Figure 4.

Mechanical properties of model B as a function of the applied compressive strain in the $z-$direction. a) Normalized strain in the $x-$ direction versus normalized strain in $z-$direction. b) Tangent Poisson's ratio ${\nu }_{\mathrm{zx}}$ versus normalized strain in the $z-$direction. c) Normalized stress versus normalized strain in the $z-$direction. d) Tangent Young's modulus versus normalized strain in the $z-$direction. e) Experimental compression deformation process. The scale bar is 100 µm. f) Numerical simulation by finite element analysis of the deformation process of model B in the $x,y$ plane. g–i) Theoretical variations of the equivalent Poisson's ratio, equivalent Young's modulus, and ${\theta }_h^{\prime }$, ${\theta }_v^{\prime }$ in the range $[{15}^{\circ }-{30}^{\circ }]$ for ${\theta }_h={\theta }_v$. ${\theta }_h^{\prime }$ and ${\theta }_v^{\prime }$ represent the values of ${\theta }_h$ and ${\theta }_v$ after deformation. Other parameters are fixed as $a=60$ µm, $t=6$ µm, $E=4.5\mathrm{GPa}$. Note that the upper and lower limits of the gray areas correspond to the cases of $t=5.5$ and $t=6.5$ µm, respectively.