2. Compression, Bending, Torsion and Multiaxial Testing

In this chapter we consider the compression, bending, torsion and multiaxial testing of materials. Compression is a fundamental test as it is tension. The initial portions of stress–strain curves in compression for most materials have the same characteristics as in tension. Various material properties such as modulus of elasticity, elastic and proportional limit, yield stress may be defined from the initial portion of the stress–strain curve in compression. Many materials, even though they have the same elastic behavior in tension and in compression, their post-yield and failure characteristics in compression are quite different than in tension. We present the specimen types and the stress–strain curves in compression, and we compare the material behavior in compression to that in tension. Also, we present the bending and torsion tests and a series of tests for the multiaxial characterization of materials. They include biaxial tension tests, biaxial tension/compression strip tests, tube tests, spherical vessel tests, combined tension/compression–torsion ring tests, combined tension/compression–torsion tube tests, combined tension/compression–torsion–internal pressure tube tests. Finally, we present failure envelopes under multiaxial loading for isotropic, anisotropic and uneven materials.