Size effects in the torsion of microscale copper wires: Experiment and analysis

Size effects in thin coarse-grained gold microwires under tensile and torsional loading

“…The overall phenomenological finding is quite similar to the findings by Fleck et al [6] and Liu et al [27]. According to Fleck et al [6], the hardening behavior of the wires under torsional loading is affected by both statistically stored dislocations (SSDs) and GNDs.…”

“…Both tensile and torsion experiments were performed at room temperature with an self-developed test apparatus based on a small table-top testing machine (Zwick, type Z2.5) [27]. The measuring principle to determine torsion moments is schematically illustrated in Fig.…”

“…They observed significant size effects in torsion, whereas only slight size effects were found in tension. The influence of grain size was considered in these investigations but was not quantitatively discussed [27].…”

Deformation patterns in cross-sections of twisted bamboo-structured Au microwires

“…In this context, the size effect in hardening results from the fact that, for a given maximum strain, the strain gradient and thus the density of GNDs must be higher for smaller sample sizes. In order to investigate this so called extrinsic size effect and to create well defined stress and strain states with and without strain gradients, several setups for tension and torsion experiments on metallic microwires have been established [10][11][12][13][14]. Given by limitations of current manufacturing techniques, long metallic wires are naturally polycrystalline.…”

A Uni-Axial Nano-Displacement Micro-Tensile Test of Individual Constituents from Bulk Material

“…Among the existing methods of micro-mechanical testing, static tests like micro-bending tests [8,9] and micro-torsion [10] as well as micro-and nanoindentation [11,12] are often used. However, for these tests, the local stress state (in the gauge section) is hard to obtain due to the interaction of the (highly) inhomogeneous loading state with the microstructure which is also inhomogeneous at the same length scale.…”