Analysis and optimization of composite helical springs

Abstract

Composite helical springs offer a lower weight, higher resonant frequency solution compared to metal springs used today. Due to the orthotropic properties of composite, traditional spring equations and theory do not accurately predict the outputs of a composite spring. There are a series of inputs that need to be optimized for the best composite spring to be produced. These include materials, wind angle, and the geometry of the spring. By optimizing these inputs, a spring with the required stiffness and displacement to shut height using composite materials is designed. This thesis uses a high-performance titanium spring used for mountain biking as a benchmark to design a composite spring with the same travel and stiffness while reducing the weight. Finite element analysis is used as a tool to understand the failure criteria of the spring and predict the spring constant. Composite springs are analyzed and iterated over to understand the failure criteria and the design parameters are optimized to design a spring that outperforms titanium and steel springs substantially. Similar springs have been manufactured to validate the results of analysis.