Design of Circular Composite Cylinders for Optimal Natural Frequencies.

Gokhan Serhat

doi:10.3390/ma14123203

Abstract

This study concerns optimizing the eigenfrequencies of circular cylindrical laminates. The stiffness properties are described by lamination parameters to avoid potential solution dependency on the initial assumptions of the laminate configurations. In the lamination parameter plane, novel response contours are obtained for the first and second natural frequencies as well as their difference. The influence of cylinder length, radius, thickness, and boundary conditions on the responses is investigated. The lamination parameters yielding the maximum response values are determined, and the first two mode shapes are shown for the optimum points. The results demonstrate that the maximum fundamental frequency points of the laminated cylinders mostly lie at the inner lamination parameter domain, unlike the singly curved composite panels. In addition, the second eigenfrequency shows a nonconvex response surface containing multiple local maxima for several cases. Moreover, the frequency difference contours appear as highly irregular, which is unconventional for free vibration responses.

Highlights

Laminated composite materials are extensively used in the construction, aerospace, automotive, and marine industries
The maximum fundamental frequency points occurred at the interior region of the lamination parameter domain, requiring layer angles of multiple absolute values in the stacking sequence retrieval
This finding demonstrates that the stiffness tailoring required to obtain optimal dynamic properties can be remarkably different for cylindrical shells compared to singly curved panels, which have been reported to possess maxima on the boundary of the feasible domain [19,20]

Summary

Introduction

Laminated composite materials are extensively used in the construction, aerospace, automotive, and marine industries. In addition to their high stiffness-to-weight ratio, such materials offer the possibility of tailoring the stiffness properties for specific applications. One particular group of laminated structures comprises cylinders, which are commonly utilized as the shells of aircraft and satellites. These structures are frequently designed to provide optimal natural frequencies to prevent resonances under expected dynamic operating conditions. In this context, the fundamental natural frequency has been prevalently selected as the design objective to be maximized. Miller and Ziemiański [5]

Methods

Results

Conclusion