Three-dimensional preforms have been developed in order to remedy and minimize the out-of-plane damage caused by 2D structures. Several researches have been done on more complex structures which have more interesting mechanical characteristics through-the-thickness. A wide spectrum of 3D textile technologies encompassing weaving, knitting, stitching, z-pinning, tufting, etc. is used to manufacture through-the-thickness reinforced materials. This kind of reinforcement aims to achieve a balance between the in-plane and out-of-plane properties. Recently, tufting shows more opportunities to develop through-the-thickness reinforcements especially with the advances in devices from manual to fully automatic. In literature, the mechanical behaviour of tufted composites has been one of the main subjects, however, few studies outline the mechanical behaviour of dry tufted fabrics. Dry stage is an essential step to understand the influence of through-the-thickness reinforcement and the formability of multilayer preforms. In this context, the present paper reviews the various technologies of through-the-thickness reinforcement as well as the microstructural defects related to both the impregnation and the kind of reinforcement. Also, this work highlights the mechanical performance of tufted 3D structures at dry and composite scales.

This article describes a contribution to the development of a numerical model for the geometrical description of multiaxial 3D woven preforms, at the scale of a unit cell. A novel approach enabling computation of preforms cross-section dimensions depending on the manufacturing and weaving parameters has been developed. The aims of this model are first to establish the relationships between geometrical parameters to construct a representative volume element of the structure, which can be used for finite element modeling, and second to optimize the description of the structure taking into account the specificities of these woven architectures. With this geometrical tool, the influence of the waviness of the binder tows, of the choice of the tows cross section on the fiber volume fraction is illustrated and discussed. Several numerical configurations of multiaxial 3D woven preforms are computed and compared. Finally to show the advantages of this woven architecture, the numerical model is used to compare the geometrical properties of multiaxial 3D woven preforms with those of other equivalent 3D preform configurations like 3D woven interlock preform or laminate preform.

The aim of this paper is to develop a textile waste-based composite material with adequate mechanical, acoustical, and thermal properties for automotive or construction fields. For this purpose, three recycled nonwoven wastes including cotton, polyester, and cotton/polyester blend are employed and blended in epoxy resin. The manufacturing of the composite panels is performed by vacuum infusion technique. Mechanical, thermal and acoustical tests are conducted to characterize the performances of both nonwoven fabrics and composite panels. Theoretical Young’s moduli of different composites are calculated based on the rule of mixtures in two ways and compared with practical results. Results show that mechanical properties of the manufactured panels are significantly improved compared to pure resin without a notable change in the thermal behavior of the epoxy resin, where composite reinforced cotton nonwoven shows a specific Young’s modulus of 3500 MPa/g·cm⁻³ and a specific tensile strength of 38 MPa/g·cm⁻³. These panels have been found to be promising materials to decrease the noise emission and good alternatives to pure epoxy products due to their contribution to reducing the textile wastes in landfills as well as the production costs.

Multilayer woven reinforcements are increasingly employed in the domain of composite materials. Delamination occurrence and resultant failure of a laminated composite piece subjected to high vibrations, is an issue of much concern in aeronautics. The situation becomes more complex in case of bended/curved pieces. In order to improve through the thickness mechanical properties, 3D-woven multilayer interlock fabric is used as composite reinforcement. Structural changes, i.e. thickness change, relative slippage of layers, change in tow aspect ratio and change of orientation of the tows columns, etc. occur in such fabrics during the forming process. These changes may lead to the gradient of the resin amount in composite, internal stresses and variations of mechanical properties in the piece. No significant research has been conducted on this aspect. Lack of knowledge or neglecting these changes may lead to prejudicial estimations of ultimate mechanical properties and fracture analysis. In the present article, the changes that occurred in 5-layer and 13-layer 3D-woven multilayer interlock fabrics have been studied, when moulded at five different angles and two different bending radii. A significant change in thickness, tow aspect ratio, tow orientation and relative layer slippage is observed.