| A finite displacement shell-type analysis for the extension-twist coupling in pretwisted laminated composite strips is presented. The influence of hygrothermal stresses, and internal and free-edge delaminations on the coupling behavior are investigated. Closed-form extension-twist relationships are derived. The accuracy of the model is assessed through comparison with test data and finite element results. A significant discrepancy among the shell-type model and two different finite element analyses is found in the torsional rigidity predictions for highly pretwisted angle-ply laminates. To address this issue, an elasticity solution free of shell theory assumptions is obtained. An iterative method for one-term approximate solution of partial differential equations is also developed. The accuracy of the method is illustrated by comparison with exact solutions. |
