Jakub Korta

Multi - material design optimization of a bus body structure

In the recent years the safety and eco-friendliness have gained much of attention of the automotive stakeholders. These two characteristics are especially important in the case of mass transportation vehicles, such as buses or coaches, which are in continues use for long periods of time, covering significant distances. In such situations, the economical aspects play major role for the transportation companies which try to minimize operational costs of their fleet, by choosing vehicles with reduced fuel consumption. In order to obtain improvements in all the mentioned areas and hence to strengthen their position on the market, bus manufacturers have recently turned their attention to multimaterial design strategies. Structures built in that manner consist not only of regular steel parts, but contain also a mix of components made from various lightweight materials like aluminum alloys or composites, which allow for significant reduction in vehicle curb weight. However, due to the differences in mechanical characteristics which are especially evident in the case of laminates, the material substitution is not a straightforward task. In order to find the material distribution pattern that meets all the requirements, a great number of prototypic numerical models must be prepared and tested. To ease the search for the final solution, optimization techniques can be applied into the design process, allowing for automatic design modifications and assessment of the obtained results. The paper presents an attempt of enhancing the operational characteristics of a bus body structure with simultaneous reduction in the structural weight. In order to find the optimal component configuration, a multimaterial optimization was employed and supplemented by sensitivity and robustness analyses. Such a technique helps to discriminate the over-optimized solutions that are often pointed out as the most desirable by the optimization algorithms which neglect the uncertainties of the analysed system.

Application of multibody simulation for semitrailer optimization

This paper presents an approach of optimization of a truck semitrailer suspension system, with utilization of multibody model; its purpose was to find the best values of operational parameters: stiffness and damping factors, in order to minimize the disadvantageous influence of force distribution in the high risk areas, where preceding strength analysis has pointed out dangerous load values. The model contains elements of two different types: flexible and rigid bodies, in purpose of increasing the accuracy level of conducted numerical calculations. A number of simulations with different parameters and under different load cases have been carried out, combined with a parametric and structural sensitivity analysis, what has enabled an estimation of individual factors influencing particular forces that have been the objectives of optimization procedure. The stiffness and damping coefficients of the construction suspension system have been adjusted by applying metamodeling techniques. Basing on the chosen design of experiment results, this procedure allows for an approximation of the behaviour of the analysed construction in the whole design space. In this process, two different approaches have been used: Kriging and polynomial regression, and both have been compared to the simulations results. Finally, using a desirability function, the most optimal solution has been found.

Simulation and optimization of heavy-duty semitrailer dynamic model/Symulacja i optymalizacja dynamicznego modelu naczepy pojazdów transportu ciężkiego

Abstract This paper presents an optimization of a multibody truck semitrailer model; its purpose was to find the best values of suspension parameters in order to minimize the disadvantageous influence of force distribution in the high risk areas. A number of simulations with different parameters and under different load cases have been carried out, combined with a parametric and structural sensitivity analysis, and in this way individual factors influencing particular forces have been estimated. The stiffness and damping coefficients of the construction suspension system have been adjusted by applying metamodeling techniques, using two different approaches: Kriging and polynomial regression. Finally, using a desirability function, the most optimal solution has been found. Streszczenie Artykuł przedstawia proces optymalizacji systemu zawieszenia wirtualnego modelu dynamicznego naczepy samochodowej, przeznaczonej dla pojazdów transportu ciężkiego. Celem podjętych prób było znalezienie wartości charakteryzujących odpowiedź układu na wymuszenia dynamiczne, minimalizujących ich niekorzystny wpływ na punkty konstrukcyjne, będące narażone na nadmierne obciążenia. Przeprowadzono szereg symulacji numerycznych, w oparciu o wyniki których określono wrażliwość systemu na zmieniające się parametry konstrukcyjne oraz użytkowe. Optymalne wartości współczynników tłumienia oraz sztywności badanego systemu obliczono z wykorzystaniem konwersji zagadnienia na monokryterialny problem decyzyjny, w oparciu o skonstruowane dwiema metodami (tj. Kriging i regresją wielomianową) powierzchnie odpowiedzi.