Visualising the loads that a structure can tolerate provides a key insight into the structural design process, especially for materials and structures that are governed by complex failure criteria. This paper proposes a general method for efficient construction of performance envelopes in load space, and demonstrates the approach with two examples. The performance envelope identifies all possible failure modes, all the redundant and non-redundant structural constraints, and the limiting failure mode in a particular direction in load space. Once the envelope has been constructed, the structural reserve factors can be calculated extremely quickly. In design such envelopes are most useful for structural analysis processes which involve a very large number of load cases, and where the cost of constructing an envelope for a given feature is relatively modest.

In the paper, the influence of shape memory alloy (SMA) by varying the parameters such as volume fraction, orientation, and temperature on the hybrid-SMA composite laminate subjected to low-velocity impact is studied. A theoretical model for the composite laminated plate bonded with SMA reinforced layers is presented. The constitutive relation of the SMA layer is obtained by using the method of micromechanics. The governing relations obtained can be used for theoretical predications of thermomechanical properties of SMA plies in this paper. The analytical expressions for the hybrid SMA composite plate are derived based on Tanaka's constitutive equation and linear phase transformation kinetics presented by Liang and Rogers.

The laminated plate theory, first-order shear deformation theory and minimal potential energy principle is utilized to solve the governing equations of the hybrid composite plate and calculate the absorbed energies including tensile, shear and bending.

An orthogonal array and analysis of variance is employed to investigate the influence of the mentioned parameters on the energy absorption of the hybrid laminated plate. The results showed that the effects of the phase transformation temperature are more significant than the effects of the volume fraction and orientation of SMA on structural energy absorption.

The effect of shape memory alloy (SMA) on the postbuckling behavior of rectangular cross-ply and angle-ply plates by varying the SMA fiber spacing was investigated using the Finite Element Method. The formulation of the location-dependent linear, nonlinear stiffness matrices due to non-homogeneous material properties and the temperature-dependent recovery stress stiffness matrix were derived. Numerical results show that the increase of SMA fiber volume fraction and prestrain may generate more recovery stress, and increase the stiffness of SMA reinforced composite laminate. Therefore, the postbuckling deflections of the plate may be decreased significantly. The buckling mode that plate will buckle into is dependent on the fiber orientation of the angle-ply laminates. When the SMA fibers are concentrated in the center of the plate, the postbuckling deflections of the plate will be decreased considerably.

For most composite structures, because of the uncertainty in some design variables, it is not possible to predict precisely the stresses during design stage. Therefore, monitoring the structural responses in service becomes crucial for structure with concerns, e.g., the composite panels on an airplane, etc. In this study, the strains at neighboring points of the interested location on surfaces of the laminate, along with the classical laminate theory and the higher-order shear deformation theory, are used to predict the interlaminar shear stresses in the cross-ply laminate. Several numerical examples using the simulated surface strains are employed to evaluate the accuracy of the proposed technique. It is found that the approach using the higher-order shear deformation theory has improved accuracy for the analysis of thick symmetric laminate over the approach using the classical laminate theory.