how to design a spring using composite material

composite materials used in ansys tutorial

Abstract

Composite materials have interesting properties such as high strength to weight ratio, ease of fabrication, good electrical and thermal properties compared to metals. A laminated composite material consists of several layers of a composite mixture consisting of matrix and fibers. Each layer may have similar or dissimilar material properties with different fiber orientations under varying stacking sequence. There are many open issues relating to design of these laminated composites. Design engineer must consider several alternatives such as best stacking sequence, optimum fiber angles in each layer as well as number of layers itself based on criteria such as achieving highest natural frequency or largest buckling loads of such structure. Analysis of such composite materials starts with estimation of resultant material properties. Both classical theory and numerical methods such as finite element modeling may be employed in this line. Further, these estimated properties are to be used for computing the dynamic properties of the members made-up of these materials as equivalent isotropic members. At this level, a Graphic User Interface (GUI) device is developed with MATLAB programming to interactively create a user friendly environment for computing overall material properties using classical laminate theory. User can enter the number of layers and layer orthotropic properties and the back end program calculates the extension, bending and coupling stiffness matrices and further it estimates the overall elastic constants, Poisson ratios and density.


Introduction

The result will be displayed in the front end interface boxes. The obtained constants are validated with an ANSYS model, where the laminate stacking sequence is built and the member is subjected to a uniform strain at free end, while the reaction stress at the fixed end is predicted. The developed interface simplifies the design process to some extent. The dynamic analysis in terms of fundamental natural frequency and critical buckling load is illustrated by using these overall material constants as a later part of analysis.Composites blend two or more materials that possess very different properties. Because they combine light weight, high strength and outstanding flexibility, composites have become standard materials for manufacturing a range of products, including complex-shaped products such as boat hulls and surfboards. These composites pose many challenges for R&D teams that need to identify the appropriate formulation for a required use. To successfully engineer layered composites, you must define the optimal material formula — which depends on the number of layers involved along with the thickness and relative orientation of each layer. The challenge is to predict how well the finished product will perform under actual working conditions. This involves considering everyday stresses and deformations as well as a range of failure criteria. Not only must you predict ultimate strength and progressive damage over time, you must identify issues related to delamination, cracking and other physical mechanisms. Knowing which layers will fail first and understanding crack characteristics and other fine levels of product
analysis are crucial to successfully fulfilling your product promise.