Fatigue test piece and test method for high-stress node of pressure-resistant hull of underwater equipment

Abstract

The invention discloses a high-stress structure node fatigue test piece and a high-stress structure node fatigue test method for a pressure-resistant hull of underwater equipment. The high-stress structure node fatigue test piece comprises a bottom plate, wall plates, a rib plate, a first panel and a second panel, the bottom end face of the rib plate is welded to the top end face of the bottom plate, the wall plates and the second panel are welded to the two ends of the rib plate respectively, the first panel is welded to the top end face of the rib plate, and the second panel is welded to the top end face of the rib plate. The bottom of the wall plate and the bottom of the second panel are connected with the bottom plate through welding, the thickness of the bottom plate is consistent with that of a shell plate of a to-be-tested actual pressure-resistant ship body, the thickness of the wall plate is consistent with that of a wall plate of a cabin of the to-be-tested actual pressure-resistant ship body, and the thickness and the width of the rib plate are consistent with those of a vertical reinforcing rib web of a cabin wall of the to-be-tested actual pressure-resistant ship body. Compared with a fatigue model in the prior art, the high-stress structure node fatigue test piece for the underwater equipment pressure-resistant hull has the advantages that the structure of the test piece is simplified, the test piece is convenient to process and manufacture, and the manufacturing difficulty, period and cost are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ship structure design, and in particular to a high-stress structural node fatigue test piece for an underwater equipment pressure-resistant hull and a testing method thereof. Background Art

[0002] For underwater equipment made of high-strength steel, increasing diving depth increases stress in the pressure hull. Due to the high yield-to-tensile ratio of high-strength steel, the crack resistance of the structure is reduced. Repeated high stresses at localized structural nodes during use can cause fatigue cracks in the pressure hull, impacting the long-term safety of the underwater equipment.

[0003] Highly stressed areas on the pressure hulls of underwater equipment (such as those at large openings in the pressure hull and at the ends of internal bulkhead reinforcement ribs) are often subject to complex biaxial or even triaxial stress states, making accurate fatigue life predictions difficult. The fatigue life of these high-stress areas is also affected by the structural welds in those areas, making finite element simulations difficult to accurately predict. To ensure equipment safety, testing and verification of structural fatigue life is essential.

[0004] The fatigue life of a pressure hull is primarily influenced by mechanical and metallurgical factors. Fatigue testing must reflect the complex stress state of the hull's local structural nodes, the actual weld form, and the welding process. Cyclic loading and external pressure testing using full-scale or scaled-down structural models can directly reflect these factors. However, these models suffer from large size, high construction costs, complex external pressure testing procedures, and long test cycles. Summary of the Invention

[0005] The main purpose of the present invention is to provide a high-stress structural node fatigue test piece and a testing method for underwater equipment pressure hull, aiming to simplify the structure of the fatigue test piece so as to simplify the test procedure.

[0006] To achieve the above object, the present invention provides a high stress structural node fatigue test piece for underwater equipment pressure hull, comprising a bottom plate, a wall plate, a rib plate, a first panel and a second panel, wherein: The bottom end surface of the rib plate is welded to the top end surface of the bottom plate, and the two ends of the rib plate are respectively welded with a wall plate and a second panel, the top end surface of the rib plate is welded with the first panel, and the bottoms of the wall plate and the second panel are connected to the bottom plate by welding. The bottom plate is consistent with the shell plate thickness of the actual pressure-resistant hull to be tested, the wall plate is consistent with the wall plate thickness of the actual pressure-resistant hull cabin to be tested, the thickness and width of the rib plate are consistent with the web plate of the vertical reinforcement of the bulkhead of the actual pressure-resistant hull to be tested, the width, steel plate thickness and corner radius of the first panel are consistent with the vertical reinforcement panel of the bulkhead of the actual pressure-resistant hull to be tested, and the shape, size and steel plate thickness of the second panel are consistent with the end panel of the vertical reinforcement of the bulkhead of the actual pressure-resistant hull to be tested.

[0007] Preferably, the base plate includes a first base plate and a second base plate, and the first base plate and the second base plate are connected by a double-sided bevel butt weld.

[0008] Preferably, the wall panel and the bottom plate are connected by a T-shaped weld with double-sided grooves.

[0009] Preferably, the rib plate and the bottom plate are connected by a T-shaped weld with bevels on both sides, and the second panel and the bottom plate are connected by a T-shaped weld with bevels on both sides.

[0010] Preferably, the rib plate is connected to the first panel and the second panel by using a T-shaped weld with double-sided bevels; the rib plate is connected to the wall panel by using a T-shaped weld with double-sided bevels.

[0011] Preferably, all weld grooves and forming dimensions are consistent with actual pressure hull structure welds.

[0012] Preferably, the bottom end surface of the rib plate is perpendicular to the top end surface of the bottom plate, and the wall plate and the second panel are parallel.

[0013] Preferably, the top surface of the rib is a curved surface.

[0014] Preferably, the bottom plate, the wall plate, the rib plate, the first panel and the second panel are all made of the same material as corresponding parts of the actual pressure-resistant hull to be tested.

[0015] The present invention also proposes a method for testing fatigue specimens of high-stress structural nodes of underwater equipment pressure hulls based on the above, comprising the following steps: According to the geometric dimensions of the actual pressure hull to be tested, a finite element simulation model with the same dimensions as the actual pressure hull to be tested is established; The finite element simulation model is loaded according to the actual load, and the circumferential membrane stress, longitudinal membrane stress and bending stress on the pressure hull shell at that location are calculated; According to the calculation results, the circumferential membrane stress, longitudinal membrane stress and bending stress are respectively applied to the long and short sides of the bottom plate of the fatigue specimen and the top surface of the stiffener, and three-way synchronous cyclic loading is performed until the specimen is cracked and damaged. The number of cyclic loading is recorded as the fatigue life of the specimen, and then divided by the welding coefficient, scale coefficient and medium coefficient to obtain the fatigue life of the actual pressure hull to be tested.

[0016] The high-stress structural node fatigue test piece for underwater equipment pressure hull proposed by the present invention has the following beneficial effects: 1. Because when designing the fatigue performance of underwater equipment pressure hulls, we need to focus on the local high-stress areas of the actual structure rather than the overall stress state of the structure. The two main factors affecting welded structures are metallurgical factors and mechanical factors. Therefore, by using the simplified version of the structure in this application to simulate the local high-stress areas of the actual structure, fatigue testing of the plate thickness and welds of the local nodes, as well as the stress state, can characterize the fatigue life of the actual structure. 2. The high-stress structural node fatigue specimen is very simple in structure. At the same time, because its specific size and material are based on the corresponding actual pressure hull, it can accurately reflect the two major factors of mechanics and metallurgy, and can also reduce test costs and shorten test cycles; 3. Compared with the fatigue models of full-scale or equal-thickness-reduced structural models in the prior art, the high-stress structural node fatigue specimens are simplified in structure and smaller in scale, making them easier to manufacture. The manufacturing difficulty, cycle, and cost are greatly reduced, solving the problems of complex implementation, high cost, and long cycle of fatigue tests of full-scale or equal-thickness-reduced structural models in the prior art. 4. The high-stress structural node fatigue specimen does not need to be subjected to cyclic loading in a large external pressure test device, but can be subjected to multiple loadings on a test bench, which greatly reduces the implementation difficulty, test cycle and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a front view of a fatigue test piece of a high-stress structural node of an underwater pressure-resistant hull equipped with the present invention; Figure 2 A top view of a fatigue test piece of a high-stress structural node of an underwater pressure-resistant hull equipped with the present invention; Figure 3 This is a left side view of a fatigue test piece of a high-stress structural node of an underwater pressure-resistant hull equipped with the present invention; Figure 4 A cross-sectional view of a fatigue test piece of a high-stress structural node of an underwater pressure-resistant hull equipped with the present invention; Figure 5 Schematic diagram of the butt weld of a fatigue test piece of a high-stress structural node of an underwater pressure-resistant hull equipped with the present invention; Figure 6This is a schematic diagram of the T-shaped weld of a high-stress structural node fatigue test piece of an underwater pressure-resistant hull equipped with the present invention.

[0018] In the figure, 1-first bottom plate, 2-second bottom plate, 3-wall plate, 4-rib plate, 5-first panel, 6-second panel.

[0019] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0020] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] It should be noted that in the description of the present invention, the terms "transverse," "longitudinal," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] The present invention provides a high-stress structural node fatigue test piece for underwater equipment pressure-resistant hull.

[0023] Reference Figures 1 to 4 In this preferred embodiment, a high stress structural node fatigue test piece for underwater equipment pressure hull includes a bottom plate, a wall plate, a rib plate, a first panel and a second panel, wherein, The bottom end surface of the rib plate is welded to the top end surface of the bottom plate, and the two ends of the rib plate are welded with a wall plate and a second panel respectively, the top end surface of the rib plate is welded with the first panel, and the bottoms of the wall plate and the second panel are connected to the bottom plate by welding. The bottom plate is consistent with the shell plate thickness of the actual pressure-resistant hull to be tested, the wall plate is consistent with the wall plate thickness of the actual pressure-resistant hull cabin to be tested, the thickness and width of the rib plate are consistent with the web plate of the vertical stiffener of the bulkhead of the actual pressure-resistant hull to be tested, the width, steel plate thickness and corner radius of the first panel are consistent with the vertical stiffener panel of the bulkhead of the actual pressure-resistant hull to be tested, and the shape, size and steel plate thickness of the second panel are consistent with the end panel of the vertical stiffener of the bulkhead of the actual pressure-resistant hull to be tested.

[0024] Specifically, with reference to Figure 1 and Figure 5In this embodiment, the bottom plate comprises a first bottom plate and a second bottom plate, which are connected by a double-sided beveled butt weld. The bottom plate is divided into two parts because the actual structure is welded from two pressure-resistant shell plates of different thicknesses.

[0025] Specifically, in this embodiment, with reference to Figure 1 and Figure 6 The hull and bottom plates are connected using double-beveled T-welds. The ribs and bottom plates are connected using double-beveled T-welds, and the second face plate and bottom plates are connected using double-beveled T-welds. The ribs and hull plates are connected using double-beveled T-welds. The ribs and first and second face plates are both connected using double-beveled T-welds. All weld bevels and profile dimensions are consistent with actual pressure hull structure welds.

[0026] In this embodiment, the bottom end surface of the rib plate is perpendicular to the top end surface of the bottom plate, and the wall plate and the second panel are parallel. The top end surface of the rib plate is a curved surface corresponding to the curved surface of the first panel.

[0027] The bottom plate, wall plate, rib plate, first panel and second panel are all made of the same material as the corresponding parts of the actual pressure-resistant hull to be tested, and are all made of high-strength steel.

[0028] The high-stress structural node fatigue test piece for underwater equipment pressure hull proposed by the present invention has the following beneficial effects: 1. Because when designing the fatigue performance of underwater pressure hulls, we need to focus on the local high-stress areas of the actual structure rather than the overall stress state of the structure. The two main factors affecting welded structures are metallurgical factors and mechanical factors. Therefore, by using the simplified version of the structure in this application to simulate the local high-stress areas of the actual structure, fatigue testing of the plate thickness and welds at the local nodes, as well as the stress state, can characterize the fatigue life of the actual structure. 2. The high-stress structural node fatigue specimen is very simple in structure. At the same time, because its specific size and material are based on the corresponding actual pressure hull, it can accurately reflect the two major factors of mechanics and metallurgy, and can also reduce test costs and shorten test cycles; 3. Compared with the fatigue models of full-scale or equal-thickness-reduced structural models in the prior art, the high-stress structural node fatigue specimens are simplified in structure and smaller in scale, making them easier to manufacture. The manufacturing difficulty, cycle, and cost are greatly reduced, solving the problems of complex implementation, high cost, and long cycle of fatigue tests of full-scale or equal-thickness-reduced structural models in the prior art. 4. The high-stress structural node fatigue specimen does not need to be subjected to cyclic loading in a large external pressure test device, but can be subjected to multiple loadings on a test bench, which greatly reduces the implementation difficulty, test cycle and cost.

[0029] The present invention further proposes a testing method for fatigue test pieces of high-stress structural nodes of underwater equipment pressure-resistant hulls.

[0030] This preferred embodiment provides a method for testing fatigue specimens of high-stress structural nodes of underwater equipment pressure hulls, comprising the following steps: Step S10, establishing a finite element simulation model with the same dimensions as the actual pressure hull to be tested according to the geometric dimensions of the actual pressure hull to be tested; Step S20, loading the finite element simulation model according to the actual load, and calculating the circumferential membrane stress, longitudinal membrane stress and bending stress on the pressure hull shell at that location; In step S30, circumferential membrane stress, longitudinal membrane stress and bending stress are applied to the long side and short side of the bottom plate of the fatigue specimen and the top surface of the stiffener respectively, and three-way synchronous cyclic loading is performed until the specimen is cracked and damaged. The number of cyclic loading is recorded, which is the fatigue life of the specimen. This fatigue life is then divided by the welding coefficient, scale coefficient and medium coefficient to obtain the fatigue life of the actual pressure hull to be tested.

[0031] The testing method proposed in the present invention has the advantage of a simple testing process, because it realizes the metallurgical and mechanical simulation of the local high-stress nodes of the actual structure under actual loads. The fatigue life of the specimen is divided by the welding coefficient, scale coefficient, and medium coefficient to obtain the fatigue life of the actual structure.

[0032] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high stress structural node fatigue test piece for underwater equipment pressure hull, characterized in that: It includes a bottom plate, a wall plate, a rib plate, a first panel and a second panel, wherein: The bottom end surface of the rib plate is welded to the top end surface of the bottom plate, and the two ends of the rib plate are respectively welded with a wall plate and a second panel, the top end surface of the rib plate is welded with the first panel, and the bottoms of the wall plate and the second panel are connected to the bottom plate by welding. The bottom plate is consistent with the shell plate thickness of the actual pressure-resistant hull to be tested, the wall plate is consistent with the wall plate thickness of the actual pressure-resistant hull cabin to be tested, the thickness and width of the rib plate are consistent with the web plate of the vertical reinforcement of the bulkhead of the actual pressure-resistant hull to be tested, the width, steel plate thickness and corner radius of the first panel are consistent with the vertical reinforcement panel of the bulkhead of the actual pressure-resistant hull to be tested, and the shape, size and steel plate thickness of the second panel are consistent with the end panel of the vertical reinforcement of the bulkhead of the actual pressure-resistant hull to be tested.

2. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 1, characterized in that: The bottom plate comprises a first bottom plate and a second bottom plate, and the first bottom plate and the second bottom plate are connected by a double-sided beveled butt weld.

3. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 2, characterized in that: The wall plate and the bottom plate are connected by a T-shaped weld with grooves on both sides.

4. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 3, characterized in that: The rib plate and the bottom plate are connected by a T-shaped weld with double-sided bevels, and the second panel and the bottom plate are connected by a T-shaped weld with double-sided bevels.

5. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 4, characterized in that: The rib plate is connected to the first panel and the second panel by adopting a T-shaped weld with double-sided bevels; the rib plate is connected to the wall panel by adopting a T-shaped weld with double-sided bevels.

6. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 1, characterized in that: All weld grooves and forming dimensions are consistent with the actual pressure hull structure welds.

7. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 1, characterized in that: The bottom end surface of the rib plate is perpendicular to the top end surface of the bottom plate, and the wall plate and the second panel are parallel.

8. The high stress structural node fatigue test piece for underwater equipment pressure hull according to claim 1, characterized in that: The top end surface of the rib plate is a curved surface.

9. The high stress structural node fatigue test piece for underwater equipment pressure hull according to any one of claims 1 to 8, characterized in that: The bottom plate, the wall plate, the rib plate, the first panel plate and the second panel plate are all made of the same material as the corresponding parts of the actual pressure-resistant hull to be tested.

10. A method for testing fatigue specimens of high-stress structural nodes of underwater equipment pressure hulls according to any one of claims 1 to 9, characterized in that: The following steps are involved: According to the geometric dimensions of the actual pressure hull to be tested, a finite element simulation model with the same dimensions as the actual pressure hull to be tested is established; The finite element simulation model is loaded according to the actual load, and the circumferential membrane stress, longitudinal membrane stress and bending stress on the pressure hull shell at that location are calculated; According to the calculation results, the circumferential membrane stress, longitudinal membrane stress and bending stress are respectively applied to the long and short sides of the bottom plate of the fatigue specimen and the top surface of the stiffener, and three-way synchronous cyclic loading is performed until the specimen is cracked and damaged. The number of cyclic loading is recorded as the fatigue life of the specimen, and then divided by the welding coefficient, scale coefficient and medium coefficient to obtain the fatigue life of the actual pressure hull to be tested.

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