Method for predicting fretting fatigue life of high-temperature alloy of aero-engine

Abstract

The invention relates to the technical field of aerospace engines, and provides a method for predicting the fretting fatigue life of a high-temperature alloy of an aero-engine, and the method comprises the steps: constructing a fretting fatigue simulation test device; clamping the position of the connecting plate of the fretting fatigue simulation test device on a fatigue testing machine chuck, and applying a preset sine tensile cyclic load to the second ends of the two middle plates to obtain a fretting fatigue index; simulating a fretting fatigue process between the middle plate and the connecting plate based on the fretting fatigue index to obtain stress-strain information of the middle plate; and obtaining a fretting fatigue life result of the aero-engine based on the stress-strain information. The fretting fatigue simulation test device is constructed to simulate the aero-engine bolt structure, the fretting fatigue performance test is performed on the fretting fatigue simulation test device, the obtained fretting fatigue index reveals the influence of the fretting fatigue life of the material, the fretting fatigue process is simulated based on the fretting fatigue index, and the fretting fatigue performance of the material is improved. And accurate prediction of the fretting fatigue life of the high-temperature alloy of the aero-engine is realized.

Description

Technical Field

[0001] The invention relates to the technical field of aerospace engines, and in particular to a method for predicting the fretting fatigue life of high-temperature alloys of aerospace engines. Background Art

[0002] Fretting is a very small amplitude relative motion between contacting surfaces, usually on the order of 100 microns. Under the combined action of applied cyclic loads and vibrations, the surfaces of two objects in contact produce small amplitude relative motion, causing crack initiation and expansion, and reducing the service performance of the components. A large number of studies have shown that fretting fatigue will produce severe stress concentration at the edge of the contact area, causing the quality of the material contact surface to deteriorate, accelerating the initiation and expansion of cracks, leading to structural failure, and endangering the integrity of the components. Bolted connection structures are typical fretting fatigue failure locations. The contact surfaces between the two surfaces of the parts to be connected and the nut and the surface of the parts are common fretting fatigue conditions. Fretting fatigue damage will cause cracks to initiate from the threaded holes, which will lead to failure of the bolted connection. Therefore, in recent years, the fretting fatigue failure problem of bolted connection structures has attracted the attention of many researchers. Bolted connection is a widely used connection structure in aircraft engine turbines. It not only plays an important role in the connection between the turbine disk and the main shaft, but also plays an important role in the fixation of other components. In order to achieve the purpose of connection, a round hole is usually set in the parts to be connected, and the screw passes through the round hole. The connection is completed by the preload of the nut and the screw. As the thrust-to-weight ratio requirements of aircraft engines continue to increase, the speed of the rotor continues to increase, the operating loads borne by the bolted joints continue to worsen, and the fretting fatigue problem of the connection structure is gradually exposed. In recent years, the fretting fatigue failure of the connection components has shown an increasing trend, posing a challenge to the operating reliability of the engine.

[0003] At present, bolt connections made of high-temperature alloys are widely used in aero-engines. Bolt pre-tightening is used to establish contact, and tangential loads are transmitted through dry friction. When an aero-engine works at high speed and high pressure, due to the small relative displacement (usually less than 100 μm), the connection surface of the bolt connection will produce fretting fatigue, which further promotes the initiation and development of fatigue cracks. Once the damage accumulates to a certain extent, it will cause the risk of rotor fracture, posing a serious threat to flight safety.

[0004] In summary, high-temperature alloy bolt connections play an important role in aircraft engines, and their fretting fatigue life is crucial to the safety of aircraft engines. Therefore, the study of the fretting fatigue life of high-temperature alloys in aircraft engines is an important issue that needs to be urgently addressed in the industry. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for predicting the fretting fatigue life of aerospace engine high-temperature alloys, which can achieve accurate prediction of the fretting fatigue life of aerospace engine high-temperature alloys.

[0006] The present invention provides a method for predicting the fretting fatigue life of aerospace engine high-temperature alloy, comprising the following steps: A fretting fatigue simulation test device is constructed, wherein the fretting fatigue simulation test device comprises two middle plates and two connecting plates, wherein the two connecting plates are arranged relatively spaced apart along a first direction, wherein a cross section of a first end of the middle plate is smaller than a cross section of a second end of the middle plate, wherein the two middle plates are arranged relatively spaced apart along a second direction, wherein the first ends of the two middle plates are clamped between the two connecting plates, and the first end of each middle plate and the two connecting plates are fixed by a connecting member; and the second direction is perpendicular to the first direction; Clamp the connection plate of the fretting fatigue simulation test device in the chuck of the fatigue testing machine, apply a preset sinusoidal tensile cyclic load to the second ends of the two middle plates, and obtain the fretting fatigue index of the fretting fatigue simulation test device, wherein the fretting fatigue index includes fretting marks, fracture surface morphology, hysteresis curve, and fretting life; Simulating the fretting fatigue process between the middle plate and the connecting plate based on the fretting fatigue index to obtain stress and strain information of the middle plate; The aero-engine fretting fatigue life result is obtained based on the stress-strain information.

[0007] According to a method for predicting the fretting fatigue life of aero-engine high-temperature alloy provided by the present invention, the fretting marks of the fretting fatigue simulation test device are obtained, comprising: Obtaining the surface morphology of the first end of the middle plate using an optical microscope; Determine the fretting marks of the fretting fatigue simulation test device based on the surface morphology.

[0008] According to a method for predicting the fretting fatigue life of aero-engine high-temperature alloy provided by the present invention, a hysteresis curve of the fretting fatigue simulation test device is obtained, comprising: Obtain the displacement data and applied load data of the fatigue testing machine chuck; The displacement data of the chuck of the fatigue testing machine is used as the abscissa and the applied load data is used as the ordinate to draw a hysteresis curve, thereby obtaining a tangential load-relative displacement hysteresis curve.

[0009] According to a method for predicting the fretting fatigue life of aero-engine high-temperature alloy provided by the present invention, the fretting fatigue life result of the aero-engine is obtained based on the stress-strain information, including: Simulate the wear process of the fretting contact surface of the fretting fatigue simulation test device to obtain a wear model; Establish a three-dimensional fretting fatigue model of the fretting fatigue simulation test device; The stress-strain information is updated based on the wear model, and the wear simulation is performed on the three-dimensional fretting fatigue model to obtain the fretting fatigue life result of the aircraft engine.

[0010] According to a method for predicting the fretting fatigue life of aero-engine high-temperature alloy provided by the present invention, the fretting contact surface wear process of the simulated fretting fatigue simulation test device is simulated to obtain a wear model, including: Determine the initial wear depth based on formula (1);

[0011] in, represents the initial wear depth at position x, α represents the wear coefficient of the total friction dissipation energy, n represents the incremental steps of the finite element numerical simulation during the cyclic loading process, q(x) represents the local shear stress at position x, Δs(x) represents the relative slip distance at position x; Determine the overall wear amount based on formula (2);

[0012] Where V represents the overall wear at position x, ∆A represents the contact area at position x; Determine the wear depth based on formula (3);

[0013] Where h(x) represents the wear depth of the node at position x, and ΔN represents the cycle jump acceleration factor; Based on the overall wear amount and the wear depth, the wear profile of the wear contact area is adjusted to obtain a wear model.

[0014] According to a method for predicting the fretting fatigue life of aero-engine high-temperature alloy provided by the present invention, the stress-strain information is updated based on the wear model, and the wear simulation is performed on the three-dimensional fretting fatigue model to obtain the fretting fatigue life result of the aero-engine, including: Adjusting the node coordinates on the contact area surface according to the wear model to obtain stress and strain information of each node under each fatigue cycle; Performing fretting fatigue cycles on the three-dimensional fretting fatigue model based on the stress-strain information; The damage parameters of fretting fatigue cycles are obtained using critical plane parameters; Based on the linear damage accumulation criterion and the damage parameter, obtaining the total accumulated damage amount; When the total accumulated damage is greater than the preset value, the result of the aircraft engine micro-fatigue life is obtained.

[0015] According to a method for predicting the fretting fatigue life of aero-engine high-temperature alloy provided by the present invention, the thickness of the middle plate is 1-2 mm, and the thickness of the connecting plate is 2.5-5 times the thickness of the middle plate.

[0016] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, a method for predicting the micro-motion fatigue life of high-temperature alloys of aircraft engines as described in any one of the above is implemented.

[0017] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for predicting the fretting fatigue life of aerospace engine high-temperature alloy as described in any one of the above is implemented.

[0018] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any of the above-described methods for predicting the fretting fatigue life of high-temperature alloys of aircraft engines.

[0019] The method for predicting the fretting fatigue life of aero-engine high-temperature alloys provided by the present invention constructs a fretting fatigue simulation test device to simulate the bolt structure of an aero-engine, and performs a fretting fatigue performance test on the fretting fatigue simulation test device. The obtained fretting fatigue index reveals the influence of the fretting fatigue life of the material, and the fretting fatigue process is simulated based on the fretting fatigue index to obtain the fretting fatigue life result of the aero-engine, thereby realizing accurate prediction of the fretting fatigue life of aero-engine high-temperature alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is one of the flow charts of the method for predicting the fretting fatigue life of high-temperature alloys of aero-engines provided by the present invention.

[0022] Figure 2 This is one of the structural schematic diagrams of the fretting fatigue simulation test device provided by the present invention.

[0023] Figure 3This is the second structural schematic diagram of the fretting fatigue simulation test device provided by the present invention.

[0024] Figure 4 It is a schematic diagram of the surface morphology of the middle plate provided by the present invention.

[0025] Figure 5 It is a schematic diagram of the hysteresis curve provided by the present invention.

[0026] Figure 6 This is the second flow chart of the method for predicting the fretting fatigue life of high-temperature alloys of aerospace engines provided by the present invention.

[0027] Figure 7a It is a structural schematic diagram of a three-dimensional fretting fatigue model of the fretting fatigue simulation test device provided by the present invention.

[0028] Figure 7b It is a grid schematic diagram of a three-dimensional fretting fatigue model of the fretting fatigue simulation test device provided by the present invention.

[0029] Figure 8 It is a structural schematic diagram of the electronic device provided by the present invention.

[0030] Reference numerals: 10. Middle plate; 20. Connecting plate; 30. Connecting piece. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The embodiment of the present invention provides a method for predicting the fretting fatigue life of aerospace engine high temperature alloys, such as Figure 1 As shown, the prediction method includes the following steps: Step 100: construct a fretting fatigue simulation test device.

[0033] It should be noted that, unlike traditional mechanical structures, the bolted connections of aircraft engines have thin walls, multiple layers, and preload characteristics, which further promote the occurrence of friction fatigue, resulting in severe stress concentration at the bolted connection position, which is an important cause of surface degradation and micro-motion fatigue crack initiation. And the further development of damage will directly lead to rotor fracture, thus posing a major threat to the safety of aircraft engines. Therefore, this embodiment constructs a micro-motion fatigue simulation test device to simulate the bolted connection of aircraft engines.

[0034] Specifically, Figure 2 and Figure 3 As shown, the micro-motion fatigue simulation test device includes two middle plates 10 and two connecting plates 20. The middle plates 10 and the connecting plates 20 are made of high-temperature alloy. The two connecting plates 20 are arranged relatively spaced apart along the first direction. The cross section of the first end of the middle plate 10 is smaller than the cross section of the second end of the middle plate 10. The two middle plates 10 are arranged relatively spaced apart along the second direction. The first ends of the two middle plates 10 are clamped between the two connecting plates 20. The first end of each middle plate 10 and the two connecting plates 20 are fixed by a connector 30. The second direction is perpendicular to the first direction. It should be noted here that the first direction can be the thickness direction of the connecting plate 20, and the second direction can be the length direction of the connecting plate 20.

[0035] Step 200, clamp the connecting plate 20 of the fretting fatigue simulation test device in the chuck of the fatigue testing machine, apply a preset sinusoidal tensile cyclic load to the second ends of the two middle plates 10, and obtain the fretting fatigue index of the fretting fatigue simulation test device, the fretting fatigue index includes fretting marks, fracture surface morphology, hysteresis curve, and fretting life.

[0036] Step 300 , simulating the fretting fatigue process between the middle plate 10 and the connecting plate 20 based on the fretting fatigue index, and obtaining stress-strain information of the middle plate 10 .

[0037] Step 400: Obtain the micro-motion fatigue life result of the aircraft engine based on the stress-strain information.

[0038] The method for predicting the fretting fatigue life of aero-engine high-temperature alloys provided by the present invention constructs a fretting fatigue simulation test device to simulate the bolt structure of an aero-engine, and performs a fretting fatigue performance test on the fretting fatigue simulation test device. The obtained fretting fatigue index reveals the influence of the fretting fatigue life of the material, and the fretting fatigue process is simulated based on the fretting fatigue index to obtain the fretting fatigue life result of the aero-engine, thereby realizing accurate prediction of the fretting fatigue life of aero-engine high-temperature alloys.

[0039] According to an embodiment of the present invention, the connecting member 30 can be a connecting bolt, and the first end of the middle plate 10 and the two connecting plates 20 are connected by the connecting bolt and locked by a self-locking nut, so that a large pre-tightening force is achieved between the middle plate 10 and the two connecting plates 20; for example, the tightening torque of the connecting bolt is greater than 30N.

[0040] It can be understood that the two connecting plates 20 are arranged relatively spaced apart along the first direction, and the two middle plates 10 are arranged relatively spaced apart along the second direction, so that the micro-motion fatigue simulation test device has a symmetrical geometric shape to avoid the secondary bending effect at the connection bolt connection.

[0041] It should be noted that the compressor shaft contacts the front end and the rear end of the sealing disk respectively. All three are connected with the short bolts on the engine, which is a typical multi-layer structure; in this embodiment, each connection bolt connection has three plates (two connection plates 20 and one middle plate 10), thereby forming a typical three-layer structure, which conforms to the characteristics of the aircraft engine bolt connection.

[0042] In one embodiment of the present invention, the thickness of the middle plate 10 is 1-2 mm, and the thickness of the connecting plate 20 is 2.5-5 times the thickness of the middle plate 10, so that the first end of the middle plate 10 is clamped between the two connecting plates 20 to simulate the thin-walled and multi-layer characteristics of the bolt connection of the aircraft engine. Preferably, the thickness of the connecting plate 20 is 3 times the thickness of the middle plate 10.

[0043] Optionally, the cross-sectional area of ​​the second end of the middle plate 10 is 1 to 3 times the cross-sectional area of ​​the first end of the middle plate 10 . Preferably, the cross-sectional area of ​​the second end of the middle plate 10 is 1.5 times the cross-sectional area of ​​the first end of the middle plate 10 .

[0044] In one embodiment of the present invention, step 200 is implemented by: The connecting plate 20 of the fretting fatigue simulation test device is clamped in the chuck of the fatigue testing machine, and the second ends of the two middle plates 10 are respectively installed on the loading jaws of the fatigue testing machine. The two loading jaws are moved closer or farther away to apply a preset sinusoidal tensile cyclic load, and the fretting fatigue test of the fretting fatigue simulation test device is carried out to obtain the fretting fatigue index.

[0045] It can be understood that the first end of the middle plate 10 is clamped between the two connecting plates 20, and the first end of the middle plate 10 and the two connecting plates 20 are tightened by connecting bolts, which is conducive to maintaining a large preload; the second ends of the two middle plates 10 are respectively installed on the loading jaws of the fatigue testing machine, and the preset sinusoidal tensile cyclic load is applied by the two loading jaws approaching or moving away from each other, and the cyclic load is applied to the middle plate 10 along the length direction of the middle plate 10. Each surface of the first end of the middle plate 10 forms a micro-motion contact (i.e., contact surface) with the corresponding surface of the connecting plate 20 in contact, then one middle plate 10 forms two micro-motion contacts, and four micro-motion contacts are formed between the two middle plates 10 and the two connecting plates 20. Therefore, in each cyclic load loading test, a total of four plane-to-plane friction contact surfaces (micro-motion contacts) are formed.

[0046] For example, a plurality of fretting fatigue simulation test devices are constructed, wherein the middle plates 10 of the plurality of fretting fatigue simulation test devices have different roughnesses, and tensile cyclic loads are applied to the plurality of fretting fatigue simulation test devices, so as to analyze the influence mechanism of roughness on fretting fatigue of bolt structure.

[0047] Optionally, the stress amplitude of the preset sinusoidal tensile cyclic load is 190~230 MPa, and the stress ratio is 0.08~0.15.

[0048] In one embodiment of the present invention, when the fretting fatigue index includes fretting marks, obtaining the fretting fatigue index of the fretting fatigue simulation test device includes obtaining fretting marks of the fretting fatigue simulation test device, which may specifically include the following contents: The surface morphology of the first end of the middle plate 10 is obtained by using an optical microscope; and the fretting marks of the fretting fatigue simulation test device are determined based on the surface morphology.

[0049] In this embodiment, the surface roughness of the middle plate 10 of the three fretting fatigue simulation test devices is 0.4μm, 0.8μm and 1.6μm respectively, the tightening torque between the middle plate 10 and the two connecting plates 20 is 45Nm, and the three fretting fatigue simulation test devices all apply a preset sinusoidal tensile cyclic load. The stress amplitude of the preset sinusoidal tensile cyclic load is 220 MPa, the frequency is 35Hz, the contact pressure is 70.53MPa, and the stress ratio is 0.1.

[0050] It can be understood that, when the surface morphology of the first end of the middle plate 10 and the connection bolt is checked with an optical microscope, the surface of the wear mark is relatively smooth; Figure 4 As shown, Figures a, b, and c respectively represent schematic diagrams of the middle plate 10 with roughness of 0.4 μm, 0.8 μm, and 1.6 μm after the fretting test is completed (the middle plate 10 is broken), the contact surface of the middle plate 10 and the connecting plate 20 is marked with a dotted box d1, the wear mark is marked with a dotted box d2, and no wear mark is indicated by d3; It can be seen that wear marks appear near the crack of the middle plate 10 (the area in the dotted box d2), so that under the action of cyclic load, the edge of the contact surface will slip; a large number of particles accumulate at the edge of the contact area. During the micro-motion fatigue test, the material on the contact surface breaks to form wear debris. In the case of a small reciprocating relative displacement, some fragments will be discharged from the contact area; the remaining fragments become small and accumulate on the contact surface to form a third body layer. On the other hand, there are almost no wear marks in the area near the threaded hole where the middle plate and the connecting bolt cooperate, and the area near the threaded hole is in a state of adhesion (the blue dotted area). Therefore, there are both slip zones and adhesion zones on the contact surface. It should be noted here that after the micro-motion test, one of the two middle plates, which is broken, helps to observe and analyze the location of the crack, and the surface of the other unbroken middle plate is used to obtain detailed micro-motion marks.

[0051] Specifically, by using an optical microscope to obtain the surface morphology of the three middle plates, it can be found that when the roughness Ra is 0.4μm, the lower edge of the contact area slips, the area near the central bolt hole of the contact area is a large adhesion area, and there is partial slip; when the roughness Ra is 0.8μm, the lower edge of the contact area slips, the area near the central bolt hole of the contact area is a small adhesion area, and there is partial slip; when the roughness Ra is 1.6μm, the lower edge of the contact area and the area near the central bolt hole are slip areas, and there is global slip.

[0052] In one embodiment of the present invention, when the fretting fatigue index includes a hysteresis curve, obtaining the fretting fatigue index of the fretting fatigue simulation test device includes obtaining the hysteresis curve of the fretting fatigue simulation test device, which may specifically include the following contents: The displacement data and applied load data of the fatigue testing machine chuck are obtained; a hysteresis curve is drawn with the displacement data of the fatigue testing machine chuck as the abscissa and the applied load data as the ordinate to obtain a tangential load-relative displacement hysteresis curve.

[0053] It can be understood that after the test, the displacement data and load data of the testing machine chuck are used as the horizontal and vertical coordinates to draw a hysteresis curve; wherein the displacement data and load data are the relative displacement and the tangential load, respectively.

[0054] like Figure 5 As shown in the figure, an example of a hysteresis loop tested under the condition of roughness Ra of 0.8 μm is shown. The nonlinear characteristics of the micro-motion fatigue simulation test device are represented by the functional relationship between the tangential force (T, in KN) and the relative displacement (δ, in mm). Specifically, it can be characterized by three contact parameters: tangential contact stiffness K, slip amplitude ΔA and dissipated energy E. Among them, E of each fatigue cycle is determined by the area enclosed by the hysteresis loop, K is the slope of the hysteresis loop in the sticking stage, which represents the deformation resistance of the joint interface. K is calculated by the following formula (4);

[0055] Where ∆T and ∆δ are the increments of the tangential force and relative displacement. ∆A is usually defined as half of the relative displacement in the hysteresis loop.

[0056] It should be noted that the shape of the hysteresis loop also reflects the sticking state. In the sticking state, the force varies linearly with δ, which also indicates that the contact surface is only elastically deformed; increase δ until the entire contact surface is sliding; as δ increases, T tends to stabilize (maximum value), and a horizontal straight line appears in the hysteresis loop, which represents the large slip of the micro-motion interface; the transition between sticking and total slip is partial slip, where part of the contact area is sliding while the other part is still sticking, corresponding to the elliptical hysteresis curve.

[0057] In this embodiment, when the roughness Ra is 0.4, 0.8, and 1.6 μm, the basic laws of the shape of the hysteresis loop, contact stiffness, and relative slip evolution are similar; when the roughness Ra is 0.4, 0.8, and 1.6 μm, the corresponding partial slip is transformed into complete adhesion for 1000 weeks, 700 weeks, and 500 weeks; the contact stiffness relationship is: 0.8>0.4>1.6, the relative slip relationship is: 0.8<0.4<1.6, and the roughness Ra is 1.6 μm. The initial global slip is more severe, resulting in severe micro-motion marks.

[0058] In one embodiment of the present invention, when the fretting fatigue index includes the fracture surface morphology, obtaining the fretting fatigue index of the fretting fatigue simulation test device includes obtaining the fretting fatigue index of the fretting fatigue simulation test device, which may specifically include the following contents: The fracture surface image information of the middle plate is obtained; based on the fracture surface image information, the fracture surface morphology is obtained.

[0059] It can be understood that after the fretting test, the contact surface of the middle plate is observed with an optical microscope, and the fretting marks can be studied by comparing before and after the test; and the fracture surface of the middle plate is examined with a scanning electron microscope to reveal the fretting fatigue damage of the fretting fatigue simulation test device, such as the starting position and extension path of the fatigue crack.

[0060] It should be noted that, under the three roughnesses of this embodiment, the crack initiation position and path characteristics are the same, the crack initiates at the edge of the middle plate contact area, and the crack path is far away from the bolt hole of the middle plate.

[0061] In one embodiment of the present invention, when the fretting fatigue index includes the fretting life, obtaining the fretting fatigue index of the fretting fatigue simulation test device includes obtaining the fretting life of the fretting fatigue simulation test device, which may specifically include the following contents: After the test, the number of cycles in which the fatigue testing machine applies the preset sinusoidal tensile cyclic load is recorded, which can be used as the fretting fatigue life.

[0062] In one embodiment of the present invention, Figure 6 As shown, step 400 may specifically include the following steps: Step 410: simulate the wear process of the fretting contact surface of the fretting fatigue simulation test device to obtain a wear model.

[0063] Step 420: Establish a three-dimensional fretting fatigue model of the fretting fatigue simulation test device.

[0064] Step 430: Update stress-strain information based on the wear model, perform wear simulation on the three-dimensional fretting fatigue model, and obtain the fretting fatigue life result of the aircraft engine.

[0065] It can be understood that the wear model is obtained by simulating the change of the surface unit size using the tangential load, and simulating the wear process of the fretting contact surface of the fretting fatigue simulation test device using the umeshmotion subroutine, adaptive grid and cycle acceleration; in the numerical analysis, the finite element software ABAQUS is used to establish a three-dimensional fretting fatigue model corresponding to the fretting fatigue simulation test device, wherein the geometric shape of the fretting fatigue simulation test device is copied in the three-dimensional fretting fatigue model, and considering the geometric symmetry of the fretting fatigue simulation test device, only half of the structure of the fretting fatigue simulation test device is established as the three-dimensional fretting fatigue model, as shown in Figure 7a. According to the experimental procedure, a middle plate and two connecting plates are connected together by connecting bolts to form a three-dimensional fretting fatigue model, and the length dimension of the connecting plate of the three-dimensional fretting fatigue model is half of the length dimension of the connecting plate of the fretting fatigue simulation test device; then the updated stress field (i.e., stress-strain information) of the wear of the contact surface (fretting contact surface) is determined by a numerical method, and the wear simulation of the three-dimensional fretting fatigue model is performed on this basis to predict the fretting fatigue life.

[0066] It should be noted that in the contact setting of ABAQUS, the finite sliding and surface-to-surface assumptions are used, the surface of the connecting plate is defined as the master surface, and the middle plate is the slave surface; the penalty method is used to establish friction contact, and the friction coefficient is set according to the experimental results. The mesh of the three-dimensional micro-motion fatigue model is shown in Figure 7b, where the mesh density in the contact area is relatively high, and the mesh size reaches 1×1×1 μm, which is suitable for simulating micro-motion damage; coarser meshes are used in areas far away from the contact area to reduce the number of elements and computational costs; incompatible mode eight-node brick elements are selected to ensure that the three-dimensional micro-motion fatigue model reaches a stable state, and the mesh convergence is also checked, which is defined as the stress change should be less than 8% when the density doubles. In this embodiment, the three-dimensional micro-motion fatigue model contains 34969 elements. In order to match the experimental results, FE simulation analysis was performed under different surface roughness.

[0067] In this embodiment, Figure 7b As shown in the figure, during the entire simulation process, the left end of the middle plate is fixed, and a total of six load steps are applied to the three-dimensional fretting fatigue model, mainly as follows: (1) A small preload of 10 N is applied along the axis of the connecting bolt to establish contact between the middle plate and the connecting plate. It should be noted here that the right side of the connecting plate is also fixed for iterative convergence.

[0068] (2) Remove the small preload and remove the fixing constraints of the connecting plate.

[0069] (3) The connecting bolt introduces actual bolt preload, the value of which is determined by the tightening torque and surface condition.

[0070] (4) Set the connection bolt load to a fixed value of the current length to reduce the number of iterations.

[0071] (5) A cyclic load with an average value of 110 MPa is applied to the right side of the connecting plate.

[0072] (6) Continuously apply a preset sinusoidal tensile cyclic load to the connecting plate.

[0073] Optionally, in the case of a small reciprocating relative displacement, the contact surface is worn, some debris is discharged from the contact area, and the remaining debris becomes smaller and accumulates on the contact surface to form a third body layer, which will cause a significant change in the stress field in the contact area.

[0074] Step 410 may specifically include the following contents: The energy model is used to simulate the surface wear of the bolted connection. The model describes the relationship between the wear amount and the total energy consumption between the contact surfaces, as shown in the following formula (5); (5) Where V is the wear volume, α is the wear coefficient of the total friction dissipated energy, and E d represents the total friction dissipated energy, which can be written as the following formula (6)

[0075] Where Q is the shear stress and s is the slip distance.

[0076] In the finite element method, the wear depth at each node is calculated by the shear stress at each node on the contact surface, rather than directly by the total friction force. Therefore, in a complete cycle loading process, the wear depth expression at position x is formula (1), that is, the initial wear depth is determined based on formula (1);

[0077] in, represents the initial wear depth at position x, α represents the wear coefficient of the total friction dissipation energy, n represents the incremental steps of the finite element numerical simulation during the cyclic loading process, q(x) represents the local shear stress at position x, and Δs(x) represents the relative slip distance at position x.

[0078] The overall wear amount at position x can be expressed as formula (2), that is, the overall wear amount is determined based on formula (2);

[0079] Where V is the total wear volume at position x and ∆A is the contact area at position x.

[0080] It should be noted that in the simulation process, if the wear depth of each node in each incremental step is calculated, the calculation cost is high. The wear depth caused by single-cycle loading can be ignored. Assuming that the friction contact surface and During the loading cycle block (ΔN), it remains unchanged. One loading step in the simulation can represent the effect of ΔN cycles, thereby accelerating the calculation and reducing the calculation cost. Therefore, in this embodiment, during the entire cycle, the wear depth of the node at the x position can be expressed as the following formula (3), that is, the wear depth is determined based on formula (3);

[0081] Where h(x) represents the wear depth of the node at position x, and ΔN represents the cycle jump acceleration factor; Based on the overall wear volume and wear depth, the wear profile of the wear contact area is adjusted to obtain the wear model.

[0082] It should be noted that in the simulation of the fretting fatigue surface wear process, the fretting fatigue was simulated using an iterative process by combining the ABAQUS commercial finite element code with the user-defined UMESHMOTION subroutine; the evolution of the wear profile of the contact area was numerically simulated after each incremental step through the UMESHMOTION subroutine and the arbitrary Lagrangian-Eulerian (ALE) technique. Among them, the UMESHMOTION subroutine can control the mesh movement during the adaptive remeshing process, which is implemented in FORTRAN language. The main steps include the following steps: S1. Create a finite element model in ABAQUS and generate an INP file. The INP file retains all node, material parameter and boundary condition information and can be directly analyzed by the solver.

[0083] S2. Solve the INP file to obtain the coordinates, contact pressure, shear stress and slip distance of each node in the contact area.

[0084] S3. At the end of each increment, the wear depth is calculated by calling the UMESHMOTION subroutine based on the energy model. .

[0085] S4, adjust the node coordinates according to the wear depth, ,Then, a new surface profile is generated. It should be noted here that the mesh of the ,nodes can be adjusted according to the ALE technology.

[0086] S5, calculate the number of cycles to determine whether the expected number of cycles is reached, if not, return to step S2, and repeat steps S2 to S5; otherwise, the simulation process ends. In this embodiment, the expected number of cycles can be 2000.

[0087] Optionally, step 430 may specifically include the following contents: Adjust the node coordinates on the contact area surface according to the wear model to obtain the stress and strain information of each node under each fatigue cycle; Fretting fatigue cycles are performed on the three-dimensional fretting fatigue model based on stress-strain information; The damage parameters of fretting fatigue cycles are obtained using critical plane parameters; Based on the linear damage accumulation criterion and damage parameters, the total accumulated damage is obtained; When the total accumulated damage is greater than the preset value, the result of the aircraft engine micro-fatigue life is obtained.

[0088] It can be understood that the combination of Smith-Watson-Thorpe (SWT) multiaxial fatigue parameters and linear damage accumulation (Miner's) law in life prediction can be written as formula (7);

[0089] in, represents the maximum normal stress, represents the strain amplitude on the critical surface during a fatigue cycle. The critical surface is defined as the plane with the largest normal strain amplitude. Indicates the number of cycles, represents fatigue strength coefficient, E represents Young's modulus, b represents fatigue strength index, is the fatigue ductility coefficient and c represents the fatigue ductility index.

[0090] Damage accumulation begins when the material moves between the middle plate and the connecting plate. The stress redistribution and evolution consider the update of the surface profile between different cycles and adopt the linear accumulation rule. When the total accumulated damage (ω) reaches 1, the failure of the material point is defined as occurring, where ω is defined as the following formula (8);

[0091] in, represents the number of failure cycles of the ith fatigue cycle predicted by the critical surface SWT method (using formula (7)), and n is the total number of fretting fatigue cycles to failure, which is used as the fretting fatigue life result of the aircraft engine.

[0092] It should be noted that, through the fretting fatigue data fitting of this embodiment, the life data under different surface roughness are fitted into a curve, and the data dispersion caused by the surface quality has been eliminated, so that this embodiment can capture the influence of surface wear and roughness.

[0093] Figure 8 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 8 As shown, the electronic device may include: a processor 810, a communication interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication interface 820 and the memory 830 communicate with each other through the communication bus 840. The processor 810 may call the logic instructions in the memory 830 to execute a prediction method for the fretting fatigue life of aerospace engine high temperature alloy, the method comprising: constructing a fretting fatigue simulation test device; clamping the connection plate position of the fretting fatigue simulation test device in the chuck of the fatigue testing machine, applying a preset sinusoidal tensile cycle load to the second ends of the two middle plates, obtaining the fretting fatigue index of the fretting fatigue simulation test device, the fretting fatigue index including fretting marks, fracture surface morphology, hysteresis curve and fretting life; simulating the fretting fatigue process between the middle plate and the connection plate based on the fretting fatigue index to obtain the stress-strain information of the middle plate; obtaining the fretting fatigue life result of the aerospace engine based on the stress-strain information.

[0094] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0095] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the prediction method for the micro-motion fatigue life of high-temperature alloys of aircraft engines provided by the above-mentioned methods, and the method includes: constructing a micro-motion fatigue simulation test device; clamping the connecting plate position of the micro-motion fatigue simulation test device in the chuck of a fatigue testing machine, applying a preset sinusoidal tensile cyclic load to the second ends of the two middle plates, and obtaining the micro-motion fatigue index of the micro-motion fatigue simulation test device, the micro-motion fatigue index includes micro-motion marks, fracture surface morphology, hysteresis curve, and micro-motion life; simulating the micro-motion fatigue process between the middle plate and the connecting plate based on the micro-motion fatigue index to obtain the stress-strain information of the middle plate; and obtaining the micro-motion fatigue life result of the aircraft engine based on the stress-strain information.

[0096] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute a prediction method for the micro-motion fatigue life of high-temperature alloys of aircraft engines provided by the above-mentioned methods, the method comprising: constructing a micro-motion fatigue simulation test device; clamping the connecting plate position of the micro-motion fatigue simulation test device in the chuck of a fatigue testing machine, applying a preset sinusoidal tensile cyclic load to the second ends of the two middle plates, and obtaining micro-motion fatigue indicators of the micro-motion fatigue simulation test device, the micro-motion fatigue indicators including micro-motion marks, fracture surface morphology, hysteresis curve, and micro-motion life; simulating the micro-motion fatigue process between the middle plate and the connecting plate based on the micro-motion fatigue indicators to obtain stress-strain information of the middle plate; and obtaining micro-motion fatigue life results of the aircraft engine based on the stress-strain information.

[0097] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, i.e., they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0098] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of each embodiment or some parts of the embodiment.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the fretting fatigue life of aero-engine high-temperature alloys, characterized in that: include: A fretting fatigue simulation test device is constructed, wherein the fretting fatigue simulation test device comprises two middle plates and two connecting plates, wherein the two connecting plates are arranged relatively spaced apart along a first direction, wherein a cross section of a first end of the middle plate is smaller than a cross section of a second end of the middle plate, wherein the two middle plates are arranged relatively spaced apart along a second direction, wherein the first ends of the two middle plates are clamped between the two connecting plates, and the first end of each middle plate and the two connecting plates are fixed by a connecting member; and the second direction is perpendicular to the first direction; Clamp the connection plate of the fretting fatigue simulation test device in the chuck of the fatigue testing machine, apply a preset sinusoidal tensile cyclic load to the second ends of the two middle plates, and obtain the fretting fatigue index of the fretting fatigue simulation test device, wherein the fretting fatigue index includes fretting marks, fracture surface morphology, hysteresis curve, and fretting life; Simulating the fretting fatigue process between the middle plate and the connecting plate based on the fretting fatigue index to obtain stress and strain information of the middle plate; The aero-engine fretting fatigue life result is obtained based on the stress-strain information.

2. The method for predicting the fretting fatigue life of aero-engine high-temperature alloy according to claim 1, characterized in that: Obtaining the fretting marks of the fretting fatigue simulation test device comprises: Obtaining the surface morphology of the first end of the middle plate using an optical microscope; Determine the fretting marks of the fretting fatigue simulation test device based on the surface morphology.

3. The method for predicting the fretting fatigue life of aero-engine high-temperature alloy according to claim 1, characterized in that: Obtaining a hysteresis curve of the fretting fatigue simulation test device includes: Obtain the displacement data and applied load data of the fatigue testing machine chuck; The displacement data of the chuck of the fatigue testing machine is used as the abscissa and the applied load data is used as the ordinate to draw a hysteresis curve, thereby obtaining a tangential load-relative displacement hysteresis curve.

4. The method for predicting the fretting fatigue life of aero-engine high-temperature alloy according to any one of claims 1 to 3, characterized in that: The method of obtaining the aero-engine micro-motion fatigue life result based on the stress-strain information includes: Simulate the wear process of the fretting contact surface of the fretting fatigue simulation test device to obtain a wear model; Establish a three-dimensional fretting fatigue model of the fretting fatigue simulation test device; The stress-strain information is updated based on the wear model, and the wear simulation is performed on the three-dimensional fretting fatigue model to obtain the fretting fatigue life result of the aircraft engine.

5. The method for predicting the fretting fatigue life of aero-engine high-temperature alloy according to claim 4, characterized in that: The simulated fretting fatigue simulation test device simulating the fretting contact surface wear process to obtain a wear model includes: Determine the initial wear depth based on formula (1); in, represents the initial wear depth at position x, α represents the wear coefficient of the total friction dissipation energy, n represents the incremental steps of the finite element numerical simulation during the cyclic loading process, q(x) represents the local shear stress at position x, Δs(x) represents the relative slip distance at position x; Determine the overall wear amount based on formula (2); Where V represents the overall wear at position x, ∆A represents the contact area at position x; Determine the wear depth based on formula (3); Where h(x) represents the wear depth of the node at position x, and ΔN represents the cycle jump acceleration factor; Based on the overall wear amount and the wear depth, the wear profile of the wear contact area is adjusted to obtain a wear model.

6. The method for predicting the fretting fatigue life of aero-engine high-temperature alloy according to claim 5, characterized in that: The updating of stress-strain information based on the wear model and performing wear simulation on the three-dimensional fretting fatigue model to obtain the fretting fatigue life result of the aircraft engine include: Adjusting the node coordinates on the contact area surface according to the wear model to obtain stress and strain information of each node under each fatigue cycle; Performing fretting fatigue cycles on the three-dimensional fretting fatigue model based on the stress-strain information; The damage parameters of fretting fatigue cycles are obtained using critical plane parameters; Based on the linear damage accumulation criterion and the damage parameter, obtaining the total accumulated damage amount; When the total accumulated damage is greater than the preset value, the result of the aircraft engine micro-fatigue life is obtained.

7. The method for predicting the fretting fatigue life of aero-engine high-temperature alloy according to claim 1, characterized in that: The thickness of the middle plate is 1-2 mm, and the thickness of the connecting plate is 2.5-5 times the thickness of the middle plate.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method for predicting the fretting fatigue life of aerospace engine high-temperature alloy as claimed in any one of claims 1 to 7 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for predicting the fretting fatigue life of aerospace engine high-temperature alloy as claimed in any one of claims 1 to 7 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for predicting the fretting fatigue life of aerospace engine high-temperature alloy as claimed in any one of claims 1 to 7 is implemented.

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