3D Braided Preform 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.

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.

Three-dimensional braiding machine with variable braiding pattern

Three-dimensional (3D) braided composites have a wide range of applications and are known for their flexible designability, structural integrity, high specific stiffness, high specific strength, and higher damage tolerance. However, the current production of 3D braided preforms primarily relies on manual labor, particularly when it comes to the special-shaped structures, resulting in limited capacity to meet diverse and large-scale demands. In order to swiftly and cheaply braid preforms of various structures, this research proposes a novel braiding machine model. The proposed machine is extendable, capable of changing patterns quickly, and incorporates multiple functionalities. So it is appropriate for automated manufacturing preforms with different cross-sections, including Τ-shaped, H-shaped, ∏-shaped, and other structures, while also facilitating the development of new braiding structures to satisfy various application requirements. More importantly, it can automatically braid a variety of shapes, such as tapered structures, branch pipes, variable thickness preforms and so on. Comparative analysis with existing machines highlights the superior mechanical structure, operational mode, and functional characteristics of the robotic arm braiding machine. This advanced machine contributes to the evolution of the braiding industry. By breaking the limitations of traditional equipment that can only produce a single type of structure, this advanced braiding machine has the potential to significantly reduce equipment costs for braiding factories.

Stress-strain characteristics of 3D-braided yarn preform

Composite researchers have not realized the potential of 3D-braided yarn preforms due to limited knowledge about their stress-strain aspects. This research presents a simple model to predict stress-strain characteristics of 3D-braided sisal yarn preforms by considering the yarn's reorientation under tensile load. The 3D-braiding machine having four carriers in the rows and columns, was used to develop 3D-braided sisal yarn preforms by varying the surface braiding angles. The experimental values were compared with predicted results, and a very good agreement was observed between them.

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.

Transverse bending fatigue behaviors and failure mechanisms of 3D five-directional braided composites at different temperatures

This paper presents transverse bending fatigue behaviors and their failure mechanisms of 3D five-directional braided composites (3D5dBC) at room and elevated temperatures. 3D five-directional braided preform was braided and relevant composite was fabricated. In order to characterize relationship between fatigue strength and fatigue life of 3D5dBC, S-N and damage index curves were plotted. The deformation and energy consumption characteristics were analyzed via hysteresis loop curves. The results showed that the composite at room temperature was more fatigue resistant and the failure showed fatigue-induced stepped fracture mode, and fibers and matrix fracture finally resulted in failure of composite while interfacial debonding finally led to structure failure at elevated temperature.

Investigation of three-dimensional braided composites subjected to steel projectile impact: Automatically modelling mesoscale finite element model

To attempt to bridge the relationships between the braiding procedure and finite element model for 3D braided structural preform plates, this paper develops a software that automatically generates the mesoscale finite element model consisted in 8-node hexahedron elements of 3D braided preform with requiring only braiding angle, dimensions and cross-section of yarns as input parameters. Taking three different representative volume elements into account, the geometric description of 3D braided preform is established with the assumptions that the braided yarns with the circle cross-section keep straight in the interior, bend and change linearly to other directions at the surface and corner regions. After that, all yarns are divided into segments and classified into eight groups according to centreline of segment orientations, which leading to easily assign material orientations and properties for transversely isotropic constitutive of yarns. Considering the different yarns jamming effect in different regions, the model involves the various diameters for yarns in the three regions, which also can ensure no interpenetrations among yarns. What’s more, a mesoscale finite element model involving matrix pockets is developed for 4-step three-dimensional rectangular braided composites subjected to a steel ball with an initial velocity of 200 m/s in LS-DYNA to validate its practicality.

An Efficient Method for Geometric Modeling of 3D Braided Composites

To estimate the precise mechanical properties of a three-dimensional (3D) braided composite, a geometric study is needed. Because of the complexity of the yarn paths inside the preform, the geometric modeling for 3D braided composites is always time consuming. In this paper, an efficient method, namely preform boundary reflection (PBR), is proposed for motion model construction in geometric studies. Furthermore, a CAD simulation system using novel combinations of parameters was developed for integral geometric descriptions of 3D braided preforms. Compared with the traditional method, the new method significantly simplifies the simulation process without affecting the precision of geometric structure. As a result, the structure design for composite preforms is effectively accelerated. The new method establishes a foundation for microstructure and mechanical properties analysis of preforms with complex geometric structures.

Microstructural characterization of additively manufactured multi-directional preforms and composites via X-ray micro-computed tomography

Additive manufacturing features “direct” and “layer-by-layer” fabrication and has significantly facilitated the microstructural design and fabrication of a wide range of highly complex parts. To enable the application of additive manufacturing in major industries and composites, it is necessary to evaluate the microstructural features of additively manufactured parts. Among the various advanced characterization techniques, X-ray micro-computed tomography (μ-CT) showed unique advantages as a high resolution, nondestructive and 3D visualization and measurement technique for material characterization. In the research reported in this article, we have fabricated an array of multi-directional preforms and composites and have characterized their microstructural features via X-ray μ-CT. First, a solid specimen as well as 3D orthogonal and 3D braided preforms have been fabricated using fused filament fabrication (FFF) and inspected with X-ray μ-CT. Then, the fabricated preforms have been infused with silicone matrix and the multi-directional preforms and composites have been tested in compression at different strain levels, to reveal their damage evolution under compressive loading. The preliminary effort made in this research demonstrates the feasibility of characterizing microstructure of additively manufactured parts via X-ray μ-CT technique and enables an investigation of the microstructural features and damage evolution of multi-directional preforms and composites.

Microstructure Analysis and Multi-Unit Cell Model of Three Dimensionally Four-Directional Braided Composites

In this paper, a new multi-unit cell model of three dimensionally braided composites is presented on the basis of the microstructure analysis of 3D braided preforms produced by four-step 1 × 1 method. According to a new unit cell partition scheme, the multi-unit cell model possesses five kinds of unit cells, namely interior, exterior surface, interior surface, exterior corner and interior corner unit cells. Each type of the representative volume cell has unique microstructure and volume fraction in braided composites. On the basis of these five unit cell models, the structural geometry parameters of the preforms are analyzed and the relationship between the structural parameters and the braiding parameters in different regions are derived in detail, such as the braiding angles, fiber volume fraction, yarn packing factor, braiding pitch and so on. Finally, by using the multi-unit cell model, the main structural parameters of braided composites specimens are calculated to validate the effectiveness of the model. The results are in good agreement with the available experimental data. In addition, the effect of braiding angle on the squeezing condition of braiding yarn is analyzed. The variations of the volume proportion of five unit cells to the whole specimen with rows and columns are discussed, respectively. The presented multi-unit cell model can be adopted to design 3D braided composites and predict their mechanical properties.

Entity Simulation of Rectangle Preform for 3D Braided Composite Based on ANSYS

According to the movement law of yarn carriers in the four-step braiding technique and the fixed grid method, a script file that calculates the space shape and location data of 3D braided rectangle preform is developed by the software matlab. Via the script file, a space grid diagram of yarns and a APDL file can be got. By calling the APDL file, the entity simulation diagram of 3D braided rectangle preform can be directly produced in the software ANSYS.

Numerical simulation on thermal expansion coefficient of 3D braided C/C composites

To effectively get the thermal expansion coefficient (CTE) of three-dimensional (3D) braided C/C composites and study the variations, a VC++ program with graphical user interfaces was obtained, based on the yarn unit model and numerical analysis. With the limited basic properties of carbon fibers and carbon matrix, CTE of 3D braided C/C composites is obtained at 85 °C. The deviation between the simulated and experimental axial CTE of 3D braided C/C composites is no more than 11 %. The effects of different parameters (including the braiding angle of 3D braided preform, the fiber volume fraction and the porosity of 3D braided C/C composites, and the elastic modulus, Poisson’s ratio and CTEs of carbon fibers and carbon matrix) were analyzed with the program. The results show that the axial CTE of C/C composites decreases with the increase of the braiding angle, the fiber volume fraction, and the porosity of 3D braided C/C composites. The transverse elastic modulus of carbon fibers has the greatest effect on the axial CTE among the studied mechanical parameters, followed by the elastic modulus and Poisson’s ratio of carbon matrix.

Unit Yarn-Addition Technique and Microstructures of Tapered 3D Braided Preform

The unit yarn-addition technique which can realize net-shape preparation of tapered 3D braided preforms was introduced. Special preform microstructures near the yarn-addition cross-section were studied by observation and modeling, respectively. Results show that a surface or an interior yarn-addition unit is the smallest yarn assembly to be added and the braiding rules should be maintained after unit yarn-addition. Two special yarn groups are formed due to the addition of a surface unit, with longer yarn lengths and larger braiding angles. When an interior unit is added, the yarn length and braiding angle of one yarn group both increase. However, the other yarn group reverses the orientation direction only.

Three-dimensional braiding for composites: A review

The aim of this study is to review three-dimensional (3D) braided fabrics and, in particular, to provide a critical review of the development of 3D braided preform structures and techniques. 3D braided preforms are classified based on various parameters depending on the yarn sets, yarn orientation and intertwining, micro-meso unit cells and macro geometry. Biaxial and triaxial two-dimensional (2D) braided fabrics have been widely used as simple- and complex-shaped structural composite parts in various technical areas. However, 2D braided fabric has size and thickness limitations. 3D braided fabrics have multiple layers and no delamination due to intertwine-type out-of-plane interlacement. However, the 3D braided fabrics have low transverse properties and they also have size and thickness limitations. On the other hand, various unit cell base models on 3D braiding were developed to analyze the properties of 3D braided structures. Most of the unit cell base models include micromechanics and numerical techniques. Multiaxis 3D braided fabrics have multiple layers and no delamination. The in-plane properties of multiaxis 3D braided fabrics may be enhanced due to the ±bias yarn layers. However, the multiaxis 3D braiding technique is at an early stage of development and needs to be fully automated.

Structure-unit cell-based approach on three-dimensional representative braided preforms from four-step braiding: Experimental determination of effects of structure-process parameters on predetermined yarn path

The aim of this study was to understand the effects of braid pattern and the number of layers on three-dimensional (3D) braided unit cell structures. Various unit cell-based representative 3D braided preforms were developed. Data generated from these structures included unit cell dimensions, yarn angle, and yarn length in the unit cell structures. It was shown that braid patterns affected the 3D braided unit cell structures. The 1 × 1 braid pattern made fully interconnected integral 3D braided unit cell structures, whereas the 2 × 1 braid pattern created disconnected braid layers that were connected to the structures edges. When the number of layers increased, 3D braided unit cell thickness also increased. Braid pattern slightly affected the braider yarn angle, whereas the number of layers did not influence it. It was observed that the number of layers considerably affected the yarn length in the unit cell structure. Increasing the layer number from five to 10 layers created a yarn path in the unit cell edge regions called the ‘multilayer yarn length’. This yarn path was not observed below five-layer 3D braided unit cell structures. In jamming conditions, minimum jamming decreased the width of the unit cell structure, but maximum jamming increased its width. On the other hand, minimum jamming decreased the surface angle of the unit cell structure, whereas maximum jamming increased the surface angle. In addition, it was realized that jamming conditions influenced the density of the unit cell but did not affect the yarn length in the unit cell structures.

Study on Manufacture Technology and Mechanical Properties of Three Dimensional Braided Composite Support with Irregular Shape

The composite components with irregular shape are often used in many application areas. Normally the formation of the composite components with irregular shape is by laminated technology. However the main problem of laminated composites is that there is a pure resin area between two lays which will degrade the mechanical properties of composite components. Three dimensional (3D) integrated braided composite can overcome this problem. In this paper, the design and manufacture technology of 3D integrated braided composite support with irregular shape were researched, including: braiding technology of 3D braided preform of composite support, the determination of process parameters of resin transfer molding(RTM) for 3D braided composite support, and the design of mold for consolidation of composite support. The compress property and shear property of this composite were investigated. The maximum compress force borne by this composite support is 2.31 kN, which is more than the design value of 1.90 kN and the maximum shear force borne by this composite support is 4.48 kN, which is more than the design value of 4.10 kN. The weight of 3D braided composite support is only 60.27% of the weight of titanium support.

Design and Manufacture of Three Dimensional Integrated Braided Composite Tube with Flange

In this paper, the design and manufacture technology of three dimensional(3D) integrated braided composite tube with flange are researched, including: braiding technology of 3D braided preform of tube with flange, the determination of process parameters of resin transfer molding(RTM) for 3D braided composite tube with flange, and the design of mould for consolidation of composite tube with flange. The fiber volume fraction of this component is calculated. The quality of composite tube with flange is good analyzed by ultrasonic A-scan. The maximum compressive force borne by composite tube flange is 56.65 kN, which has met the need of usage of 38 kN. The research result will provide a good way for designing and manufacturing high performance 3D integrated braided composite components with irregular shape.

Calculation and Design of Parameters for Four-step 3D Braided Preform with Complex Rectangular Cross Sections

The complex rectangular configuration refers to the geometrical shape jointed by two or more rectangles together. The calculation and design of parameters for 3D braided preform with simple rectangular cross-section are not suitable for those with complex rectangular cross-section because there are special microstructures in complex shaped preform. According to the unit cell models of 3D braided preform with complex rectangular cross-section, the method for computing the amount and volume of each unit cell is presented, the equation for calculating the fiber volume fraction is derived, and the relationships between preform parameters are developed. Based on the equations and relationships established, the procedure for designing the numbers of yarns arrangement is presented from preform dimensions, yarns linear density, fiber density, and fiber volume fraction. A preform with complex rectangular cross-section is designed and produced. The procedure for designing is supported by experimental results.

Microstructure of 3D Braided Preform for Composites with Complex Rectangular Cross-section

Microstructure of four-step 3D braiding preform with 1 × 1 pattern and complex rectangular cross-sections is studied by means of the control volume method. The complex rectangular configuration refers to the geometrical shape jointed by two or more rectangles together. Following the formation rule of the braiding process, the paths of the carriers are traced, particularly in the joint region where two rectangles join together. According to the formation procedures, three unit cell models, both topological and geometrical, are developed corresponding to the microstructure of the interior, surface, and corner in the joint region. The study shows that, in the joint region, the control volume of the unit cell is a cube in the interior, a hepta-prism in the corner, and a penta-prism in the surface, respectively. In addition, the study is able to demonstrate the difference in the braiding pattern and the spatial orientation of braiding yarns in the unit cells between those in the joint region of a complex rectangle and the corresponding region of a simple rectangle by four-step braiding process.

Automatically generated geometric description of 3D braided rectangle preform

Based on the study of moving regulation of yarns in the carbon fiber preform, the yarn unit model with elliptical cross section was presented. This model involved the cross-section deformation and the space orientation of yarn through which the braided structure and the braiding parameters were connected. A software was developed by employing the model on which the integral geometric descriptions of 3D braided preform with different parameters were automatically generated. As a result, the pore’s shape and distribution among the yarns in the preform were expressed clearly. The effect rule of the braiding parameters on the shape and volume of the pores in the preform was that the pores became smaller and more separated with the increasing of the fiber volume fraction when the other parameters were invariant. The geometric descriptions are helpful for the calculation of whole permeability values for braided preform and the investigation of yarn stress distributions in 3D braided preform.