Braided Composite Materials Research Articles

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.

Nonlinear resonant responses and chaotic dynamics of three-dimensional braided composite cylindrical shell

The advanced three-dimensional braided composite structure has excellent integrity, which can effectively avoid the problems of interlayer stress jump and interface debonding that may occur in traditional composite laminated structures. However, most of the existing references on the three-dimensional braided composite structure are fragmented, and there is little research on their vibrations. Taking the cylindrical shell of a rocket as the object and considering the complex flight environment, a general framework for the vibration problems of the three-dimensional braided composite shell is proposed for the first time. The equivalent mechanical parameters of the three-dimensional braided composite material are calculated based on the volume averaging method. Then, the nonlinear dynamic model of the three-dimensional braided composite cylindrical shell is established, and the natural vibration characteristics are analyzed. Under the case of 1:1 internal resonance, the pseudo-arc length continuation method is used to solve the nonlinear resonant responses of this nonlinear system. Finally, we apply the fourth-order Runge-Kutta algorithm to study the chaotic dynamics of the three-dimensional braided composite cylindrical shell model. This framework presented in this paper can be extended to the study of nonlinear vibrations and chaotic dynamics of other three-dimensional braided composite structures.

Comparative Study of Vibration Response in Steel and Braided-Carbon-Fiber Bicycle Handlebars: A Numerical-Experimental Approach with Various Sensors.

The comfort and safety of a cyclist are directly influenced by the vibrational behavior of the handlebar. Hence, the objective of this article is to comparatively assess the vibrational characteristics of two bicycle handlebars: one made of steel and the other made of braided composite material. The transmissibility function represents the relationship between the excitation applied to both handlebars through their stems and the corresponding response in the handle area, which was experimentally obtained by applying a random vibrating signal (constant amplitude of 0.01 g2/Hz) using a shaker. This signal was applied in a frequency range between 100 Hz and 1200 Hz, and the response was measured at one of the two cantilevered ends of the handlebar. Different sensors, including a laser vibrometer and a control accelerometer in the shaker, were utilized. The transmissibility, natural frequencies and damping functions were obtained. Subsequently, another experimental analysis was carried out with the instrumented handlebars mounted on a bicycle, placing three accelerometers and a GPS meter and traveling through a real test circuit, with a rough surface, speed bumps and areas with shaped warning bands. Power Spectral Density (PSD) curves were obtained for the steel and carbon-fiber-composite handlebars in order to quantify the signal intensity. Finally, a fatigue analysis was carried out in order to evaluate the expected life of both handlebars under the experimentally applied load, which is considered the reference cycle. This study offers a comparative analysis of the vibration behavior exhibited by steel and carbon-fiber-composite bicycle handlebars under experimentally applied load. In conclusion, data on natural frequencies, damping functions and fatigue life expectancy for both handlebar materials were obtained. Our study provides valuable insights into the vibrational behavior and performance characteristics of steel and carbon-fiber-composite bicycle handlebars, contributing to the understanding of their comfort and safety implications for cyclists.

Structural design and dynamic characteristics analysis of braided composite two-stage gear transmission system

In order to realize the lightweight design of the transmission system, the braided composite material is applied to the two-stage gear transmission system. According to the structural characteristics of the two-stage gear reducer box, the whole box is designed to be assembled with the braided base and the box wall. Woven composite materials are applied to the web parts of mixed metal composite gears to realize the design goal of lightweight gears. Then, under the assumption of ignoring the influence of friction, bearings and other factors on the system, the dynamic model of the two-stage gear transmission system considering the box is established. By normalizing and dimensionless processing of the equations, the dimensionless differential equations of motion are obtained. The fourth-order Runge–Kutta method is used to analyze the relationship between the connection parameters and the dynamic characteristics of the system under the two working conditions of rigid and flexible connection between the composite base and the box wall.Through the analytical analysis of vibration displacement of two-stage gear reducer and box, the theoretical basis is found for the numerical analysis results. Finally, the dynamic characteristics of the transmission system are studied by vibration resonance analysis through high and low frequency interference. It is found that in a certain frequency range, with the decrease of the mass and moment of inertia of the transmission parts corresponding to the mixed metal composite gear, the amplitude-frequency characteristic Q of the lightweight gear and gearbox transmission system is slightly lower than that of the common gear and gearbox system, and the stability of the system is increased, and the dynamic characteristics of the system are improved.

A novel braided bamboo composite material with balanced strength and good energy absorption capacity inspired by bamboo

Engineering bamboo composite materials are widely used in construction industry. However, the impact load will inevitably affect the structural safety and service time of the engineering bamboo composite material. In this work, a braided glued laminated bamboo (BGLB) strong with balanced strength and good energy absorption capacity is developed, which was systematic characterized by tension, compression and bending tests at the angle of 0°, 45° and 90° and low-velocity impact tests. Results show that the progressive damage improves BGLB in 45° and 90° of the mechanical properties significantly compared to bamboo scrimber (BS). The absorbed energy of BGLB bending specimens increased by 55%, 1734% and 3983% more than that of BS under the angle of 0°, 45° and 90°. There is little difference between the transverse (0°) and longitudinal (90°) mechanical properties of BGLB. At the impact energy of 300 J, the specific energy absorption (SEA) of BGLB (1.07 J/g) is 15% larger than that of BS (0.93 J/g). The unique design makes BGLB to have better impact resistance and secondary load capacity than BS. The work balances the strength and good energy absorption capacity of BGLB, which can provide a new design idea for bamboo/wood engineering materials and help the development of high-strength bamboo/wood engineering materials.

Electro‐mechanical coupling analysis of three‐dimensional embedded braided composite piezoelectric vibration energy harvester

AbstractIn this article, the piezoelectric patches are embedded into three‐dimensional (3‐D) braided composite material (BCM), and a 3‐D embedded braided composite piezoelectric vibration energy harvester (BCPEH) is designed. The 3‐D embedded BCPEH can be applied in more complex working environments to protecting the piezoelectric patches, and has a longer lifespan. The material parameters of the 3‐D BCM are obtained by analyzing the representative volume units (RVU). Using Hamilton's variational principle, the vibration control equation, and the output voltage and power expression are derived. The influence of excitation frequency, load resistance, and external excitation on the output voltage and power are simulated under different braided angles and embedded depths.

Prediction of effective mechanical properties of 2D triaxially braided composites using a geometrical model incorporating flat portions of composite yarns

This study aims to predict the effective mechanical properties (EMPs) of a 2-D triaxially braided composite (TBC) using an analytical model and to investigate the effects of various geometric parameters on them. The 2-D TBC, a type of braided textile composite, consists of an axial yarn and two braider yarns that are oriented in different diagonal directions within a plane, alternating between running below and above each other. A geometrical model is built considering the flat portion of the composite yarn to adjust the fiber volume fraction of the 2-D TBC while keeping other parameters constant. The prediction method is verified by comparing it with experimental and predicted results reported in various references, demonstrating good agreement. A parametric study indicates that geometric parameters affect the undulation path of a braider yarn and the volume content or each composite yarn, resulting in significant impacts on EMPs. The proposed prediction method is competitive in terms of computing time compared to finite element-based methods and can contribute to the design and improvement of composite structures.

Effect of Braid Angle on Crushing Performance of Double-Layer Carbon Fiber Composite Pipe

Three-dimensional braided composite materials have the advantages of high specific strength and good specific rigidity, they are widely used in various fields. With the help of the full-scale macrostructure model finite element analysis method to pre-test the mechanical properties of the axial compression, the simulation can observe the failure process, stress distribution and propagation form of the pipe, and study its failure mechanism. Then verify the correctness of the simulation through experiments. The conclusion is that the compressive performance of the material changes with the change in the braid angle. A smaller braiding angle can bear a larger load, but its material failure process is relatively rapid, and the load drop increases as the braiding angle decreases.

Finite-element analysis on the compression-recovery process of cotton fiber assembly

In order to analyze the compression and recovery behavior of cotton fiber assembly, and to improve the quality of cotton bales. a cotton fiber assembly model is established based on the modeling idea of three-dimensional braided composite material. At the same time, the compression modulus and recovery modulus of the cotton fiber assembly are measured by experiments. The finite-element analysis of the cotton fiber assembly is carried out with the obtained compression and recovery modulus, the recovery rate and the compression power recovery rate of the cotton fiber assembly are predicted. By further study of the effect of moisture regains on the recovery rate and compression power recovery rate of cotton fiber assembly, a referenced moisture regain value of 8.8% in cotton baling process is given. The results show that the analyzed results are consistent with the actual situation; the model has certain application value.

Complex Structure of Braid in Fiber Art Creation with Multisensor IoT Technology

Fiber-fabric composites have the characteristics of lighter texture, higher strength, higher damage resistance, better toughness, and flexibility than laminated composites, but their complex structures have not been well studied. This paper is aimed at study the complex structure of woven fabrics in fiber art creation based on multisensor Internet of Things technology and at studying the impact of its composite material mechanical properties. In this paper, it is proposed to use glass fibers and carbon fibers to weave the required structural preforms in a two-dimensional braiding machine and then use the obtained preforms and epoxy resin to prepare three-dimensional two-dimensional braided composite materials with different structures through a molding process. The composites were tested in tension, bending, and compression to obtain data and their failure modes, and the data were compared to obtain correlations. The experimental results in this paper showed that through the tensile, bending, and compression tests of the three kinds of hybrid structure braided composites, the tensile properties of the glass fiber braided composites decreased by about 77%; the influence of angle on the bending properties of carbon fiber braided composites has the largest downward trend of 63%. Two-dimensional biaxial and two-dimensional triaxial preforms are made by weaving glass fiber and carbon fiber, and the angle deviation is basically kept within 2.2%.

Investigation of Thermal and Mechanical Properties of Three-Dimensional Braided Composite Materials

Investigation of Thermal and Mechanical Properties of Three-Dimensional Braided Composite Materials

A Mixed Wavelet-Learning Method of Predicting Macroscopic Effective Heat Transfer Conductivities of Braided Composite Materials

A Mixed Wavelet-Learning Method of Predicting Macroscopic Effective Heat Transfer Conductivities of Braided Composite Materials

The effect of loading rate on the in-plane shear strength of tri-axial braided composites

The in-plane shear strength of tri-axial braided composite materials was measured for three different braid angles (30°, 45°, and 60°) and two strain rates (0.001 s−1; 3 s−1) using the three-rail shear test. The in-plane shear strength was found to be sensitive to both—the braid angle and the strain rate. An increase of braid angle resulted in a reduction of shear strength, whilst an increase of loading rate resulted in an increase of shear strength of 8%–17%, depending on the braid angle.

Postbuckling response of unitized stiffened textile composite panels: Computational modeling

A computational investigation of unitized stiffened textile composite panels that are manufactured from triaxially braided textile composites and loaded in axial compression into the postbuckling regime is presented. The stiffened panels are unitized because the textile nature of the constituent material, in conjunction with an alternative stiffener design, form a near-net shape one-piece stiffened panel structure where the textile laminae that form the skin section of the panel are also used, without discontinuity of material, to form the stiffener. A multiscale computational model is presented where the architecture-dependent behavior of a discretely modeled mesoscale representative volume element is passed up to the orthotropic homogenized macroscale stiffened panel shell model. The mesoscale model is automatically executed based on input from the macroscale shell model. Progressive damage initiation and propagation is accomplished by implementing a crack band model in the macroscale model to simulate a material softening behavior. The experimental results are compared to the computational multiscale framework analysis results where a mesoscale triaxially braided textile composite architecture-based model serves as the damage initiation criterion for a smeared progressive damage crack band model in the orthotropic homogenized stiffened panel macroscale shell model.

A Modified Compact Tension Test for Characterization of the Intralaminar Fracture Toughness of Tri-Axial Braided Composites.

The application of braided composite materials in the automotive industry requires an in-depth understanding of the mechanical properties. To date, the intralaminar fracture toughness of braided composite materials, typically used for describing post-failure behavior, has not been well-characterized experimentally. In this paper, a modified compact tension test, utilizing a relatively large specimen and a metallic loading frame, is used to measure the transverse intralaminar fracture toughness of a tri-axial braided composite. During testing, a relatively long fracture process zone ahead of the crack tip was observed. Crack propagation could be correlated to the failure of individual unit cells, which required failure of bias-yarns. The transverse interlaminar fracture toughness was found to be two orders of magnitude higher than the reference interlaminar fracture toughness of the same material. This is due to the fact, that intralaminar crack propagation requires breaking of fibers, which is not the case for interlaminar testing.

In-plane compression failure mechanism of two-dimensional triaxial braided composite (2DTBC) material subjected to different load directions

Two-dimensional triaxial braided composite (2DTBC) often fails by external force from different directions in service. In this work, the in-plane compression failure mechanism of 2DTBC was studied along the axial (0°), off-axial (±60°) and perpendicular (90°) directions at quasi-static and high strain rate. The progressive failure process was recorded by infrared thermography with the final morphology using computer tomography technology. A three-dimensional mesoscale finite element model was established to simulate the initiation, accumulation and propagation of various damages. The results show that the in-plane compression strength, strain, energy absorption and failure mode of 2DTBC depends on whether there are main load-bearing (axial or braided) yarns directly transferring stress along load directions. The occurrence and development of localized damages can be captured by high-speed IR thermography and verified by final morphology. The in-plane failure mechanism of 2DTBC is induced by different dominating factors under different load directions, such as the out-of-plane movement of braided yarns, kinking effect at crimp positions, structure antisymmetry effect, buckling and shear instability. • Effect of main load-bearing (axial or braided) yarns during the in-plane compression. • Occurrence and development of damages captured by high-speed IR thermography. • Effect of yarns out-of-plane movement, kinking, buckling and shear instability.

The Influences of Projectile Material and Environmental Temperature on the High Velocity Impact Behavior of Triaxial Braided Composites

Two-dimensional (2D) triaxial braided composites with braiding angle (± 60°/0°) have been used as aero-engine containing casing material. In the current paper, three types of projectile with the same mass and equivalent diameter, including cylinder gelatin projectile, carbon fiber-reinforced plastics (CFRP), and titanium alloy blade-like projectile, were employed to impact on triaxial braided composites panels with thickness of 4.3 mm at room temperature (20 °C) to figure out the influences of projectile materials on the damage pattern and energy absorption behavior. Furthermore, the influences of environmental temperature were also discussed considering the aviation service condition by conducting ballistic impact tests using CFRP projectile at cryogenic temperature (−50 °C) and high temperature (150 °C). The triaxial braided target panel were pre-heated or cooled in a low-temperature chamber before mounted. It is found that soft gelatin project mainly causes global deformation of the target and therefore absorb much more energy. The triaxial braided composite absorb 77.59% more energy when impacted with CFRP projectile than that with titanium alloy projectile, which mainly results in shear fracture. The environmental temperature has influences on the damage pattern and energy absorption of triaxial braided composites. The cryogenic temperature deteriorates the impact resistance of the triaxial braided composite material with matrix cracking damage pattern, while high temperature condition improves its impact resistance with shearing fracture damage pattern.

Intralayer hybridization of triaxially braided composite lamina using carbon and basalt fibers: Experimental and numerical study

The objective of this study is to investigate the tensile properties of hybrid triaxially braided composites of carbon and basalt fibers. Two non-hybrid preforms and two hybrid preforms were prepared using a circular braiding machine. Then, the prepared preforms were fabricated by vacuum assisted resin transfer molding. Uniaxial tensile tests were performed in longitudinal and transverse directions. Experimental results showed improved tensile moduli in longitudinal direction when carbon and basalt fibers were used as axial and braid yarns, respectively. In general, most tensile properties improved when triaxially braided carbon composite material was hybridized with basalt fibers. In addition, an attempt was made to predict the tensile behavior of triaxially braided composites using meso-scale finite element modeling. Comparison of the results showed that the current meso-scale finite element modeling could not capture the nonlinear behavior of the hybrid composites. However, the linear responses were well predicted. Therefore, possible sources of error and solutions to overcome them were discussed.

Temperature and structure effects on the impact damage distribution of 3D braided composites

Three-dimensional braided composite materials are prepared by fiber bundle braiding and composite material forming. These materials can realize the integration of material structure to manufacture complex structural parts in a near net-shape way and reduce the number of assembly connections. This material has been widely used in the aerospace industry, high-speed vehicles, and important civil facilities. Computed tomography (CT) and finite element method (FEM) were used to characterize the relationship between the internal damage distribution of 3D braided carbon fiber/epoxy resin composites under multiple transverse impact loading, ambient temperature, and microstructure. It is determined that with an increase in the temperature, the failure mode of resin changes from brittle failure to ductile failure, the interface bond strength decreases, and the failure mode changes to fiber/resin interface cracking and resin debonding. With an increase in the braiding angle, the failure mode changes from interface cracking to resin debonding cracking; interface cracking simultaneously occurs, impact tolerance increases, and local temperature increases with an increase in the absorbed energy. With an increase in the number of impacts, the accumulation of impact damage leads to the clear cumulative effect of reinforcement deformation, interface cracking, and resin debonding.

Prediction of mechanical properties on 3D braided composites with void defects

Void defects have appeared inevitably during the manufacturing process of braided composites, which directly affect the mechanical properties and strength of braided composites. First, the influence of internal void and porosity on the mechanical properties of resin was predicted. Second, the evolution in the mechanical properties of three dimensional (3D) braided composites was obtained using the Mori-Tanaka method. Finally, the strength prediction, failure mode, stress and strain field of 3D braided composites with void defects were investigated by means of finite element simulation based on the progressive damage theory in ABAQUS, which will compare the simulation results with the theoretical results and other scholar's experiments. The innovation of this work is to establish the constitutive model and finite element model of 3D braided composite material with voids and predict the evolution of the mechanical properties of 3D braided composite material with defects. The results will provide the theoretical and design basis for evaluating the influence of void defects on the mechanical properties of 3D braided composites.