Method for measuring large deformation flow stress curve of metal plate

Abstract

The invention discloses a method for measuring a large deformation flow stress curve of a metal plate in the field of metal plate volume forming engineering, which comprises the following steps: taking the metal plate, and performing initial stretching test to acquire a real stress-strain curve; acquiring an equivalent strain interval of a subsequent rolling process; diving the equivalent strain interval into n equal parts to acquire the thickness of the plate after each theoretical rolling; taking n blocks of the metal plate, and cold-rolling and machining each block of the metal plate according to the thickness of the plate after theoretical rolling to acquire n actual thickness and then acquire each actual rolling equivalent strain; performing re-stretching test for the cold-rolled n metal plate blocks to acquire n subsequent flow stresses and n subsequent real strains; and further acquiring n data points to acquire the large deformation flow stress curve of the metal plate. The method of the invention can provide accurate material performance parameters for the numerical simulation in a plate volume forming process, and provide basis for engineering personnel to select an extrapolation model.

Description

technical field [0001] The invention relates to a measuring method in the technical field of measurement, in particular to a measuring method for a large deformation flow stress curve of a metal sheet. Background technique [0002] In the field of medium and thick plate forming, as an important metal precision forming technology, sheet metal volume forming has become an important forming method. It is a typical local large deformation process, and the traditional trial and error method is often used for process and mold design. Such methods are time-consuming and laborious, and cannot adapt to the requirements of high-speed, high-efficiency, and large-scale production in today's society. The emergence of numerical simulation technology fundamentally solves this contradiction. As a computer-aided engineering method, the material flow stress curve is one of the important basis for numerical simulation. However, for medium and thick plate materials, the traditional method of...

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Problems solved by technology

However, for medium and thick plate materials, the traditional method of testing the flow stress curve of the material has the following disadvantages: the local necking phenomenon occurs earlier in the tensile test process, resulting in the measured flow stress range and the actual flow of the sheet metal volume forming. The stress range is quite different

[0003] When the measured large-deformation flow stress curve cannot be obtained, engineers often use mathematical models to extrapolate the flow stress curve beyond the range for numerical simulation, but there are many models to choose from and irregular. Models such as Ludwik, Ghosh, Voce, Hockett-Sherby, Swift, etc., even if there is a large gap in the flow stress values ​​of large deformation materials estimated for the same material

Therefore, once the extrapolation model is improperly selected, the numerical simulation cannot accurately describe the actual forming process and its phenomena

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