Classic exact solutions for anisotropic plates The analytical solutions available in Lekhnitskii’s Anisotropic Plates cover various applications of anisotropic beams and plates. The Stanford Composite Design Group started a project to develop a computational tool based on the solutions for nearly all cases presented in this classic book. The first version has been released as MicMac-Hole and includes sections on stress distribution in a plate with elliptic or circular openings. Arbitrary normal and shear inplane loads can be applied to the orthotropic plate with elastic inclusion. The inclusion in the openings can be either open or filled with elastic or rigid materials. Inner pressure and shear loads and rigid interferences can be applied to the holes. In addition to stress distribution around the open or filled hole, strength ratios after failure analyses are calculated and plotted in Excel worksheets. Figure 9 shows stress and failure index profiles along the circumference of a hole in a carbon/epoxy plate for different inclusions. These solutions are effective preliminary design tools for many problems involving bolted joints, hole repair and others. Fig. 6: Stress-strain curves of undamaged, damaged and repaired laminates Fig. 7: Experimental results (top) versus predictions (bottom) 3D beam analysis Beam models can be used to represent a variety of major structural members. Such members need to be analyzed to ensure the integrity of the whole structure. To this effect, an easy-to-use Excel-based design tool was developed to predict the deformation and strength of 3D composite beams: 3D-Beam. When combined with Super MicMac+, it can be used to predict a structure’s life. An example is given in Figure 8. Fig. 9: Stress and failure index profile along an opening in a quasi-isotropic composite plate; three different inclusions are considered Nanocomposites The potential for developing materials with novel properties has made nanocomposites one of the areas of greatest interest in composites research. Composite material properties are designed to Fig. 8: 3D-Beam modelling of a fuselage and wing with stringers and spars Fig. 10: Nanoscale structure Ref (INCTMN/ CMDMC) No56 April 2010 / jec composites magazine 91