MPI ENABLED SHAPE OPTIMIZATION OF SOLID ISOTROPIC PLATES TO MITIGATE THE EFFECTS OF AIR BLAST LOADING

Open Access
Author:
Argod, Vikas
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Ashok D Belegundu, Thesis Advisor
Keywords:
  • Blast Loading
  • Shape Optimization
  • MPI
Abstract:
This work presents a formal approach for optimizing the shape of freely supported isotropic plates to withstand air blast loading. Unique difficulties are presented in optimizing for short-duration dynamic loading, viz. transient dynamic response, monitoring of maximum plastic strain failure at every point in the panel over time, optimizers that can handle non-differentiable, non-convex and computationally expensive functions, and mesh distortion. The goal is to minimize the dynamic displacement of the plate relative to the test fixture, while monitoring plastic strain values, mass, and envelope constraints. An approach based on coupling LS-DYNA finite element software and a differential evolution (DE) optimizer is presented. Since DE involves a population of designs which are then mutated and crossed-over to yield an improved generation, it is possible to use coarse parallelization wherein a computing cluster is used to evaluate fitness of the entire population simultaneously. However, owing to highly dissimilar computing time per analysis, owing to mesh distortion and variable time step in explicit finite element analysis, implementation of the parallelization scheme is challenging. Sinusoidal basis shapes are used to obtain an optimized ‘double-bulge’ shape for a centrally located charge. The optimized shape shows vast improvement over a flat (baseline) plate of equal mass; the blast waves are smoothly deflected away and the maximum plastic strain is evenly smeared along the plate edges, indicating better utilization of material