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FASTAR is an interactive graphics post processor to MSC NASTRAN created to do modal animation, structural modifications, frequency response and sensitivity analysis using either analytical results obtained from solutions 63, 67 or 71 of MSC NASTRAN or modal data obtained from experimental measurements. In addition, complex modes may be computed in FASTAR using the modal viscous damping matrix from solution 71 of NASTRAN and a state space formulation. Further viscous damping modifications may be made to the structure with the possibility of creating critically damped modes. For each complex mode, FASTAR identifies the amount of damping present. Correlation of analytical and experimental modal data may be made visually using a split screen display. In addition, a modal assurance criterion (i. e. MAC) may be computed for each pair of analytical and experimental modes by finding nodal coordinate matches and ignoring rotational degrees of freedom.

In the initial design stages of a vehicle, one desires to analyze and improve the response of the vehicle when sitting at idle or when travelling down various roads. One can perform such analyses and improvements to an FEM model using NASTRAN. However, a faster and easier method has been developed into a postprocessor to NASTRAN called FASTAR. Initially FASTAR was created to supplement NASTRAN by providing interactive graphics modal animation, structural modifications, and sinusoidal frequency response using a reduced modal space. With greater emphasis on vehicle analysis, FASTAR has been modified to process much more complicated loads generated by engines and road profiles. To simplify user input, engine data and road data have been integrated into two comprehensive data bases. As a result, one can now very easily choose in FASTAR specific engines and quickly compute the engine induced vehicle response.

Crashworthiness programs to simulate frontal impact of a full vehicle structure into a rigid barrier can require 20 to 30 CPU hours on a single processor of a CRAY X-MP. Any techniques which significantly diminish that time enable engineers to produce economical crash simulations which can, in turn, reduce the necessary physical crashes which often can cost between $50,000 and $750,000 per test on a prototype vehicle. The focus of this paper is on a technique which can improve the vectorization of crashworthiness codes and thereby cut the CPU time for full car crash simulations as well as for structural subassembly problems. The technique involves sorting shell and solid elements by rearranging them by material properties first into separate sets and then by rearranging each material set into subsets of disconnected elements. By so doing, certain Fortran DO loops which dominate CPU activity can be vectorized and thus speed up code execution.

In the analysis of automotive structures using finite element models, areas of stress concentration are often uncovered. The calculated linear stress at these locations may exceed the yield strength of the material. In these situations, the analyst is confronted with the choice of making a nonlinear analysis of the structure or using an approximate technique to predict nonlinear strains. The former can be excessively expensive while the latter can lead to results of questionable accuracy. This paper will discuss a technique which substantially reduces the cost of the nonlinear analysis of complex structures with areas of localized plasticity. The basis of the technique is the substructuring of the localized plasticity areas. They are identified and disconnected from the linear elastic part of the model by boundary points.