Design and Analysis of Laminated Composite Materials

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.