The following is an excerpt from an Algor, Inc. white paper. For the full paper, see www.algor.com. Event simulation, as an engineering methodology, is vastly different from the techniques that have been taught to engineers since the onset of formal engineering training begun by the Greek mathematician Archimedes around 200 BC. Event simulation is engineering by simulating a physical event in a virtual laboratory. To perform an engineering analysis using event simulation requires a different viewpoint from that of a classical stress analysis.
According to the conventional view, stress is a function of force, or = f(force), and that the deformation, or displacement, is another function of force, or d = g(force). In virtual engineering, however, the design force is usually indeterminate and results from some type of action or motion. In this scenario, force and stress are functions of displacement or deformation; that is force = f(d) and = g(d). The deformation or displacement is calculated directly from the governing physics equations.
There are three commonly used methods to estimate force values for input into classical FEA: experience, rigid body dynamic analysis, and physical experimentation.
Some engineers rely on prior experience with similar problems as means by which to estimate these forces. Usually these engineers rely on safety factors, hoping that they are sufficient to prevent failure, yet not overly conservative so as to produce an over-designed part.
Rigid body dynamics programs calculate motion-generated forces using a model of the part. In order to arrive at numerical values for these forces, such programs use vaguely defined stiffnesses. Because these programs are limited by the rigid-body assumption, using these stiffnesses to calculate forces cannot be reliable.
Performing an experiment on a prototype of the part is an accurate means by which to obtain these forces. But, such an approach completely defeats the economic savings of using computer analysis.
Event simulation allows one to model an entire physical event with the least number of assumptions. Specifically, one does not have to assume a static situation or have to estimate values for forces that result from motion. Furthermore, event simulation has the useful byproduct of generating a "frame-by-frame" record of the event, not just a "snap-shot" at its conclusion.