Experimental and numerical study on stiffness and damage of glass/epoxy biaxial weft-knitted reinforced composites

Abstract

This paper deals with investigating the tensile characteristics of biaxial weft-knitted reinforced composites in terms of stiffness, strength and failure mechanism. The biaxial weft-knitted fabric was produced on an electronic flat knitting machine by E-glass yarns and then was impregnated with epoxy resin. Using an accurate geometrical model, the composite unit cell was designed in Abaqus software’s environment. Tensile tests were simulated in different directions on the created unit cell and the stiffness was calculated. By applying the proper failure theories, the composite strength was predicted and then critical regions of the unit cell were determined. In the next step, a micromechanical approach was also applied to estimate the same tensile features. Failure theories were also applied to predict the strength and most susceptible areas for failure phenomenon in the composite unit cell. The tensile properties of the produced composites were measured and compared with outputs of the finite element and micromechanical approaches. The results showed that the meso-scale finite element analysis approach can well predict the composite strength. In contrast, the meso-scale analytical equation model was not able to predict it acceptably because this model ignores the strain concentration. Both meso-scale finite element analysis and meso-scale analytical equation approaches predicted the similar locations for the composite failure in wale and course directions.

Inverse analysis of metamaterials and parameter determination by means of an automatized optimization problem

“…The design and construction of structures with peculiar mechanical properties are of paramount interest. The design and topology optimization of structures possessing high toughness such as composite materials [1–4] has been widely studied. Metamaterials are the family of materials that are architectured with tailored material properties by using an optimized topology with an inner substructure.…”

Multi-scale finite element modeling of bending behavior of 3D multi-cell spacer weft-knitted composites with different structures

“…19,20 Recently, researchers have used Vassiliadis et al's 15 model to create weft-knitted loop geometry at the meso scale. 7,9,[21][22][23] In this model, the geometry of the weft-knitted loop based on the coordinate points of the loop geometry is created in a three-dimensional space. Despite all efforts regarding prediction of the mechanical properties of the 3D spacer weft-knitted composites, only some limited researches have been focused on the failure behavior of these structures.…”

Additive manufacturing introduced substructure and computational determination of metamaterials parameters by means of the asymptotic homogenization

“…Another prominent structure-related anisotropy occurs in composite materials, where the microscale is composed of fibers and matrix. The alignment of fibers, and how different plies are stacked up, causes the anisotropy as well as values of effective parameters at the macroscale [23][24][25][26][27]. Porous materials are frequently modeled as a full material with voids as given inclusions at the microscale, we refer to [28][29][30][31][32][33].…”