3D Woven Preforms Research Articles

Numerical analysis of L-shaped wrinkling behavior of 3D woven preforms based on a novel hybrid element yarn model

Numerical simulation is a key means to evaluate the forming performance of 3D woven preforms (3DWPs). However, the macroscopic continuous model of 3DWPs cannot predict the orientation and deformation of yarns, while the microscopic discrete model is unsuitable for large-size samples forming simulation due to computational constraints. A novel mesoscopic hybrid element yarn model is thus proposed to establish a large-size 3D woven virtual yarn preform (VYP) model and the L-shaped virtual forming simulation model. The L-shaped forming experiment of the 3DWP is designed and executed, and the accuracy of the numerical simulation models is verified from three aspects: the mechanical curve, the sample's macroscopic morphology, and the local meso-structure features. Subsequently, the deformation behavior of the yarn structure inside the 3DWP during the L-shaped forming process is analyzed by combining experimental and simulation results. Furthermore, the effects of the L-shaped angle and chamfer radius on the deformation behavior of the 3DWP are studied, which helps guide the structural design of 3DWPs.

Effect of stable-structural 3D woven preform on tensile and flexural properties of carbon fiber/epoxy composites

The geometry of yarns effect the structural stability of 3D woven preform, which influence the mechanical properties of carbon fiber/epoxy composites. To investigate the effect of stable-structural preform on the elastic properties of 3D woven composites, the factors that caused the unstable structure of preform were discussed, and comparative study was conducted. The geometric models of yarn cross-section and preform were established to discuss the stability. The results showed that increasing the opening angle of warp yarns and the elongation of yarn outer contour can improve the stability of preform. The tensile and bending tests of 3DLAC and 3DBAC with stable and unstable structural preform were conducted. The results showed that the tensile and flexural elastic moduli were inversely proportional to the curvature of load-bearing yarns, and the elastic modulus of composites with stable-structural preform can increase by 9%–13%. The redistribution of internal stress in composites was macroscopically manifested as stable changes in experimental process. 3D woven composites with stable-structural preform showed the regular fracture cross-section, and fiber fracture and interface adhesion effect were the main failure mode in tensile tests, and fiber fracture on the compression surface and matrix cracking were the main failure modes in bending tests.

Manufacturing seamless three-dimensional woven preforms with complex shapes based on a new weaving technology

A new weaving technology using a modified z-binder interlacement system was designed to demonstrate its potential for the effective, continuous, efficient, and rapid manufacturing of various three-dimensional (3D) woven structures. First, three representative 3D woven preforms were fabricated. Then, epoxy resin was transferred to a preform. The manufactured 3D woven textile-reinforced composites were investigated using micro-CT analysis, tensile tests, and bending tests to study the effect of the z-binder interlacing on the structure. Furthermore, a design rule was established that could seamlessly create complex 3D woven structures with non-uniform heights in the z-direction, such as boxes, bowls, and pyramids, demonstrating that the seamless 3D woven preform of the complex shape can be fabricated with structural integrity.

Geometrical modeling and experimental validation of 3D woven honeycomb fabric for lightweight aircrew helmet liner manufacturing

This research focused on the development of a honeycomb fabric by predicting the areal density suitable for aircrew helmet liner. The aim was to fulfill the requirements for the lightweight and mechanical properties of composite liner. The model was based on the structural characteristics of the preform, including the weave design and geometric parameters. The predicted areal density, based on varying yarn linear density and the number of picks in the free and bonded wall, was compared to experimental results and showed good agreement. A geometric model was derived to predict the areal density of 3D woven honeycomb preforms for producing the composite liner of aircrew helmet. The model was validated using experimental data from a variety of 3D woven honeycomb preforms, showing that it accurately predicts the areal density and can be used as a tool to design 3D woven honeycomb preforms for advanced composites.

Preparation and electromagnetic performance of a light-weight, thin, and high-gain three-dimensional woven hollow structure microstrip antenna

With the popularity of 5 G, there is an increasing request for a light, high-performance, and stable structure for wireless communication. To solve the problems of delamination cracking and its own heavy weight of the conventional microstrip antenna, this study used ultra-high molecular weight polyethylene (UHMWPE) filament tows and purple copper filament tows as raw materials to prepare 3D woven hollow structure microstrip antenna preforms on a common loom. Using the prepared preforms for reinforcement and resin as the matrix, the VARTM process was used to prepare a 3D woven hollow structure microstrip antenna with a height of 6.8 mm, a weight of 35 g, and a bulk density of 0.7 g/cm3. The combination of the electromagnetic performance test and HFSS software simulation shows that the antenna has excellent radiation performance with a gain of 7.5 dB and a measured VSWR of 1.25. The mechanical performance test results show that it can withstand a maximum compression load of 2982 N and a maximum bending load of 364 N with no obvious delamination at the fracture. It is light, thin, and load-bearing with excellent radiation performance. There will be great potential in the unmanned field and the space field in the future.

Development of Three-Dimensional (3D) Biodegradable Polyglycolic Acid Fiber (PGA) Preforms for Scaffold Applications: Experimental Patterning and Fiber Volume Fraction-Porosity Modeling Study.

Three-dimensional (3D) biodegradable polyglycolic acid fiber (PGA) preforms were developed as temporary scaffolds for three-dimensional tissue regeneration applications. Three-dimensional biodegradable polyglycolic acid fiber (PGA) preforms including various degrees of interlaced structures called 3D plain, semi-interlaced, and orthogonal woven preforms were designed. Analytical relations and finite element model-based software (TexGen) on fiber volume fraction and porosity fraction were proposed to predict scaffolds' stiffness and strength properties considering micromechanics relations. It was revealed that yarn-to-yarn space, density, and angles of all 3D PGA fiber preforms were heterogeneous and demonstrated direction-dependent features (anisotropy). Total fiber volume fractions (Vfp) and porosity fraction (Vtpr) predicted by analytic and numerical modelling of all 3D scaffolds showed some deviations compared to the measured values. This was because yarn cross-sections in the scaffolds were changed from ideal circular yarn (fiber TOW) geometry to high-order ellipse (lenticular) due to inter-fiber pressure generated under a tensile-based macrostress environment during preform formation. Z-yarn modulus (Ez-yarn) and strength (σz-yarn) were probably critical values due to strong stiffness and strength in the through-the-thickness direction where hydrogel modulus and strengths were negligibly small. Morphology of the scaffold showed that PGA fiber sets in the preform were locally distorted, and they appeared as inconsistent and inhomogeneous continuous fiber forms. Additionally, various porosity shapes in the preform based on the virtual model featured complex shapes from nearly trapezoidal beams to partial or concave rectangular beams and ellipsoid rectangular cylinders. It was concluded that 3D polyglycolic acid fiber preforms could be a temporary supportive substrate for 3D tissue regeneration because cells in the scaffold's thickness can grow via through-the-thickness fiber (z-yarn), including various possible mechanobiology mechanisms.

A novel method for design and simulation of 3D woven preform

Increasing demand for high-performance applications of composite materials requires an integral forming process for complex components. As a composite reinforcement, 3D (three-dimensional) woven fabric has advantages in producing near-net-shaped preforms. However, previous studies focused on plates with uniform thickness, which are often variable thicknesses or special-shaped parts in practical applications. Some structures are prepared by stitching and then formed in the mold, but this increases the fiber damage. This study proposes a fabric design method based on yarn movement. By controlling the movement direction and distance of each yarn, the warp path in the fabric can be designed, which cause the change of fabric structure and achieve the integrated forming of special-shaped preforms. Based on this method, a software package for the preforms design and simulation is developed, which can be used for various woven and 3D textiles to illustrate its versatility.

Research on the thermal conductivity and ablation performance of gradient 3D woven carbon/carbon composite

This paper presents a method to manufacture gradient three-dimensional (3D) orthogonal preforms by controlling fiber tension in the flexible oriented 3D woven process (FO3DWP). The method was then adopted to fabricate three groups of gradient and uniform 3D woven preforms in order to conduct fiber volume fraction analysis. The precursors were simultaneously prepared into carbon/carbon (C/C) composites by means of the precursor infiltration and pyrolysis (PIP) process. The experimental results demonstrated that the outer interlayer distance of the gradient C/C composite was smaller than the inner interlayer distance, leading to the increase of the pore distribution diameter in gradient C/C composites. Thermal conductivity test and ablation properties test were conducted experimentally via oxyacetylene flame and transient hot-wire test, respectively. The out-of-plane thermal and ablation rate of the gradient composites were found to be lower than the ones of uniform composites. Furthermore, both the ablation resistance and the thermal conductivity increased with increasing fiber volume fraction. During the ablation test, carbon fibers in the x- and y-yarn area were shown to be able to protect the matrix and interface from further ablation, compared with the z-yarn area. Those results, successfully demonstrating the thermophysical property improvement, proved great potential of the gradient 3D woven C/C composites in aerospace applications.

Experimental and numerical investigation of inter-ply shear behavior of 3D woven preform

The inter-ply shear deformation of 3D woven preform is inevitable in the forming process. Numerical simulation of the inter-ply shear process is therefore necessary to establish the high-precision fiber structure model and understand the deformation mechanisms. Here, a research strategy for inter-ply shear behavior of 3D woven preform is proposed. A new fixture is developed for inter-ply shear experiments. The unit cell model of the preform is generated using virtual fibers. Then the inter-ply shear test is replicated through numerical simulation. Micro-CT tests are carried out on the sample before and after inter-ply shear deformation, which confirmed that the virtual fiber model can accurately reproduce the fiber structure and micro-deformation. The virtual experiment results show that the macro-scale inter-ply shear deformation of the preform is composed of several yarn level deformations including the local tension, extrusion and buckling of warp/binder yarns, and slippage between warp and weft yarns.

Effect of carbon fiber preform structures on the mechanical properties of Cf@PyC/SiC composites

Cf@PyC/SiC composites, using needle-punched preforms, 3D orthogonal woven preforms and 3D 4-step braided preforms (braiding angles of 10°, 20° and 30°) as the reinforcement, were obtained through chemical vapor infiltration (CVI) method. The tensile strength before and after oxidation of the composites were investigated, and the microstructure, appearance of fracture and phase component of the composites were also analyzed. The results show that the mechanical properties and oxidation resistance of composites are greatly affected by the preform structures. The tensile strengths of 3D 4-step braided composites with the braiding angle of 10° are the best among all composites before and after oxidation, which are 266.40 ± 16.98 MPa and 238.66 ± 14.98 MPa. Before oxidation, the fibers and matrix at the fracture of 3D 4-step braided composites are in staggered distribution. The mechanical enhancement mechanisms of composites such as crack deflection, interface debonding and fiber pull-out, were beneficial to good performance and excellent mechanical properties. After oxidation, the deflection and branching effects of the interface on the crack are not fully manifested, and enhancement and toughening mechanisms are not fully played due to the oxidation of the carbon fiber and the PyC interface.

A digital implantation system for Z-direction yarn of three-dimensional preform based on flexible oriented woven process

The implantation of Z-direction yarn is crucial in the process of forming flexible oriented 3D woven preforms, but manual implantation of Z-direction yarn is both time-consuming and inefficient. In this study, the digital Z-direction yarn implantation process and device are developed. Firstly, in view of many targets, small diameter, and serious interference in the identification process of the guide sleeve, a modified YOLOv3 algorithm is proposed to improve the accuracy and speed of detection, completing the coarse identification of guide sleeve. Then, an algorithm with modified Hough transform is proposed to improve the accuracy and speed of circle detection of coarse identification guide sleeve. Finally, based on the 1.2 mm diameter guide sleeve, a digital yarn replacement device was built to precisely replace the guide sleeve with replacement needles and implant the Z-direction yarn into the preform. The identification error of the guide sleeve is within 0.31% and the error between the reconstructed coordinates and the actual coordinates is within 3.08%. This study is crucial to the identification and positioning of small targets under complex working conditions and the development of digital forming of preform.

Effect of weaving parameters on fiber structure of 3D woven preforms: A Micro-CT investigation

The fiber structure of three-dimensional (3D) woven preform is generally complex due to the contact interactions and micro-scale deformations of the yarns during the weaving process. The present study explores the effect of weaving parameters on the fiber architecture of 3D woven preforms. Two groups of samples were prepared and observed using micro‐computed tomography (Micro-CT) technology. Semantic segmentation of Micro-CT images was conducted using deep learning algorithm to create explicit models of different yarn systems. Two novel indicators were proposed for quantifying the changes of weft yarn position and warp/binder yarn path. This work clarifies the micro-scale deformation mechanisms of 3D woven structures. The influence of weaving parameters including weft density and weaving structure on the geometric variations of fiber structures was analyzed. The connection between weaving parameters and unit cell variations was established within the scope of this study. The conclusions of this paper would be helpful for the design of preforms with stable fiber structure.

A Cost Model for 3D Woven Preforms

Lack of cost information is a barrier to acceptance of 3D woven preforms as reinforcements for composite materials, compared with 2D preforms. A parametric, resource-based technical cost model (TCM) was developed for 3D woven preforms based on a novel relationship equating manufacturing time and 3D preform complexity. Manufacturing time, and therefore cost, was found to scale with complexity for seventeen bespoke manufactured 3D preforms. Two sub-models were derived for a Weavebird loom and a Jacquard loom. For each loom, there was a strong correlation between preform complexity and manufacturing time. For a large, highly complex preform, the Jacquard loom is more efficient, so preform cost will be much lower than for the Weavebird. Provided production is continuous, learning, either by human agency or an autonomous loom control algorithm, can reduce preform cost for one or both looms to a commercially acceptable level. The TCM cost model framework could incorporate appropriate learning curves with digital twin/multi-variate analysis so that cost per preform of bespoke 3D woven fabrics for customised products with low production rates may be predicted with greater accuracy. A more accurate model could highlight resources such as tooling, labour and material for targeted cost reduction.

Evaluation of the Sensitivity of Various Reinforcement Patterns for Structural Carbon Fibers to Open Holes during Tensile Tests.

This paper is devoted to the experimental study of polymeric composite specimens, with various types of reinforcement, in order to evaluate the breaking strength of specimens with open holes when undergoing uniaxial compression and tensile tests. Four types of interlaced 3D woven preforms were considered (orthogonal, orthogonal combined, with pairwise inter-layer reinforcement, and with pairwise inter-layer reinforcement and a longitudinal layer), with a layered preform used for comparison. Tensile tests of solid specimens without a hole, under ASTM D 3039, and of specimens with an open hole, under ASTM D 5766, were carried out using the Instron 5989 universal electromechanical testing system. Movements and strains on the specimen surface were recorded using a Vic-3D contactless optical video system and the digital images correlation method (DIC). For all the series of carbon fiber tension specimens, strain and stress diagrams, mechanical characteristics, and statistical processing for 10 specimens were obtained. The paper evaluated deformation fields for certain points in time; the obtained fields showed an irregular distribution of deformation and dependency on types of reinforcing fibers. A coefficient of strength variation is introduced, which is defined as a ratio of the ultimate stress limits obtained on solid samples with and without open holes. Within the framework of ASTM D 5766, when calculating the ultimate stress, the hole is not taken into account, and the paper shows that for certain structures a hole cannot be excluded. The hole size must not be neglected when calculating the ultimate stress.

Geometric Characterization of Three-Dimensional (3D) Woven Jute Fiber Preforms for Composites

Fiber-reinforced composite materials have many advantages in various engineering applications when compared to traditional materials such as glass, metals, ceramics and unreinforced plastics. Recently, textile-reinforced composites are increasingly used in various industries including aerospace, construction and automotive. This study aims to investigate the geometric characteristics of three-dimensional (3D) woven preforms which are used as reinforcement materials in composites. To this end, 3D woven preforms with three different weave types were produced namely 3D orthogonal, 3D plain z-orthogonal and 3D satin z-orthogonal. The effect of weave pattern and the number of layers on the geometric characteristics of the produced fabrics was investigated. For this purpose, yarn-yarn distances and density, yarn lengths and yarn angles were measured. The effect of the number of layers on the geometric parameters was limited. Yarn-to-yarn distances in plain-weave fabrics were found to be greater when compared to other types of fabrics whereas the yarn density decreased in plain woven fabrics due to a large number of interlacements. This shows that in composite form, the fiber volume fraction in the filling and z-directions will be lower in the semi-interlaced fabrics when compared to the non-interlaced orthogonal structures. It was also shown that filling and warp angles are a function of weave type while z yarn angle is associated with the weaving operations such as beat-up, multi-layer filling insertion and warp yarn let off.

Investigation on the Properties of 3D Warp Interlock Fabrics Based on Moroccan Sisal Yarns as Reinforcement for Composite Materials

ABSTRACT Despite the variability of Moroccan natural resources, few Moroccan natural fibers are exploited as natural textile composites. This study aims to investigate the characteristics of 3D warp interlock fabrics based on Moroccan sisal yarns. Before weaving, the characteristics of sisal yarns have been analyzed following standards. Based on these natural yarns, six different 3D fabric architectures were manufacturing on the same manual dobby loom. During the weaving process, process parameters have been kept constant for all the 3D woven architectures to ensure a similar value for both the warp and weft yarn densities. Different values of the fabric areal density and thickness of 3D fabrics have been measured under the same test and related conditions. Different parameters play an important role on these different product parameter values as; the non-regularity of the yarn and the significant differences of warp and weft shrinkages depending on the 3D woven architecture. At the same time, yarn damage has been checked before and after the weaving of the produced 3D woven preforms. At the end of this study, new knowledge on the mechanical performance of 3D warp interlock sisal fabric have been revealed for facilitating the suited choice of architecture for a composite material solution.

Maximizing the Performance of 3D Printed Fiber-Reinforced Composites

Fiber-reinforced 3D printing technology offers significant improvement in the mechanical properties of the resulting composites relative to 3D printed (3DP) polymer-based composites. However, 3DP fiber-reinforced composite structures suffer from low fiber content compared to the traditional composite, such as 3D orthogonal woven preforms solidified with vacuum assisted resin transfer molding (VARTM) that impedes their high-performance applications such as in aerospace, automobile, marine and building industries. The present research included fabrication of 3DP fiberglass-reinforced nylon composites, with maximum possible fiber content dictated by the current 3D printing technology at varying fiber orientations (such as 0/0, 0/90, ±45 and 0/45/90/−45) and characterizing their microstructural and performance properties, such as tensile and impact resistance (Drop-weight, Izod and Charpy). Results indicated that fiber orientation with maximum fiber content have tremendous effect on the improvement of the performance of the 3DP composites, even though they inherently contain structural defects in terms of voids resulting in premature failure of the composites. Benchmarking the results with VARTM 3D orthogonal woven (3DOW) composites revealed that 3DP composites had slightly lower tensile strength due to poor matrix infusion and voids between adjacent fiber layers/raster, and delamination due to lack of through-thickness reinforcement, but excellent impact strength (224% more strong) due to favorable effect of structural voids and having a laminated structure developed in layer-by-layer fashion.

Continuous and rapid production of three-dimensional woven fabric preforms using a new weaving technique

A new manufacturing method has been developed to fabricate three-dimensional (3D) woven fabric preforms. The new method can solve problems such as delamination and fiber buckling in composites, which are known disadvantages of two-dimensional (2D) laminated fabric-reinforced composites. The new 3D weaving equipment allows for continuous and rapid production of 3D woven fabric preforms with various 3D structures. We conducted 3D modeling of the resulting fabric structures to assess the capability of the new method and the machinery involved therein. We manufactured 3D woven carbon fiber-reinforced composites using the 3D fabric preforms and epoxy resin via the resin transfer molding process. The internal architecture of the 3D composites was evaluated using micro-computed tomography and compared to the 3D modeling results; it was confirmed that 3D fabric preforms with the desired structure can be manufactured successfully by adjusting the weaving conditions of our novel weaving machine.

Flexible low-cost tooling solutions for a one-shot resin infusion of a 3D woven and multi-textile preform

3D woven materials are extremely capable for high-performance aerospace applications. Traditionally, components comprised of 3D wovens are manufactured using Resin Transfer Moulding, requiring matched tooling that can result in high costs. Increasingly this is not feasible for mid-to-large structures, therefore flexible tooling strategies are necessary to facilitate low-cost one-shot vacuum mouldings of multi-textile composites. Towards this need, the authors investigated tooling materials and infusion strategies for an as-designed 3D woven pi-section incorporating a Non-Crimp Fabric (NCF) skin. Engaging with stakeholders presented two infusion strategies (flow ‘up’ or ‘down’ pi-NCF geometry) and three inserts (Polyetherimide, Silicone, and Aluminium) for the pi internal channel. Six infusions were completed with manufacturing data recorded followed by X-ray CT analysis to evaluate geometry and infusion quality; and manufacturing costs estimated. In combination, results suggest that coupling flexible tooling materials is most effective in both reducing costs and maximising injection quality, ensuring geometrical performance.

Influences of weave parameters on the mechanical behavior and fracture mechanisms of multidirectional angle-interlock 3D woven composites

As a novel 3D textile composite material, the effects of weave parameters on the mechanical performance of the multidirectional angle-interlock 3D woven composites directly determine the final engineering application. In this paper, three multidirectional angle-interlock 3D woven preforms with different layer stacking sequences or bias orientations were designed and manufactured. Computerized tomography (CT) scan was used to capture the typical internal architecture of the composites. The composite specimens were respectively examined with tension in the warp and weft directions and the full-field strain distributions during the tests were recorded using the digital image correlation (DIC) system. Additionally, the 3D microscopy was adopted to characterize the ultimate fracture surfaces. It was concluded that the composites within [+θ/0/0/-θ] stacking sequence exhibited enhanced tensile strength, and the failure morphology of three composites were sensitive to their corresponding weave parameters. The stacking sequence had little effect on the surface strain distributions of multidirectional angle-interlock 3D woven composites. However, the bias orientation had a great influence on the strain distributions for the loading case in the weft direction. This study has provided the basis for the structural design and application of multidirectional angle-interlock 3D woven composites.