Abstract
The optimum geometry of a specimen used for an in-plane compression test on sheet metal was investigated by FEM. Geometrical parameters were determined to minimize the stress measurement error, i.e., the difference between the mean stress, which is calculated from the measured load and compressive strain data assuming a constant volume, and the Cauchy stress at the center of the specimen, where a strain gauge is mounted. The stress measurement error decreases with increasing aspect ratio of the gauge area, where L and W are the length and width of the gauge area, respectively. A maximum error of 1% was achieved by taking an aspect ratio 2.2. Furthermore, the effects of the radius of the fillet, R, connecting the chucking area and gauge area, and the width of the chucking area, B, on the accuracy of stress measurement were investigated. It was found that 1.6 and 1.4 minimize the stress measurement error. Moreover, the optimum geometrical parameters for successfully applying a compressive strain of over to the specimen without in-plane buckling were clarified. The chucking area should be fully covered by chucking jigs to prevent the in-plane buckling of the gauge area.
