Image Scaling Technique for Accurate Strain Distribution Measurement During Large Deformations of Composite Materials Using Sampling Moiré Method

ABSTRACT Full‐field strain measurement is a critical technique for evaluating the mechanical properties and fracture behaviour of diverse materials. Imaging methodologies based on the sampling moiré (SM) method, which employ digital camera and grating patterns, offer remarkable versatility and effectiveness in strain analysis. In this study, we propose an improved SM method incorporating an image scaling technique for comprehensive strain measurement under varying deformation conditions. The proposed method was validated through simulations and tensile tests on angle‐ply carbon fibre reinforced polymer (CFRP) laminates, effectively capturing strain distributions during large deformation events, such as necking. Key results include precise strain distribution measurements beyond 2%, identification of necking deformation within the 2.5%–17% strain range and determination of material failure above 26.4% strain. These findings demonstrate the method's effectiveness and potential for advanced strain analysis, addressing limitations of conventional SM approaches in large deformation scenarios.