Design and Testing of Composite Laminates for Optimum Extension-Twist Coupling

Abstract

A constrained optimization scheme is used to determine the stacking sequence that maximizes the extension-twist coupling in a composite laminate while maintaining its hygrothermal stability. The results are compared with the hygrothermally stable laminates obtained by stacking a set of rotated [0/90] plies. It is found that the laminate configurations resulting from the optimization scheme have improved coupling. Their coupling magnitude, however, is very sensitive to changes in fiber angle. Eight sets of laminates with varying extension-twist coupling were fabricated and tested using a custom loading transducer designed to allow the laminate end to twist while undergoing extension. Test results were compared with analytical predictions.

Design of Optimal Hygrothermally Stable Laminates with Bending-Twist Coupling by Ant Colony Optimization

“…(3) Remove from the ants memories al sites which have been explored unsuccessfully more than P local a i   consecutive times. (4) Perform recruitment (best site copying between two randomly selected ants) (5) If more than T iterations have been performed Then Change the nest location and Reset memories of all ants (6) Go to (2) or Stop if a stopping criteria is satisfied Figure 1 illustrates the global and local hunting strategy. The parameters which govern the spread of global and local sites are Asite and Alocal.…”

“…Extension-twist coupling is only achievable using asymmetric stacking sequences, which often produce hygrothermal instabilities, meaning temperature or moisture changes cause bending or warping [1]. Past design methods involve obtaining the desired coupling properties then attempting to minimize hygrothermal effects [2]. Seequential Quadratic Programming (SQP) has previously been used to satisfy hygrothermal stability as the primary constraint then investigates the achievable elastic properties.…”

Isogeometric analysis and Genetic Algorithm for shape-adaptive composite marine propellers

“…In addition to bend-twist coupling, the use of non-symmetric laminates to utilize the extension-twist capabilities of composite laminates can potentially be used to achieve better performance [22,23]. The extension-twist coupling can potentially be used to prevent depitching (blade becoming increasingly flat) at high rotational speeds due to the increased flexibility.…”

Families of Hygrothermally Stable Asymmetric Laminated Composites

“…However, asymmetric stacking sequences can result in significant hygrothermal instability [1,2], defined as out-of-plane deformation due to temperature or moisture changes. Previous attempts to design laminates with elastic tailoring focused first on obtaining the desired coupling properties and then trying to meet the hygrothermal stability constraints [3]. In this work a different approach is taken where hygrothermal stability is considered to be the objective rather than a constraint.…”