Authors
Mazen A Albazzan, Nicole Pascale, Tyler Dillard, Zafer Gürdal, Ramy Harik, Jesse Hartzell
Journal
Composite Structures, 248, 112524.
Abstract
Laminated composites generally provide anisotropic stiffness properties depending on their stacking sequences. These anisotropic properties are not desired for certain applications that are subjected to multi-directional loadings requiring optimal stiffness properties in all directions. As a result, this paper aims to present a formulation for assessing the degree of isotropy of thin laminated composites. The starting laminate configuration chosen is a quasi-isotropic laminate in which extensional isotropy is inherently satisfied. As for the degree of bending isotropy, it can be quantified from a generalized eigenvalue problem of the bending stiffness tensor. A new lay-up strategy is proposed for thin-ply non-crimp fabric (NCF), and a parametric design study was conducted on quasi-isotropic NCF to maximize the degree of bending isotropy. Using mid-plane symmetric and non-symmetric laminate configurations, the maximum degree of bending isotropy is achieved for non-symmetric ones. A fully isotropic laminate (FIL) can be obtained when both in-plane and bending stiffness tensors are equivalent to the isotropic stiffness counterpart with null coupling stiffness. Starting with a quasi-isotropic 3-ply NCF as the building block, a non-symmetric fully isotropic laminate with 18 plies was obtained. Two laminate designs composed of NCFs with different degrees of bending isotropy were manufactured for experimental verification using three-point bending testing, and the results validate a direct relation between the degree of bending isotropy and the flexural stiffnesses at multiple directions.
Keywords
composite laminate, non-crimp fabric, NCF, quasi-isotropic laminate, bending isotropy, fully isotropic laminate, FIL
Citation
Mazen Albazzan, Nicole Pascale, Tyler Dillard, Ramy Harik, & Jesse Hartzell. (May 2020). Analysis and Verification of the Degree of Bending Isotropy of Thin Laminated Composites Manufactured using Non-Crimp Fabric. Composite Structures, 248, 112524. doi:https://doi.org/10.1016/j.compstruct.
Link: https://www.sciencedirect.com/science/article/pii/S0263822319345490