A New Paradigm for the Design of Safety Critical Castings

Recent developments in a NIST sponsored program on Design, Non-Destructive Evaluation and the Manufacturing Sciences (being conducted at Iowa State and Northwestern Universities) have led to the realization of a new paradigm for the design of safety critical components made by metal casting. The paradigm is based on the simultaneous integration of design for casting, design for fatigue performance and design for inspection. In a concurrent environment, foundry process simulation is used to predict an array of porosity related defects in the subject casting. The probability of detection of these defects is investigated with a radiographic inspection simulation tool (XRSIM). The likelihood that the predicted array of defects will lead to a failure is determined by a fatigue crack growth simulation. When properly utilized, this kind of system gives visibility to casting manufacturing, performance, and inspectability issues during the earliest stages of product definition. This paper will first give a brief review of the physics engines used in each of the computer simulation tools. Experimental validation of these simulation tools with controlled castings will then be discussed. Finally, the preliminary results of applying this design paradigm to a permanent mold, cast aluminum motor mount will be presented.