Hole-containing metal plate sample capable of realizing different stress states
By designing perforated metal plate specimens and controlling the stress triaxiality using deflection distance, the problem of studying the damage and fracture characteristics of plates under complex stress states in existing technologies has been solved, and controllable measurement of stress state in actual working conditions has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YANGZHOU UNIV
- Filing Date
- 2025-04-22
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies are insufficient for studying the damage and fracture characteristics of metal sheets under complex stress states in actual working conditions, especially under combined tensile and shear stress states, and there is a lack of suitable specimen designs.
A perforated metal plate specimen is designed. By setting a centrally symmetrical transverse notch and a semi-circular notch in the specimen, and providing a circular hole in the shear region, the stress triaxiality is controlled by adjusting the deflection distance d, so as to achieve controllable fracture under different stress states.
It realizes the creation of a combined shear and tension-shear stress field in a porous metal plate specimen. The structure is simple, easy to process, and suitable for macroscopic and microscopic mechanical experiments. The deflection distance has an approximately linear relationship with the stress triaxiality, which is easy to calculate.
Smart Images
Figure CN224262893U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of metal material performance testing devices, and in particular to a porous metal plate sample that can achieve different stress states. Background Technology
[0002] Metal sheets possess excellent properties and are therefore widely used in various fields, such as aerospace, marine engineering, and bioengineering. In practical applications, metal sheets are subjected to various stress states, which affect deformation and damage, ultimately leading to failure. Therefore, researching how to control stress changes in metal sheets and studying the impact of different stress states on their mechanical properties is of great practical significance for predicting fracture trajectories and preventing major safety accidents. Under load, damage to metal sheets accumulates continuously; cracks first nucleate and then propagate, eventually leading to failure. Stress triaxiality is crucial for the nucleation and growth of micropores. By designing sheets of different shapes and controlling the stress triaxiality at the fracture location, it is possible to study the damage and fracture characteristics of sheets under different stress states, providing a scientific basis for material reliability design and damage prevention.
[0003] Currently, most studies on the damage and fracture characteristics of sheet metal under different stress states use defect-free sheet metal. In actual engineering activities, the damage caused by loads on sheet metal accumulates continuously, especially defects within the strain range. The influence of stress triaxiality on the deformation and failure of materials is mainly studied through specimens such as uniaxial tension and plane shear. However, single tension or shear states are relatively rare in actual working conditions, and simple stress states lack guidance for practical engineering applications. In actual working conditions, metal sheet metal is often under complex stress states such as tension and shear combinations. It is necessary to design a sheet metal specimen that can realize different stress states within the strain range with defects to meet measurement needs. Utility Model Content
[0004] The purpose of this invention is to overcome the defects in the prior art and provide a porous metal plate sample that can achieve different stress states. By adjusting the deflection distance, the stress triaxiality of the sample fracture position can be controlled, thereby achieving material failure fracture under controllable stress state.
[0005] The purpose of this invention is achieved as follows: A perforated metal plate specimen for achieving different stress states includes a plate body. Two centrally symmetrical notches penetrating the thickness direction of the specimen are formed on opposite sides of the plate body. Each notch includes two parallel transverse notches pointing towards the center of symmetry. The ends of the two transverse notches near the center of symmetry are connected by rounded corners to two opposing convex semicircular notches. The two semicircular notches are vertically oriented. The area between the two semicircular notches is a shear region. A circular hole penetrating the plate body is provided at the center of the shear region. The transverse distance between the centers of the two semicircular notches is a deflection distance d. By adjusting the deflection distance d, the stress state of the metal plate specimen can be controlled.
[0006] When this invention is in operation, it uses a clamp to hold the plate body at both ends of two opposite short sides, and changes the lateral distance to achieve triaxial stress control at the fracture position of the plate sample, thereby controlling the stress state.
[0007] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model uses a metal plate sample without holes to create a combined stress field of pure shear and tensile shear, and then studies the stress distribution law of a metal plate sample with holes by adding defects and holes; the plate specimen structure of this utility model is simple, easy to process and manufacture, and suitable for macroscopic and microscopic mechanical experiments; the deflection distance of the tensile shear specimen of this utility model has an approximately linear relationship with the stress triaxiality, and the stress triaxiality value at the corresponding deflection angle can be calculated by linear interpolation.
[0008] Furthermore, the center of the circular hole coincides with the center of symmetry, and the intersection of the vertical center line of the plate body and the line connecting the centers of the two semi-circular notches passes through the center of symmetry.
[0009] Furthermore, the plate body is a rectangular flat plate, and the four corners at opposite ends along the length of the plate body are clamping ends for clamping the plate body.
[0010] Furthermore, the entrance of the transverse notch is a rectangular opening that cuts vertically into the long side of the board body and extends towards the center of the board body. The transverse notch is connected to the semi-circular notch by a rounded corner transition.
[0011] Furthermore, the minor radius of the fillet between the transverse notch and the semi-circular notch is 2mm, and the major radius of the fillet is 5mm.
[0012] Furthermore, the width of the lateral notch is 3mm.
[0013] Furthermore, the radius of the semi-circular notch is 2mm, and the radius of the circular hole in the shearing region is 0.5mm.
[0014] Furthermore, the sheet material has a length of 50mm, a width of 36mm, and a thickness of 1mm. The sheet material is made of 316L stainless steel with a density of 7.9g / mm³. 3 . Attached Figure Description
[0015] Figure 1 The stress triaxiality contour plot is for a metal sheet specimen without holes.
[0016] Figure 2 This is a schematic diagram of the structure of the metal sheet sample of this utility model when the lateral distance is -3mm.
[0017] Figure 3 This is a schematic diagram of the structure of the metal sheet sample of this utility model when the lateral distance is -1mm.
[0018] Figure 4 This is a schematic diagram of the structure of the metal sheet sample of this utility model when the lateral distance is 2mm.
[0019] Figure 5 This is a triaxial stress contour plot of a perforated metal sheet sample according to this invention.
[0020] In the above diagram, 1 is the first sheet body, 101 is the first clamping end, 102 is the first transverse notch, 103 is the first semi-circular notch, 104 is the first shearing area, and 105 is the first round hole; 2 is the second sheet body, 201 is the second clamping end, 202 is the second transverse notch, 203 is the second semi-circular notch, 204 is the second shearing area, and 205 is the second round hole; 3 is the third sheet body, 301 is the third clamping end, 302 is the third transverse notch, 303 is the third semi-circular notch, 304 is the third shearing area, and 305 is the third round hole. Detailed Implementation
[0021] Example 1:
[0022] like Figure 2As shown, a perforated metal plate specimen for achieving different stress states includes a plate body 1. Two centrally symmetrical notches penetrating the thickness direction of the specimen are formed on opposite sides of the plate body 1. The notches include two parallel transverse notches 102 pointing towards the center of symmetry. The ends of the two transverse notches 102 near the center of symmetry are connected by rounded corners to two opposing convex semicircular notches 103. The two semicircular notches 103 are vertically oriented. The area between the two semicircular notches 103 is a shear region 104. A circular hole 105 penetrating the plate body is provided at the center of the shear region 104. The transverse distance between the centers of the two semicircular notches 103 is the deflection distance d. By adjusting the deflection distance d, the stress state of the metal plate specimen can be controlled. In this embodiment, the deflection distance d is -3 mm.
[0023] The center of the circular hole 105 coincides with the center of symmetry. The intersection of the vertical center line of the plate body 1 and the line connecting the centers of the two semi-circular notches 103 passes through the center of symmetry.
[0024] The plate body 1 is a rectangular flat plate, and the four corners at opposite ends along the length of the plate body 1 are the clamping ends 101 for clamping the plate body 1.
[0025] The entrance of the horizontal notch 102 is a rectangular opening. The rectangular opening cuts vertically into the long side of the board body 1 and extends towards the center of the board body 1. The horizontal notch 102 is connected to the semi-circular notch 103 through a rounded transition.
[0026] The minor radius of the fillet between the horizontal notch 102 and the semi-circular notch 103 is 2mm, and the major radius of the fillet is 5mm.
[0027] The width of the transverse notch 102 is 3mm; the radius of the semi-circular notch 103 is 2mm; and the radius of the circular hole 105 in the shearing area 104 is 0.5mm.
[0028] Sheet body 1 is 50mm long, 36mm wide, and 1mm thick. Sheet body 1 is made of 316L stainless steel with a density of 7.9g / mm³. 3 .
[0029] Example 2:
[0030] like Figure 3As shown, a perforated metal plate specimen for achieving different stress states includes a plate body 2. Two centrally symmetrical notches penetrating the thickness direction of the specimen are formed on opposite sides of the plate body 2. Each notch includes two parallel transverse notches 202 pointing towards the center of symmetry. The ends of the two transverse notches 202 near the center of symmetry are connected by rounded corners to two opposing convex semicircular notches 203. The two semicircular notches 203 are vertically oriented. The area between the two semicircular notches 203 is a shear region 204. A circular hole 205 penetrating the plate body 205 is provided at the center of the shear region 204. The transverse distance between the centers of the two semicircular notches 203 is the deflection distance d. By adjusting the deflection distance d, the stress state of the metal plate specimen can be controlled. In this embodiment, the deflection distance d is -1 mm.
[0031] The center of the circular hole 205 coincides with the center of symmetry. The intersection of the vertical center line of the plate body 2 and the line connecting the centers of the two semi-circular notches 203 passes through the center of symmetry.
[0032] The second plate body 2 is a rectangular flat plate, and the four corners at opposite ends along the length direction of the second plate body 2 are the clamping ends 201 for clamping the second plate body 2.
[0033] The entrance of the horizontal notch 202 is a rectangular opening. The rectangular opening cuts vertically into the long side of the board body 2 and extends towards the center of the board body 2. The horizontal notch 202 is connected to the semi-circular notch 203 through a rounded transition.
[0034] The minor radius of the fillet between the horizontal notch 202 and the semi-circular notch 203 is 2mm, and the major radius of the fillet is 5mm.
[0035] The width of the second horizontal notch 202 is 3mm; the radius of the second semi-circular notch 203 is 2mm; and the radius of the second circular hole 205 in the second shearing area 204 is 0.5mm.
[0036] Plate body 2 is 50mm long, 36mm wide, and 1mm thick. It is made of 316L stainless steel with a density of 7.9g / mm³. 3 .
[0037] Example 3:
[0038] like Figure 4As shown, a perforated metal plate specimen for achieving different stress states includes a plate body 3. Two centrally symmetrical notches penetrating the thickness direction of the specimen plate are formed on opposite sides of the plate body 3. Each notch includes two parallel transverse notches 302 pointing towards the center of symmetry. The ends of the two transverse notches 302 near the center of symmetry are connected by rounded corners to two opposing convex semicircular notches 303. The two semicircular notches 303 are vertically oriented. The area between the two semicircular notches 303 is a shear region 304. A circular hole 305 penetrating the plate body 3 is provided at the center of the shear region 304. The transverse distance between the centers of the two semicircular notches 303 is the deflection distance d. By adjusting the deflection distance d, the stress state of the metal plate specimen can be controlled. In this embodiment, the deflection distance d is 2 mm.
[0039] The center of the circular hole 305 coincides with the center of symmetry. The intersection of the vertical center line of the plate body 33 and the line connecting the centers of the two semi-circular notches 303 passes through the center of symmetry.
[0040] The plate body 3 is a rectangular plate, and the four corners at opposite ends along the length of the plate body 3 are the clamping ends 301 for clamping the plate body 3.
[0041] The entrance of the horizontal notch 302 is a rectangular opening. The rectangular opening cuts vertically into the long side of the board body 3 and extends towards the center of the board body 3. The horizontal notch 302 is connected to the semi-circular notch 303 through a rounded transition.
[0042] The minor radius of the fillet between the horizontal notch 302 and the semi-circular notch 303 is 2mm, and the major radius of the fillet is 5mm.
[0043] The width of the third horizontal notch is 3mm; the radius of the third semicircular notch is 2mm; and the radius of the third circular hole in the shearing region is 0.5mm.
[0044] Plate body 3 is 50mm long, 36mm wide, and 1mm thick. It is made of 316L stainless steel with a density of 7.9g / mm³. 3 .
[0045] To understand the stress distribution law of the porous metal plate specimen of this invention, a combined stress field of pure shear and tensile-shear was first created using a non-porous metal plate specimen. The loading process of the plate specimens with and without holes was numerically simulated using ABAQUS finite element software. Then, the stress triaxiality of the shear region was extracted.
[0046] The simulation process is as follows:
[0047] (I) Constructing the Finite Element Model
[0048] The finite element model is a three-dimensional solid model, including a specimen plate with a length of 50 mm, a width of 36 mm, and a thickness of 1 mm. Eight-node reduced integral solid elements (C3D8R) are used, with a mesh size of 1 mm for the fixed and non-tensioned parts. Since the primary focus is on observing the stress distribution in the expected fracture region, the mesh for this region is refined. The mesh size is 0.2 mm in the central region of the specimen, and also 0.2 mm in the thickness direction.
[0049] (2) Material parameters and boundary conditions
[0050] The specimen plate is defined as an elastic material, specifically 316L stainless steel, with a density of 7.9 g / mm³, a Young's modulus of 16284 Pa, and a Poisson's ratio of 0.3. The boundary conditions are as follows: one end of the specimen plate is fixed, and a displacement boundary condition is applied to the other end. The forces acting on the end with the displacement boundary condition are coupled to a single point.
[0051] (3) Analysis of simulation results
[0052] Stress triaxiality is defined as the ratio of hydrostatic pressure to Mises equivalent stress:
[0053]
[0054] Where, σ m For hydrostatic pressure, σ e The stress is the Mises equivalent stress, and σ1, σ2, and σ3 are the first, second, and third principal stresses, respectively.
[0055] The stress triaxiality contour plot of a metal sheet specimen without holes is shown below. Figure 1 As shown, when the deflection distance d is 2 mm, the stress triaxiality of the sample is around 0, indicating a pure shear state; when the deflection distance d is -1 mm or -3 mm, the stress triaxiality of the sample is around 0.1 and 0.15, indicating a combined tension and shear state; a stress triaxiality value greater than 0.33 indicates a uniaxial tension state, at which point the plate is not subjected to shear stress.
[0056] The stress triaxiality contour plot of a metal plate specimen with holes is shown below. Figure 5 As shown, when the deflection distance d is 2 mm, the stress triaxiality of the sample is around 0, indicating a pure shear state; when the deflection distance d is -1 mm and -3 mm, the stress triaxiality of the sample is around 0.1 and 0.15, indicating a combined tension and shear state. The experiment revealed that the stress triaxiality distribution of the perforated metal sheet sample of this invention exhibits the same distribution pattern as that of the non-perforated metal sheet sample, proving that the perforated metal sheet of this invention can meet the measurement needs of different stress states.
[0057] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed in this utility model, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.
Claims
1. A porous metal plate specimen for achieving different stress states, comprising a plate body, characterized in that: Two centrally symmetrical notches penetrating the thickness direction of the sample plate are opened on opposite sides of the plate body. The notches include two relatively parallel transverse notches pointing towards the center of symmetry. The ends of the two transverse notches near the center of symmetry are connected by rounded corners to two opposing convex semicircular notches. The two semicircular notches are vertically arranged, and the area between the two semicircular notches is a shearing region. A circular hole penetrating the plate body is provided at the center of the shearing region. The transverse distance between the centers of the two semicircular notches is the deflection distance d. The stress state of the metal plate sample can be controlled by adjusting the deflection distance d.
2. The porous metal plate specimen according to claim 1, characterized in that: The center of the circular hole coincides with the center of symmetry, and the intersection of the vertical center line of the plate body and the line connecting the centers of the two semi-circular notches passes through the center of symmetry.
3. The porous metal plate specimen according to claim 1, characterized in that: The plate body is a rectangular flat plate, and the four corners at opposite ends along the length of the plate body are the clamping ends for holding the plate body.
4. A porous metal plate specimen according to claim 1, characterized in that: The entrance to the horizontal notch is a rectangular opening that cuts vertically into the long side of the board body and extends towards the center of the board body. The horizontal notch is connected to the semi-circular notch by a rounded corner transition.
5. A porous metal plate specimen according to claim 4, characterized in that: The minor radius of the fillet between the horizontal notch and the semi-circular notch is 2mm, and the major radius of the fillet is 5mm.
6. A porous metal plate specimen according to claim 1, characterized in that: The width of the horizontal notch is 3mm.
7. A porous metal plate specimen according to claim 1, characterized in that: The radius of the semi-circular notch is 2mm, and the radius of the circular hole in the shearing region is 0.5mm.
8. A porous metal plate specimen according to any one of claims 1 to 7, characterized in that: The sheet material is 50mm long, 36mm wide, and 1mm thick. It is made of 316L stainless steel with a density of 7.9 g / mm³. 3 .