Suppression of coupling-induced guided-wave steering in composite laminates using tailored antisymmetric architectures

Tailored Antisymmetric Composite (TAC) laminates have recently emerged as a new laminate architecture capable of achieving near-orthotropic bending behavior while simultaneously eliminating the bending–twisting coupling terms D ₁₆ and D ₂₆ . Although these coupling terms are known to influence the mechanical response of anisotropic laminates, their effect on guided-wave propagation and Structural Health Monitoring (SHM) performance has not been isolated analytically. This work demonstrates that TAC laminates provide a fundamentally different wave-propagation behavior from conventional anisotropic laminates by suppressing the coupling-induced steering mechanism associated with non-zero D ₁₆ and D ₂₆ . A low-frequency guided-wave formulation is developed from laminated plate theory and explicit analytical expressions for the group-velocity direction are derived. The analysis reveals that the odd-order coupling terms D ₁₆ and D ₂₆ introduce propagation-direction asymmetries that distort energy transport and produce a deterministic coupling-induced source-localization bias in SHM systems. A stiffness-matched comparison is performed between a conventional quasi-isotropic laminate and a TAC laminate possessing closely matched principal bending stiffnesses. Two complementary angular metrics are used throughout. The coupling-induced steering component is isolated by comparing a laminate with an otherwise identical uncoupled reference in which only D ₁₆ and D ₂₆ are set to zero. Separately, the actual conventional–TAC propagation-direction difference compares the two physically realizable laminate architectures and therefore also contains the small residual effect of their non-identical orthotropic bending terms. For the baseline conventional laminate, the maximum coupling-induced component is approximately 4.10°, whereas the maximum absolute conventional–TAC difference is approximately 4.90°. An independent transient finite-element verification in Abaqus/Explicit using S4R composite shell elements assesses the latter physical laminate-pair difference at 40 kHz. The results establish that suppression of D ₁₆ and D ₂₆ not only simplifies the bending response of composite laminates but also reduces coupling-associated propagation asymmetry within the low-frequency flexural regime considered here. TAC laminates therefore provide a design pathway in which laminate architecture itself can improve wave-propagation fidelity while retaining tailored anisotropic stiffness characteristics. The finite-element results also delineate the limits of the Kirchhoff idealization and show that transverse-shear effects reduce the predicted steering amplitude without changing the principal angular trends.