3D Braiding Research Articles

Multifunctional 3D carbon fiber/epoxy braided composites with excellent compression performance and electromagnetic interference shielding

The multifunctional composites with electromagnetic interference (EMI) shielding performance and mechanical property are in urgent demand. In this work, the carbon fibers reinforced 3D braided preforms (3DBPs) were fabricated by a four-step braiding method. Then, the 3D braided composites (3DBCs) were prepared via vacuum assisted resin transfer molding technique. The establishment of a comprehensive 3D conductive network conferred upon the 3DBCs an exemplary EMI shielding efficiency of 54.01 dB in the X-band. Furthermore, the 3DBPs served the reinforcing function, attaining an exceptional compressive strength of 211.48 MPa at a density of 1.37 g/cm3. It is of great significance to apply the 3D braiding technology to develop EMI shielding composites to realize the structure-function integration.

Bifurcation and chaos analysis of the closed-loop gear system of the 3D braiding machine

Bifurcation and chaos analysis of the closed-loop gear system of the 3D braiding machine

Horngear and carrier design for braiding tailorable composite preforms

Braids can be found in structural composite parts used in the car and the aerospace industries. The architecture of the braid has a direct impact on its mechanical properties. However, traditional braiding machines are limited to a single braid architecture. Few braiding machines, so called “3D braiding machines”, have been developed to enable variable carrier’s paths. This allows fabrication of several braid architectures using the same machine. These machines use a switching mechanism, which complexifies the machine and the braiding process. A new type of braiding machine was introduced in Assi et al. [1], which uses a “chain and sprocket” mechanism, allowing variable carrier’s paths without any switching mechanism. Nevertheless, the original chain and sprocket braiding machine cannot be used for vertical braiding. When placed in the vertical position, the carrier jam between the horngears due to the force of gravity. This limitation does not allow braiding over a mandrel or coupling the braiding machine with a pultrusion line. This paper presents design guidelines for enabling vertical braiding for the chain and sprocket braiding machine. A new carrier design is proposed as well as a new horngear design. Additionally, the carrier is fitted with a guiding foot and a track is machined into the braider’s bedplate. A functional prototype has been developed to validate the design. The design complexity has been assessed and compared to existing braiding machines. The design proposed in this paper remains 30% less complex compared to other vertical braiding machines enabling variable carrier’s paths.

Fiber-level modeling of 3D braided preforms using virtual braiding method

High fidelity geometry models of the preforms are essential in mechanical property analysis for composite materials. The paper presents a virtual braiding method to generate digital material twins of 3D braided preforms. The four-step 3D braiding process is simulated based on the concept of virtual fiber and according to the rule of yarn movement. Fiber-level models of the preform are constructed which display the micro-scale architectures explicitly, including compressive deformations of yarn cross-sections and variations of yarn paths. The Micro-CT test is employed to investigate the internal fiber structures of 3D braided preform and quantitatively verify the accuracy of the proposed modeling method. Influence of the braiding parameters, such as yarn tension and arrangement angle in the initial state on geometric parameters of the preform is then investigated.

Simulation of the hexagonal 3D braiding process for stent preforms

Due to the complex braiding process and long development cycle of the hexagonal three-dimensional braided stent, a MatLab based computer-aided braiding method for a stent is proposed to speed up the development process. First, an oblique coordinate system for the chassis and a polar coordinate system for the chassis unit are constructed, respectively, precisely to coordinate the carrier’s movements on the chassis. Subsequently, an iterative formula delineating the trajectory of the carrier is introduced. The formula effectively translates the entire braiding process into the positional coordinates of the carrier on the chassis and the yarn heights on the mandrel during different stages. Based on the specific characteristics of the braiding process and the stent’s structure, the stent is divided into pressing and twisting sections. The interwoven pattern for both the pressing and twisting sections is determined by establishing the basic tiling form, solving the yarn interwoven sequence, judging the interwoven type and computing the number of kinks. Finally, while considering the stent's dimensional parameters and the interwoven pattern of the yarn, the spatial curve equations for the yarns in both the pressing and the twisting sections are formulated. By concatenating these equations for each section, the three-dimensional trajectory equations and a comprehensive solid model of the stent are successfully derived. Through a rigorous comparative analysis of dimensions and the braiding pattern between the three-dimensional solid model and the physical stent preform, the accuracy and fidelity of the model generated through the implementation of computer-aided braiding technology are verified.

Functionalization of All-Oxide Ceramic Matrix Composites Elements Using Three-Dimensional Braiding and Pressure Slip Casting for Composite Processing: Approaches to Reduce the Filter Effect of Dense Reinforcement Textiles

Abstract A key element for the transition to sustainable energy lies in the transformation of the power plant fleet, which is dominated by fossil fuels, toward sustainable energy production from renewable energy sources. An increase in efficiency and reduction of exhaust gas emissions, especially the minimization of CO2 emissions, is possible through the use of new turbine materials, which can withstand higher temperature levels. Oxide ceramics are well known for their high stability in aggressive environments, low density, high melting point, high stiffness, and great creep resistance, but their brittleness has strongly limited their number of applications. Therefore, the implementation of fiber reinforcement using the three-dimensional (3D) braiding process shows great potential to increase the damage tolerance of ceramic matrix composites (CMC) and consequently the performance of thermal machines significantly. Currently, the impregnation of 3D braids for the reinforcement of ceramic composites poses a challenge due to the high packing density of the textiles. In order to enable a homogeneous impregnation of the fiber structures using highly viscous ceramic slurries, the CMC research group at RWTH Aachen University's Institute of Textile Technology (ITA) is investigating the combination of 3D braiding and pressure slip casting for an economical production of all-oxide CMCs. To increase the impregnation quality of dense textiles, this paper describes approaches to reduce the filter effect of braids. The results of an initial investigation into the functionalization of two-dimensional braided reinforcement structures by using support structures and flow aids are described. The effectiveness of the impregnation ability is assessed by evaluating the residual porosity of generated green compacts via μCT analysis.

Programmable 3D bifurcated braided structures for system-adaptable and integrated triboelectric sensing

Textiles are a flexible framework for devising soft triboelectric nanogenerators (TENGs) that can monitor or harvest mechanical energy generated from body motion. Despite various structures and impressive performance, integrated textile TENGs that can regulate the contact-separation between triboelectric materials are rarely explored. Herein, we report a programmable three-dimensional (3D) braiding strategy to construct Y-profile bifurcated textile TENGs (3D Y-TENG) by the industry-compatible hexagonal braider. Through the regulation of interlaced and bifurcated regions along 3D Y-TENGs, different contact-separations can be obtained. 3D Y-TENGs were constructed by braiding two sets of core-sheath yarns with nylon and polytetrafluoroethylene (PTFE) as the triboelectric materials, with both yarns exhibiting exceptional abrasion resistance (i.e., 3000 cycles of abrasion without structural disintegration). Five 3D Y-TENG with different bifurcation patterns were designed and fabricated to tailor the contact-separation, all presenting triboelectric response towards mechanical compressing, stretching, and bending. 3D Y-TENGs are featured with remarkable stretchability, softness, flexibility, foldability, and mechanical endurance, enabling their comfortable contact with the human body. This work presents programmable braided structures that can be tailored, adapted, and integrated with different systems for seamless electronic garments.

The asymptotic homogenization evaluation of effective mechanical property of the C/C-ZrC composite by the reconstruction technique

In this framework, we formulate a procedure to reconstruct the structure of general random 3D braid heterogeneous media based on transformation of Gaussian random fields, where the correlation of the underlying Gaussian field is determined explicitly rather than through iterative methods. The reconstructed media can meet the key microstructural information contained in the micrographs and two-point correlation function of the reference media. A robust and efficient algorithm is the operation for accurate determination the effective physical properties from a local heterogeneous material based on the methods of asymptotic homogenization and the finite element. Comparison of the present result to the experimental data from the literature shows a good agreement. The correlation length, Gaussian complexity, representative volume element size and mesh size are investigated and selected to highlight the importance of morphologically realistic microstructures. The effective properties of 3D braid composites are evaluated numerically and the respective effect of the volume fraction and relative material parameters of the reinforcement is assessed numerically. This breakthrough is the possibility to design, predict properties, and even manufacture materials not only with the help of experiments but also with computer science.

Real-Time 3D Topological Braiding Simulation with Penetration-Free Guarantee

We present an efficient approach for simulating 3D topological braiding while guaranteeing non-penetration. Our method combines eXtended Position-Based Dynamics (XPBD) with Incremental Potential Contact (IPC), leveraging XPBD’s efficiency, robustness, and numerical stability with IPC’s non-penetration capabilities. However, incorporating IPC introduces nonlinearity errors that result in instability, numerical issues, and CCD failures in stiff systems. To resolve this, we propose a correction method that ensures non-penetration while retaining XPBD’s benefits, resulting in an efficient algorithm for simulating 3D yarn braiding with correct topology. We also propose a parallel implementation of our algorithm on the GPU, achieving real-time simulation of complex braiding. Experimental results show that our method outperforms traditional XPBD in terms of plausibility and non-penetration guarantees while maintaining comparable efficiency and enhanced robustness under extreme collision conditions.

High-temperature heat transfer simulation and optimization of quartz fiber-aerogel composite multilayer 3D fabric

Quartz fabrics, which have excellent mechanical properties and high temperature resistance abilities, had been widely applicated in aerospace, military, and other thermal insulation fields. However, single-layer quartz fabric has poor thermal insulation performance, which is unfavorable to the high temperature application of this material. In order to improve the thermal insulation effect of quartz fiber fabric, silica aerogel materials with outstanding thermal insulation performance were introduced to the fabrication of quartz fabrics. Thermal insulation properties of quartz fiber and mechanical properties of silica aerogel were improved by a 3D braiding technique. Firstly, a 3D-fabric structure of quartz fiber-aerogel multilayer composite was designed. Silica aerogel and quartz yarn were woven into 3D composite fabric by textile technique. Through 3D braiding technique, silica aerogels were protected by quartz yarns while enhancing their mechanical properties. The thermal insulation performance and high temperature erosion resistance of the fiber-aerogel fabric are improved. Secondly, to explore the influence of the internal structure of the 3D fiber-aerogel composite fabric, a full-scale 3D simulation model for the heat transfer performance of fiber-aerogel multilayer composite was established. The thermal insulation performance of the composite fabric at 700 °C was predicted. Finally, the temperature of different positions inside the fabric in different environments (300 °C, 400 °C, 500 °C, 600 °C, 700 °C) was tested. It has been proved that introducing aerogel materials to the quartz fabric could reduce the surface temperature by about 60%.

Engineering Ligament Scaffolds Based on PLA/Graphite Nanoplatelet Composites by 3D Printing or Braiding

The development of scaffolds for tissue-engineered growth of the anterior cruciate ligament (ACL) is a promising approach to overcome the limitations of current solutions. This work proposes novel biodegradable and biocompatible scaffolds matching the mechanical characteristics of the native human ligament. Poly(L-lactic acid) (PLA) scaffolds reinforced with graphite nano-platelets (PLA+EG) as received, chemically functionalized (PLA+f-EG), or functionalized and decorated with silver nanoparticles [PLA+((f-EG)+Ag)], were fabricated by conventional braiding and using 3D-printing technology. The dimensions of both braided and 3D-printed scaffolds were finely controlled. The results showed that the scaffolds exhibited high porosity (>60%), pore interconnectivity, and pore size suitable for ligament tissue ingrowth, with no relevant differences between PLA and composite scaffolds. The wet state dynamic mechanical analysis at 37 °C revealed an increase in the storage modulus of the composite constructs, compared to neat PLA scaffolds. Either braided or 3D-printed scaffolds presented storage modulus values similar to those found in soft tissues. The tailorable design of the braided structures, as well as the reproducibility, the high speed, and the simplicity of 3D-printing allowed to obtain two different scaffolds suitable for ligament tissue engineering.

3D-Braided Poly-ε-Caprolactone-Based Scaffolds for Ligament Tissue Engineering.

The anterior cruciate ligament (ACL) is the most commonly injured intra-articular ligament of the knee. Due to its limited intrinsical healing potential and vascularization, injuries of the ACL do not heal satisfactorily, and surgical intervention is usually required. The limitations of existing reconstructive grafts and autologous transplants have prompted interest in tissue-engineered solutions. A tissue engineering scaffold for ACL reconstruction must be able to mimic the mechanical properties of the native ligament, provide sufficient porosity to promote cell growth of the neoligament tissue, and be biodegradable. This study investigates long-term biodegradable poly-ε-caprolactone (PCL)-based scaffolds for ACL replacement using the 3D hexagonal braiding technique. The scaffolds were characterized mechanically as well as morphologically. All scaffolds, regardless of their braid geometry, achieved the maximum tensile load of the native ACL. The diameter of all scaffolds was lower than that of the native ligament, making the scaffolds implantable with established surgical methods. The 3D hexagonal braiding technique offers a high degree of geometrical freedom and, thus, the possibility to develop novel scaffold architectures. Based on the findings of this study, the 3D-braided PCL-based scaffolds studied were found to be a promising construct for tissue engineering of the anterior cruciate ligament.

Multi-scale and multi-step modeling of thermal conductivities of 3D braided composites

To accurately predict the Effective Thermal Conductivities (ETCs) of Three-Dimensional (3D) braided composites, this work proposes a multi-scale and multi-step Mean-Field Homogenization (MFH) method. The composites are considered as the composites with 3D multi-directional braiding yarns as inclusions at the meso-scale, and the braiding yarns are viewed as unidirectional fibers reinforced composites at the micro-scale. The ETCs of the braiding yarns are firstly determined using the MFH method at the micro-scale. According to the yarn orientation, the composites are virtually decomposed into several pseudo-grains, each of which consists of the oriented braiding yarns and matrix, and the multi-step MFH method is then developed to predict the ETCs of the pseudo-grains and the composites sequentially at the meso-scale, i.e. the MFH prediction of the ETCs of each pseudo-grain individually and the composites consisting of all the pseudo-grains in two sequential steps. The proposed multi-scale and multi-step MFH method is validated by comparing with the multi-scale FE homogenization method and the available experimental test. The modeling results show that the through-thickness and in-plane ETCs of the composites increase with the increase of fiber volume fraction and transverse ETC, and decrease and increase with the increase of interior braiding angle, respectively. The proposed multi-scale and multi-step MFH method possesses the advantages of better computational efficiency and simpler implementation compared with the multi-scale FE homogenization method.

Optimized cyclic and electrochemical performance by organic ion N(CH3)4+ pre-inserted into N(CH3)4V8O20 cathode and hierarchy distributive Zn anode in aqueous zinc ion batteries

Vanadate based cathode materials have been enormously investigated into aqueous zinc-ion batteries (AZIBs) in current research due to high specific capacity and large layer spacing that can accommodate sufficient ions. However, bulk vanadate based cathode materials suffer from a rapid capacity decaying as a result of low electronic conductivity, inferior ion diffusion kinetics and unstable structure during the zinc ion de/intercalation. Meanwhile, the inescapable zinc dendrite formation and reactive irreversibility during long cyclic testing also lead to growing polarization and poor cyclic performance. Herein, we put forward a strategy of structural design by synergistically introducing quaternary ammonium cation within vanadium bronze structure. The desired N(CH3)4V8O20 material, pure monomorph phase, was firstly synthesized by facile one-step hydrothermal method, which owns lattice spacing of 11.5 Å and stable crystalline structure for faster kinetics, higher capacity and better cyclic stability. Combined with the optimized 3D braid architecture of Zn@carbon paper anode, the as-obtained AZIBs exhibit a high capacity of 360 mAh g−1 at 0.5 A g−1. While the current density raises to 100 folds from 0.5 A g−1 to 50 A g−1, appreciable capacity of 105 mAh g−1 and outstanding stability of ultra-long lifespan with capacity retention 97% after 5000 cycles are achieved. Combining the sound investigations of experimental practices and computational research, mechanism of rapid and stable Zn2+ storage was systemically demonstrated. The optimized electrochemical performance could be attributed to highly reversible ion de/intercalation, superior ion diffusion kinetics and no side reactions. This work leads to a new strategy of the design for cathodes in AZIBs and unfolds a new path for the actualization of high-up vanadate based materials.

Aachen Technology Overview of 3D Textile Materials and Recent Innovation and Applications

This paper provides an overview of the recent definition, technologies and current trends regarding 3D fabrics. In this paper a definition of 3D fabrics, including spacer fabrics, is given and the recent technologies regarding weaving, braiding, weft and warp knitting and tailored fiber placement are presented. Furthermore, an overview of the latest developments in 3D fabrics at the Institut für Textiltechnik of RWTH Aachen University is presented including: large circular 3D knitting, braided and woven structures for medical purposes, newest testing methods and equipment for spacer fabrics, multiaxial fabrics for composites, warp knitted spacer fabrics for space and construction applications, ceramic matrix composite 3D braiding and 4D textiles.

On the tribology of complex 2D/3D composites bearing

In the present work, a hierarchical braided polymer composite consists of Polytetrafluoroethylene (PTFE) fibers, reinforcement fibers, and epoxy resin was designed as a self-lubricant composite and bearing. Different reinforcements such as glass, carbon, and Kevlar fibers were employed to investigate the effect of reinforcement on the wear characteristics of composites. Besides, the influence of 2D/3D braid fabric was examined on the wear behavior of samples. Also, 90 and 120 N loads were applied to assess the load impact. Results illustrated that compared to glass and Kevlar, carbon could lead to a greater wear weight loss and friction coefficient. However, PTFE tribofilm was observed according to scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) analysis. Moreover, with the increase of load, the wear stability of the composites faded significantly. Furthermore, the tribological features became inappropriate with the deployment of the 3D braid structure. Finally, the modeling of tribological parameters was carried out using response surface methodology-based D-optimal design. The adequacy of the models was checked by analysis of variance. Results implied that there is an excellent correlation between the model and the experiments.

Designing of the Tracks and Modeling of the Carrier Arrangement in Square Rotary Braiding Machine

This paper describes the splicing of an 8 × 8 484 cross-break track, based on the carrier arrangement characteristics (CAC) method for track splicing technology. The arrangement period of the carrier (T) in the track is obtained in order to discern which slot has a carrier in a period and which one does not. Six basic types of track unit are deconstructed, and a mathematical model is established to determine the possible state of the carrier in each slot of the track unit. Finally, the specific pattern of the carrier arrangement in the 484 cross-break track unit is obtained and verified using a three-dimensional (3D) rotary braiding machine with a square track disc. This provides a reference for solving the carrier arrangement of a 3D square rotary braiding machine.

Innovation in 3D Braiding Technology and Its Applications

Braids are generally divided into 2D braids and 3D braids. Two-dimensional braids include flat braids and circular braids. Circular braids represent three-dimensional textiles, as they enclose a volume, but consist of a two-dimensional yarn architecture. Three-dimensional braids are defined by a three-dimensional yarn architecture. Historically, 3D braids were produced on row and column braiding machines with Cartesian or radial machine beds, by bobbin movements around inlay yarns. Three-dimensional rotary braiding machines allow a more flexible braiding process, as the bobbins are moved via individually controlled horn gears and switches. Both braiding machines at the Institut für Textiltechnik (ITA) of RWTH Aachen University, Germany, are based on the principal of 3D rotary machines. The fully digitized 3D braiding machine with an Industry 4.0 standard enables the near-net-shape production of three-dimensionally braided textile preforms for lightweight applications. The preforms can be specifically reinforced in all three spatial directions according to the application. Complex 3D structures can be produced in just one process step due to the high degree of design freedom. The 3D hexagonal braiding technology is used in the field of medical textiles. The special shape of the horn gears and their hexagonal arrangement provides the densest packing of the bobbins on the machine bed. In addition, the lace braiding mechanism allows two bobbins to occupy the position between two horn gears, maximizing the number of bobbins. One of the main applications is the near-net-shape production of tubular structures, such as complex stent structures. Three-dimensional braiding offers many advantages compared to 2D braiding, e.g., production of complex three-dimensional geometries in one process step, connection of braided layers, production of cross-section changes and ramifications, and local reinforcement of technical textiles without additional process steps. In the following review, the latest developments in 3D braiding, the machine development of 3D braiding machines, as well as software and simulation developments are presented. In addition, various applications in the fields of lightweight construction and medical textiles are introduced.

The micro/macro mechanical approach of reinforced braid composite used in tribology

Self-lubricant composite is a flourish scope of technology that merits academic and industry attention, as it is a specific part which essentially employed in acute operation conditions. In the present study, the mechanical properties of the self-lubricating composite of two-dimensional (2D) and three-dimensional (3D) braid were investigated. The composites contained Polytetrafluoroethylene (PTFE) fibers as a lubricant and glass, carbon, and Kevlar as a reinforcement, hierarchically incorporated into the structure. In order to study the composite behavior as well as to determine the modulus and hardness of the sample, an indentation test, which is very similar in loading to abrasion tests, was applied. A microband test was also conducted to assess the adhesion between the resin and the PTFE fiber. Shear punch tests were performed to evaluate the total shear strength and impact test to estimate energy absorption and impact strength. The results showed that PTFE/epoxy matrix has poor adhesion. Composites with higher PTFE volume fraction had good energy absorption and, at the same time, low shear strength. The higher modulus of carbon composites was concerned.

Carrier delay-based method for development of the tracks for the transitions between patterns on 3D braiding machines with continuous rotating horn gears

The pattern changes on the 3D rotary braiding machines (maypole principle with horn gears with full and empty slots) require complex planning of the carrier positions and timing and allow for production of bifurcated and other complex braids with variable cross sections for medical and technical applications. Another common application of pattern changes is to make a visually different pattern for marking of the remaining length of rope when used in a climbing context or for generally lengthened pieces for medical sutures. The development of such samples has previously been done using the trial-and-error method. This paper presents one rule for supporting a more systematic and purposeful trial, which significantly speeds up the development process. After a short review of the related literature, the main theoretical background is given and two practical cases for pattern change are demonstrated. The patterns were developed using numerical simulation before being tested on a real braiding machine. With this paper the authors hope to give some motivation for the remaining braiders in the world to continue working on the development of systematic rules for this complex process.