Determination of the microscale stress-strain curve and strain gradient effect from the micro-bend of ultra-thin beams

A simple method is established to determine the microscale uniaxial stress-strain curve from the load and deflection data for a doubly clamped beam. The method is based on the fact that, for beam deflection much larger than the beam thickness, the axial stretching dominates the deformation in the doubly clamped beam and the doubly clamped beam behaves like a simple plastic hinge. The microscale uniaxial stress-strain curve, together with the cantilever beam experiments, is used to determine the strain gradient effect in Au thin beams. By comparing with the experimental data for a cantilever Au thin beam, the parameter α was obtained as 0.246. The effect of finite rotation is accounted for, and the results agree well with the experiments for a cantilever Au thin beam subjected to large deflection.