Theoretical & Experimental Shape Optimization Of Cantilever Beam by Constrained Optimization Method

The term structural optimization is commonly used for the optimization of engineering structures, such as building, automobile, or airplane structures for improved strength, stiffness properties, fatigue life and reduced weight or cost. Main purpose of this study is to find a practical and proven method to reduce the weight of cantilever beam by using constrained optimization method with respect to desired stress levels. Thus, reducing the weight of components which are similar material and geometry used such as heavy commercial vehicle wheels ventilation holes shows that this approach will be applicable. Additionally, due to reducing weight of heavy commercial vehicle wheels fuel efficiency and cooling performance of brake/hub system increased, if only if desired stress levels are provided. Constrained optimization method is used to ensure that stress levels remain within acceptable limits while optimizing the weight of the cantilever beam. This study conducted in two stages. Firstly, constrained optimization problem is simulated in Altair Hypermesh which is well known computer aided engineering program in literature and industry. Design variable is the hole shape on the cantilever beam. This hole shape constrained to grow or shrink only one planar plane and as a principal stress is restricted 75MPa or less under 9,81N vertical force. On second stage optimized cantilever beam design which is obtained by simulation result is produced. A strain rosette is applied on optimized hole shape critical point. Strain values are measured under same load conditions which are as same as simulation loads. Strain rosette values are converted to principal stress for comparison to simulation results. In this way optimization results are verified by experimental application. Initial design principal stress simulation result is calculated 132,3MPa where this result reduced to 74,6MPa after optimization study. Experimental principal stress measurements are observed 70,2MPa which is around %6 lower than simulation results. And design variable hole weight reduction is observed 11,2gr to 4,7gr which is 2,38 times lighter. Achieved results leads to cost saving on components. Beside cost saving, constrained optimization method may mitigate heavy commercial wheels weight as a first benefit. Due to weight reduction, inertial resistances will decrease and this effect leads to increase fuel efficiency. Additionally, heavy commercial truck vehicle brake/hub systems cooling performance will be positively affected.