A generalized equivalent volume theory and model including Poisson interactions for layered composite structures
Composite Structures, vol.381, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 381
- Publication Date: 2026
- Doi Number: 10.1016/j.compstruct.2025.120025
- Journal Name: Composite Structures
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chimica, Compendex, INSPEC
- Keywords: Laminated composites, Equivalent volume, Poisson effect, Mechanical behavior, Elastic constants, Zor Model, Numerical model, Layered structures
- Dokuz Eylül University Affiliated: Yes
Abstract
This study proposes a new equivalent volume model that incorporates Poisson effects to represent the planar elastic behavior of n-layered composite structures. Although each layer may exhibit orthotropic or monoclinic behavior in its own local coordinate system, the equivalent volume shows a monoclinic mechanical response in the global x-y plane. The theory assumes perfect bonding between layers, leading to equal directional strains across the structure under tensile or compressive loading in the layer plane. It is formulated to generalize the model for all n-layered structures by considering each layer with different thickness and locally orthotropic properties. The unique aspect distinguishing the theory from other methods is the incorporation of Poisson interactions between layers into the calculations and the ability to express equivalent volume properties through closed-form equations. Specially defined Poisson interaction coefficients are introduced, allowing the mechanical interaction potential of each layer with others to be integrated into the model. As a result, directional elastic properties such as Ex, Ey, vxy and vyx are derived analytically, while the shear modulus Gxy is calculated by volumetric averaging under the assumption of common shear deformation in all layers. The model is applicable to both symmetric and non-symmetric n-layered structures and has been evaluated against classical methods such as Voigt, Reuss, CLT and other methods for laminates composed of orthotropic layers. Comparisons show that changes in fiber orientation or layer properties lead to distinct differences between the model and classical methods.