Tensile behaviour and residual stress characterisation of bio-inspired laser weld joints

Inspired by principles observed in nature, bio-inspired welding patterns can be designed to emulate the load-bearing capacity and resilience of natural interlocking structures. This study introduces bio-inspired interlocking weld patterns as alternatives to traditional linear welds, aiming to modify residual stress distribution and examine the effects on static tensile properties. Quasi-static mechanical properties and residual stress of two bio-inspired patterns were assessed and compared to linear welds and base material. Neutron diffraction was used to evaluate residual stresses, while mechanical testing and Finite Element Method (FEM) were employed to evaluate the stress–strain response of the analysed materials. This model generated numerical values for the heat-affected zone (HAZ) properties, enabling the creation of an empirical relationship to predict HAZ extent based on weld geometry. Experimental validation showed strong agreement with the model, and a parametric analysis investigated how weld shape and dimensions influence the joint performance. While the study did not reveal a significant reduction in residual stress magnitudes for the studied geometric configurations, it provided valuable insights into the ways welding patterns can influence stress distribution. Tensile properties were notably affected by the bio-inspired patterns, showing a significant increase in yield strength. An interpretation of these results is also provided.