دانلود رایگان مقاله روش بهینه سازی فیبر جدید بر اساس تابع توزیع نرمال با تغییر پیوسته مسیر فیبر

Abstract

Tailoring fiber orientation has been a very interesting approach to improve the efficiency of composite structures. For the discrete angle selection approach, previous methods use formulations that requires many variables, increasing the computational cost, and they cannot guarantee total fiber convergence (which is the selection of only one candidate angle). This paper proposes a novel fiber orientation optimization method based on the optimized selection of discrete angles, commonly used to avoid the multiple local minima problem found in fiber orientation optimization methods that consider the fiber angle as the design variable. The proposed method uses the normal distribution function as the angle selection function, which requires only one variable to select the optimized angle among any number of discrete candidate angles. By adjusting a parameter in the normal distribution function, total fiber convergence can be achieved. In addition, a usual problem in fiber angle optimization methods is that because fibers can be arbitrarily oriented, structural problems may exist at the intersection of discontinuous fiber paths. Besides, composite manufacturing technologies, such as Advanced Fiber Placement (AFP), produce better results when fiber paths are continuous. These problems can be avoided by considering continuously varying fiber paths. In the proposed method, fiber continuity is also achieved by using a spatial filter, which improves the fiber path and avoids structural problems. Numerical examples are presented to illustrate the proposed method.

8. Concluding remarks

A novel method for optimizing fiber orientation has been proposed, which is based on elemental individual fibers that can assume arbitrary angles. It is also based on the discrete material optimization (DMO) method to find the appropriate angle for each element. The proposed method, called NDFO (Normal Distribution Fiber Optimization) uses the generic form of the normal distribution function to select only one discrete angle among any number of candidate angles. By applying the continuation method to the parameter ph, total fiber convergence is achieved. Additionally, fiber continuity is achieved by including a spatial filter, such as the filter proposed in this work, where the level of fiber continuity can be controlled by the size of the filter radius. Numerical examples have shown that the proposed method has obtained better results than previous methods based on elemental fibers, considering the final configuration of fibers and the value of compliance. With fiber continuity, the fibers are disposed in a more organized way, improving the manufacturability of the solution. However, the compliance is greater than the solutions without the filter. Even though, some results with fiber continuity are still better than the solution from previous methods. Because the solution of the proposed method is element-based, there is still need for post-processing of the fiber paths before manufacturing process. Thus, additional investigations are needed in order to reduce the gap between numerical results and manufacturing.