Visualizing dual-surface stress distribution of transparent soft materials by combining fluorescence imaging-based dual-surface DIC and hyperelastic constitutive modeling

Transparent soft materials are critical components in flexible electronics. The inherent material heterogeneity and complex microstructures within these devices often lead to highly non-uniform stress distributions, causing local stress concentrations that precipitate deformation and failure. However, it has so far been challenging to experimentally visualize the full-field stress distribution in transparent soft materials. To address this challenge, a practical and effective stress reconstruction method that combines fluorescence imaging-based dual-surface digital image correlation (DIC) and hyperelastic constitutive modeling is presented. By fully utilizing deformation data from both surfaces together with through-thickness deformation to determine the principal stretches required for hyperelastic stress calculation, this method enables simultaneous dual-surface stress reconstruction. To show the applicability of the proposed method, an adhesive specimen composed of transparent soft materials is prepared and subjected to tensile testing. A comparison of reconstructed dual-surface stress field results with simulated reference values demonstrates the efficacy of the proposed method. The stress reconstruction method combining fluorescence imaging-based dual-surface DIC and hyperelastic constitutive modeling provides a novel approach for evaluating and optimizing the mechanical reliability of transparent soft materials.