Braid Angle Research Articles

Biaxial tubular hybrid braided structures with supreme tensile performance: Experimental and statistical assessments

Biaxial tubular braided structures are increasingly being recognized as superior alternatives to traditional materials in structural engineering due to their enhanced tensile properties and durability. In this study, the mechanical characteristics of these structures are examined, focusing on the influence of braiding angle, yarn hybridization, and layer configurations on tensile behavior. Sixteen diverse specimens, crafted from polyester and basalt yarns using a 32-carrier vertical braiding machine, are explored, incorporating variations across four braiding angles, three hybridizations, and both single and dual-layer setups. Each specimen underwent rigorous uniaxial tensile testing, revealing critical insights into the relationships between structural configuration and mechanical performance. It was found that increasing the braiding angle significantly enhances elongation, strain, and energy absorption capacities. Additionally, a higher basalt yarn content was observed to amplify tensile strength, suggesting potential for tailored structural optimization. Notably, dual-layer configurations were found to outperform single layers in tensile efficiency, underscoring the advantage of layered designs in engineering applications. A significant gap in current literature is filled by this study, as a detailed analysis of biaxial tubular hybrid braids is provided, paving the way for their informed application in advanced composite structures.

Study on the folding damage mechanism of SiC fiber braided fabric based on synchrotron radiation CT and finite-element analysis

Silicon carbide (SiC) fiber exhibits high strength, thermal resistance, and chemical stability, but its insufficient flexural strength renders it unsuitable for use in flexible structural materials. In this study, the microstructure evolution and damage mechanisms of SiC fiber braided fabric were investigated at different braiding angles and folding stages using synchrotron micro computed tomography (µ-CT) and finite-element analysis. Results from synchrotron radiation CT scans indicate that, with an increase in the number of folding cycles, both fiber surface fractures and slippage gradually increased, leading to a looser internal structure and diminished fiber continuity. The SiC fiber braided fabric at 37.8° was predominantly influenced by the folding behavior, exhibiting a higher frequency of fiber breakages. Conversely, the 43.1° SiC fiber braided fabric was primarily affected by inter-bundle abrasion, resulting in looser fiber bundles and increased slippage. In the case of the 41.2° SiC fiber braided fabric, under the combined effects of friction and folding, the highest occurrences of fiber slippage and breakages were observed. Finite-element simulation results reveal that the stress at the folding site of the 40° braided fabric was higher than those of the 45° and 50° braided fabrics, confirming the experimental conclusion that the folding resistance of SiC fiber fabrics is poorest at a braiding angle of around 41° to 42°. This research is of significant importance for a deeper understanding of the folding performance and damage behavior of SiC fiber braided fabric, providing valuable insights for further optimizing material design and applications.

Comprehensive analysis of the effect of braiding angle on the wettability and mechanical properties of 3D braided carbon fiber fabric-reinforced composites

Fiber-reinforced composites are designed to enhance strength, stiffness, and lightweight properties. However, while the use of continuous fibers offer substantial performance benefits it presents challenges in achieving complex configurations. This study focused on evaluating the effects of different braiding angles on the mechanical properties of braided fabric-reinforced composites (B-CFRP). Continuous fiber tows were braided around a mandrel, with meticulous control over the key process parameters to ensure consistency. The composites were then processed using the Vacuum Assisted Resin Transfer Molding (VARTM) technique to achieve optimal impregnation of the resin. Mechanical properties, including tensile, flexural, compressive strength, interlaminar shear strength (ILSS), and impact strength, were performed to establish the relationship between resin impregnation and mechanical properties with different braid angles. Additionally, resin flow experiments and scanning electron microscopy (SEM) analysis were conducted to investigate how variations in braiding angle influence fiber arrangement, resin distribution, and fracture behavior. These insights aim to guide the design and manufacturing of high-performance composites.

Dynamic Progressive Failure Analysis of 3D Five-directional Braided Composites under Transverse Compression Based on Macro-scale Heterogeneous Model

At present, there are few systematic researches on macro-scale heterogeneous modeling and numerical simulation of dynamic mechanical properties of 3-D braided composites. In this paper, the parametric virtual simulation model of 3D five-directional braided composites is realized in the way of “point-line-solid” based on the integrated design idea of process-structure-performance. And the impact compression numerical simulation of the material is carried out by using multi-scale analysis method. The effects of strain rate and braiding angle on transverse impact compression properties and fracture characteristics of composites is studies and verified by comparing the test results with the numerical simulation results systematically. The dynamic failure mechanism of the matrix and fiber bundles during the impact compression process is revealed. The results show that the macro-scale heterogeneous simulation model of 3D five-directional braided composites established is effective, and the numerical simulation results agree well with the test results. The matrix fracture and shear failure of fiber bundles are presented simultaneously under transverse impact compression. The failure of fiber bundles and matrix mainly concentrates on two main fracture shear planes. And the included angle between the fracture shear planes and the vertical direction is consistent with the corresponding internal braiding angle of specimens.

Hoop tensile properties and crack propagation investigation of 2D braided SiCf/SiC composite tubes: Experiments and simulations

SiCf/SiC composites are promising candidates for advanced pressurized water reactors (PWRs) fuel cladding materials due to their enhanced accident tolerance. Their mechanical properties are strongly influenced by the braided structure of continuous SiC fibers. This study fabricated SiCf/SiC composite tubes with braid angles ranging from 30° to 50°, evaluating their hoop tensile properties through expansion-due-to-compression (EDC) experiments and analyzing the damage process using finite element method simulation. Results indicate that variations in braid angles significantly affect structural density, thereby impacting mechanical strength under hoop tensile stress. Increased braid angles result in smaller pore units and higher pore density, leading to local stress concentrations and varied deflections at overlapping regions. The dynamic propagation behavior of cracks was investigated through acoustic and structural nondestructive testing methods. Finite element analysis of different braid configurations highlights the pivotal role of pore units in the initiation and propagation of hoop tensile cracks. This study enhances the understanding of toughening structures in 2D braided composites and provides a theoretical basis for future accident-tolerant fuel cladding design.

An integrated approach toward digital design and simulation of the automated overbraiding process for composite manufacturing

The study presents a new integrated hybrid modeling framework that combines kinematic models with Finite Element Analysis (FEA) to simulate the overbraiding process on non-circular and variable cross-section mandrels in composite manufacturing. By combining the computational efficiencies of kinematic models with the detailed physical insights from FEA simulations, this hybrid method provides a holistic solution for designing and prototyping overbraided structures. Specifically applied to a complex rectangular-to-square mandrel, the approach accurately predicts braid angles, validated against physical braiding experiments covering a range of target angles. The achieved results highlight the model's accuracy and emphasize its potential to boost the efficiency and precision of overbraiding in industrial settings, thereby reducing the need for costly and time-consuming physical braiding iterations.

Investigation of the dynamic compression behavior of 3D braided composites based on a virtual fiber embedding method

The three-dimensional braided composites (3DBCs) possess a complex spatial structure, which can lead to microscopic deformation of fibers under high-speed impact. This paper proposes a quasi-fiber scale model using virtual fiber-embedded (VFE) method to simulate the impact behavior and failure of 3DBCs. The results reveal that the maximum eccentricity of the VFE model yarn cross-section is 0.318, representing a 194% improvement compared to solid yarns. According to the characteristics of damage, it can be deduced that interactions among fibers play a pivotal role in determining the failure behavior of composites, particularly concerning non-linear changes. The modulus, strength and the time of initial damage rise with an increasing braiding angle, whereas the resin stress, yarn stress, and degree of damage exhibit opposite trends. The stress distribution over the braiding path shows that the main load-bearing component at 20° braiding angles is internal yarns, whereas the surface yarns take precedence at 40°. The maximum deformation of the yarn cross-section always occurs at the center of the shear band, with a maximum eccentricity of 0.456 at 20° braiding angles. The deformation in yarn flexing and cross-section flattening cause an uneven distribution of stress and strain, leading to localized damage and ultimately catastrophic destruction.

Integration of 3-D 4-directional braided composites into dynamic modeling of plates with large overall motions

In this study, a dynamic model of a 3-D 4-directional braided composite plate with large overall motions is proposed. Based on the Kirchhoff’s plate hypothesis, the deformation of the orthotropic plate is described. The assumed mode method is employed to discretize the displacement variables, and the rigid-flexible coupled dynamic model of the plate is derived from the Lagrange equation. The equivalent stiffness matrices of 3-D 4-directional braided composites with different braided angles are obtained using the homogenization method. The effects of different velocities and braided angles on the dynamic characteristics of the plate with translational motion and fixed-axis rotation, respectively, are investigated. The present study lays the theoretical foundation for analyzing the dynamic properties of orthotropic plates in engineering components. For example, the dynamic model established in this study can be used to estimate the dynamic responses of braided composite parts in aeronautical structures.

Compressive Failure Characteristics of 3D Four-Directional Braided Composites with Prefabricated Holes.

The low delamination tendency and high damage tolerance of three-dimensional (3D) braided composites highlight their significant potential in handling defects. To enhance the engineering potential of three-dimensional four-directional (3D4d) braided composites and assess the failure mode of hole defects, this study introduces a series of 3D4d braided composites with prefabricated holes, studying their compressive properties and failure mechanisms through experimental and finite element methods. Digital image correlation (DIC) was used to monitor the compressive strain on the surface of materials. Scanning acoustic microscope (SAM) and scanning electron microscopy (SEM) were used to characterize the longitudinal compression failure mode inside the material. A macroscopic model is established, and the porous materials are predicted by using the general braided composite material prediction theory. While reducing the forecast cost, the error is also controlled within 21%. The analysis of failure mechanisms elucidates the damage extension mode, and the porous damage tolerance ability aligns closely with the bearing mode of braided material structure. Different braiding angles will lead to different bearing modes of materials. Under longitudinal compression, the average strength loss of 15° specimens is 38.21%, and that of 30° specimens is 8.1%. The larger the braided angle, the stronger the porous damage tolerance. Different types of prefabricated holes will also affect their mechanical properties and damage tolerance.

A scale-span method to characterize the mechanical property of BCF/PEEK considering uncertain structural characteristics

The focus of this study is exploring a scale-span characterization method to predict the mechanical properties of Braided Carbon Fiber Reinforced Poly Ether Ether Ketone (BCF/PEEK) considering structural uncertainty. Firstly, a complicated micro-scale Representative Volume Element (RVE) model that considers the random position and size of fiber was established via the developed Python script. Analogously, a mathematical expression adopted by the trust region algorithm was proposed to accurately describe the detailed cross-sectional shapes and fluctuation amplitude characteristics of BCF/PEEK for the sake of establishing the precision meso-scale RVE model. Then, the corresponding elastic properties that consider fiber volume fraction and fiber distribution location were characterized via the span-scale characterization method. Meanwhile, the influence of fiber bundle fluctuation amplitude and fiber volume fraction on the mechanical properties was investigated as well. In addition, the mechanical properties of BCF/PEEK with the change of the braid angle between warp and weft yarn were predicted via the established meso-scale RVE model. Finally, a series of experiments have been carried out. The maximum and minimum absolute prediction deviation of all elastic property parameters were only 4.07 % and 1.41 %, respectively, which verified the proposed scale-span characterization method can predict the mechanical properties of composites well.

Experimental Analysis of the Low-Velocity Impact and CAI Properties of 3D Four-Directional Braided Composites after Hygrothermal Aging.

Three-dimensional braided composites (3D-BCs) have better specific strength and stiffness than two-dimensional planar composites (2D-PCs), so they are widely used in modern industrial fields. In this paper, two kinds of 3D four-directional braided composites (3D4d-BCs) with different braided angles (15°, denoted as H15, and 30°, denoted as H30) were subjected to hydrothermal aging treatments, low-velocity impact (LVI) tests, and compression after impact (CAI) tests under different conditions. This study systematically studied the hygroscopic behavior and the effect of hygrothermal aging on the mechanical properties of 3D4d-BC. The results show that higher temperatures and smaller weaving angles can significantly improve the moisture absorption equilibrium content. When the moisture absorption content is balanced, the energy absorption effect of 3D4d-BC is better, but the integrity and residual compression rate will be reduced. Due to the intervention of oxygen molecules, the interface properties between the matrix and the composite material will be reduced, so the compressive strength will be further reduced. In the LVI test, the peak impact load of H15 is low. In CAI tests, the failure of H15 mainly occurs on the side, and the failure form is buckling failure. The main failure direction of H30 is 45° shear failure.

Electrical/thermal triggering on shape memory composite tubes with different braiding angles

2D braided shape memory composite (SMPC) tubes, with near-net shape manufacturing and programmable, are widely utilized in smart structures. Here we have developed braided tubes of continuous carbon fiber reinforced shape memory polyurethane (SMPU) composites. This innovative design yields a synergistic boost in both mechanical strength, shape memory functionality, and dual-trigger responsiveness. The mechanical properties, electrical/thermal shape memory performance, and recovery force of the SMPC tubes with various braiding angles have been investigated. The effects of braiding angle, temperature dependence, and applied current on the mechanical properties and shape memory properties were revealed. We found a substantial increase in compression load and ring stiffness as the braiding angle increased and the temperature decreased. The SMPC tubes exhibited a recovery ratio of 99% under electrical and thermal triggering, demonstrating a more rapid shape recovery compared to the SMPU tubes solely under thermal triggering. The large-angle specimens exhibited shorter recovery times, higher recovery forces (up to 11.40 N), and faster responses upon electrical stimulation. The ability of SMPC tubes to generate a recovery force several times greater than their weight holds great potential for expanding the applications of smart actuators.

Electro-Mechanical Coupling Analysis of L-Shaped Three-Dimensional Braided Piezoelectric Composites Vibration Energy Harvester.

In this article, an L-shaped three-dimensional (3D) braided piezoelectric composite energy harvester (BPCEH) is established, which consists of an elastic layer composed of a 3D braided composite, flanked by upper and lower layers of piezoelectric material and two tuning mass blocks. Glass fiber and epoxy resin are used to produce a 3D braided composite. This L-shaped 3D BPCEH is mechanically designable and can be adapted to different work requirements by varying the braided angle of the 3D braided composite layer. The material parameters of 3D braided composites are predicted for different braided angles by means of a representative volume element (RVE). Electro-mechanical coupled vibration equations for the L-shaped 3D BPCEH are established. The impact of braided angles on voltage and power output is discussed in this article. Simulations using finite element method are conducted to analyze the voltage and power output responses at various braided angles. In addition, the effects of the mass of mass block B and the length of the beam on the output performance of the L-shaped 3D BPCEH are analyzed.

Irradiation multi-scale damage and interface effects of 3D braided carbon fiber/epoxy composites subjected to high dose γ-rays

The serious damage caused to 3D braided carbon fiber (CF)/epoxy (EP) composites in high-energy irradiation environments is a pressing research topic that has not yet been reported. This study analyzed the γ-irradiation multi-scale damage of the matrix, interfaces, and near-interface regions in 3D braided CF/EP composites with three different braiding angles (18°, 28°, 38°) at atomic, microscopic, and macroscopic scales. The molecular structure and atomic charge information alterations of epoxy matrix were characterized using soft X-ray absorption spectroscopy (sXAS). When the irradiation dose reached 1000 KGy, the compressive strength of composites decreased by 20.88 %, 18.07 %, and 16.60 %, respectively, with an increase in the braiding angle. Micro-CT observation, along with statistical computing, confirmed that irradiation causes interface damage and increases the defect volume of 3D braided composites. Nanoindentation was used to compare the modulus of carbon fiber, interface, near-interface regions and matrix in irradiated composites and the function of CF/resin interface as an irradiation defect capture site in the irradiation resistance of resin-matrix composites has been newly established. In addition, the mechanism behind the effect of braiding angle on macroscopic properties was also analyzed.

A novel modeling method to study compressive behaviors of 3D braided composites considering effects of fiber breakage and waviness defects

Fiber breakage and waviness defects are two significant and inevitable defects existing in three-dimensional braided composites (3DBCs). This work proposed a new method to create the numerical model containing fiber breakage and waviness defects at the micro-scale level according to experimental characterization results. The experimental tests of 3DBCs with various braiding angles and matrix types are then designed to verify the reliability and adaptability of the model. The results indicate that the fiber breakage and waviness defects both gave rise to an apparent decrease in the axial mechanical properties of the unidirectional and braided composites. The influences of two kinds of defects on 3DBCs are also related to the braiding angles. In addition, the effect of matrix type on the 3DBC is apparent that should not be neglected. The primary reasons of the change of compressive properties of 3DBCs with different matrix types are the variations of the matrix and interfacial properties. The proposed modeling method in this work can be extended for those composites that include a large quantity of fiber breakage and waviness defects.

Safety and effectiveness assessment of the surpass evolve (SEASE): a post-market international multicenter study

BackgroundFlow diverters are the first-line treatment for specific intracranial aneurysms (iA). Surpass Evolve (SE) is a new-generation 64-wire flow diverter with a high braid angle. Current literature on the SE...

Enhancing damage resistance in tubular triaxial hybrid braided composites: Innovative production and tensile modulus prediction with damage analysis

AbstractBraided composite structures, characterized by their inherent brittleness, necessitate precise damage prediction and prevention to ensure structural integrity/reliability. This study introduces an innovative method for enhancing damage resistance in tubular triaxial hybrid braided composites. These composites employ Epoxy resin as the matrix, with polyester serving as the bias yarn, and glass and basalt as the axial yarns, woven at varying braiding angles. Tensile tests reveal a compelling trend: a reduction in the braiding angle correlates with an increase in the failure load, indicative of quasi‐ductile behavior. A model is also derived for predicting tensile elastic modulus, which demonstrates a strong correlation with experimental results. Furthermore, finite element simulations are utilized to analyze damage within the triaxial hybrid braided composite specimens, providing empirical confirmation of progressive damage occurrence. This research offers a promising avenue for designing/manufacturing advanced composite materials with superior damage‐resistance holding immense potential across a spectrum of engineering applications.Highlights The tubular triaxial hybrid braided composites were produced by Epoxy resin as the matrix, with polyester as the bias yarn, and glass and basalt as the axial yarns at different braiding angles. An innovative method was introduced for enhancing damage resistance in tubular triaxial hybrid braided composites. The effect of operating parameters (braiding angle, type of bias yarns, production method) was investigated. Was tried to predict tensile modulus values in tubular triaxial hybrid braided composites by finite element simulation and developed equations. Finite element simulation exhibited excellent performance in the prediction of tensile behavior of structures manufactured by the innovative method.

Impact of composition and knitting methods of fiberglass grid on the progression of reflective crack in asphalt pavement

In the asphalt pavement with semi-rigid base, the shrinkage cracks initiating from base course often propagate upward to surface course to develops into reflective cracks. The fiberglass grid, as a woven geotextile, is widely used to retard the occurrence of reflective cracks in China, but the impacts of material composition and knitting methods of it on reflective cracks are still not clear. In this paper, two kinds of models, including a two-scale model of fiber bundle-fiberglass grids layer and a coupled thermo-mechanical model of pavement structure, are established. In the two-scale model, the elastic constants (ECs) of fiber bundle and fiberglass grids layer are calculated under different compositions and knitting methods and then assigned to the coupled thermo-mechanical model to estimate the fatigue lives at initiation phase (FL-IP) and propagation phase (FL-PP) of reflective cracks based on an estimation theory. Moreover, this study designs the laboratory tests to validate this estimation method of fatigue life. Then, based on the predicted fatigue life at different phases of crack progression, the sensitivity analysis is implemented to analyze the impacts of composition and knitting methods on the fatigue life. As a result, the recommendations on design and preparation of fiberglass grid are proposed. The results show that, in material composition, the glass fibers with high elastic modulus and volume fraction and the coating materials with high elastic modulus are beneficial to retarding the initiation and propagation of reflective cracks and in knitting methods, increasing density of fiber bundles parallel to the traffic direction and reducing braided angle also has positive effect. These results can be used to optimizing design and preparation of fiberglass grid to reduce the occurrence of reflective cracks in asphalt pavement.

Investigation of the film cooling performance of ceramic matrix composites plate with different braided structures

The ceramic matrix composite (CMC) materials have been gradually applied in the high temperature components, due to its excellent heat resistance and mechanical performance. The CMC component still need cooling to protect its safe operation in the high temperature environment of aero engine, such as film cooling structure. This study focuses on the influence of braided structure on the film cooling effect over a three-dimensional braided CMC plate. The full-size calculation model reflecting the internal mesoscale structure of CMC plate was established. The thermal properties of fibers and matrix are also introduced in mesoscale. The geometric parameter which is braided angle of braided structure is changed in different models, to analyze its impacts on the comprehensive film cooling effect. The results show that the fiber bundles inside the CMC plate are the main heat transfer channel, due to its relatively higher thermal conductivity. The different braided angles affect the anisotropic thermal conductivity of CMC on the three main directions. There exists an optimal braided angle near 40° that maximizes the heat dissipation effect in the region near the film cooling holes. While in the downstream region away from holes, the influence of braided angle is weak.

Folding endurance of continuous silicon carbide fibres: A comparative study

The limited folding resistance of continuous silicon carbide (SiC) fibres hinders their application as flexible, foldable materials. With this objective in mind, the folding endurance and damage properties of the second (2nd) and third (3rd) generation continuous SiC fibre tows were investigated through repeated folding tests, optical microscope observation and tensile tests. These SiC fibre tows were disassembled from two-dimensional (2D) SiC fibre braided fabrics with varying braiding angles. The braiding process can alleviate the force on fibre tows during the textile forming process. The investigation of damage mechanisms and analysis of force conditions are instrumental in optimizing structural parameters. The research findings suggested that, in comparison to the 3rd generation continuous SiC fibres, the 2nd generation SiC fibre tows demonstrated higher resistance to repeated folding. In contrast, the 2nd generation fabrics exhibited slightly lower folding endurance values. After repeated folding, the SiC fibre tows in fabrics showed the highest strength losses near the braiding angle of 37.8? to 38.3?. In comparison, the SiC fibre fabric demonstrated the lowest folding endurance values (approximately 760 times) near the braiding angle of 41? to 42?. Considering factors such as folding endurance value, the strength loss rate of fibre tows and fabric strength loss rate, it can be concluded that SiC fibres in fabrics with large braiding angles exhibit optimal performance in terms of folding endurance.