pin hole.

[0072] The present invention further provides a damping unit group formed by stacking and overlapping the arc-shaped damping elements.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] 1. The fatigue-resistant arc-shaped damping element of the present invention has the characteristics of small planar size, large design damping displacement, large damping force, and good damping force symmetry.

[0075] 2. The fatigue-resistant arc-shaped damping element of the present invention has the advantages of simple structure, simple manufacturing method and low manufacturing cost.

[0076] 3. The fatigue-resistant arc-shaped damping element of the present invention is easy to miniaturize and lighten, can adapt to the large transverse displacement requirements of bridges in high-intensity seismic isolation areas, and requires little installation space and is easy to maintain later.

[0077] 4. The fatigue-resistant arc-shaped damping element of the present invention also has good atmospheric corrosion resistance. Attached Figure Description

[0078] Figure 1 A three-dimensional structural schematic diagram of a fatigue-resistant arc-shaped damping element;

[0079] Figure 2 A schematic diagram of the main structure of a fatigue-resistant arc-shaped damping element;

[0080] Figure 3 A side view of the fatigue-resistant arc-shaped damping element;

[0081] Figure 4 This is a schematic diagram of austenitic steel material in a bending forming device before bending forming;

[0082] Figure 5A schematic diagram of bending and forming austenitic steel material;

[0083] Figure 6 The engineering stress-engineering strain curves of the austenitic steel material in Example 1 are shown.

[0084] Figure 7 The fatigue deformation hysteresis curve of the arc-shaped damping element with a medium rectangular cross-section in Example 1 is shown.

[0085] Figure 8 This is a three-dimensional structural diagram of a damping unit group formed by stacking and overlapping arc-shaped damping elements with equal rectangular cross-sections;

[0086] Figure 9 This is a schematic diagram of the main structure of the arc-shaped damping element with a variable rectangular cross-section in Comparative Example 1;

[0087] Figure 10 The fatigue deformation hysteresis curve of the arc-shaped damping element with variable rectangular cross-section in Comparative Example 1 is shown.

[0088] Figure 11 The stress-strain curves of Q355B steel in Comparative Example 2 are shown.

[0089] The meanings of the labels in the figure are as follows: 1-Anti-fatigue arc-shaped damping element, 2-Central arc surface of arc-shaped damping unit, 3-Pin shaft hole, 4-Adjusting roller of bending forming device, 5-Transmission roller of bending forming device, 6-Austenitic steel material, 7-Rotation direction of adjusting roller and transmission roller, 8-Moving direction of adjusting roller. Detailed Implementation

[0090] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0091] Example 1

[0092] An austenitic steel forging has a rectangular cross-section with dimensions of 76 mm (thickness) × 55 mm (width). The chemical composition of the austenitic steel forging is as follows (mass percentage): 0.06% C, 4.3% Si, 29.8% Mn, 1.8% Al, 0.02% P, with the remainder being Fe and unavoidable impurity elements.

[0093] The preparation method of the austenitic steel forging includes: (1) smelting and casting an austenitic steel billet according to the chemical composition ratio of the austenitic steel forging; (2) forging the austenitic steel billet into a forging through a forging process. In the forging process, the billet is heated at 1150℃ and held for 3 hours; the temperature of the forging deformation pass is ≥850℃, and the ratio of the cross-sectional area of ​​the billet before and after forging (i.e., the ratio of the cross-sectional area of ​​the billet to the cross-sectional area of ​​the forging) is 11.

[0094] The austenitic steel forgings are sequentially subjected to room temperature bending, machining of pin holes, and annealing heat treatment to produce fatigue-resistant arc-shaped damping elements with a uniform rectangular cross-section, such as... Figure 1 The three-dimensional structure is shown in the diagram. Figure 2 The main view shown and Figure 3 As shown in the side view, the geometry of the arc-shaped damping element 1 is as follows: the radius of the central arc surface 2 is r = 495 mm, the width is b = 76 mm, the central angle 360° - θ between the two end pin holes 3 is approximately 208°, the diameter of the pin hole 3 is 38 mm, and the center distance between the two end pin holes 3 is L = 960 mm. The thickness of the arc-shaped damping element 1 is h = 55 mm.

[0095] The specific manufacturing method of the fatigue-resistant arc-shaped damping element is as follows:

[0096] (1) Bending and forming

[0097] A fatigue-resistant arc-shaped damping element is manufactured using a bending forming device. The bending forming device includes one adjustable roller 4 and two fixed drive rollers 5. The center of the adjusting roller 4 is located on the perpendicular bisector of the line connecting the centers of the two drive rollers 5, and the center of the adjusting roller 4 can move along this perpendicular bisector towards the drive roller 5. The bending forming process for austenitic steel forgings is implemented as follows:

[0098] Implement step 1), such as Figure 4 As shown, the austenitic steel forging 6 is placed between the adjusting roller 4 and the transmission roller 5 of the bending forming device, so that the austenitic steel forging 6 is in close contact with the adjusting roller 4 and the transmission roller 5.

[0099] Implement step 2), such as Figure 5 As shown, the adjusting roller 4 is moved in direction 8 to reduce the relative distance between the adjusting roller 4 and the transmission roller 5; the transmission roller 5 and the adjusting roller 4 are driven in the rotation direction 7 to cause the austenitic steel forging 6 to bend and deform by passing through the transmission roller 4 and the adjusting roller 5; when the austenitic steel forging 6 is bent and deformed to one end, the driving of the adjusting roller 4 and the transmission roller 5 is stopped.

[0100] Step 3) Continue moving the adjusting roller 4 in direction 8 to further reduce the relative distance between the adjusting roller 4 and the transmission roller 5. Change the rotation direction 7 of the transmission roller and the adjusting roller to drive the transmission roller 5 and the adjusting roller 4 in the opposite direction, so that the austenitic steel forging 6 passes through the transmission roller 5 and the adjusting roller 4 in the opposite direction and undergoes further bending deformation. When the austenitic steel forging 6 is bent and deformed to its other end, stop driving the adjusting roller 4 and the transmission roller 5.

[0101] Step 4) involves repeating steps 2) and 3) to bend and deform the austenitic steel forging 6 into a sector ring until the radius of the central arc surface of the sector ring reaches the specified value r = 495 mm. The sector ring is then removed from the bending and forming device.

[0102] (2) Machining the pin hole

[0103] After bending and forming, pin holes 3 are machined at both ends of the sector ring. The diameter of the pin holes 3 is 38mm (0.5 times the width of the sector ring), and the central angle 360°-θ corresponding to the center arc surface between the two pin holes 3 is approximately equal to 208°.

[0104] (3) Annealing heat treatment

[0105] The sector ring with pin holes at both ends was subjected to annealing heat treatment. The annealing temperature was 900℃ and the annealing time was 1 hour. After that, it was air-cooled to room temperature.

[0106] The austenitic steel forgings are sequentially subjected to room temperature bending, pin hole machining, and annealing heat treatment to produce fatigue-resistant arc-shaped damping elements. The fatigue-resistant arc-shaped damping elements possess the following mechanical and microstructural characteristics: the material of the arc-shaped damping element is austenitic steel with a yield strength of approximately 338 MPa and a fracture elongation of 57%. Figure 6 The engineering stress-strain curve of austenitic steel, the material of the arc-shaped damping element, is shown. When the strain amplitude is 1%, the strain ratio is -1, and the loading frequency is 0.1 Hz during periodic alternating tensile-compression elastoplastic deformation, the fatigue life of the austenitic steel is approximately 12,000 cycles. The microstructure of the austenitic steel is metastable austenite. During tensile or compressive elastoplastic deformation, the metastable austenitic structure of the austenitic steel undergoes an ε-martensite phase transformation induced by strain, while the α′-martensite phase transformation is suppressed. During periodic alternating tensile-compression elastoplastic deformation, a reversible phase transformation between austenite and strain-induced ε-martensite occurs within the austenitic steel.

[0107] The designed damping displacement of the aforementioned fatigue-resistant arc-shaped damping element is 450 mm (approximately 0.47 times the center distance L between the pin holes at both ends of the arc-shaped damping element). Under this designed damping displacement condition, at a loading frequency of 0.03 Hz, the arc-shaped damping element completes 30 cycles of cyclic alternating tensile-compression elastoplastic deformation without damping force attenuation. Subsequently, under a damping displacement of 1.2 times the design displacement (i.e., a damping displacement of 540 mm), at a loading frequency of 0.03 Hz, the arc-shaped damping element continues to complete 5 cycles of cyclic alternating tensile-compression elastoplastic deformation without damping force attenuation. At this point, the arc-shaped damping unit still has not cracked or failed. Figure 7The figure shows the fatigue deformation hysteresis curves of the fatigue-resistant arc-shaped damping element under different damping displacement conditions. In the figure, positive values ​​above zero on the vertical axis represent the damping force in the compression direction, and negative values ​​below zero represent the damping force in the tension direction. Figure 7 It can be seen that when the applied damping displacement is the design damping displacement (=450mm), approximately, the average value of the tensile and compressive damping forces = (tensile damping force + compressive damping force) / 2 = (95+83) / 2KN = 89KN, and the relative difference in damping forces = (tensile damping force - compressive damping force) / average value of tensile and compressive damping forces = 13.5%. The above calculations show that the fatigue-resistant arc-shaped damping element of the present invention has the characteristic of good damping force symmetry.

[0108] In engineering applications, the aforementioned fatigue-resistant arc-shaped damping elements are typically used in combination. When used in combination, multiple of these arc-shaped damping elements are stacked together to form a damping unit group, such as... Figure 8 As shown, the damping unit groups are connected together by pins passing through the pin holes at both ends. The average value of the tensile and compressive damping forces acting on the damping unit groups is the average damping force provided by a single damping element multiplied by the number of damping elements.

[0109] Examples 2-11

[0110] The arc-shaped damping element with a uniform rectangular cross-section is manufactured by bending, machining pin holes, and annealing heat treatment. The bending process is the same as in Example 1.

[0111] The raw material for the preparation of the arc-shaped damping element is hot-rolled austenitic steel plate, and its main chemical composition is shown in Table 1.

[0112] The preparation method of the austenitic steel hot-rolled plate includes: (1) smelting and casting an austenitic steel billet according to the component proportions shown in Table 1. (2) hot-rolling the austenitic steel billet into a hot-rolled plate. In the hot rolling process, the billet is heated at 1080℃ and held for 3 hours; the hot rolling deformation is >50% and the final rolling temperature is ≥850℃.

[0113] The planar geometry of the arc-shaped damping element is shown in the figure. Figure 2 As shown, the radius of the central arc surface is r, the width is b, the central angle corresponding to the central arc surface between the two end pin holes is 360° - θ, the diameter of the pin hole is 0.5b, and the center distance between the two end pin holes is L. The specific planar dimensions of each damping element are shown in Table 2. The thickness of each damping element is approximately 55mm.

[0114] The specific annealing heat treatment process during the manufacturing of the arc-shaped damping element is shown in Table 3.

[0115] Table 4 shows the mechanical properties and microstructure characteristics of the austenitic steel material for each arc-shaped damping element after bending and annealing heat treatment. When the microstructure of the austenitic steel contains initial heat-induced ε-martensite and carbides, the volume fractions of heat-induced ε-martensite and carbides do not exceed 10% and 2%, respectively.

[0116] The design damping displacement, fatigue deformation performance, and damping force symmetry of each arc-shaped damping element are shown in Table 5. As can be seen from Table 5, the above-mentioned arc-shaped damping elements have the characteristics of large design damping displacement, excellent fatigue performance, and good damping force symmetry.

[0117] Table 1. Mass percentage (wt%) of main alloying elements in austenitic steel, the material of fatigue-resistant arc-shaped damping components.

[0118]

[0119] Table 2 Planar geometric dimensions of fatigue-resistant arc-shaped damping elements

[0120]

[0121]

[0122] Table 3 Annealing heat treatment process for the preparation of fatigue-resistant arc-shaped damping elements.

[0123]

[0124]

[0125] Table 4. Mechanical and microstructure of fatigue-resistant arc-shaped damping elements (austenitic steel)

[0126]

[0127] Table 5. Design damping displacement, fatigue deformation performance, and damping force symmetry of fatigue-resistant arc-shaped damping elements.

[0128]

[0129]

[0130]

[0131] Comparative Example 1

[0132] A variable rectangular cross-section arc-shaped damping element, 55 mm thick, is obtained from a hot-rolled and annealed steel sheet by waterjet cutting. The annealing process of the hot-rolled steel sheet is as follows: annealing temperature is 900℃, and the annealing time is 1 hour. The steel sheet is made of austenitic steel, and its chemical composition by mass percentage is: 0.06% C, 4.3% Si, 29.8% Mn, 1.8% Al, 0.02% P, with the remainder being Fe and unavoidable impurity elements. The geometry of the variable rectangular cross-section arc-shaped damping element is as follows. Figure 9 As shown, the radius of the central arc surface of the arc-shaped damping element is r = 495 mm, the maximum width is 76 mm, the central angle 360° - θ between the central arc surfaces of the two end pin holes is approximately 208°, and the center distance between the two end pin holes is L = 960 mm.

[0133] Similar to the material of the uniform rectangular cross-section fatigue-resistant arc-shaped damping element in Example 1, the aforementioned variable rectangular cross-section arc-shaped damping element has the following mechanical and microstructural characteristics: the material of the arc-shaped damping element is austenitic steel with a yield strength of approximately 342 MPa and a fracture elongation of approximately 57%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1, and the loading frequency is 0.1 Hz, the fatigue life of the austenitic steel is approximately 12,000 cycles. The microstructure of the austenitic steel is metastable austenite; during tensile or compressive elastoplastic deformation, the metastable austenitic structure of the austenitic steel induces ε-martensite phase transformation under strain, while the α′-martensite phase transformation is suppressed; during periodic alternating tensile-compression elastoplastic deformation, a reversible phase transformation between austenite and strain-induced ε-martensite occurs within the austenitic steel.

[0134] The design damping displacement of the aforementioned variable rectangular cross-section arc-shaped damping element is 450 mm. Under this design damping displacement condition, at a loading frequency of 0.03 Hz, the arc-shaped damping element completes 30 cycles of cyclic alternating tensile-compression elastoplastic deformation without damping force attenuation. Subsequently, under a damping displacement of 1.2 times the design displacement (i.e., a damping displacement of 540 mm), at a loading frequency of 0.03 Hz, the arc-shaped damping element continues to complete 5 cycles of cyclic alternating tensile-compression elastoplastic deformation without damping force attenuation. The arc-shaped damping unit did not crack or fail. Figure 10 The figure shows the fatigue deformation hysteresis curves of the variable rectangular cross-section arc-shaped damping element under different damping displacement conditions. In the figure, positive values ​​above zero on the vertical axis represent the damping force in the compression direction, and negative values ​​below zero represent the damping force in the tension direction. Figure 10It can be seen that when the applied damping displacement is the design damping displacement (=450mm), approximately, the average value of the tensile and compressive damping forces = (tensile damping force + compressive damping force) / 2 = (81+48) / 2KN = 64.5KN, and the relative difference in damping force = (tensile damping force - compressive damping force) / average value of tensile and compressive damping forces = 51.2%. The above calculations show that the magnitude and symmetry of the damping force provided by the above-mentioned variable rectangular cross-section arc damping element are significantly lower than those provided by the medium rectangular cross-section fatigue-resistant arc damping element in Embodiment 1 of the present invention.

[0135] Comparative Example 2

[0136] A variable rectangular cross-section arc-shaped damping element, 55 mm thick, is obtained from hot-rolled annealed steel sheet by waterjet cutting. The steel sheet is made of Q355B ferritic structural steel, with the following chemical composition by mass percentage: 0.18% C, 0.33% Si, 1.35% Mn, with the remainder being Fe and unavoidable impurities. The geometry of the variable rectangular cross-section arc-shaped damping element is as follows... Figure 9 As shown, the radius of the central arc surface of the arc-shaped damping element is r = 590 mm, the maximum width is 76 mm, the central angle 360° - θ between the central arc surfaces of the two end pin holes is approximately 208°, and the center distance between the two end pin holes is L = 1145 mm.

[0137] The material of the above-mentioned variable rectangular cross-section arc damping element has the following mechanical properties: yield strength of about 370 MPa and elongation at break of about 27%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1 and the loading frequency is 0.1 Hz, the fatigue life of the Q355B material is less than 1120 cycles. Figure 11 The figure shows the engineering stress-strain curve of Q355B material. As can be seen from the figure, when entering the plastic deformation stage, the work hardening degree of Q355B ferritic steel is significantly lower than that of austenitic steel (e.g., ...). Figure 6 (The austenitic steel is shown in Example 1). Therefore, although the yield strengths of the two materials are comparable, the damping force provided by the damping element made of ferritic steel Q355B is less than that provided by the damping force provided by the damping element made of austenitic steel due to the lower work hardening degree of ferritic steel Q355B.

[0138] The aforementioned variable rectangular cross-section arc-shaped damping element underwent periodic alternating tensile-compression elastoplastic deformation under a damping displacement of 440 mm and a loading frequency of 0.03 Hz. After the 19th cycle of cyclic deformation, significant local deformation appeared in the central part of the arc-shaped damping element. When fatigue deformation was continued at a damping displacement of 440 mm, the damping force rapidly decreased by more than 20%, at which point the arc-shaped damping element was determined to have failed. The 440 mm damping displacement is approximately equivalent to 0.384 times (less than 0.4 L) the center-to-center distance of the pin hole (1145 mm). The arc-shaped damping element could not withstand 25 cycles of fatigue deformation under a damping displacement of less than 0.4 L. Furthermore, examining the symmetry of the damping force at a 440 mm damping displacement, calculations based on the tensile and compressive damping forces showed that the calculated relative difference in damping force was greater than 48%. Compared with Embodiment 1 of the present invention, although the central arc radius of the variable rectangular cross-section arc damping element in Comparative Example 2 is 19.2% larger than that of the medium rectangular cross-section arc damping element in Embodiment 1 (equivalent to: the central arc radius of the medium rectangular cross-section arc damping element in Embodiment 1 is 16.1% smaller than that of the variable rectangular cross-section arc damping element in Comparative Example 2), the fatigue resistance and damping force symmetry of the damping element in Comparative Example 2 are significantly lower than those of the damping element in Embodiment 1.

[0139] Comparative Example 3

[0140] A rectangular cross-section arc-shaped damping element, 55 mm thick, is obtained from hot-rolled annealed steel sheet by waterjet cutting. The steel sheet is made of Q355B ferritic structural steel, with the following chemical composition by mass percentage: 0.18% C, 0.33% Si, 1.35% Mn, with the remainder being Fe and unavoidable impurities. The geometry of the rectangular cross-section arc-shaped damping element is as follows... Figure 2 As shown, the radius of the central arc surface of the arc-shaped damping element is r = 495 mm, the width is 76 mm, the central angle 360° - θ between the central arc surfaces of the two end pin holes is approximately 208°, and the center distance between the two end pin holes is L = 960 mm.

[0141] The material of the above-mentioned rectangular cross-section arc-shaped damping element has the following mechanical properties: yield strength of about 370 MPa and elongation at break of about 27%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1 and the loading frequency is 0.1 Hz, the fatigue life of the Q355B material is less than 1120 cycles.

[0142] The aforementioned rectangular cross-section arc-shaped damping element underwent periodic alternating tensile-compression elastoplastic deformation under a damping displacement of 375 mm and a loading frequency of 0.03 Hz. After the 12th cycle of deformation, significant local deformation and edge cracks appeared in the center of the arc-shaped damping element. When fatigue deformation was continued at a damping displacement of 375 mm, the damping force rapidly decreased by more than 20%, at which point the arc-shaped damping element was determined to have failed. The 375 mm damping displacement is approximately 0.39 times (less than 0.4 L) the center-to-center distance of the pin hole (960 mm). Therefore, the rectangular cross-section arc-shaped damping element could not withstand 25 cycles of fatigue deformation under a damping displacement of less than 0.4 L.

[0143] Comparative Example 4

[0144] A type of arc-shaped damping element with a uniform rectangular cross-section is manufactured by bending a hot-rolled austenitic steel sheet. The manufacturing process also includes pin hole machining and annealing heat treatment. The austenitic steel sheet has the following chemical composition by mass percentage: 0.03% C, 6.2% Si, 33.4% Mn, 0.03% P, with the remainder being Fe and unavoidable impurity elements. The planar geometry of the arc-shaped damping element with a uniform rectangular cross-section is as follows... Figure 2 As shown, the radius of the central arc surface of the arc-shaped damping element is r = 495 mm, the width is b = 76 mm, the central angle 360° - θ between the central arc surfaces of the two end pin holes is approximately 208°, and the center distance between the two end pin holes is L = 960 mm. The arc-shaped damping element is 50 mm thick.

[0145] The austenitic steel material of the arc-shaped damping element with a uniform rectangular cross-section has the following mechanical and microstructural characteristics: yield strength of approximately 310 MPa and elongation at break of approximately 29%; when subjected to periodic alternating tensile-compressive elastoplastic deformation with a strain amplitude of 1%, a strain ratio of -1, and a loading frequency of 0.1 Hz, the fatigue life of the austenitic steel is approximately 2100 cycles. The microstructure of the austenitic steel consists of metastable austenite and thermally induced ε-martensite with a volume fraction of approximately 30%; during tensile or compressive elastoplastic deformation, the metastable austenite microstructure undergoes an ε-martensite phase transformation under stress / strain.

[0146] The aforementioned rectangular cross-section arc-shaped damping element underwent 25 cycles of alternating tensile-compression elastoplastic deformation under a design damping displacement of 375 mm (0.39 L) and a loading frequency of 0.03 Hz. However, after the 23rd cycle, obvious fatigue cracks appeared at the edge of the arc-shaped damping element. Subsequently, the arc-shaped damping element continued to undergo cyclic deformation under a damping displacement of 450 mm (equivalent to 1.2 times the design damping displacement) and a loading frequency of 0.03 Hz. Before completing one cycle of fatigue deformation, the damping element failed. Therefore, the design damping displacement of the rectangular cross-section arc-shaped damping element should be less than 0.4 L.

[0147] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A fatigue-resistant arc-shaped damping element, characterized in that, The material of the anti-fatigue arc-shaped damping element (1) is austenitic steel, and the geometry of the anti-fatigue arc-shaped damping element (1) is a sector-shaped ring with an equal rectangular cross-section and pin holes (3) at both ends. The austenitic steel has a yield strength of not less than 250 MPa and a fracture elongation of not less than 40%; when the strain amplitude of the periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1 and the loading frequency is 0.1~0.2 Hz, the fatigue life of the austenitic steel is not less than 3000 cycles. The microstructure of the austenitic steel consists of metastable austenite, thermally induced α-martensite with a volume fraction not exceeding 10%, and carbides with a volume fraction not exceeding 2%. Under tensile or compressive elastoplastic deformation, the metastable austenitic structure of the austenitic steel undergoes an α-martensite phase transformation under strain. Martensitic phase transformation is suppressed; during periodic alternating tensile-compression elastoplastic deformation, a reversible phase transformation between austenite and strain-induced α-martensite occurs inside the austenitic steel; In the geometry of the fatigue-resistant arc-shaped damping element (1), the ratio of the width b of the fan-shaped ring to the radius r of its central arc surface (2) is between 1 / 10 and 1 / 3; the central angle 360° - θ corresponding to the central arc surface between the two end pin holes (3) is between 180° and 215°; the diameter of the pin hole is 0.4 to 0.6 times the width b of the fan-shaped ring. The design damping displacement of the fatigue-resistant arc-shaped damping element (1) is not less than 0.4 times the center distance L of the pin holes (3) at both ends of the arc-shaped damping element (1); under this design damping displacement condition, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element (1) can complete at least 25 cycles of periodic alternating tensile-compression elastoplastic deformation and the damping force decay is less than 15%; thereafter, under the condition of 1.2 times the design damping displacement, when the loading frequency is not less than 0.01Hz, the arc-shaped damping element (1) can continue to complete at least 3 cycles of periodic alternating tensile-compression elastoplastic deformation and the damping force decay is less than 15%.

2. The fatigue-resistant arc-shaped damping element according to claim 1, characterized in that, The austenitic steel has the following chemical composition by mass percentage: C≤0.20%, 3.4%≤Si≤6.0%, 24.0%≤Mn≤34.0%, Al≤2.0%, Ni≤5.0%, P≤0.12%, Ti≤1.0%, Nb≤1.0%, V≤1.0%, with the remainder being Fe and unavoidable impurity elements; among which, the mass percentage content of Ni and Al elements must also satisfy Al+0.4Ni≤2.8%; and the mass percentage content of Ti, Nb, and V elements must also satisfy Ti+Nb+V≤1.0%.

3. The method for manufacturing the fatigue-resistant arc-shaped damping element according to claim 1 or 2, characterized in that, The steps include: 1) Bending and forming Austenitic steel material with equal rectangular cross-section structure is formed into a sector ring by bending forming process. The ratio of the width b of the sector ring to the radius r of the central arc surface of the sector ring is between 1 / 10 and 1 / 3, and the central angle corresponding to the central arc surface of the sector ring is not less than 180°. 2) Machining the pin hole After bending and forming, pin holes are machined at both ends of the sector ring. The central angle 360° - θ corresponding to the center arc surface between the two pin holes is between 180° and 215°. The diameter of the pin hole is 0.4 to 0.6 times the width b of the sector ring. 3) Annealing heat treatment The sector-shaped ring with pin holes machined at both ends is 750~1100. o Incubate at temperature C for 0.5~10 h, then air cool to room temperature after the incubation period.

4. The method for manufacturing the fatigue-resistant arc-shaped damping element according to claim 3, characterized in that, Step 1) The austenitic steel material with the characteristic of a uniform rectangular cross-section is an austenitic steel forging or austenitic steel hot-rolled plate; and, when the austenitic steel material with the characteristic of a uniform rectangular cross-section is at a temperature of 750~1100... o After annealing at temperature C for 0.5~10 h, it needs to have the following mechanical and microstructure characteristics: Mechanically, the yield strength of austenitic steel is not less than 250 MPa and the elongation at break is not less than 40%; when the strain amplitude of periodic alternating tensile-compression elastoplastic deformation is 1%, the strain ratio is -1 and the loading frequency is 0.1~0.2 Hz, the fatigue life of austenitic steel is not less than 3000 cycles. In terms of microstructure, austenitic steel consists of metastable austenite, thermally induced α-martensite (volume fraction not exceeding 10%), and carbides (volume fraction not exceeding 2%). Under tensile or compressive elastoplastic deformation, the metastable austenite structure of austenitic steel undergoes an α-martensite transformation under strain. Martensitic transformation is suppressed; during periodic alternating tensile-compression elastoplastic deformation, a reversible phase transformation between austenite and strain-induced α-martensite occurs inside austenitic steel.

5. The method for manufacturing the fatigue-resistant arc-shaped damping element according to claim 3, characterized in that, The bending forming process described in step 1) is implemented using a bending forming device; The bending forming device includes one adjustable adjusting roller and two fixed driving rollers; the center of the adjusting roller is located on the perpendicular bisector of the line connecting the centers of the two driving rollers, and the center of the adjusting roller can move along the perpendicular bisector toward the driving roller. The bending forming process includes the following steps: 1.1) Place the austenitic steel material (6) between the adjusting roller (4) and the transmission roller (5) of the bending forming device so that the austenitic steel material (6) is in close contact with the adjusting roller (4) and the transmission roller (5); 1.2) Move the adjusting roller (4) to reduce the relative distance between the adjusting roller (4) and the transmission roller (5), drive the transmission roller (5) and the adjusting roller (4) so ​​that the austenitic steel material (6) is bent and deformed by passing through the transmission roller (5) and the adjusting roller (4); when the austenitic steel material (6) is bent and deformed to one end, stop driving the adjusting roller (4) and the transmission roller (5). 1.3) Continue to move the adjusting roller (4) to further reduce the relative distance between the adjusting roller (4) and the transmission roller (5), and change the rotation direction (7) to drive the transmission roller (5) and the adjusting roller (4) in the opposite direction, so that the austenitic steel material (6) passes through the transmission roller (5) and the adjusting roller (4) in the opposite direction and undergoes further bending deformation; when the austenitic steel material (6) is bent and deformed to its other end, stop driving the adjusting roller (4) and the transmission roller (5). 1.4) Repeat steps 1.2) and 1.3) to bend and deform the austenitic steel material (6) into a sector ring until the radius of the central arc surface of the sector ring reaches the specified value r; remove the sector ring from the bending forming device.

6. The method for manufacturing the fatigue-resistant arc-shaped damping element according to claim 3, characterized in that, Step 1) describes the bending and forming process of austenitic steel material at room temperature to 250°C. o Implemented within a temperature range of C.

7. The application of the fatigue-resistant arc-shaped damping element according to claim 1 or 2, characterized in that, The fatigue-resistant arc-shaped damping element can be used alone or in combination; When used in combination, the fatigue-resistant arc-shaped damping elements are stacked together to form a damping unit group, which is connected together by pins passing through pin holes at both ends. The fatigue-resistant arc-shaped damping element or the damping unit group formed by stacking and overlapping fatigue-resistant arc-shaped damping elements is connected to the bridge bearing via a connector, which plays the role of tensile limiting and dissipating external vibration energy; the fatigue-resistant arc-shaped damping element or the damping unit group is connected to the connector via a pin at the pin hole.

8. The application of the fatigue-resistant arc-shaped damping element according to claim 7, characterized in that, The arc-shaped damping elements or damping units are used in pairs, that is, under the action of damping displacement, one arc-shaped damping element or damping unit group is under tension while the other damping element or damping unit group is under compression.

9. A damping unit group formed by stacking and overlapping the fatigue-resistant arc-shaped damping elements as described in claim 1 or 2.

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