Investigations of the failure mode for additive manufactured interlocked interface structure based on X-Ray CT image guided finite element analysis and experimental comparisons

Abstract

Suture-inspired interlocked interfaces in nature exhibit promising industrial application potentials for advanced mechanical structures, devices and equipment. It is of significant scientific interest for studying the pull-out response and failure mode of interlocked structure as well as internal stress variations during the loading process. In this paper, finite element analysis (FEA) simulation based on X-Ray tomographic images is proposed for understanding the effects of manufacturing defects on the performances of interlocked structures, which are of critical importance for controlling the stress evolution of the interface structure and corresponding failure modes. Firstly, X-ray micro computed tomography (micro-CT) was applied for non-destructive scanning inspection of aluminum alloy additive manufacturing samples, high spatial resolution and calculation efficiency can be realized through tomographic image guided FEA scheme for generating high fidelity simulation results. Afterwards, non-uniform rational B-splines fitting method was employed for optimizing sample boundaries harvested from CT images, which allows smooth conversion from CT pixel images to high precision fitted finite element model. The B-spine fitting model can significantly improve the computational efficiency for finite element simulation without losing calculation reliability and resolution, overcoming the inherent contradictions between efficiency and resolution of the traditional pixel image finite element method. Finally, considering the mechanical contributions and interactions of external and internal porosity defects, the failure modes of the interlocked structures were further analyzed based on the results of finite element analysis.