A standard experimental method for determining the material length scale based on modified couple stress theory

A standard experimental method for determining the intrinsic material length scale of modified couple stress theory is proposed based on a non-contact laser Doppler vibration measurement system. The first-order resonant frequencies of two different cantilever microbeams made of copper and titanium with thickness ranging from 15 to 2 mu m are measured, respectively. The elastic size effects are obviously observed from the experimental results. The length scale parameters are obtained by fitting the experiment data with the modified couple stress theory. Multiply verified by different kind of materials, we considered this method a standard and valid way for determining the material length scales of modified couple stress theory.