Significance and Use
5.1 Deformation and damage under biaxial loading conditions can be significantly different from that typically observed under uniaxial loading conditions. In particular, cyclic hardening in fatigue tests depends upon biaxial loading ratio (λ(σ) or λ(ɛ)) and biaxial phase angle (φ). As a result, fatigue, crack growth, and fracture data generated under uniaxial conditions may not be appropriate for predicting material behavior under biaxial loading conditions. Biaxial deformation and fatigue behaviors of metallic materials are typically investigated with either tubular or planar cruciform-type specimens. ISO technical report (ISO TR/12112) contains a summary of principles and designs of different types of specimens and test equipment used in multiaxial fatigue testing. Practice E2207 provides details for performing strain-controlled axial-torsional fatigue testing with thin-walled tubular specimens. It is not possible to achieve all combinations of biaxial load or strain ratios under combined axial-torsional loading only without using internal and/or external pressurization of the tubular specimens. Moreover, material form available (bars or rods versus plates or sheets) and specific structural applications require evaluation of the material behavior under biaxial loading conditions with planar specimens. In particular, this guide provides relevant details on the following for testing planar cruciform-type specimens:
5.2 Evaluation of material’s deformation, fatigue and crack growth behavior under various biaxial loading conditions.
5.3 Generation of biaxial test data at ambient and elevated temperatures, which can be useful for designing engineering components subjected to similar loading conditions and for estimating fatigue crack initiation or crack growth lives of such components.
Scope
1.1 The purpose of this standard is to serve as a guide for testing and characterization of homogeneous metallic materials using cruciform type specimens subjected to in-plane biaxial loading conditions at isothermal, ambient or elevated temperatures. Test conditions covered by this standard guide include biaxial deformation and strength (under combined tension/compression), fatigue crack initiation and fatigue crack growth under cyclic, biaxial loading conditions.
1.2 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
