Simple shear methodology for local structure–property relationships of sheet metals: State-of-the-art and open issues

Simple shear presents a local material structure–property relationship and plays an important role in the development of material design, mechanical modeling, and manufacturing processes for sheet metals. Simple shear tests are extensively adopted to reveal the stress-state-dependent mechanisms of material microstructure evolution with their corresponding mechanical properties, to develop sophisticated constitutive models capturing complex mechanical behaviors, and to precisely characterize the failure limits for shear-dominated or large-strain deformation processes. Thus, the simple shear methodology including specimen geometry, fixing and loading device, data acquisition and the set of procedures for results analysis, has become a topic of growing interest because of its various distinctive capacities. Over the years, several simple shear analyses and test methods have been proposed without a unified understanding. Interpreting the experimental results can be confusing due to the complexity of finite deformation, variety of boundary conditions in practice, and complexity of the mechanical behavior of materials; however, neither a widely accepted protocol nor a systematic overview of this topic exists. To fill this gap, the present study attempts to provide a comprehensive review of the simple shear methodology for sheet metals, which will serve as a reference for summarizing substantial efforts to improve the understanding and gain valuable scientific insight, a guideline to discover local structure–property relationships of materials, and a solid step for shedding light on its standardization. In this paper, the motivation for the development of a simple shear methodology is first discussed, and the recent progress in experimental mechanics and experimental technologies is summarized. Its application in understanding the mechanical behaviors (hardening, yielding, and ductile fracture) is focused on, and the structure–property relationships revealed by simple shear are further highlighted. The challenges and prospects for future research are discussed. The principles, methodologies, and perspectives provided are highly relevant and are expected to benefit emerging areas such as heterostructured materials, micro/nanoscale mechanical testing, nonlocal plasticity, and additive manufacturing (AM).