Experimental Methods for Characterizing of Sheet Metals at High Strain Rates

Abstract

Beside tension tests and measuring of Lankford coefficients (r-values), compression tests on small cubes in the sheet plane over a wide range of strain rates are also performed using special devices. The material behavior under shear loading is measured according to Miyauchi using appropriate equipment with the application of optical measurement of speckle strain field. A biaxial tension/tension stress state can be realized in the layer compression test. Through the compression, shear and layer compression tests, large deformations are reached, which can not be measured in the tension test due to necking. These four test types are performed not only quasi-statically but also quasi-dynamically on a servo hydraulic machine and under impact loading in a drop weight machine and rotary tensile impact tester (flywheel) with a precise measurement of force and displacement to determine the strain rate dependency of the investigated materials. Extra points of the yield loci can be measured in the plane strain tension test using a specimen ratio of B/L ≥ 20.