On the Feasibility of Using Thermal Gradients for Active Control of Interlaminar Stresses in Laminated Composites

Abstract

In this paper, a method is proposed to actively control interlaminar stresses near the free edges of laminated composites by through-thickness thermal gradients. Theoretical solutions are given for optimal steady-state through-thickness temperature distributions under uniaxial loading that are required to elmininate or reduce the interlaminar stresses below a prescribed level. The optimal solutions are obtained by minimizing appropriate performance indices that are functions of the far-field properties, with respect to the through-thickness temperature differences. In the second part, an experimental investigation is conducted on a glass/epoxy cross-ply laminate with embedded piezoelectric sensors and a thermal heater. Through the experiment, the feasiblity of the thermal control of interlaminar stresses is demonstrated.

Control of free-edge interlaminar stresses in composite laminates using piezoelectric actuators

“…Nevertheless, due to their passive nature, these techniques do not work effectively, and other required design goals may not be achievable. Kim [8] proposed a thermal control method by applying through-thickness temperature gradients. Interlaminar stresses generated by mechanical loading were significantly reduced by applying proper temperature fields to each layer.…”

The shape control of a composite beam with embedded shape memory alloy wire actuators

“…An active shape control to change the shape of a flexible structure member such as a submarine stern, aerospace control surfaces and wings needs actuators which can generate the force and/or moment. Various actuators have been used in shape control: piezoelectric materials [5][6][7], shape memory alloys [8,9], imposed thermal gradients [10] and so on. Among these, shape memory alloy (referred to as SMA hereafter) is receiving much attention as actuators for controlling the shape of structures because SMA has a distinctive shape recovery effect (referred to as SME hereafter) which can generate significant forces during shrinkage as it undergoes its unique phase transformation by temperature change.…”