Design for laser powder bed additive manufacturing of AlSi12 periodic mesoscale lattice structures

Abstract

The advances in additive manufacturing (AM) over the past decades have enabled the manufacturing of increasingly complex parts which were previously difficult or infeasible to be fabricated using traditional formative or subtractive manufacturing processes. Various configurations of periodic lattice structures are now designed and fabricated via AM in virtue of the advantages they provide such as weight reduction, high energy absorption, and superior stiffness-to-weight ratio. Such functional and mechanical properties can be tuned to meet the application requirements by varying the unit cell type, unit cell size, and volume fraction. Exploring the achievable volume fraction ranges of different lattice structure configurations and precise control of the volume fraction of AM fabricated lattice structures will significantly enlarge the scope of the application, which are the main objectives of the present study. A simple strategy is developed for periodic mesoscale lattice structures fabricated via laser-powder bed fusion (L-PBF) process to quantify the manufacturable volume fraction ranges and the relationship between designed and fabricated volume fractions. Firstly, the relationship between the lattice design parameters (unit cell type, unit cell size, and strut diameter) and designed volume fraction was formulated. Next, the theoretically achievable volume fraction ranges of lattice structures were calculated. The lattice coupons of specific designed volume fractions within the previously obtained ranges were built and the fabricated volume fractions were measured. A multiple linear regression model was set up to determine correlation factors between designed and fabricated volume fractions based on the available data and the model accuracy was validated. In the current work, AlSi12 was utilized as a model material system to demonstrate the applicability of the proposed framework. It is worth mentioning that this framework is applicable to other material systems. Based on the case study results on AlSi12, insights were developed to aid the design and manufacturing processes of periodic mesoscale lattice structures in general for fabrication by L-PBF.