Surrogate models of elastic responses from truss lattices for multiscale design
Channel: Charles Jekel
Date: 2021-06-21

This work proposes an optimization problem to find where your elastic surrogate models are non-positive definite.


This work was presented at the 14th World Congress of Structural and Multidisciplinary Optimization.



There is much interest in the community to generate designs which can be directly manufactured using 3D printing techniques. The design of multiscale structures has been one approach, where the structure is designed from repeated unit cells to help ensure a printable structure. Micro-architectures can include the Iso truss, Octet truss, and ORC truss which are created from different arrangements of connecting struts within a unit cell. The mechanical properties of each unit cell are dependent upon their unique micro-architecture. Thus, to design efficiently, surrogate models have been used to predict the elastic response and volume fraction for a particular strut configuration. Then density based topology optimization can be applied on the structure, where the design variables consist of the strut relative density of each cell. This work created surrogate models to predict the orthotropic response for both solid and hollow strut unit cell configurations. Previous works have not explicitly considered whether the surrogate models produced are energetically admissible when considering the elastic responses. However, this work demonstrates techniques which can be taken to ensure the surrogate model produces valid elastic responses. A novel formulation is presented in the learning phase of the surrogate model, which penalizes elastic responses that are not positive definite. In addition, a macroscopic structural optimization problem is resolved to verify the surrogate models produced positive-definite tensors on the entire design domain of possible strut geometries.


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