MODELING OF THE THERMOMECHANICAL RESPONSE OF ACTIVE LAMINATES WITH SMA STRIPS USING THE LAYERWISE FINITE-ELEMENT METHOD

A study on the effective thermomechanical response of a composite lami nate with shape memory alloy (SMA) layers based on the implementation of the layerwise laminate theory in the finite element method is carri ed out in this paper. The SMA thermomechanical constitutive response i s based on a thermomechanical model recently developed by Boyd and Lag oudas. The numerical implementation of the constitutive model is based on a return mapping integration algorithm which is employed in studyi ng the SMA response characteristics in the composite laminate under th ermal loading. In modeling the laminate, a displacement based finite e lement approach is used in conjunction with the layerwise laminate the ory of Reddy, incorporating piecewise continuous distribution of trans verse strains through the thickness. As an illustrative example, the d eformations caused by two prestrained SMA strips placed symmetric to t he mid-plane of an elastic plate, when thermally activated are Studied . The top SMA strip starts transforming from the martensitic into the austenitic state upon actuation through resistive heating, simultaneou sly recovering the prestrain, thus causing the laminate to bend. A par ametric study investigating plane strain and generalized plane strain is carried out, and the accuracy of the results is compared with the c ommercial finite element code ABAQUS. The main feature of the presente d methodology is an accurate evaluation of actuation stresses in the S MA strips, efficiently combining the layerwise geometry with the finit e element method.