USNCCM 15: US National Congress on Computational Mechanics
Prof. Ahmad R. Najafi presented at the USNCCM15: US National Congress on Computational Mechanics, July 28-August 1, Austin, Tx.
Title:
Hybrid Topology/Shape Optimization of Microvascular Composite using an Analytic Sensitivity Analysis over a Stationary Mesh
Authors:
Reza Pejman, Marcus H.Y. Tan, Sherif H. Aboubakr, William H. Martin, Jason F. Patrick, Ahmad Raeisi Najafi
Abstract:
We present a gradient-based topology/shape optimization of microvascular composites over a stationary mesh using the Interface-enriched Generalized Finite Element Method (IGFEM). The emphasis of this presentation is placed on the novel scheme which simultaneously can perform the topological change as well as the shape optimization of microvascular composites. We previously developed a fully analytical sensitivity analysis of the shape optimization of microvascular composites in IGFEM framework over a fixed mesh. The developed analytical sensitivity analysis circumvents the problems frequently observed in finite differences and semi-analytical sensitivity approaches. In the current study, we present a new feature which enables the optimizer to appear/disappear the microchannels and change the topology of the network during the optimization process. This task has been carried out by introducing a new set of design parameters which act analogous to the penalization factor of Solid Isotropic Material with Penalization (SIMP) method. The analytical sensitivity of the newly introduced design parameters has been developed and their accuracy is verified against the finite difference method.
Reduced-order thermal and hydraulic models are implemented in this analysis. Using these simplified thermal and hydraulic models result in a significant reduction in the computational cost. Furthermore, the produced network configurations are suitable for large-scale manufacturing without the essence of post-processing because the microchannel boundaries are precisely represented in the proposed model.
The method has been validated by experiment and three sets of application problems have been solved to demonstrate the benefits of using the suggested hybrid topology/shape optimization scheme rather than using only the shape optimization method for microvascular materials. In the first set of examples, we have shown that in contrast to the shape optimization scheme the design space in the topology/shape optimization method is not locked down to the topology of the initial configuration. The second set of problems represent the ability of the topology/shape optimization method to handle strict constraints. Finally, the third set of examples have illustrated how topological changes and network branching can lead to vascular redundancy, which is of great importance in designing microvascular cooling networks for blockage tolerance.