3D Braiding Research Articles

Single‐view procedural braided hair modeling through braid unit identification

AbstractWe propose the first approach that can generate procedural three‐dimensional (3D) hair involving braids modeled from a single‐view photograph. Existing single‐view image‐based hair modeling methods fail to handle braided hairstyles. Our approach combines image processing, deep neural networks, as well as two‐dimensional (2D) and 3D geometric algorithms. In order to train our neural network, we create a braid unit data set. Our recognition and segmentation system can successfully segment hair regions, braid and non‐braid regions, using convolutional neural networks. We further process the images to obtain the locations, sizes, and orientations of the braid units. Given these braid units, we perform braid structure analysis to obtain the braid strand curves. The procedural modeling of the 3D braids is represented using 3D helical curves where the parameters are extracted from the 2D image analysis. Furthermore, we extract 2D hair strands from the non‐braid region using the Gabor filter and orientation maps. Then, a 3D hair volume is generated with the hair region silhouette information. We project the 2D hair strands and braids on the 3D hair volume to obtain the 3D hair strands and 3D braids. The strands for the braid and non‐braid regions are used as guides to generate dense hair strands. Dense strands are emitted from the hair root triangle mesh and follow the guide strands. With a sparse set of landmarks, the hair region of the photograph is texture mapped to the 3D hair root mesh and used to color the strands. We successfully tested our approach on photographs showing variations of braid styles and hair color.

Numerical simulation of electromechanical coupling properties of three-dimensional braiding piezoelectric composite actuator

In this paper, an innovative three-dimensional braiding piezoelectric composite actuator (3D-BPCA) is proposed. Based on the 3D braiding technology, the geometric model and representative volume unit (RVU) model of the 3D-BPCA are established. The effective elastic constant, dielectric constant and piezoelectric constant of the braiding piezoelectric composite layer (BPCL) are predicted. The electromechanical properties of the 3D-BPCA under the electromechanical coupling field is theoretically analyzed and numerically simulated, and compared with the piezoelectric ceramics actuator (PZT-5A). Numerical results show that the 3D-BPCA has better actuating properties than the PZT-5A and has a wide application prospects.

Track design and realization of braiding for three-dimensional variably shaped cross-section preforms

The preforms of three-dimensional (3D) braided composites have a monolithic structure that is braided with high-performance fibers using 3D braiding technology. Compared with traditional laminate composites, braided composites are widely favored because of their superior overall performance and mechanical properties. The capability of fabricating various yarn structures with a flexible 3D rotary braiding method, however, has not been systematically investigated, especially for a variable-section braiding structure. In accordance with the principles of braiding technology and the characteristics of a 3D braiding structure, in this study, we examined a braiding technology for the production of 3D variably shaped cross-section fabric, focusing on three key factors: the topology design of tracks, the arrangement of carriers, and the matrix algorithm of the braiding of variably shaped cross sections. We calculated new kind of structural synthesis approach to a 3D braiding track for a variable section based on the carrier arrangement characteristic method and completed the entire braiding scheme of the variable cross section. In addition, this approach represents an important step toward a simplified understanding of the carrier motion and the operator-independent operation of a 3D rotary braiding machine.

3D printing process for textile composites

The geometry of a braid influences its mechanical properties directly. On the other hand, the path of the carriers dictates the geometry of the braid. In traditional braiding machines, the carriers move along a fixed path, via horngears, which cannot be changed during the braiding process. This limitation does not allow braiding with variable geometry parameters along its axis, such as variable thickness and variable cross-sections. This paper presents a braiding machine design allowing a completely independent carrier movement. This process is analogous to 3D printing where layer-by-layer deposition produces a final part. In our case, controlling the position of each intertwining yarn will create a 3D braid. Each carrier can move without affecting the position of its neighbors allowing an easier and total control on the position and morphology of each intertwining yarn. A novel horngear design is proposed. The horngears are independently driven. They occupy the bedplate area in a hexagonal compact arrangement. The carrier path can be divided into multiple pre-defined unitary displacements. Driven by the horngears, the carrier follows these successive unitary displacements. A prototype of the braiding machine has been developed and tested with three independent carriers. As a first step, a flat braid with three yarns is produced. In the second step, a braid with a variable cross section is produced: a flat braid turning into yarn twisting. This proof of concept opens-up the possibility of 3D-printing textile composites with tailorable mechanical properties.

Non-Linear Dynamic Feature Analysis of a Multiple-Stage Closed-Loop Gear Transmission System for 3D Circular Braiding Machine

Aiming at the particularity of a multiple-stage closed-loop gear transmission system for 3D circular braiding machine, the model of gear transmission system in radial braiding machine was simplified. The non-linear dynamic equations of a n-elements closed-loop gear transmission system with symmetrical structure including static transmission error, the random disturbance of meshing damping and backlash were considered. For convenience of calculation n = 3, the equations were solved numerically by using Runge-Kutta. The dynamic transmission error(DTE) with different backlash, dynamic meshing forces with and without the random disturbance of meshing damping, the amplitude of dynamic transmission error at n = 1000 r/min and b = 2.65 × 10−5 m, root mean square(RMS) of DTE and the mean value of DTE of the first pair of gears were analyzed. The simulation results show that different backlash and the random disturbance of meshing damping have a great influence on the dynamic displacement error and meshing force of the gear pair, and RMS and the mean value of DTE changes at different rotational speeds. The results will provide a reference for realizing the smoothness of the closed-loop gear transmission system with symmetrical structure for 3D braiding machine and have great practical significance for improving the braiding quality.

Braided Fabrication of a Fiber Bragg Grating Sensor.

Our objective was to construct textile braiding manufacturing methods to facilitate high precision and accurate measurements using optical fiber Bragg grating sensors for various structures. We aimed to combine three-dimensional (3D) braiding processing with the optical Bragg grating sensor’s accurate metrology. Outside the limits of the sensor’s epoxy attachment methods, the textile braiding method can diversify the scope of application. The braiding process can be used to design a 3D fabric module process for multiple objective mechanical fiber arrangements and material characteristics. Optical stress–strain response conditions were explored through the optimization of design elements between the Bragg grating sensor and the braiding. Here, Bragg grating sensors were located 75% away from the fiber center. The sensor core structure was helical with a 1.54 cm pitch, and a polyurethane synthetic yarn was braided together with the sensor using a weaving machine. From the prototype results, a negative Poisson’s ratio resulted in a curled braided Bragg grating sensor. The number of polyurethane strands was studied to determine the role of wrap angle in the braiding. The 12-strands condition showed an increase in double stress–strain response rate at a Poisson’s ratio of 1.3%, and the 16-strands condition was found to have noise affecting the sensor at a Poisson’s ratio of 1.5%. The findings suggested the application of braiding fabrication to the Bragg grating sensor could help to develop a new monitoring sensor.

Process modelling of 3D hexagonal braids

The hexagonal braiding is a novel 3D braiding technique that can generate a large family of complex fiber architectures for composite preforms. In order to fully exploit this technology, a fiber architecture based model was constructed connecting the braiding process parameters with the resulting fabric structures through machine emulation. First, an oblique coordinate system is established according to the loom arrangement, which is the foundation to digitalize the braiding process. Then, an algorithm is proposed to trace the carrier path through the calculation on digitalized braiding process parameters. Finally, with a knowledge of the relationship between the carrier path and yarn trajectory, a simulation tool was developed to generate fabric structures from the input braiding process parameters. The simulation results were verified by experiments and discussions were made on the effect of process parameters on the fiber architecture.

Open hole tension and compression behavior of 3D braided composites

AbstractThe damage tolerant behavior of 3D braided composites is evaluated in terms of the open‐hole notch strength test under tensile and compressive loading. The influence of fiber architecture is evaluated by comparing 3D braid with and without axial yarns as well as laminated composites based on ASTM quasi‐static tension and compression testing standard. The results show that the notched and un‐notched properties of the two types of 3D braided composites are similar under tension and compression loading. Comparing to laminates, both types of 3D braided composites demonstrated superior notch insensitivity than laminated composites. For the failure behavior of the 3D braided composites, under tension loading, crack of both notched specimens tends to propagate along the notch and finally render the specimen to failure. Clear cracks usually presented on the samples without axial yarns, while not for the specimens with axial yarn. Under compression loading, the two types of 3D braided composite are also macroscopically similar, showing transverse fracture. The modified Fabric Geometry Model is used to predict the tensile properties of 3D braided composite. The predicted and experimental results are shown to be in good agreement.

Acoustic emission characterization of tensile damage in 3D braiding composite shafts

The acoustic emission (AE) method was used to monitor the tensile damage in a 3D braiding composite shaft. The 3D braiding composite shaft was manufactured via Vacuum Assisted Resin Transfer Moulding (VARTM) and the tensile experiment was conducted accompanied by AE monitoring. The AE signals were analyzed using the wavelet transformation for time-frequency analysis. The characteristic values of the AE signals were decomposed by the principal component analysis (PCA). The damage mode of the 3D braiding composite shaft under tension was identified and classified by the fuzzy clustering method (FCM). The results showed that the AE method could monitor the damage evolution process of the 3D braiding composite shaft under tension and the FCM combined with the PCA effectively divided the damage mode of the 3D braiding composite shaft. The results will provide an effective method for health monitoring of the 3D braiding composite shaft within engineering.

HHT-based AE characteristics of 3D braiding composite shafts

Abstract In this paper the Hilbert-Huang transform (HHT) was used to analyze the acoustic emission (AE) signals of 3D braiding composite shafts under tensile and torsion. First, tensile and torsion experiments were carried out on 3D braiding composite shafts with different braiding angles, and AE was used to monitor the damage evolution during the experiments. Then the AE signals were decomposed by empirical mode decomposition (EMD) and intrinsic mode functions (IMF) were analyzed by Hilbert transform to obtain the energy distribution spectrum in the time-frequency domain. The results show that HHT can realize modal separation of AE signal and distinguish different damage types. Matrix damage mainly concentrates in 125–200 kHz band. Fiber fracture and fiber/matrix pull out concentrate in 200–400 kHz band.

Modeling and analysis of carbon fiber carrier tension systems used in 3D braiding machine

Carbon fiber braids are widely applied in various industrial fields as structural components. However, using braiding machines to braid carbon fibers is an emerging technology, but some technical problems must be solved. For instance, carbon fibers are easily fluffed when using traditional carriers; with increasing braiding speed, the machine fiercely vibrates. To investigate these problems, an improved mechanical structure of the carrier is designed, which reduces the friction between the carbon fiber and guide hole and changes the carbon fiber storage quantity. Based on the carrier, the corresponding mathematical model of the tensioning system is established by the dynamical equations, and numerical analyses and simulations are carried out. Moreover, the validation of the established mathematical model is verified. According to the results of the simulation, the fluctuation in the tensioning force is smaller than that in previous studies, and the trend is in accordance with previous research results. As a result, the present model provides a better description of the dynamic process of carbon fiber braiding.

Clustering of AE signals collected during torsional tests of 3D braiding composite shafts using PCA and FCM

In this work, the acoustic emission (AE) signals collected during the torsional tests of the 3D braiding composite shafts were clustered using the principal component analysis (PCA) and the fuzzy clustering method (FCM). The 3D 4-directional braided composite shafts with various braiding angles were prepared using Vacuum Assisted Resin Transfer Moulding (VARTM). The torsional tests were performed on the static torsion machine and the AE was used to monitor the damage progression. The AE signals were analyzed by PCA and FCM. The accumulated damage was manifested by matrix cracking, fiber bundle-matrix debonding, and fiber breakage by the proposed method. The failure modes and the mechanisms of the 3D 4-directional braided composite shafts were characterized. The results will play important engineering roles in the design and the application of the 3D 4-directional braided composite shaft.

Acoustic emission monitoring of damage progression in 3D braiding composite shafts during torsional tests

In this work, damage progression in 3D braiding composite shafts during torsional tests was monitored using the acoustic emission (AE) method. The 3D 4-directional braided composite shafts with various braiding angles were prepared using Vacuum Assisted Resin Transfer Moulding (VARTM). The torsional tests were performed on the static torsion machine and the AE method was used to monitor the damage progression. The continuous wavelet transform method was used to analyze the AE signals for time-frequency analysis. The accumulated damage is manifested via matrix cracking, fiber bundle-matrix debonding, and fiber breakage, which were identified by the frequency of the AE signals. The failure modes and the mechanisms of the 3D 4-directional braided composite shafts were characterized. The results will enable the design and the application of the 3D 4-directional braided composite shafts within engineering.

Subtractive Manufacturing of Microfluidic 3D Braid Mixers

Subtractive manufacturing using the thread template approach is an emerging technique for rapid prototyping of complex, true 3D microfluidic systems, offering advantages to photolithography in terms of process complexity, and achieving excellent structure fidelity compared to 3D printing and micro‐milling. This paper explores subtractive manufacturing for novel high‐performance microfluidic 3D braid mixers. The broad freedom of design with subtractive manufacturing, that is achievable with minimal process complexity is exploited to study the impact of design parameters of such braid mixers on mixing performance. The braid mixer is compared by computational fluid dynamics and experimentally with a number of existing mixer designs using colorimetric chemical reactions. The use of a braid mixer in a streamlined production of nanomaterials in a multistep procedure, shows highly competitive performance compared to other microfluidic designs and nanoparticle assembly methods.

Virtual development and numerical simulation of 3D braids for composites

The 3D maypole braiding process is characterized with complex and often variable tracks for the carriers. During the last years smaller size (4x4 horn gears or larger) variable track machines become available on the market and the areas of industrial application of these increased. The design of the new products and the controlling of such machine is complex task, possible only with process simulation. The latest development of the algorithms and their implementation in the TexMind Braiding Machine Configurator software allows numerical simulation of any configuration of maypole braiding machine, with variable tracks. For the simulated geometry of the 3D braids an automated FEM mesh generator is developed, so that the input file for LS-Dyna is created automatically from the machine configuration. This speeds up significantly the preparation process of the FEM data and allow rapid numerical simulations of the mechanical properties of the different configuration of braided structures for composites

Numerical Modelling of 3D Braiding Machine with Variable Paths of the Carriers

This paper presents latest development of a modelling algorithms and simulation results, related to 3D braiding machines with individually driven switches and horn gears. The early developed 3D braiding machines and the current software from the braiding producer covers only rectangular sets of horn gears. Based on complete emulation of the braiding process with the carrier motion, a generalized method for the simulation of any configuration of horn gears with different sizes was developed and reported earlier by the author. In this work, an extension of the algorithms with individually controlled switches is presented. These switches allow production of profiles for textiles reinforced composites with complex cross section, changing during the production. The machine emulation can be coupled with FEM based braiding process simulation and the complete product can be virtually produced and analyzed.

Extended horn gears in 3D maypole braiding

This article presents the theoretical background for the arrangement of horn gears in maypole braiding machines in order to act as equivalent larger gears. The theoretical analysis is verified with numerical simulation and experiments. After review about the state of the art, an analysis of the process for one specific configuration of horn gears is given. This analysis demonstrates how a set of horn gears can be arranged to work as an equivalent to a larger one horn gear. The braiding equation is checked as remaining valid for such extended configurations, too. The theoretical result is verified using numerical simulation for all cases and practical validation for several variants. The theoretical rules give a clear extension of the current braiding knowledge and make the design of complex configurations of braiding machines more systematic and clear.

Modeling and analysis of the carrier arrangement in three-dimensional circular braiding

In this paper, the carrier arrangement in three-dimensional (3D) circular braiding is studied. To obtain suitable arrangements, the guide grooves of carriers are defined and divided into several types. Restricted conditions of the carrier positions are derived by obeying the characteristics of the carrier motion. Based on the restricted conditions, a mathematical model is established and applied to determine the possible carrier positions. Using the model, reasonable carrier arrangements are discussed. In comparison with practical engineering, the model is proven to be a useful tool for the 3D circular braiding process and helpful for designing a 3D circular braiding machine.

Matrix Algorithm for Braiding Simulation of Three-Dimensional Four-Step Braided Composites

This paper proposes a new kind of computational approach of three-dimensional (3D) braiding simulation based on matrix theory and symbol operation, which is suitable for batch integral calculation. The approach can be used to calculate braiding matrix at any step. Different braiding matrices fully reflect yarn carrier position changes. Using the braiding matrix calculation, the approach can provide data for storing yarn carrier paths, also termed braiding paths. The 3D braiding paths study was conducted to better visualization and thereby analyse the carrier’s movement characteristics and principles of operation. Finally, a program was designed to provide a reference for the mathematical model in further research.

Spectral stiffness microplane model for damage and fracture of textile composites

This contribution proposes a general constitutive model to simulate the orthotropic stiffness, pre-peak nonlinearity, failure envelopes, and the post-peak softening and fracture of textile composites.Following the microplane model framework, the constitutive laws are formulated in terms of stress and strain vectors acting on planes of several orientations within the material meso-structure. The model exploits the spectral decomposition of the orthotropic stiffness tensor to define orthogonal strain modes at the microplane level. These are associated to the various constituents at the mesoscale and to the material response to different types of deformation. Strain-dependent constitutive equations are used to relate the microplane eigenstresses and eigenstrains while a variational principle is applied to relate the microplane stresses at the mesoscale to the continuum tensor at the macroscale.The application of the model to a twill 2×2 shows that it can realistically predict its uniaxial as well as multi-axial behavior. Furthermore, the model shows excellent agreement with experiments on the axial crushing of composite tubes, this capability making it a valuable design tool for crashworthiness applications.The formulation is computationally efficient, easy to calibrate and adaptable to other kinds of composite architectures such as 2D and 3D braids or 3D woven textiles.