Implementing a structural continuity constraint and a halting method for the topology optimization of energy absorbers

Abstract

This study investigates topology optimization of energy absorbing structures in which material damage is accounted for in the optimization process. The optimization objective is to design the lightest structures that are able to absorb the required mechanical energy. A structural continuity constraint check is introduced that is able to detect when no feasible load path remains in the finite element model, usually as a result of large scale fracture. This assures that designs do not fail when loaded under the conditions prescribed in the design requirements. This continuity constraint check is automated and requires no intervention from the analyst once the optimization process is initiated. Consequently, the optimization algorithm proceeds towards evolving an energy absorbing structure with the minimum structural mass that is not susceptible to global structural failure. A method is also introduced to determine when the optimization process should halt. The method identifies when the optimization method has plateaued and is no longer likely to provide improved designs if continued for further iterations. This provides the designer with a rational method to determine the necessary time to run the optimization and avoid wasting computational resources on unnecessary iterations. A case study is presented to demonstrate the use of this method.

Topology optimization incorporating a passageway for powder removal in designs for additive manufacturing

“…For models with uniform cross-section requirements, a grouping operation method developed by Stojanov et al (2016Stojanov et al ( , 2017 is applied to make sure the BESO design has a (9)…”

A General Meta-graph Strategy for Shape Evolution under Mechanical Stress

“…Graphs Representations Used with ESO Stojanov et al (2016) use graphs to represent of FEA meshes, so that each graph vertex represents an FEA element. In this work, graphs are used to check the connectivity of the generated structures.…”

“…In these two papers (Stojanov et al 2016;Munk et al 2017), graph representations have been mainly used to find valid (or nonvalid) configurations of FEA meshes while using ESO algorithms and when a nonvalid configuration is found, this branch of the optimization process is not taken into account. Additionally, graphs abstractions are not integrated to the material removal process.…”

Axisymmetric structural optimization design and void control for selective laser melting

“…This constraint is determined indirectly. The procedure and its integration into the framework of the BESO method is available in the literature (Stojanov et al 2016). …”

“…A further constraint was that the energy absorbing structure needed to successfully absorb the energy from the applied load without mechanical failure. This was addressed in previous work (Stojanov et al 2016) in which a structural continuity constraint controlled to the volume ratio to ensure sufficient structural mass was present to absorb the energy from the load.…”