The use of topology optimization gives us the capability to create an optimal design for a product, taking into consideration a set of predefined constraints, under certain load cases to which it is subjected. However, its results exhibiting jagged and/or no well-defined boundaries, lead into difficulties, regarding the interpretation of these results into proper CAD geometry, which subsequently could be used downstream in the CAD based product development process or could be parametrized and further optimized. Moreover, the manufacturing process, that will be followed to build the parts or the structure, adds an extra variable and increases the degree of difficulty to the task of creating adequate CAD geometry.
When performing an optimization, it is important to avoid introducing unnecessary variables that do not impact the design objectives and constraints. Such variables increase the design space size and lead to unnecessary sample evaluations, which can significantly increase the overall computation time or cost. A sensitivity analysis can be performed to quantify the significance of the variables; only the important variables are then used in the sampling and optimization, thus reducing the computational cost.
To reduce the head impact injuries in case of traffic accidents, the design of an automotive hood must consider many design requirements including impact of the head against the hood at different locations, be lightweight but with enough stiffness to resist various loads imposed on the hood, and have NVH characteristics such as the fundamental frequency. Methodologies to solve this type of design optimization problem that integrates multiple design criteria are rare to non-existent in the automotive design field. This paper shows how to conduct the worst-case design of the hood for multiple head impact locations, which is required by the pedestrian safety code. In addition, a topology optimization problem of the hood that combines statics, impact, and eigen frequency load cases is solved by using LS-TaSC to provide the optimal lightweight hood structure satisfying the design constraints. This is possibly the first demonstration of both the worst-case design and multi-disciplinary design optimization considering both impact and frequency load cases on an industrial problem.
LS-OPT Version 7.0 was released in November 2020 with several new features which are briefly summarized here:
Material models for high-performance thermoplastic polymers need to capture highly complex material characteristics accurately to enable lightweight and sustainable designs. ULTEMTM 1000 Polyetherimide Resin from SABIC’s Specialties business display different behavior under impact loading under multi-axial loading compared to uniaxial tensile testing.
Creation of 3D geometry from topology optimization results, for thin-walled and casted parts