| Material constitutive properties, which describe the mechanical behavior of a material under loading, are vital to the design and implementation of engineering materials. For homogeneous materials, the standard process for determining these properties is the tensile test, which is used to measure the material stress-strain response. However, a majority of the applications for engineering materials involve the use of heterogeneous materials and structures (i.e. alloys, welded components) that exhibit heterogeneity on a global or local level. Regardless of the scale of heterogeneity, the overall response of the material or structure is dependent on the response of each of the constituents. Therefore, in order to produce materials and structures that perform in the best possible manner, the properties of the constituents that make up the heterogeneous material must be thoroughly examined.; When materials exhibit heterogeneity on a local level, such as in alloys or particle/matrix composites, they are often treated as statistically homogeneous and the resulting “effective” properties may be determined through homogenization techniques. In the case of globally heterogeneous materials, such as weldments, the standard tensile test provides the global response but no information on what is occurring locally within the different constituents. This information is necessary to improve the material processing as well as the end product.; The present work is concerned with the determination of local material constitutive properties of structures that are heterogeneous on a global scale using a technique employing standard tensile testing procedures and digital image correlation (DIC). In particular, the study is focused on friction stir welds (FSW) in aluminum alloy 2024 and the determination of the material properties associated with the heterogeneous structure. The experimentally determined local constitutive data is verified by 2-D and 3-D finite element simulations of the global and local mechanical response of the friction stir weld. |
