The Application of the Double Ligament Tensile Test in Deformation Processing

Abstract

The foundation of the double ligament tensile test for determining mechanical properties of wrought as well as cast materials has been established. With the aid of the finite element stress analysis the design geometry of the double ligament specimen has been improved and correction factors for three design geometries have been calculated. Tensile properties of two low-carbon, very low-alloy steel plate materials and a high-strength wrought aluminum alloy have been determined by the double ligament tensile test. The corrected yield strength values and percent elongation data compare favorably with those obtained by conventional test methods where geometry considerations allow the sampling of full-size test bars. The test bar size is such that random sampling of multiple specimens (8) is quite permissible and desirable to determine representative tensile properties of a material. The test has been found to be particularly suitable in evaluating tensile properties in the short transverse direction of wrought plate and across cross sections of complex-shaped forgings or castings less than 1 in. (2.5 cm) in thickness.