Non-contact forming limit diagram construction method

Abstract

The invention relates to a non-contact forming limit diagram construction method, and belongs to the technical field of metal material forming methods. According to the technical scheme, a tensile test method is adopted, the main strain and the secondary strain of a frame before material fracture are accurately obtained through the DIC technology, and a forming limit diagram of a metal material is accurately constructed. The method has the beneficial effects that in the whole test process, a main deformation part does not need to be in contact with any die, so that the problems that in a traditional forming limit test, strain at a fracture position cannot be collected, and a test result is affected by friction force when a male die is in contact with a plate are effectively solved; the forming limit diagram obtained through the method more accurately describes the comprehensive forming capacity of the metal material, and a reliable judgment basis is provided for stamping forming simulation calculation of the plate.

Description

technical field [0001] The invention relates to a method for constructing a non-contact forming limit diagram, and belongs to the technical field of metal material forming methods. Background technique [0002] The forming limit diagram is the ultimate principal strain ε when the sheet is cracked locally under different strain paths 1 and secondary strain ε 2 The formed strip-shaped area reflects the ability of sheet metal to resist necking or cracking under the action of uniaxial tension, plane and bidirectional tensile stress, and is widely used to evaluate the comprehensive forming ability of sheet metal. At present, the commonly used method to obtain the forming limit diagram is to use the movement of the rigid punch to deform the specimen to rupture, and measure the principal and secondary strains of the complete grid near the crack, rather than the strain distribution at the fracture position, resulting in low test results , at the same time, the contact sample metho...

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Problems solved by technology

At present, the commonly used method to obtain the forming limit diagram is to use the movement of the rigid punch to deform the specimen to rupture, and measure the principal and secondary strains of the complete grid near the crack, rather than the strain distribution at the fracture position, resulting in low test results , at the same time, this contact sample method between the punch and the sheet cannot avoid the influence of friction on the test results, which in turn affects the accuracy of the forming limit diagram construction

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