Design method of deep sea stress corrosion equivalent test piece of titanium alloy shell structure
Through the method of finite element analysis and testing shell length adjustment, the high cost and high difficulty problems caused by multiple reinforcement ribs or welds in the equivalent test parts of titanium alloy shell are solved, and the low cost, efficient processing and stress component reduction of the equivalent test parts are achieved.
Patent Information
- Application Number
- CN202411932949.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-04-25
AI Technical Summary
In the prior art, there are multiple reinforcement ribs or welds in the equivalent test pieces of titanium alloy shells, resulting in high processing costs and material costs and increasing processing difficulty.
The finite element method is used to calculate the outer surface stress component of the reinforcement ribs or welds on the original shell. After equal proportion reduction, the excess reinforcement ribs or welds are removed, only one reinforcement ribs or welds are retained, and the length of the test shell is adjusted so that the relative error of the stress component under the target sea-deep hydrostatic pressure is <2%.
The low-cost and efficient processing of equivalent test parts of titanium alloy shells is achieved, which reduces the processing difficulty, and reduces the outer surface stress component at the reinforcement ribs and welds, which can replace the original shell for deep-sea stress corrosion research.
Smart Images
Figure CN119880547A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of material testing, and in particular to a design method for a deep-sea stress corrosion equivalent test piece for a titanium alloy shell structure. Background Art
[0002] Titanium alloys' low density, high strength, and excellent corrosion resistance make them a promising material for deep-sea equipment. However, due to factors such as the environmental media and pressure during deep-sea service, stress corrosion remains a significant threat to the safety of deep-sea titanium alloy structures.
[0003] Currently, there is no simple and effective equivalent test piece design and research method for stress corrosion research in large titanium alloy pressure-resistant structures. In particular, the presence of internal reinforcement ribs and welds in large titanium alloy shells increases the difficulty of stress corrosion research.
[0004] When fabricating equivalent test pieces, the common method is to directly scale down the titanium alloy shell structure. However, large titanium alloy shell structures typically have multiple ribs and / or welds along their length. In scaled-down titanium alloy shells, adjacent ribs or welds are too close together, resulting in densely packed ribs and welds. This increases both the processing and material costs of the equivalent test shell and the difficulty of fabricating smaller equivalent test shells. Summary of the Invention
[0005] The purpose of the present invention is to provide a design method for a deep-sea stress corrosion equivalent test piece of a titanium alloy shell structure, so as to solve the technical problems in the prior art that the titanium alloy shell equivalent test piece has multiple reinforcing ribs or welds, high processing cost and material cost, and high processing difficulty.
[0006] To solve the above technical problems, the present invention provides a method for designing a deep-sea stress corrosion equivalent test piece for a titanium alloy shell structure, comprising the following steps:
[0007] The finite element method is used to calculate the magnitude of the stress components on the outer surface of the original shell at the locations where the ribs or welds are installed under the net water pressure at the target sea depth;
[0008] The original shell is scaled down to obtain a test shell;
[0009] Remove any excess ribs or welds from the test shell, leaving only one rib or weld in the test shell;
[0010] The length of the test shell is adjusted so that the relative errors of the stress components on the outer surface of the ribs or welds on the test shell and the stress components on the outer surface of the ribs or welds on the original shell under the same target sea depth and hydrostatic pressure are less than 2%, thereby obtaining an equivalent test shell.
[0011] As a preferred embodiment of the present invention, an iterative method is used to adjust the length of the test shell. After each adjustment of the length of the test shell, a finite element method is used to calculate the magnitude of each stress component on the outer surface of the ribs or welds on the test shell under the net water pressure at the target sea depth.
[0012] If the relative errors of the stress components on the outer surface of the ribs or welds on the test shell under the same target sea depth and hydrostatic pressure are greater than 2% compared with the stress components on the outer surface of the ribs or welds on the original shell, continue to adjust until the error is less than 2%.
[0013] As a preferred solution of the present invention, the test shell consists of a central cylindrical portion and hemispherical portions at both ends, and the initial length of the cylindrical portion of the test shell is twice the distance between two adjacent reinforcing ribs after the original shell (1) is proportionally reduced.
[0014] Compared with the prior art, the present invention has the following beneficial effects:
[0015] The present invention is based on the research demand on the influence of deep-sea stress corrosion on the ribs and weld positions of titanium alloy shells. For the original shell provided with multiple ribs and / or welds, after the original shell is proportionally reduced to obtain a test shell, only one rib or one weld in the test shell is retained, and then the length of the test shell is adjusted so that the relative error of the stress components on the outer surface of the ribs or welds of the test shell under the same target sea depth hydrostatic pressure and the stress components on the ribs or welds of the original shell are less than 2%, thereby obtaining the final equivalent test piece.
[0016] This test shell not only restores the magnitude of each stress component on the outer surface at the reinforcing ribs and welds, and can replace the original shell for deep-sea stress corrosion research, but also sets a rib or a weld on the test shell, which not only greatly reduces the processing cost and material cost of the equivalent test piece, but also greatly reduces the processing difficulty for small-sized equivalent test pieces. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the present invention, a brief introduction to the embodiments or the present invention will be given below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can, without inventive effort, derive other embodiments from the provided drawings.
[0018] Figure 1 This is a schematic structural diagram of an original shell provided with multiple reinforcing ribs in an embodiment of the present invention;
[0019] Figure 2This is a schematic structural diagram of an equivalent test shell provided with only one reinforcing rib in an embodiment of the present invention;
[0020] Figure 3 The figure shows a comparison between the stress components on the outer surface of the reinforced portion of the equivalent test shell in an embodiment of the present invention and the stress components at the same position of the original shell. DETAILED DESCRIPTION
[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.
[0022] The present invention specifically provides a method for designing a deep-sea stress corrosion equivalent test piece for a titanium alloy shell structure, comprising the following steps:
[0023] The finite element method is used to calculate the magnitude of each stress component on the outer surface of the original shell 1 where the reinforcement ribs 2 or welds are provided under the target sea depth net water pressure;
[0024] The original shell 1 is scaled down to obtain a test shell;
[0025] Remove the redundant reinforcement ribs 2 or welds in the test shell, leaving only one reinforcement rib 2 or one weld in the test shell;
[0026] The length of the test shell is adjusted so that the relative errors of the stress components on the outer surface of the ribs 2 or welds on the test shell and the stress components on the outer surface of the ribs 2 or welds on the original shell 1 under the same target sea depth and hydrostatic pressure are less than 2%, thereby obtaining an equivalent test shell 3.
[0027] When making the equivalent test shell 3, the general method is to directly reduce the titanium alloy shell structure proportionally. However, a large titanium alloy shell structure is generally provided with multiple reinforcing ribs 2 and / or multiple welds inside. The distance between adjacent reinforcing ribs 2 or adjacent welds in the proportionally reduced titanium alloy shell is too close, and the reinforcing ribs 2 and welds are densely distributed. On the one hand, it increases the processing cost and material cost of the equivalent test shell 3, and on the other hand, it increases the difficulty of processing the small-sized equivalent test shell 3.
[0028] The present invention is based on the research demand on the influence of deep-sea stress corrosion on the ribs 2 and weld positions of titanium alloy shells. For an original shell 1 provided with multiple ribs 2 and / or welds, after the original shell 1 is proportionally reduced to obtain a test shell, only one rib 2 or one weld in the test shell is retained, and then the length of the test shell is adjusted so that the relative errors of the stress components of the ribs 2 or welds of the test shell and the stress components of the ribs 2 or welds of the original shell 1 under the same target sea depth hydrostatic pressure are less than 2%, thereby obtaining an equivalent test shell 3.
[0029] The equivalent test shell 3 not only restores the magnitude of each stress component on the outer surface of the reinforcing rib 2 and the weld, and can replace the original shell 1 for deep-sea stress corrosion research, but also has a rib or a weld set on the equivalent test shell 3, which not only greatly reduces the processing cost and material cost of the equivalent test shell 3, but also greatly reduces the processing difficulty for the small-sized equivalent test shell 3.
[0030] Furthermore, an iterative method is used to adjust the length of the test shell. After each adjustment of the length of the test shell, the finite element method is used to calculate the magnitude of each stress component on the outer surface of the stiffener 2 or the weld on the test shell under the net water pressure at the target sea depth;
[0031] If the relative errors of the stress components of the outer surface of the stiffener 2 or weld on the test shell and the stress components of the outer surface of the stiffener 2 or weld on the original shell 1 under the same target sea depth and hydrostatic pressure are both greater than 2%, continue to adjust until the error is less than 2%.
[0032] Furthermore, the initial length of the cylindrical portion of the test shell is twice the distance between two adjacent reinforcing ribs after the original shell 1 is proportionally reduced, and the length of the test shell is iteratively adjusted.
[0033] The following provides a specific embodiment of making a test shell:
[0034] design Figure 1 The stress corrosion equivalent test piece of the original shell 1 at the outer surface of the reinforcement at a sea depth equivalent to 10 MPa hydrostatic pressure is shown.
[0035] First, the finite element method is used to Figure 1 The stress of the original structure shown is analyzed under a hydrostatic pressure of 10 MPa, and the magnitudes of the stress components on the outer surface of the reinforced portion of the original shell 1 and along the thickness direction are obtained.
[0036] Then, based on Figure 1The structural features of the original shell 1 shown in the figure are as follows: the original shell 1 is scaled down in proportion, and the redundant reinforcement ribs 2 are removed, leaving only one reinforcement rib 2. By adjusting the length of the cylindrical shell portion of the reduced original shell 1, the stress components of the outer surface of the reinforcement at the 10MPa hydrostatic pressure are Figure 1 The relative error of the stress component corresponding to the reinforcement of the original shell 1 is less than 2%, and the equivalent test shell 3 is obtained as shown in Figure 2 shown.
[0037] like Figure 3 The finite element analysis results show that the stress components of the outer surface of the reinforcement of the equivalent test shell 3 are Figure 1 The magnitudes of the stress components corresponding to the original shell 1 are almost the same, and the relative errors are all less than 1%.
[0038] The above embodiments are merely exemplary embodiments of the present application and are not intended to limit the scope of the present application. The scope of protection of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and scope of protection of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the present application.
Claims
1. A design method for a deep-sea stress corrosion equivalent test piece of a titanium alloy shell structure, characterized in that: The following steps are involved: The finite element method is used to calculate the magnitude of each stress component of the outer surface of the original shell (1) where the reinforcing ribs (2) or the welds are provided under the net water pressure at the target sea depth; The original shell (1) is scaled down to obtain a test shell; Removing redundant reinforcing ribs (2) or welds in the test shell, and retaining only one reinforcing rib (2) or one weld in the test shell; The length of the test shell is adjusted so that the relative errors of the stress components of the outer surface of the reinforcing ribs (2) or the welds on the test shell and the stress components of the outer surface of the reinforcing ribs (2) or the welds on the original shell (1) under the same target sea depth hydrostatic pressure are less than 2%, thereby obtaining an equivalent test shell (3).
2. The design method of a deep-sea stress corrosion equivalent test piece of a titanium alloy shell structure according to claim 1 is characterized in that: The length of the test shell is adjusted using an iterative method, and after each adjustment of the length of the test shell, the stress components of the outer surface of the stiffener (2) or the weld on the test shell under the net water pressure at the target sea depth are calculated using a finite element method; If the relative errors of the stress components of the outer surface of the reinforcing rib (2) or the weld on the test shell under the same target sea depth hydrostatic pressure and the stress components of the outer surface of the reinforcing rib (2) or the weld on the original shell (1) are both greater than 2%, continue to adjust until the error is less than 2%.
3. The design method of a deep-sea stress corrosion equivalent test piece of a titanium alloy shell structure according to claim 2 is characterized in that: The test shell is composed of a cylindrical part in the middle and hemispherical parts at both ends. The initial length of the cylindrical part of the test shell is twice the distance between two adjacent reinforcing ribs after the original shell (1) is proportionally reduced.