Structure-Property Relationship in Metals

Structure-topology-property relationship in additively manufactured lattice structures

This project aims at understanding and quantifying the correlation between the microstructure and topology on the mechanical behavior and failure mode of additively manufactured (AM) metallic lattice structures (LS), or AMLS. Development of AMLS leads to wide ranging benefits such as fulfilling the need of having a range of physical and mechanical properties in one part such as high stiffness in conjunction with very low specific weight, or high permeability combined with high thermal conductivity (e.g., thermal insulation), which are not readily available in traditional solids. However, and more specific to small-scale LS, the significant role of microstructure on mechanical behavior of AMLS is overlooked and is markedly absent in the literature.

The results from this project can be used to guide design and manufacturing of AMLS on how the hierarchical macro-structure i.e. topology—and microstructure can be leveraged, using AM techniques, to allow for building of complex topologies with controlled mechanical properties. Qualitative effect of lattice structure topology on failure and mechanical properties are demonstrated in the figure. Therefore, the main objective of this research is to establish a correlation between the microstructure of the constituent struts in AMLS and their deformation and failure mode through a a combined experimental and analytical study.

Specific tasks to fulfill the objectives are:

• Performing struts level characterization that includes measuring porosity size and distribution, grain size and orientation, and tension and compression of the building struts
• Identifying deformation and failure mechanisms of AMLS such as unit cell buckling, node fracturing, macroscopic shear, etc the onset of yielding, which ultimately leads to a specific failure mode
• Correlating and quantifying the contribution of topology vs. microstructure to the above mentioned mechanisms through model development that is informed with information from struts level experiments
• Validating model results with global macroscopic level experimental data