Angle-interlock Woven Research Articles

Quasi-Static Tensile Properties and Damage Mechanism of Three-Dimensional Angle-Interlock Woven Composites

The uniaxial tensile properties of three-dimensional angle-interlock woven composites (3DAWCs) under quasi-static loading were investigated in this paper. The samples were manufactured into dog-bone shape and tested on Material Test System 810.23. The strain-stress curves in warp direction indicating the Young’s moduli, maximum stress and maximum strain are achieved from the uniaxial tensile test. The effects of microstructure and damage morphology of 3DAWC under quasi-static tension are discussed. Furthermore, we will focus on the energy absorption mechanism from the view of tensile failure mode. The material parameters of 3DAWC in warp direction can be evaluated for developing quantitative approach to design polymer matrix composite structures.

Experimental Investigation on the Low-Velocity Impact Damage of 3D Angle-Interlock Woven Composites

In this paper, the low-velocity impact behavior of the 3D angle-interlock woven glass-fiber/epoxy composites (3DAWCs) were tested and analyzed under several levels of impact energies. The energy-time curves, deflection-time curves and load-deflection curves were obtained to show the impact damage behavior. It was found that the damage magnitude increases with the impact energy, and the composite structure can effectively reduce the in-plane shear failure. In addition, the failure modes were also photographed to illustrate the damage mechanisms of the3DAWCs.

Generating virtual textile composite specimens using statistical data from micro-computed tomography: 3D tow representations

Recent work presented a Monte Carlo algorithm based on Markov Chain operators for generating replicas of textile composite specimens that possess the same statistical characteristics as specimens imaged using high resolution x-ray computed tomography. That work represented the textile reinforcement by one-dimensional tow loci in three-dimensional space, suitable for use in the Binary Model of textile composites. Here analogous algorithms are used to generate solid, three-dimensional (3D) tow representations, to provide geometrical models for more detailed failure analyses. The algorithms for generating 3D models are divided into those that refer to the topology of the textile and those that deal with its geometry. The topological rules carry all the information that distinguishes textiles with different interlacing patterns (weaves, braids, etc.) and provide instructions for resolving interpenetrations or ordering errors among tows. They also simplify writing a single computer program that can accept input data for generic textile cases. The geometrical rules adjust the shape and smoothness of the generated virtual specimens to match data from imaged specimens. The virtual specimen generator is illustrated using data for an angle interlock weave, a common 3D textile architecture.

Cumulative fatigue damage for 3-D angle-interlock woven composite under three-point bending cyclic loading

This article presents the quantitative characterization of cumulative fatigue damage behavior for the three-dimensional angle-interlock woven composite undergoing three-point bending cyclic loading. The S–N curve was obtained to demonstrate the fatigue life of the three-dimensional angle-interlock woven composite under different stress levels. The increment of cycles for each 5% interval of stress level was reported to show the difference of fatigue resistance performances of the three-dimensional angle-interlock woven composite among the high, middle, and low intervals of stress level. In addition, the Cumulative Fatigue Damage versus Number of Cycles (D–N) curve and the Deflection Index versus Number of Cycles (F–N) curve were deduced to characterize the three-stage cumulative fatigue damage. Furthermore, the damage morphologies of the three-dimensional angle-interlock woven composite after fatigue tests were photographed to compare with those in quasi-static test. The cracks initiation and propagation in the three-dimensional angle-interlock woven composite during the process of cyclic loading were summarized to find the mechanisms of fatigue damage development.

Generating virtual textile composite specimens using statistical data from micro-computed tomography: 1D tow representations for the Binary Model

A Monte Carlo algorithm is defined for generating replicas of textile composite specimens that possess the same statistical characteristics as specimens imaged using high resolution computed tomography. The textile reinforcement is represented by one-dimensional tow loci in three-dimensional space, which are easily incorporated into the Binary Model of textile composites. A tow locus is expressed as the sum of non-stochastic, periodic variations in the coordinates of the tow centroid and stochastic, non-periodic deviations. The non-stochastic variations have period commensurate with the dimensions of the unit cell of the textile, while the stochastic deviations, which describe geometrical defects, exhibit correlation lengths that may be incommensurate with the unit cell. The model is calibrated with data deduced in prior work from computed tomography images. The calibration obviates the need for assuming any ideal shape functions for the tow loci, which can take very general form. The approach is therefore valid for a wide range of textile architectures. Once calibrated, a Markov Chain algorithm can generate numerous stochastic replicas of a textile architecture very rapidly. These virtual specimens can be much larger than the real specimens from which the data were originally gathered, a necessary feature when real specimen size is limited by the nature of high resolution computed tomography. The virtual specimen generator is illustrated using data for an angle interlock weave.

Three-point bending fatigue behavior of 3D angle-interlock woven composite

This study reports the three-point bending fatigue behavior of three-dimensional angle-interlock glass/polyester woven composite (3DAWC). The S–N curve was obtained under the different bending stress levels. The bending stress vs. bending deflection curves were recorded to show the stiffness degradation and bending deformation of the 3DAWC during the fatigue test. The failure modes of the 3DAWC under the different fatigue loading conditions were photographed and compared with those in quasi-static bending tests. It was found that the integrated construction structure of the 3D angle-interlock woven fabric can resist the delamination of the 3DAWC under high-cycle fatigue loading. The cracks propagation and breakages of the warp yarns that run through the thickness direction of the 3DAWC dominate the fatigue failure. The resin cracks and resin-yarn interface debonding are the secondary factors for determining the fatigue behavior.

Fiber inclination model for finite element analysis of three-dimensional angle interlock woven composite under ballistic penetration

A three-dimensional (3D) finite element model is created from finite element code LS-DYNA to simulate the ballistic penetration of a hemispherical cylindrical steel projectile into a 3D angle-interlock woven composite (3DAWC). ‘Fiber inclination model’ [Yang JM, Ma CL and Chou TW. Fiber inclination model of three-dimensional textile structural composites. J Compos Mater 1986; 20(9): 472—484] is employed to decompose the composite to four inclined unidirectional laminae which have the same fiber volume fraction and thickness as the 3DAWC. The commercial finite element code LS-DYNA is used to simulate the ballistic penetration of 3DAWC. The residual velocity of the projectile after perforating the 3DAWC panel is calculated. Comparing the simulated residual velocity of the projectile and the damage morphology of the 3DAWC with those of experimental results, we found that the ‘fiber inclination model’ for finite element analysis of the 3DAWC under ballistic penetration is valid and reasonable in ballistic impact simulation. Such an effort could be extended to the ballistic performance design of the 3DAWC in a simplified way.

FEM simulation of 3D angle-interlock woven composite under ballistic impact from unit cell approach

Ballistic impact damage of 3D angle-interlock woven composite (3DAWC) under a hemispherical-cylindrical steel projectile has been investigated in experimental and finite element method (FEM) based on a unit cell model. In the unit cell model, the composite was simplified into a combination of resins, weft yarns and warp yarns to define the stiffness matrix and failure evolution of the material. VUMAT (FORTRAN vectorized user-material) subroutine which based on the unit cell model has been developed and connected with commercial FEM code ABAQUS/Explicit (ver. 6.8) to calculate the ballistic impact damage and energy absorption of the composite. The experimental and FEM results of residual velocities of the projectile, and damages of the composite target were compared. Good agreement between experimental and theoretical proves the unit cell model and the VUMAT subroutine are reasonable for ballistic performance design of the 3D angle-interlock woven composite.

Analysis of Compressibility and Permeability of Selected 3D Woven Reinforcements

For three 3D woven carbon fiber reinforcements with different architectures, the compressibility, geometrical structure, and permeability were studied. At low levels of compression, the thickness of an angle-interlock weave is reduced mainly by local reduction of the height of inter-bundle voids and permanent reordering of the fiber bundles. At higher compression levels, bundle compaction is dominant. For an orthogonal weave fabric, the main compression mechanism is compaction of the fiber bundles. The in-plane permeability is modeled by superimposing a disturbance, caused by the binder yarns, to the permeability of a regular layered fiber structure. It is characterized mainly by the dimensions of the inter-bundle voids in each layer, and the pattern and dimensions of the binder yarns. Because of the dependence on the inter-bundle void dimensions, the fabric compression behavior is reflected. The through-thickness permeability is determined by flow-enhancing channels in the structure of the reinforcement, formed around the binder yarns. It is modeled as a function of the number of binder yarns per unit surface area, and the dimensions and orientation of the binder yarns.

Use of 3D Angle-Interlock Woven Fabric for Seamless Female Body Armor: Part 1: Ballistic Evaluation

In contrast to making male body armor, manufacturers of body armor encounter problems in design and manufacture of female body armor because of the curvaceous body shape of females. The traditional cut-and-sew method could be used to form the dome shape to accommodate the bust area but it gives rise to weakness at the seams against projectile impact. Fabric folding has been another way to form the domes but it also leads to reduced impact performance and wearing discomfort. In this paper, angle-interlock woven fabrics are proposed as an alternative to the conventional plain woven fabrics in making female body armor due to their advantages in moldability without the need of cutting or folding and ease in manufacture. However, it is vital that the angle-interlock fabrics satisfy the ballistic requirements before being employed for the body armor application. Part Ι of this paper reports on an investigation on the ballistic performance of angle-interlock fabrics. It has been found that the angle-interlock fabric is not less than the conventional fabric constructions used for body armor against ballistic impact. Based on the employment of the angle-interlock fabric, Part ΙΙ presents the mathematical modeling of molding of angle-interlock fabrics to form the front panel of female body armor, which would lead to quick creation of female body armor based on the input of the body and bust sizes.

Three-dimensional textile structural composites under high strain rate compression: Z-transform and discrete frequency-domain analysis

Z-transform theory was applied to several three-dimensional (3D) textile structural composites, including an angle-interlock woven composite, a multilayer multi-axial warp knitted composite and a 4-step braided composite, to characterize their system dynamic behaviour in the frequency domain. More specifically, the analysis focused on the relationship between the compressive load and the system response under static (strain rate 0.001 s−1) and impulsive (strain rate up to 2700 s−1) strain along both the in-plane and out-of-plane directions, respectively. The high strain rate compressions were tested using a split Hopkinson pressure bar apparatus, and the input and output (the stress–strain curve) of the test specimen was obtained by recording the signals using a computer for further analysis. Z-transform was then used to analyze the dynamic response and stability of the composites of different preform structures and at various loading conditions. This is the first such attempt to study the compression behaviour of 3D textile structural composites at various strain rates in the frequency domain in order to reveal their mechanical behaviour and features of the materials from a new perspective.

Frequency Analysis of Stress Waves in Testing 3-D Angle-interlock Woven Composite at High Strain Rates

This article presents Fourier transform and wavelet packet analysis of stress waves in a split Hopkinson pressure bar apparatus where the compressive behaviors of 3-D angle-interlock woven composite were tested at strain rate of 800/s, 1600/s and 2100/s. The stress waves in incident and transmission bar are transformed into frequency domain to analyze the impact energy spectrum under different lengths and impact velocities of the strike bar. It was found that the energy-frequency distribution is irrelevant to impact velocity and will be left-shifted when the length of the striker bar (i.e., width of incident stress wave) increases. The impact energy is mainly concentrated on the low-frequency region. The wavelet packet analysis of the incident and transmission stress waves shows that the transform coefficients decrease from the low-frequency region to the high-frequency region. Furthermore, the coefficients in the high-frequency region only occur at the ascending and descending part of stress waves. Based on the time-frequency analysis results, a unique start point of the stress wave can be determined for the stress-time and strain-time history calculation. This method can improve the calculation precision of stress—strain curves of the 3-D woven composite under different strain rate compression. The calculating results indicate that the stress—strain curves of the 3-D angle-interlock woven composites are sensitive to strain rate. The compressive modulus, maximum compressive stress linearly increases with strain rate. The failure strain decreases when the strain rate increases. This start point determination method can also be extended to high strain rate tests (including compression, tension, etc.) of other materials with split Hopkinson bar apparatus.

Development of Design Analysis Methods for Carbon Silicon Carbide Composite Structures

The stress—strain behavior at room temperature and at 1100° C (2000°F) is measured for two carbon fiber-reinforced silicon carbide (C/SiC) composite materials: a two dimensional (2D) plain-weave quasi-isotropic laminate and a 3D angle interlock woven composite. Previously developed micromechanics-based material models are calibrated by correlating the predicted material property values with the measured values. Four-point beam-bending subelement specimens are fabricated with these two fiber architectures and four-point bending tests are performed at room temperature and at 1100°C. Displacements and strains are measured at the mid-span of the beam and recorded as a function of load magnitude. The calibrated material models are used in concert with a nonlinear finite-element solution using ABAQUS to simulate the structural response of the two materials in the four-point beam bending tests. The structural response predicted by the nonlinear analysis method compared favorably with the measured response for both materials and both test temperatures. Results show that the material models scale-up fairly well from coupons to subcomponent level.

Elastic behavior analysis of 3D angle-interlock woven ceramic composites

ABSTRACT A micromechanical model for elastic behavior analysis of angle-interlock woven ceramic composites is proposed in this paper. This model takes into account the actual fabric structure by considering the fiber undulation and continuity in space, the cavities between adjacent yarns and the actual cross-section geometry of the yarn. Based on the laminate theory, the elastic properties of 3D angle-interlock woven ceramic composites are predicted. Different numbers of interlaced wefts have almost the same elastic moduli. The thickness of ceramic matrix has little effect on elastic moduli. When the undulation ratio increases longitudinal modulus decreases and the other Young's moduli increase. Good agreement between theoretical predictions and experimental results demonstrates the feasibility of the proposed model in analyzing the elastic properties of 3D angle-interlock woven ceramic composites. The results of this paper verify the fact that the method of analyzing polyester matrix composites is suitable for woven ceramic composites.

Stress and Failure Analysis of 3D Angle Interlock Woven Composites

A three-dimensional woven composite strength model is presented for predicting the failure behavior of three-dimensional angle interlock woven composites under on-axis uniaxial static tensile loading and shear loading. The model is based on two-level discretization of the repeating unit cell. The repeating unit cell is discretized into sections, elements, subsections and subelements. The model predicts the stress levels at which the secondary failures take place at subelementlevel. The effectof secondary failure is considered for further analysis and the ultimate tensile strength and shear strength and the corresponding strains are predicted. A parametric study has been carried out for different 3D angle interlock woven composite configurations.

Fatigue behavior of 3D multi-layer angle interlock woven composite plates

This study was aimed at investigating the fatigue behavior of three-dimensional (3D) multi-layer angle interlock woven composite plates. Tensile cyclic stress was applied to the specimen along the weft yarn direction. Unnotched three-layer and five-layer plates were used in this work in order to compare their fatigue properties and damage processes. The effect of a center hole on the fatigue behavior was also investigated by using notched three-layer and five-layer plates. The experimental results showed that the three-layer specimen exhibited higher static ultimate tensile strength (UTS), but lower fatigue limit strength or higher fatigue sensitivity than the five-layer specimen for both the unnotched and notched plates. Normalized S/N curves of the unnotched and notched specimens, the maximum cyclic stress being divided by the appropriate UTS, were observed almost to coincide on a single line for both the three-layer and five-layer plates. This indicated that a center hole did not affect the fatigue sensitivity of these plates. Metallography was employed to study the microscopic fatigue damage process. According to the observations, the fatigue process could be divided into five stages. The fatigue damage mechanism primarily involved transverse cracks in the warp yarns, debonding between the warp and weft yarns, debonding extension and deflection into the matrix, and weft fiber breakage.

Micromechanics models for mechanical and thermomechanical properties of 3D through-the-thickness angle interlock woven composites

Abstract In this paper, a laminate block modeling approach for three-dimensional (3D) through-the-thickness angle interlock woven composites is used to develop one finite element analysis (FEA) model and two analytical models, namely the “ZXY model” and the “ZYX model”. These models can be used to determine the mechanical properties and the coefficients of thermal expansion for 3D through-the-thickness angle interlock woven composites. A parametric study shows that there is good agreement between these FEA and analytical models. The parametric study also demonstrates the effects of the fiber volume fraction of the warp weaver (i.e., z yarn) and the space between two adjacent filler yarns on the mechanical properties and the coefficients of thermal expansion. Finally, the present models are found to correlate reasonably well with the predicted and measured results available in the literature.

Ceramic-matrix composites fatigue and fracture

Fiber-reinforced ceramic-matrix composites (CMCs) have been shown to exhibit excellent high-temperature properties. There are some published data on the mechanical properties of Nicalon fiber-reinforced composites with various matrices, but much of the work was performed in bending, and there is little information on the failure modes in textile-reinforced CMCs, especially under cyclic-loading conditions. This article is an interim report on research that examines the tensile deformation, fracture, smoothbar fatigue, and fatigue crack-growth behavior of several CMCs. Unidirectional, two-dimensional eight-harness satin weave, and three-dimensional angle-interlock weave Nicalon fiber architectures infiltrated with polymers and then pyrolized were investigated and are compared with similar experiments on Nicalon-reinforced calcium-silicate glass-ceramic-matrix composites.

Mechanisms of compressive failure in 3D composites

Angle interlock woven polymer matrix composites have been studied under uniaxial monotonic compression. With considerable variations arising from the geometry of the reinforcement and the degree of constraint in the test, the materials were found to be macroscopically ductile, with compressive strains to failure occasionally exceeding 15%. In contrast, some tests on stiched laminates showed brittle behavior, with essentially no load bearing capacity beyond the strain for peak load (∼1%). The mechanisms of failure in the woven composites were determined by a combination of optical microscopy (both in situ and of sectioned specimens), moiré interferometry, stereoscopy, and digital image comparison. In all cases, the central failure event was kink band formation in the primary load bearing, axial tows. Various characteristics of the reinforcement geometry were observed to influence kink band formation, including initial misalignment of the load bearing tows and intersections of load bearing tows and through-thickness reinforcing tows. Such geometrical characteristics acted as flaws, tending to lower macroscopic stiffness and strength, but promoting the broad distribution of damage throughout the specimen and averting catastrophic failure. Guidelines for achieving the optimum compromise between strength and damage tolerance may be inferred from these observations.

Modeling and Experimental Investigations of Pressure Infiltration of Sol-Gel processed 3-D Ceramic Matrix Composites

ABSTRACTA parabolic rate kinetics model has been developed and verified by experiments for the pressure infiltration of textile ceramic matrix composites using sol-gel processing with added solid particles. Darcy's law and a global permeability of the whole system were adopted in the model. The permeability of the whole system consisting of fiber preform, compaction, and filter was derived from the individual permeabilities of the fiber preform and particle compaction inside the preform which were based on the Kozeny-Carman equation. Experiments were conducted using 3-D angle interlock woven carbon fiber preforms and silica sol containing silica particles of 0.25μm and 0.5μm sizes. The total infiltration time was inversely proportional to the constant processing pressure and increased significantly with reducing the solid particle size by a factor of two. This is because the permeability of particle compaction layer is the dominant term and it is proportional to the square of particle size.