Influence of bending–twisting coupling on compression and shear buckling strength [Keynote]

No abstract available

Bounds on the natural frequencies of laminated rectangular plates with extension-twisting (and shearing-bending) coupling

Anti-symmetric angle-ply laminates are widely believed to uniquely possess Extension-Twisting (together with Shearing-Bending) coupling behaviour. The results in this article serve to dispel this misconception by presenting solutions for both standard laminates, containing combinations of angle plies (+45 and -45) and cross plies (90 and/or 0), and angle-ply laminates, containing only +45 and -45 ply orientations; chosen to reflect current industrial design practice, and also because they serve to produce hygro-thermally curvature-stable properties in some standard laminate configurations, i.e., with immunity to the thermal distortions that generally arise in this class of mechanically coupled laminate as a result of the high temperature curing process. Details of the algorithm used to develop the definitive list of laminate stacking sequences, with up to 21 plies, are given first. Closed form natural frequency solutions for each of these sub-groups are then presented, identifying significant differences in the frequency spectrum bounds across a range of aspect ratios, with respect to the ubiquitous anti-symmetric angle-ply designs

Compression and Shear Buckling Performance of Infinitely Long and Finite Length Plates with Bending-Twisting Coupling

No abstract available

Insights Into the Buckling Behaviour of Finite Length Composite Plates with Continuity Over Supports

No abstract available

Unconventional laminate design using thin-ply technologies

The work describe here is part of an on-going study addressing Mechanically Coupled (Composite) Laminates. 24 distinct classes of coupled laminate have previously been identified, containing all possible interactions between Extension, Shearing, Bending and Twisting. These laminate classes were derived for UD material using (but not restricted to) combinations of standard fibre angle orientations, i.e. 0, 90 and/or ±45. The derivation of these laminate classes involves the added restrictions that each layer in the laminate: has identical material properties; has identical thickness and; differs only by its orientation. This presentation focuses on important aspect of laminate designs, including taper and ply contiguity, firstly for UD material and then for thin-ply Non-Crimp Fabric and Woven cloth materials, in which: stacking sequence symmetries are unconstrained and; the coupling matrix, B = 0

Compression and Shear Buckling Performance of Infinitely Long and Finite Length Plates with Bending-Twisting Coupling

No abstract available

Insights Into the Buckling Behaviour of Finite Length Composite Plates with Continuity Over Supports

No abstract available

Test Validation of Extension-Twisting Coupled Laminates with Matched Orthotropic Stiffness

An experimental validation study is presented for three classes of coupled laminate with matching Extension-Twisting coupling. The designs also have matching orthotropic stiffness in extension and bending, which have been chosen specifically to investigate the influence of mechanical Extension-Shearing and/or Bending-Twisting on the performance of Extension-Twisting coupled designs under axial tension loads. All designs are hygro-thermally curvature stable (HTCS) or warp-free

Test Validation of Extension-Twisting Coupled Laminates with Matched Orthotropic Stiffness

An experimental validation study is presented for three classes of coupled laminate with matching Extension-Twisting coupling. The designs also have matching orthotropic stiffness in extension and bending, which have been chosen specifically to investigate the influence of mechanical Extension-Shearing and/or Bending-Twisting on the performance of Extension-Twisting coupled designs under axial tension loads. All designs are hygro-thermally curvature stable (HTCS) or warp-free

On tapered warp-free laminates with single-ply terminations

This article reviews the current state of the art in the design of traditional uni-directional fibre laminate construction; beyond the ubiquitous balanced and symmetric design. A ply termination algorithm is then employed to develop permissible tapered designs, with single-ply terminations and ply contiguity constraints, which are free from undesirable changes in mechanical coupling characteristics. More importantly however, is the fact that all tapered designs have immunity to thermal warping distortion; which include all combinations of anti-symmetric (or cross-symmetric), non-symmetric and symmetric angle- and cross-ply sub-sequence symmetries. Tapered designs are presented for laminates with fully uncoupled properties, and those possessing extension-shearing and/or bending-twisting coupling. Such designs represent typical fuselage skin thicknesses, i.e., with between (n =) 12 and 16 plies, but due consideration is also given to new fuselage design concepts with grid-stiffeners and/or geodesic stiffener arrangements, for which thinner designs (n ≥ 8) are of interest