This presentation was made at the NAFEMS European Conference on Simulation-Based Optimisation held on the 15th of October in London.

Optimisation has become a key ingredient in many engineering disciplines and has experienced rapid growth in recent years due to innovations in optimisation algorithms and techniques, coupled with developments in computer hardware and software capabilities. The growing popularity of optimisation in engineering applications is driven by ever-increasing competition pressure, where optimised products and processes can offer improved performance and cost-effectiveness which would not be possible using traditional design approaches. However, there are still many hurdles to be overcome before optimisation is used routinely for engineering applications.

The NAFEMS European Conference on Simulation-Based Optimisation brings together practitioners and academics from all relevant disciplines to share their knowledge and experience, and discuss problems and challenges, in order to facilitate further improvements in optimisation techniques.

Resource Abstract

Simulation driven design has become a must in all industries dealing with product design and development. Weight reduction is one of the most significant goals in the transportation industry, thus topology optimization is applied as an essential tool in product design. With well-defined objectives and constraints, a weight reduced, and properly utilized structure layout can be obtained by topology optimization.



The railway industry is a follower, conservative industry. Thus, the generally applied product design cycle is a conventional one, in which the major role of simulation is product evaluation at the end of the design process, thus the required input data (e.g. geometry, material, boundary conditions, etc.) for these simulations are well-detailed. Optimization can be performed in 3 different phases in our practice.



If the design is in the final stage of readiness and only small details can be changed, parameter optimizations are widely used. The main challenge of these optimization tasks is the appropriate determination of ranges of optimized parameters. It is important to note that the time required for simulation-based parameter optimization is comparable to the time required for an experienced design engineer to perform manual or intuitive design optimization.

In case of optimization at redesigning phase of an existing part based on conventional FEA given results is performed, a lot of manual iterations are needed from both design and simulation engineers, which also involves the need for close cooperation.



In contrast the topology optimization in early design phase has the greatest potential for weight reduction. However, many challenges must be overcome to be able to perform it successfully. The main issues related to determining the design space, loads, objective functions and manufacturing and other constraints.



Together with the number of required simulation tasks to be performed, the complexity of simulations is rapidly increasing, as well. Detailed models are analyzed, which contain all kinds of nonlinearities (geometric, material and contact nonlinearity). These nonlinear finite element analyses require significant computational capacity. On one hand, the complex nonlinear models must be simplified to perform topology optimization efficiently in an industrial environment and on the other hand, these simplified models must represent the physics of interest as realistic as possible to have plausible results. The other challenges in topology optimization are related to stress constraint optimization, application of nonlinear models and optimization for fatigue strength.



The aim of the presentation is to show the first steps of the application of topology optimization in the early design phase at Knorr-Bremse Rail Systems Budapest division via case studies of casted parts.