Search Results

This paper is a discussion of topics presented by the author at the Panel Session “Evaluation of Studies on Non-Deterministic Approaches (NDA) for Complex Systems” at the 2007 SAE World Congress. The emphasis herein is on issues in conducting model based reliability assessments, by combining verification and validation (V&V) of the model with a process compatible with traditional reliability assessments conducted as part of Reliability Based Design Optimization (RBDO). Formulations are presented and simplified to isolate each of the terms in V&V, and make each term compatible with subsequent RBDO while still accommodating non-deterministic design situations. The paper concludes with overall issues regarding V&V and Reliability, and compares this combined method with some other methods in use in the community and discussed at a follow-on SAE panel in 2008.

The implementation of Verification and Validation (V&V) of a computational model of a physical system can be simply described as a 4-step process. One of the steps in the 4-step process is that of Solution Verification. Solution Verification is the process of assuring that a model approximating a physical reality with a discretized continuum (e.g. finite element) code converges in each discretized domain to a converged answer on the quantity of validation interest. The modeling reality is that often we are modeling a problem with a discretized code because it is neither smooth nor continuous spatially (e.g. contact and impact) or in relevant physics (e.g. shocks, melting, etc). The typical result is a non-monotonic convergence plot that can lead to spurious conclusions about the order of convergence, and a lack of means to estimate residual error or uncertainty.