Evaluation of material damage in welded joints using reflection of a bounded ultrasonic guided wave beam

Welded-plate structures containing welded joints and parent plates are widely used in the engineering field. This paper presents a new method for assessing damage in welded joints by leveraging the reflection effect of a bounded ultrasonic guided wave (UGW) beam propagating in the parent plate. The reflection characteristics of the bounded UGW beam when it travels from the parent plate to the welded joint were initially analyzed theoretically. Subsequently, finite element (FE) simulations were conducted to assess the feasibility of using the reflection characteristics of the bounded UGW beam for material damage evaluation in the welded joint. The influence of different factors on the reflected field, including the incident angle and the extent of material damage (quantified by the reduced Young's modulus), was examined. It was observed that the defined damage index exhibited a significant correlation with the degree of material damage. To address practical engineering applications, a simulation of surface damage assessment in welded joints was conducted using a bounded UGW beam. The damage index showed a notable increase as the Young's modulus scaling factor decreased at a specific incident angle. Finally, the experimental results demonstrate that the polyvinylidene fluoride (PVDF) comb transducer can effectively excite and capture the bounded UGW beam in the parent plate, enabling the effective evaluation of surface corrosion damage in the welded joint. The significant increasing trend of the maximum amplitude and damage index with the increase of the corrosion level proves that the reflection effect of a bounded UGW beam incident from the parent plate is more sensitive and reliable for evaluating surface corrosion damage in the welded joint. This study provides a theoretical basis, FE simulation, and experimental validation of a bounded UGW beam using PVDF comb transducers for damage evaluation in welded joints, showcasing its tremendous potential for practical engineering applications.