3D Woven Preforms Research Articles

Novel optimization method to estimate the geometrical properties of a multiaxial 3D woven preform

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.

Innovative Material Systems for Composite Vehicle Structures

Prepreg-based materials currently used in high-end applications as well as SMC/BMC-based materials used in automotive body panels are not likely to lead the future growth in the application of fibre-reinforced composites in primary as well as secondary vehicle structures. Out-of-autoclave techniques based on rapid fibre preforming and part consolidation will drive the structural composites applications in aerospace and automotive sectors. Fibre preforming has been identified as a key bottleneck in the composites supply chain, considering recent growth predictions in civil airframe and automotive markets. Automated Tape Laying machines have modest deposition rates, and global autoclave capacity is not likely to cope with projected growth rates in composites. This paper investigates the potential for near-net preforming using conventional textile technology as well as robotic approaches. Robotic or multi-axial machines have been shown to extend the preforming capability of weaving, braiding and stitching concepts. A multi-axial weaving machine, equipped with automated trimming of non-interlaced tows, can create 3D woven preforms tapered in width as well as length directions. 3D preforms with through-thickness reinforcement have been created with a robotic system equipped with dry fibre lay-up and tufting capability. A 9-axis complex winding machine in conjunction with braiding has been demonstrated for preforming over complex mandrels.

Experimental study of joining thick composites reinforced with non-crimp 3D orthogonal woven E-glass fabrics

A comprehensive experimental study was performed to determine the strength of several co-cured and adhesively bonded joints of composite panels reinforced with non-crimp 3D orthogonal woven E-glass fiber fabrics. Various single-lap and double butt-strap joints were fabricated using co-curing and adhesive bonding and tested in uniaxial in-plane tension. The co-cured joints included special stepped 3D woven preforms, stitched and stapled joints. The joint strength appears to have the lowest values for the co-cured single-lap joints, intermediate values for the co-cured double butt-strap joints and the highest values for the adhesively bonded double butt-strap joints. Stitching and stapling dry preforms resulted in significant increase of the co-cured single-lap joint strength. In the range of strap thicknesses studied for the bonded joints, thinner straps provide a higher joint break force than thicker ones. Tapering strap ends to as small angle as possible was found to be the most effective method of increasing break force of double butt-strap bonded joints.

Dimensional stability of multiaxis 3D-woven carbon preforms

Multiaxis 3D-woven carbon preforms are fabricated using prototyped multiaxis weaving. The fabricated preform has structural instability at thickness. For this reason, the structural parameter and processing parameters were evaluated to make uniform preform and to understand the preform-process relations. The important process parameters are identified and described to enhance the preform and unit cell architecture. Also, preform structural parameters are analyzed in terms of fiber cross-section and fiber tow size, bias angle, and fiber waviness. The useful recommendation is also to make uniform multiaxis 3D-woven preform for composites.

Multiaxis 3D Woven Preform and Properties of Multiaxis 3D Woven and 3D Orthogonal Woven Carbon/Epoxy Composites

In this study, multiaxis 3D woven preform was developed with five yarn sets: + bias, -bias, warp, filling, and z-yarns. The orientation of the yarns on the five axis have improved the mechanical properties of the preform. The yarns of the preforms, which were made of polyacrylonitrile (PAN)-based carbon fibers, were consolidated with an epoxy resin. These preforms were tested and compared with the 3D orthogonal woven carbon composites. It was found that in-plane shear strength and modulus of multiaxis 3D woven composite were higher than that of the 3D orthogonal woven composite. However the bending strength, bending modulus, and the interlaminar shear strength of the multiaxis 3D woven composite were slightly lower than that of the 3D orthogonal woven composite because of the orientations of +/-bias yarns on both surfaces of the multiaxis 3D woven structure. The failures of both woven samples were also analyzed for the assessment of their mechanical behaviors. The unit cell of the multiaxis 3D woven preform was described. Depending on the unit cell geometry, some relationships were developed to predict the volume fraction of each yarn set in the preform and these predicted results were also compared with the measured values.

Preparation and Properties of Carbon Fiber Needling Preform Reinforced Silicon Carbide Composites

Carbon fiber needling preform reinforced C/SiC composites were prepared by"CVI+PIP"combined process.The densification efficiency,the microstructure and properties of the C/SiC com- posites reinforced by carbon fiber needling preform were investigated compared with 3D woven preform and pre-oxidation PAN fiber needling preform reinforced C/SiC composites.The results show that the densification efficiency of carbon fiber needling preform is higher than that of 3D woven preform.Un- der the same densification processing condition,the densitis of the composites reinforced with carbon fiber needling preform and pre-oxidation PAN fiber needling preform reach 2.08g/cm~3 and 2.02g/cm~3, respectively,while the density of the composites reinforced with 3D woven preform is merely 1.81g/cm~3. The composites reinforced with carbon fiber needling perform exhibits good mechanical properties with flexural strength of 237MPa and shear strength of 26MPa,respectively.

Conventional Approach on Manufacturing 3D Woven Preforms Used for Composites

The major barrier to accelerating the transition from 2D fabric lamination to integral 3D textile preforms is the high costs. Toward this end, substantial researches have been conducted. This paper reports on a conventional approach to the forming of 3D flat woven preforms in a shuttle-weaving machine. The factors in determining woven pattern design and weaving process are discussed. Twelve 3D woven samples with various fiber architectures are produced to test the feasibility of the forming techniques. The design and manufacturing method is validated by comparing the fiber volume fraction of samples between design values and testing ones. Modification details of the weaving machine are described. Some key issues, such as warp yarn arrangement and selvedge pattern design are also discussed. It is demonstrated that conventional weaving machines with minimum modifications can be employed as a potentially cost-effective mean to successfully manufacture 3D flat woven preforms.

A modified system for design and analysis of 3D woven preforms

This paper describes a modified system to predict the properties, in particular the areal density and z-axis fibre content, of a 3D woven preform. Previously a model used had incorporated an idealised tow path to describe the placement of a warp tow within the fabric. The idealised tow path was found to provide some correlation between predicted and actual values particularly for integrated type structures. It was realised however that the idealised yarn model did not truly reflect the actual tow path for an interlinked type structure. Hence a modified model still using a lenticular cross-section, but incorporating a more realistic path for the through-the-thickness part of the binder is put forward as an alternative. Following the procedure used in previous work, fabrics were produced and tested. Predictions made using the modified-model were shown to have a closer correlation than previously in terms of both areal density and percentage z-axis fibre prediction.

Weaving Method of 3D Woven Preforms for Advanced Composite Materials

A weaving method 'for three-dimensional (3D) I-shaped and dou e-cross-shaped woven preforms for advanced composites is presented in this study. Special heddles are designed to sort the warps into three sections that form the mainframe and flanges of the 3D woven preforms. The preforms are woven into a plane construction and then unfolded to form a near-net-shape construction. This paper demonstrates weaving mechanisms for single-layer and tri-layer I-shaped and double-cross-shaped woven fabrics.

Design and Analysis of 3D Woven Preforms for Composite Structures

Design and Analysis of 3D Woven Preforms for Composite Structures

Effect of tow alignment on the mechanical performance of 3D woven textile composites

Three-dimensional (3D) woven preforms are currently being considered for use as primary structural components. Lack of technology to properly manufacture, characterize and predict mechanical properties, and predict damage mechanisms leading to failure are problems facing designers of textile composite materials. Two material systems with identical specifications but different manufacturing approaches are investigated. One manufacturing approach resulted in an irregular (nonuniform) preform geometry. The other approach yielded the expected preform geometry (uniform). The objectives are to compare the mechanical properties of the uniform and nonuniform angle interlock 3D weave constructions. The effect of adding layers of laminated tape to the outer surfaces of the textile preform is also examined. Damage mechanisms are investigated and test methods are evaluated.