Hygrothermal effects in composites: Influence of geometry and determination of transverse coefficient of thermal expansion

Abstract

This work evaluates the influence of geometric properties, the length-to-width ratio, named Aspect Ratio, on curvatures in [θ − 90/θ]T carbon/epoxy composite laminates at room temperature due to thermal residual stresses. A new method to determine experimentally thermal residual curvatures in composites laminates by defining small-length increments on the surface of deformed plate has been exposed. [–454/454]T was considered to obtain a simple analytical expression of twisting curvature. A new way to determine transverse coefficient of thermal expansion α2 is proposed in squared laminates based on experimental values of twisting curvatures of [–454/454]T laminates.

Design and Analysis of Multi-Patch Composite Plates for a High Multi-Stability of a Morphing Skin

“…Also, Moore et al [48] presented the effects of mechanical properties especially the thermal expansion coefficients on cured shape of laminates and also tested a sample winglet for application of bi-stable structure. Cantera et al [49] studied the influence of geometric properties on curvatures for [θ-90/θ]T family laminates using a new method to experimentally determine thermal residual curvatures by finding small-length that arises on the surface. The analytical expression of twisting curvature is obtained for [-454/454]T laminates.…”

Hygroscopic influence on bistable characteristics of antisymmetric composite cylindrical shells: An experimental study

“…1, 2 are the moisture expansion coefficients in the longitudinal and transverse of the material, respectively. Zhang et al 19 studied the residual thermal strains and twisting curvatures change caused by thermal expansion coefficient when the cylindrical shell was exposed to high temperature and determined the thermal expansion coefficient of cylindrical shell by using the method proposed by Cantera et al 42 ð3Þ where 1 * , 2 * are the equivalent longitudinal and transverse thermal expansion coefficients, respectively. This simulation technique is divided into three steps: 1The temperature is applied on the shell by the option of predefined field, leading to the temperature of the shell reaching to the needed level.…”

Modelling and testing of the snap-through process of bi-stable cross-ply composites

“…The laminate was air cool-down and it curled into a cylindrical shape. The thermal [6] and mechanical properties of T6T/F593 [39] are given in Table 1. The stress free temperature for the material used was determined to be 145°C [6] and therefore the temperature change DT is À120°C.…”

“…The thermal [6] and mechanical properties of T6T/F593 [39] are given in Table 1. The stress free temperature for the material used was determined to be 145°C [6] and therefore the temperature change DT is À120°C. After manufacturing, the laminates were cut with a diamond saw to obtain squared laminates of side-length L. Before testing, in order to avoid humidity absorption, they were kept in an oven at 120°C during 72 h.…”

“…In snap-through the specimen is forced to snap from the first to the second equilibrium shape and in snap-back the specimen snaps from the second to the first equilibrium shape. In multi-stability of laminates, the geometry [6] and the negative influence of moisture effects should be taken into account [7][8][9]. The study of loss of bifurcation has been widely addressed in [9,10].…”