Ultrasonic stress measurement in thin-walled structures via shear wave birefringence

Stress measurement in thin-walled structures has attracted considerable engineering interest for use in structures with high sensitivity to loads or in safety-critical applications. Ultrasonic stress measurement offers broad material applicability, rapid acquisition, and low cost, enabling in-situ residual-stress evaluation of thin-walled components. However, systematic studies on such structures remain limited. In this work, we analyze shear-wave birefringence, as an acoustoelastic-based method to quantify stresses in thin plates. A quantitative model relating multi-echo acoustic anisotropy to stress has been established, and a dedicated ultrasonic stress-measurement system for thin plates has been implemented. Experimental results show that the birefringence approach is insensitive to propagation distance and is well suited to thin-plate applications, with average measurement error within 5% when fifth echo are employed. The method has been further validated on a U-shaped thin-walled specimen, where ultrasonic results align with those coming from X-ray diffraction. Our findings confirm the practicability of the proposed technique and underscore its potential impact on stress evaluation in thin-walled structures.