Discussion on the HAZ Softening Effect on the Impact Responses of Welded Aluminum Structures

This paper investigates the impact responses of welded AA6061-T6 aluminum structures with quasi-static manner, and emphasis is put on the HAZ softening effect on the damage characteristics of welded aluminum plates. Different weld number and impact position are designed for aluminum specimens, and impact responses and damage shapes of different specimens are analyzed. Material tests are carried out to provide mechanical properties for materials surrounding the weld, which provides reliable mechanical input for numerical simulations. On this basis, finite element simulations of impact tests are performed, and detailed modeling of materials in the vicinity of the weld is considered, including base metal, HAZ and weld zones. Meanwhile, some common modeling methods for HAZ softening zones are employed in numerical modelling, including the methods based on the tensile tests and empirical rule. By comparison of experimental and numerical results, the reliability of three different modelling techniques under different impact cases is discussed in detail. Results indicate that the numerical model considering the detailed modeling of the softening zone can yield a reliable estimation of the impact force responses as well as the damage shapes. For other empirical methods, damage characteristics cannot be accurately captured due to homogenized material properties in the softening zone, especially when structures experience complex deformation process.