where θ 0 is the initial angle of the platelet ( Figure S6 , Supporting Information ) . By comparing the predictions of this geometrical model with the experimental data , we find that the theoretical analysis slightly overestimates the absolute θ values but captures   reasonably well the dependence of the platelet angle on the applied global strain . A more detailed analysis of the platelet angle as a function of the imposed strain can be obtained by performing finite element simulations of the platelet - laden composite ( Figure 3B and Movie S4 , Supporting Information ) . To enable a direct comparison with the experimental observations , a composite containing platelets aligned out - of - plane was first strained along the direction that was mechanically loaded in the experiment ( x axis ) . Top and side views of the platelets at an applied strain of 100 % show a good qualitative agreement between the simulations and the experimental microscopy images ( Figure 3A , B ) . With the help of these simulations , we also studied the response of the platelets when the global strain is applied parallel to the alignment plane ( y axis ) . Our simulations indicate that this loading configuration does not lead to any significant rotation of the platelets , which explains the anisotropic nature of the strain - induced color change ( Figures 2E and 4A ) . A quantitative comparison between simulations and experiments for composites loaded along the color - changing direction reveals that the finite element analysis correctly captures the experimentally observed trend between the platelet angle and the applied strains .