Dynamic Finite Element simulation of Ultrasonic Consolidation

Ultrasonic Consolidation (UC) is a promising solid state rapid manufacturing process that provides the ability to create functional, multilayered, and often geometrically complex parts. This thesis seeks to address one of the primary obstacles faced when using the process, namely the apparent build height limit encountered when using UC to construct high aspect ratio specimens. A fully transient, three dimensional Finite Element model is created to study the dynamic behavior of an ultrasonically consolidated part during the UC process. The model is used to find the cause of bond failure at the build height limit and a potential way to mitigate this problem. Natural frequencies are found to be excited in the build specimens in proximity to the apparent build height limit which are believed to be causing bond failure. Experimental work is conducted to compare with results of the numerical model. The FE model predicts that support materials may alleviate the build height limitation by supplementing the lateral stiffness of the build specimens. Experimental verification of these simulations demonstrates the importance of the thermal expansion properties of any candidate support materials.