Session: 13-06-01: Multiscale Models and Experimental Techniques for Composite Materials and Structures I

Paper Number: 166515

Prediction of Poisson's Ratio of Fiber-Matrix Composites From Classic Laminate Theory and Finite Element Simulations 

Poisson’s ratio is a fundamental elastic property that characterizes the lateral strain response of a material to applied axial stress. In classical elasticity, thermodynamic constraints impose bounds on Poisson’s ratio within the range −1 < 𝜈 < 0.5 for isotropic solids. However, fiber-reinforced composite (FRC) laminates can exhibit unconventional Poisson’s ratio behavior, including values greater than 0.5 or even negative, depending on their material composition, fiber orientation, and stacking sequence. Understanding and predicting the effective Poisson’s ratio of laminated composites is critical for engineering advanced materials with tailored mechanical properties for aerospace, automotive, and biomedical applications.

This study employs Classical Laminate Theory (CLT) and Finite Element (FE) simulations to investigate the influence of fiber orientation, fiber volume fraction, phase contrast, and ply configuration on the effective Poisson’s ratio of fiber-matrix composites. A composite laminate is modeled as a stacking of multiple unidirectional (UD) fiber laminae, where each lamina exhibits quasi-homogeneous orthotropic behavior. The mechanical response is governed by generalized Hooke’s law, and analysis is conducted under plane stress conditions assuming small displacements. The CLT framework provides a semi-analytical approach to predict the macroscopic elastic response based on individual ply properties and stacking sequences, while FE simulations offer a numerically validated assessment of Poisson’s ratio variations across different fiber-matrix configurations. Key assumptions of CLT-based analysis include: Quasi-homogeneous and orthotropic behavior of individual plies. Thin laminate assumption, where the laminate dimensions are significantly larger than the thickness. Small displacement and linear variation of in-plane displacements across the thickness direction. Negligible transverse shear strains, ensuring that normal lines to the mid-surface remain straight after deformation.

The FE simulations use a detailed unit cell approach with periodic boundary conditions to validate analytical predictions. Explicit simulations incorporate surface-to-surface contact, fiber-matrix interactions, and progressive failure mechanisms. The numerical model provides insights into the coupling effects between axial and shear deformation, which is the primary reason for the nontraditional Poisson’s ratio behavior in laminated composites.

Preliminary results indicate that fiber orientation plays a dominant role in dictating Poisson’s ratio, with specific configurations exhibiting negative Poisson’s ratio due to extension-shear coupling effects. Increasing fiber volume fraction enhances anisotropy, further influencing Poisson’s ratio trends. Additionally, phase contrast and ply stacking sequence significantly affect deformation modes, validating the necessity of both analytical and numerical approaches.

 

This work provides a systematic methodology for predicting Poisson’s ratio in laminated composites, offering insights into designing advanced materials with customized deformation characteristics. The findings contribute to improving composite performance modeling and optimizing structural applications where tunable mechanical behavior is required.

Presenting Author: AMMAR BATWA Northeastern Univeristy

Presenting Author Biography: I am a Ph.D. candidate in Mechanical Engineering at Northeastern University, specializing in
bio-inspired architectured composites. My research focuses on experimental testing of 3Dprinted prototypes, analytical modeling, and finite element analysis. I have been a Teaching
Assistant at King Abdulaziz University since 2015 and a Graduate Teaching Assistant at
Northeastern since 2018. I hold an M.S. in Mechanical Engineering from Northeastern and
certifications in SOLIDWORKS. My work integrates research and teaching to advance
engineering design and manufacturing

Authors:

AMMAR BATWA Northeastern University
Yaning Li Northeastern University