Influence of manufacturing defects on mechanical behaviors of lattice structures fabricated by metal additive manufacturing

Lattice structures are among intricate geometries that can be fabricated by an additive manufacturing (AM) process. Due to its high strength-to-weight ratio, the lattice structures are wildly used in many industries including automotive, aerospace, and medical. Nevertheless, additively made metal lattice structures contain several types of manufacturing defects which could lead to undesirable mechanical properties and short service life. Besides, the components are likely to fail an industrial standard due to defects. Therefore, to develop a better understanding of how defects can affect the mechanical properties of AM lattice structures, the present study aims to examine various defect types which could happen during the fabrication process. The selective laser melting (SLM), one of the processing techniques for additive manufacturing, and titanium alloy (Ti-6Al-4V) are chosen in the present study. As lattice structures are comprised of struts with various sizes and orientation, various additively manufactured struts will be made. Struts will have building angles varied from 0 to 90 degrees and diameter varied from 0.3 - 2.0 mm. These struts conditions are made because they are commonly found in many lattice geometries. In addition to the defect examination, mechanical properties under tensile loading will be carried out. Subsequently, the FE model will be developed based on experimental data to advance our understanding of how manufacturing defects can severely affect mechanical responses. Mechanical properties of struts with and without defects will be investigated and compared. Upon the completion of this project, we hope to gain a better insight into the role of defects found in AM samples so that the solution can be proposed. As a result, AM parts can be made with better quality, and mechanical properties can be optimized.