Design for lightweight and superior performance in TOSCA
In the years to come, fuel efficiency and reduced emissions will be key factors in determining success within the transportation & mobility industry. Fuel economy is often directly associated with the overall weight of the vehicle. Composite materials have been widely used in the aerospace industry for many years to achieve the objectives of light weight and better performance at the same time.
The transportation & mobility industry has been following the same trends, and it is not uncommon to see the application of composites in this industry sector nowadays; however, unlike the aerospace industry, wide application of composites instead of metals is not feasible in the automotive industry. Hence, apart from material replacement, other novice methods to design and manufacture lightweight structures without compromise in performance will find greater utilization in this segment. In this blog post, I will discuss the application of TOSCA, a finite element based optimization technology.
The lightweight design optimization using virtual product development approach is a two-step process: concept design followed by improved design.
Design concept: The product development costs are mainly determined in the early concept phase. The automatic generation of optimized design proposals will reduce the number of product development cycles and the number of physical prototypes; quality is increased and development costs are significantly reduced. All you need is the definition of the maximum allowed design space – Tosca helps you to find the lightest design that fits and considers all system requirements. The technology associated with the concept design phase is called topology optimization that considers all design variables and functional constraints in optimization cycle while chasing the minimum weight objective function. The technique is iterative that often converges to a best optimal design.
HOW IT WORKS
The user starts with an initial design by defining design space, design responses, and objective function. Design space is the region from where material removal is allowed in incremental steps and objective function is often the overall weight of the component that has to be optimized. With each incremental removal of material, the performance of the component changes. Hence each increment of Tosca is followed by a finite element analysis to check existing performance against target performance. If target performance criteria is satisfied, the updated design increment is acceptable and TOSCA proceeds to the next increment. This process of incremental material removal is continued until the objective function is satisfied or no further design improvement is feasible. The image below depicts a complete CAD to CAD process flow in Tosca. The intermediate processes include TOSCA pre-processing, TOSCA and a finite element code based co-simulation and TOSCA post processing.
During the material removal process, TOSCA may be asked to perform the optimization that provides a feasible solution not only from a design perspective but from a manufacturing perspective as well. For example, TOSCA may be asked to recommend only those design variations that can be manufactured using casting and stamping processes. This is possible by defining one or more of manufacturing constraints available in TOSCA constraints library.
While the topology optimization is applicable only on solid structures, it does not mean TOSCA cannot perform optimization on sheet metal parts. The sizing optimization module of TOSCA allows users to define thickness of sheet metal parts as design variables with a lower bound and an upper bound. Even large-scale industrial applications with up to millions of design variables are optimized highly efficiently. Through consideration of multiple complex load scenarios, stiffness, and manufacturing requirements, the Tosca sizing optimization module helps to meet performance and production goals for an overall increase in eco-efficiency.
Design Improvement: Once the concept design is ready, it is sent for validation using the finite element simulation. TOSCA offers automatic validation runs for some of its supported pre-processors. The validation results may justify overall lightweight design, but there may be further scope of local improvements. For example, the validation run may reveal local stress hot spots that the user wishes to eliminate by making small changes in the vicinity of hot spots. Again, TOSCA does not leave any scope of guesswork at any level of design optimization; the shape optimization module of TOSCA can perform this local refinement very efficiently. The displacement of nodes on the surface of design space act as design variables. If material needs to be added locally to reduce stresses, these nodes move out of the surface. If material needs to be removed locally to increases stresses, these nodes move into the surface. The overall effect is the stress homogenization keeping the component weight constant.
Summary: The various modules of TOSCA optimization suite offers a full range of capabilities that allows user to define and perform light weight design optimizations tasks with ease of use. It’s fast, it’s effective, it’s open platform, it’s reliable, and it’s industry proven.
Do you have any questions for me about Tosca or any of its functionalities? Leave a comment on this post or click here to get in touch with our entire Dassault team.