DIC technology-based automobile thin plate FLC curve determination device and method

Abstract

The invention discloses a DIC technology-based automobile thin plate FLC curve determination device and method. The device comprises a material tester, a video camera, a computer and a bulging tester. The bulging tester comprises an upper base, a female die, a blank holder, a lower base and a puncher pin. The upper base is fixed to an installation platform of the material tester, the female die is connected to the lower surface of the upper base, the blank holder is installed on the upper surface of the lower base, the lower base is fixed to a lifting platform of the material tester and the puncher pin is installed on a hydraulic cylinder. The method comprises tightly clamping a test sample between the female die and the blank holder by the lifting platform, punching the test sample to produce cracks by the puncher pin under the action of the hydraulic cylinder, shooting a test sample mesh deformation process by the video camera, computing a limiting strain value by the computer through DIC software, changing the test sample until all limiting strain values of all the samples are obtained, and drawing a FLC curve of an automobile thin plate by connection of all the limiting strain value points. The device and method are convenient for operation, save time and labor, greatly improve a measurement precision and are convenient for observation and research of necking phenomenon.

Description

technical field [0001] The invention belongs to the field of automobile plate formability inspection, and in particular relates to a DIC technology-based FLC curve measuring device and a measuring method for an automobile thin plate. Background technique [0002] FLC curve (Forming Limited Curve, forming limit curve) is the most intuitive and effective method to evaluate the formability of sheet metal, and it is widely used in stamping forming of automobile sheet. Theoretical research on FLC curve is of great significance for revealing the cause of actual effect, law of actual effect and accurate solution to engineering problems in the process of sheet metal forming. [0003] The experimental, theoretical and numerical analysis of the FLC curve has been a hot topic of research by many scholars at home and abroad. After extensive methodological studies, the way of obtaining FLC curves by the bulging test method was accepted. During the bulging experiment, in order to obtain...

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Problems solved by technology

[0004] The traditional grid method (CGA technology) or digital image correlation technology (DIC technology) can only measure the strain value of the deformed specimen after the end of the experiment, and cannot monitor the experimental process (the necking of the specimen to rupture). Specific tracking, so the accuracy of the experimental data is low; due to the influence of light and the surface quality of the steel plate, it is often necessary to repeat the test, wasting a lot of manpower and material resources

At the same time, because the experience and methods of experimental work vary from person to person, this method also has certain errors in the measurement accuracy and accuracy of strain values, and the experimental cost is relatively high.

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