Architectured material systems (AMS) are characterized by shaping or segmenting a bulk material to achieve intentional geometric features, thereby seeking to achieve material performance not available in the bulk material. It is common practice to analyze the mechanical response of AMS solely with input of the system architecture, geometry and a homogeneous representation of the bulk material properties. This approach ignores that material architectures is the result of some manufacturing process, and that residual effects from the manufacturing processes will impact the behavior of the AMS.
Here, an AMS is investigated under consideration of the actual manufacturing process. We are concerned with an AMS employing both segmentation and shaping. We study the mechanical response of flexible stainless steel tubes with a multi-layer and corrugated architecture. Such AMS are known as bellows and find application in deformable hot gas exhaust systems. The architectured tubes are created by a multi-ply hydro-forming process.
The as-formed architectured tube model leads to a predicted mechanical response and fatigue failure significantly different than a model of an architectured tube solely based on geometric consideration. The stiffness of tubes is increased by including effects from manufacturing processes. Fatigue failure becomes dependent on residual stresses from manufacturing rather than on the cyclically varying stresses induced by loading. Altering tube wall segmentation (sheet metal ply thickness) and manufacturing processes parameters on the mechanical behavior are also considered. Sheet metal thickness modulates the effective stiffness of the AMS while alterations to the manufacturing process parameters influence the corrugation geometry and the as-formed wall thickness as well as the stress/strain state.
This work is supported by TruFlex LLC through the Indiana Consortium for Simulation-based Engineering of Materials and Structures.