ADMISSIBLE MODELING ERRORS OR MODELING SIMPLIFICATIONS

Discovering modeling errors on large finite element models is complex and can often go unnoticed, particularly once good ''correlation'' is achieved. The signs of trouble and/or inaccuracies need to be recogniz ed and, at the very least, the effects of system simplifications on a model's accuracy need to be known. One danger in using simplified mode ls occurs when the models, which have been correlated to test results, are used for predictive work. When predictive work begins, it is extr emely difficult to determine if model ''simplifications'' have a small or large influence on the predictions. Fortunately, there are things that can be done to help recognize potential trouble. Similar to the e xamples shown in this paper, a library of small test models should be created in order to evaluate modeling techniques and code features. Th e evaluation should include determining limitations of the techniques and features that may cause modeling errors when applied to larger sys tems. This is analogous to the design process itself, where components must first be designed and thoroughly tested and understood before th ey can be reliably used in larger systems. (C) 1998 Elsevier Science B .V. All rights reserved.