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Direct Optimization

 In this example a direct optimization method, the Genetic Algorithm, is used instead of a metamodel-based approach to solve the optimization problem explained in Crashworthiness Optimization.

The problem is of a simplified vehicle moving at a constant velocity and crashing into a pole.

 vehicle_crash1.png vehicle_des_var2.png 
Fig. 1(a): Deformed vehicle after 50 ms Fig. 1(b): Design variables with part numbers

The problem illustrates the following features:

  • A direct simulation-based optimization (Direct Genetic Algorithm)
  • Dealing with an infeasible design formulation
  • Use of composite functions
  • Use of the LS-DYNA result interfaces

The criteria of interest are the following:

  • Head injury coefficient (HIC) of a selected point (15ms)
  • Component Mass of the structural components (bumper, front, hood and underside)
  • Intrusion computed using the relative motion of two points

Design variables:

  • The hood, front and underside (parts 3, 4 and 5 in Fig. 1(b)) are grouped under a single design variable: thood
  • The bumper (part 2 in Fig. 1(b)) is identified as another design variable: tbumper

Design Formulation

The design formulation is as follows:

  • Minimize HIC(15 ms) subject to Intrusion (50 ms) < 550 mm and mass < 0.5. The intrusion is measured as the distance between the nodes 167 and 432 (for the location of the nodes see Fig. 1).

Problem Solution

⇒ Solution with LS-OPT