Vibration and thermoelastic analysis of SMA embedded composite panels

Abstract

External shell panels of hypersonic aerospace vehicles are subjected to high temperatures due to aerodynamic heating. The aerodynamic loads can also cause dynamic instabilities such as flutter. Therefore, a layered shell structure with improved thermal and vibration characteristic is always desirable. Use of smart materials such as Shape Memory Alloys (SMAs) can enhance the structure’s strength through their recovery stress. SMAs have a unique ability to recover large strains under thermal loads. If constrained, pre-strained SMA wires develop large tensile stresses. These stresses are added into the stiffness and thus the structure’s stiffness can be enhanced. Shape Memory Alloy Hybrid Composite (SMAHC) shell panels can have improved stiffness which enhances its thermal and vibration characteristics. In the present study, vibration and thermal analyses with various volume fractions of SMAs have been performed and the effect of SMA recovery stress on the panel’s vibration and thermoelastic characteristics has been demonstrated. The panel’s stiffness is significantly increased due to the presence of recovery stress. In addition to the vibration analyses, thermoelastic analyses have been performed aimed at determining the critical reference temperature of a SMAHC shell panel. The critical reference temperature can be used as a reference temperature for modeling postbuckling response of cylindrical and conical panels. The finite element formulation is based on layerwise displacement theory. The layerwise theory approximates the in-plane displacements more accurately compared to single-layer theories. The need for refined theories increases to account for physically layered structures such as composites. The linear strain displacement relations have been used in the numerical formulation for conical shells. The critical reference temperature has been found from two methods; Variation in Natural Frequency of the structure and an iterative eigenvalue scheme. ...