Method for constructing forming limit stress diagram of metal sheet

A technology of forming limit and sheet metal, which is used in the preparation of test samples, the use of stable tension/pressure to test the strength of materials, sampling, etc. It can solve the problem of difficulty in measuring stress, and achieve the effect of solving the difficulty of direct measurement of stress.

Inactive Publication Date: 2017-06-06
SHOUGANG CORPORATION
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[0005] The purpose of the present invention is to provide a method for constructing the limit stress diagram of shee

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  • Method for constructing forming limit stress diagram of metal sheet
  • Method for constructing forming limit stress diagram of metal sheet
  • Method for constructing forming limit stress diagram of metal sheet

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[0030] 1. Put the DP780+Z high-strength steel with a thickness of 0.9mm according to the following figure 1 , figure 2 , image 3 Dimensions shown are cut into pre-uniaxial tensile specimens according to Figure 5 Dimensions cut into pre-plane strain specimens, according to Figure 6 The dimensions are cut into pre-biaxial tensile strain specimens;

[0031] 2. Use the electrolyte corrosion method to print grids or speckles in the uniformly deformed area in the middle of the sample;

[0032] 3. Pre-strain the sample. The pre-uniaxial tension was realized by a triaxial loading test machine, and the figure 1 , figure 2 , image 3 The specimens shown were subjected to uniaxial tension with a predetermined amount of strain, and the pre-plane strain and pre-biaxial tensile strains were Figure 7 Schematic of the hemispherical rigid punch bulge test setup. The principal strain ε of the pre-strained specimen is measured by an off-line or on-line strain measurement system 1...

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Abstract

The invention discloses a method for constructing forming limit stress diagram of metal sheet, belonging to the technical field of forming metal sheets. The method comprises the following steps: printing grids or speckles on a metal sheet material by using an electrolyte corrosion method; applying prestrain to the sheet; then measuring the main strain and secondary strain of a prestrain test sample; preparing a second-stage test sample from a pre-deformed test sample by adopting a linear cutting manner, and bulging by adopting a semispherical rigid convex die, until the test sample has necking or fracture, and measuring the main strain and secondary strain of a second-stage deformation test sample; and acquiring the strain values of two stages, and acquiring the forming limit stress diagram by adopting corresponding yield criterion and conversion formula. The method has the advantages that the forming limit stress diagram of metal sheet can be rapidly and accurately obtained, and the problem that the stress is difficult to measure directly can be solved.

Description

technical field [0001] The invention belongs to the technical field of sheet metal forming, in particular to a method for constructing a limit stress diagram of sheet metal forming. Background technique [0002] In the field of sheet metal forming, the forming limit diagram (Forming Limit Diagram, FLD) is an important method to evaluate the sheet metal formability, which reflects the ultimate strain of the sheet metal when plastic instability occurs. FLD provides a basis for conveniently studying sheet forming limit and evaluating tensile instability theory. However, most of the FLD determined by experiments or theoretical derivation are obtained by linear or approximately linear strain paths. The stamping of actual sheet metal, especially in the case of more complex parts or multi-process forming, often deviates from the The linear strain path cannot be accurately judged for the instability of the sheet metal. [0003] The study found that the ultimate strain is only dete...

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Application Information

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IPC IPC(8): G01N3/08G01N1/28
CPCG01N3/08G01N1/286G01N2001/2873G01N2203/0017G01N2203/0256
Inventor 郑学斌李涛杨建炜
Owner SHOUGANG CORPORATION
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