Toward the development of plasticity theories for application to small- scale metal structures

Experiments are performed on micron- scale single- crystal prototypical structural eleand pure torsion. In addition, the experiments systematically reveal the strengthening size- dependence of structural elements whose surface has been passivated by a very thin Cr coating, an effect shown to have substantial strengthening potential. A state- of- the- art strain gradient plasticity theory is used to analyze the structural elements over the entire range of size and loading. While the computed trends replicate the experimental trends with reasonable fidelity, the predictive exercise, which is representative of those that will be required in micron- scale structural analysis, brings to light constitutive and computational issues which will have to be addressed before micron- scale plasticity theory can serve as effectively at the micron scale as conventional plasticity does at larger scales.

Automated summary

This study investigates the mechanical properties of micron-scale single-crystal structural elements through experiments and theoretical analysis. The experimental results show that the size-dependent strengthening of structural elements can be achieved by surface passivation. A strain gradient plasticity theory is used to analyze the structural elements, and the computed trends replicate the experimental trends with reasonable fidelity. However, the study also highlights the need to address certain constitutive and computational issues before the theory can be effectively applied at the micron scale.