Multiscale Simulation Methodology for  Part Qualification of Additive Manufacturing (AM) Parts

The presentation elaborates on a new method of validation and verification of parts produced by laser powder bed fusion using a multiscale analysis approach. Recent advances in Additive Manufacturing (AM)create the potential for manufacturing novel shapes, lightweighting with lattice geometries and monolithic components from consolidated assemblies. Such designs not only lead to more efficient designs, but they may also bring process efficiencies with reduced component inventories and more flexible and responsive production. However, a complex multifunctional, and monolithic design brings new challenges to product verification and quality control. Processes such as laser powder bed fusion use granular stock material for the manufacturing process. The resulting part may have porosity as a result of suboptimal processing conditions. In this scenario, the fitness of the part for field deployment requires the determination of the extent of the porosity and its location. Once the extent and the location of porosity are detected, we need a method to quantify the effect of the porosity on the performance and the effect on the product life. We show a multiscale analysis approach using the Gurson material model to capture the effect of porosity on the part strength. The demonstration utilizes a gyroid-based monolithic heat exchanger design that replaces a traditional heat exchanger assembly with more than 40 components. Several scenarios of varying porosity are presented as potential use cases in a production line environment. The robustness of the part is analyzed with the finite element method for an individual production build. This simulation-based verification method may be utilized with input data from CT scans or similar image-based methods that have recently gained traction in verifying AM part production. Alternatively, the methodology can use microscale simulations of the AM process at the level of the melt pool to predict part density throughout the manufacturing process. Subsequently, a Finite Element simulation of the part for field conditions will account for the effect of porosity specific to that build. Such a simulation is an effective tool for the prediction of part fitness and part life. The methodology illustrated in this presentation may be extended to other manufacturing techniques using powder materials, such as hot-isostatic pressing (HIP).