Three-dimensional Angle-interlock Woven Composites Research Articles

Multiscale modeling for the impact behavior of 3D angle-interlock woven composites

In this paper, a multiscale modeling framework predicting the impact response of three-dimensional angle-interlock woven composites (3DAWCs) is presented. Multiscale modeling is performed sequentially at the mirco, meso, and macroscales. A microscopic representative volume element (RVE) model is established to characterize the yarn's nonlinear mechanical properties and damage behavior at different strain rates. At the mesoscale, a novel subcell-based discretization scheme is proposed to discretize 3DAWCs, and developing six representative subcells (RSCs) that bridge the microscale and macroscale effective properties. Based on it, a ballistic impact model involving six kinds of homogeneous material bricks is established. Furthermore, elastic-viscoplastic damage constitutive models are developed for the epoxy matrix and the yarn, respectively, to enhance the predicted accuracy of the multiscale model. Ballistic impact tests of 3DAWCs are conducted, and X-ray micro-computed tomography is employed to evaluate the internal damage of the 3DAWC target after impact. Validation work is conducted by comparing the experimental and numerical results of the ballistic impact of the 3DAWC target, which indicates the effectiveness and efficiency of the developed multiscale framework in the impact damage prediction of 3DAWCs.

Size-dependent mechanical behaviors of 3D woven composite under high strain-rate compression loads

Dynamic characterization of textile composites is confronted with great challenges due to its large unit-cell size and the inherent limitations in specimen size for the Hopkinson bar-based test system. The small specimen size will inevitably introduce variations in effective mechanical response and failure mechanism, and bring about additional problems in determining the realistic dynamic properties of the material. This work experimentally investigated the dynamic compression behavior of three-dimensional angle interlock woven composite (3DWC) using the split Hopkinson pressure bar (SHPB). Specimens with different sizes were designed to explore the size dependency, strain-rate dependency and orientation dependency for the compressive behavior of the 3DWC. A high-speed camera and an optical microscope were introduced to elaborate on the damage progressing process and fracture morphology under different loading conditions. With an increase in strain rate, the measured strength of warp-direction specimens increased by approximately 7.6%, 4.8%, and 2.6% for three different sizes of specimens, accompanied by more severe intra-tow damage. Different-sized dynamic specimens exhibited comparable failure processes but modest variations in measured properties. When the number of unit cells in a specimen increased from two to three and four, the strength was observed to rise by around 14.9% and 21.9% respectively. In comparison to the warp-direction specimen, the weft-direction specimens exhibited substantially higher strength and failure strain, as well as distinct dominant failure modes of yarns. This work provides valuable insights into the determination of dynamic properties for 3D woven composites, and the designing and interpretation of dynamic test methods.

Ballistic performance and damage behavior of three-dimensional angle-interlock woven composites under high velocity impact: Experimental and numerical studies

Three-dimensional angle-interlock woven composites (3DAWCs) are usually employed as exposed components in aerospace and other high-tech areas due to their superior impact resistance. In this work, the experimental characterization and numerical modeling are combined together to study the ballistic performance and damage behavior of 3DAWCs under high velocity impact (HVI). The initial-residual velocity relation is examined by ballistic impact test and the penetration process is recorded by high-speed camera. A nonlinear finite element (FE) model based on a multi-scale modeling framework is established to simulate the ballistic impact response and damage behavior of 3DAWCs. The proposed FE model is verified by comparing the predicted initial-residual velocity curve and penetration propagation with the experimental data. Parameter analysis is conducted to address the influences of projectile diameter and impact angle on the impact performance of 3DAWCs and the corresponding damage mechanisms are revealed in detail. The present work provides a transferable approach for studying the HVI problems of other textile composite structures.

Fiber inclination model for the anti-penetration performance of a new type three-dimensional angle-interlock woven composite

This study establishes a fiber inclination model suitable for a new three-dimensional angle interlocking woven UHMWPEF/epoxy composite, and evaluates its anti-penetration performance. Specifically, the microstructural characteristics of the composite material were analyzed by CT scan images, the mesostructure model of the material was established with the help of the software TexGen, and the calculation method of the fiber volume fraction of the material was designed. The meta-software ANSYS/LS-DYNA simulated and analyzed the failure mode and stress after ballistic penetration, before verifying it with the ballistic penetration test of the composite material as the target. The results show that the fiber volume fraction of the material is calculated to be 49.5% according to the derivation formula, which is consistent with that measured in the laboratory (50%±1%). By simplifying the numerical simulation model of composite ballistic penetration with the “fiber inclination model,” the residual velocity of the projectile calculated is in good agreement with the experimental value with an error of <7%. In the target penetration test, the damage patterns of the target surface and the ejection surface are similar to the numerical simulation results. In the fiber inclination model, the failure shape of the projectile penetrating the horizontal one-way plate is almost circular, while the failure shape in the inclined one-way plate is irregular with a more severe damage along the inclined direction. In both unidirectional plates the damage area of the incoming surface is smaller than that of the ejected surface. Therefore, it is valid to use the fiber inclination model established to study the penetration performance of composite materials.

Compressive behaviors of thermo-oxidative aged three-dimensional angle-interlock woven composites under different strain rates

The mechanical behaviors of three-dimensional angle-interlock woven composites (3DAWCs) after thermo-oxidative aging under different strain rates are imperative to retain safety in high-temperature conditions. This work presents the thermo-oxidative aging effects on strain rate sensitivity and compression failure mechanism of 3DAWCs based on the digital image correlation technique and finite element analysis. The results revealed that the compressive modulus and maximum stress of the 3DAWCs are strain rate sensitive, while the thermo-oxidative aging would reduce the strain rate sensitivity. The strain rate coefficient of the resin and composite decreased by approximately 9% and 25% after thermo-oxidative aging, respectively. The compressive damage failure modes of the 3DAWCs mainly include resin cracks, interfacial debonding, and yarn fracture. The strain rate has effects on damage initiation and brittle-ductile fracture behavior. The aging effect changes the crack propagation path, but does not affect the inclined 45° shear mode. In addition, the strain rate effects on strain localization were found and will be enhanced after thermo-oxidative aging.

Experimental research on the compressive properties of a new type three-dimensional angle-interlock woven composite

The new three-dimensional angle-interlock woven UHMWPEF/epoxy composite was prepared by the VARIM method, and its mechanical properties were studied. Specifically, quasi-static and dynamic compression tests were carried out by universal testing machine and split Hopkinson pressure bar (SHPB) apparatus. Stress-strain curves under the quasi-static and high strain rates (800, 1000, 1400, and 1600 s−1) reveal the destructive characteristics of the composite material. The results indicate that the UHWMPEF/epoxy composite is a strain rate sensitive material and shows different levels of sensitivity at various strain rates. In the quasi-static compression test, when the strain rate was increased from 4.2 × 10−4 to 1.4 × 10−3 s−1, the failure load and ultimate strength increased by about 19.1% and 20.1%, respectively, and the failure strain and specific energy absorption decreased by about 1.53% and 6.1%, respectively. In the dynamic compression test, when the strain rate increased from 800 to 1600 s−1, the failure load and ultimate strength increased by about 16% and 15.9%, respectively, and the failure strain and specific energy absorption decreased by about 64.7% and 60.3%, respectively. The failure fracture surface of the specimen under quasi-static compression was at an angle of 40°–45° with the load direction. The matrix fragmentation at the fracture was obvious, and the warp fiber bundle was broken and peeled off from the matrix. The damage of specimen under dynamic compression develops quickly and the deformation process is short, which shows a relatively symmetrical shear fracture failure morphology.

In-plane and out-of-plane characterization of a 3D angle interlock textile composite

The present work focuses on the characterization of the in-plane and out-of-plane behavior of a three-dimensional angle-interlock woven composite. In-plane tensile and compression tests, short beam shear tests and through-the-thickness compressive tests were carried out to assess the mechanical behavior of the composite material. The results are presented in terms of stress–strain responses, elastic moduli, failure strains and strengths. In addition, the material elastic properties were measured using an ultrasonic method. Results are compared with the values of the elastic properties determined by mechanical testing. A good correlation is observed which demonstrates the pertinence of this technique to measure in particular the through-thickness elastic properties of the material.

Influence of fabric structure on the tensile and flexural properties of three-dimensional angle-interlock woven composites

The application of three-dimensional angle-interlock woven composites (3DAC) as structure components in aerospace field creates tremendous demands for mechanical properties. A new kind of 3DAC with bidirectional fabric structure was proposed in this paper. The tensile properties of 3DAC and 3D bidirectional angle-interlock composites (3DBAC) were conducted by quasi-static tensile tests. According to three-point bending method, the flexural properties of 3DAC and 3DBAC were experimentally tested. The load–displacement curves of specimens showed that 3DBAC presented the better stability due to the higher noncrimp rate. The stress–strain curves indicated that the tensile modulus of elasticity in 3DBAC was larger than 3DAC, and the flexural modulus of 3DBAC gained an advantage over 3DAC. Based on the mesostructure of fabrics, the failure characterizations of specimens were analyzed. Results showed that the yarns in 3DBAC bear the maximum load, and the tensile fracture was regular. Through the analysis of crack morphologies, it is found that 3DBAC exhibits better flexural properties. The results supply the theoretical support for the manufacturing of structural components in the field of lightweight design.

X-ray tomography and numerical study on low-velocity impact damages of three-dimensional angle-interlock woven composites

Three-dimensional (3D) angle-interlock woven composites reinforced with carbon fibers were tested under low velocity impact with energies of 3 J, 9 J, 15 J, 30 J. Inner damages were photographed with Micro-CT (computer tomography). It is revealed that the damage mechanisms of samples with 3 J impact energy are matrix cracks and fiber tow splitting, while interfacial damage occurs when the impact energy reaches 9 J. The delamination, fiber tow crushing and fiber breakage will appear when the impact energy raises to a higher value such as 15 J or 30 J. Finite element analyses (FEA) results show that weft yarn is the main load carrier, and yarns at the bottom of the composite bear greater impact load than the top yarns. Both the damage morphology of experimental and numerical results demonstrate that resin cracks appear along the weft yarn on the top of the composite, and exhibit a divergence centered on the impact location at the back surface. Farther from the impact center, the delamination and matrix cracks propagate from the bottom surface to the top surface along the paths of weft yarns and epoxy resins. It is recommended that the high modulus weft yarns should be used to provide the high impact resistance performance.

High-speed visualizing and mesoscale modeling for deformation and damage of 3D angle-interlock woven composites subjected to transverse impacts

The dynamic mechanical responses and progressive damage process of the three-dimensional angle-interlock woven composites (3DAWC) under repeated transverse impacts were investigated experimentally and numerically. Hopkinson pressure bar apparatus incorporating with a high-speed camera were employed to conduct impact tests and to illustrate damage development characteristics. Based on actual geometrical architecture of the 3D woven preform, a mesoscopic scale finite element model considering the interface was established to analyze the transient deformation process and damage mechanisms of 3DAWC. The interfacial failure, matrix cracking and yarn fracture were captured through the finite element analysis model and show good correlation with experimental observations. The study suggests that although the through-thickness binder yarns can improve the delamination resistance of 3D textile composites, the undulation of yarns caused stress concentration and buckling instability under compression and further kinking failure and matrix cracking.

Experimental and numerical comparisons of ballistic impact behaviors between 3D angle-interlock woven fabric and its reinforced composite

This paper compares the ballistic impact damage behaviors between the three-dimensional angle-interlock woven fabric and its reinforced composite (three-dimensional angle interlock woven composite) under various ballistic strike velocities based on experimental and numerical finite element analysis. In experiments, the residual velocities of projectiles were recorded to compare their ballistic proof properties undergoing different impact loading conditions. Furthermore, the ultimate damage morphologies of both types of materials were also compared to deduce the specific ballistic impact performance and energy absorption mechanisms between the three-dimensional angle interlock woven fabric and three-dimensional angle interlock woven composite. It was found that the three-dimensional angle interlock woven composite has absorbed more energy than the three-dimensional angle interlock woven fabric under the “high” ballistic velocities (higher than 350 m/s). And it shows the opposite phenomena under the “low” ballistic velocities (lower than 350 m/s). In finite element analysis, the simplified finite element models were established for both materials to characterize the critical importance of resin matrix in transferring and dissipating the high velocity impact energy. Especially for three-dimensional angle interlock woven composite, the impact energy was transferred to the large area during a relatively short period of time, thereby resulting in an overall bearing capacity of the composite structure, therefore absorbed most of the impact energy, which was well applied to explain the experimental results.

Impact damage and compression behaviours of three-dimensional angle-interlock woven composites after thermo-oxidation degradation

This paper reports impact and compression behaviours of three-dimensional angle interlock woven composites after the thermal ageing degradation in both experimental and finite element analyses. The composite coupons have been aged in atmospheric environment for 4, 8, 16 and 32 days at 180℃. Barely visible impact damage was induced by low velocity impact test and the residual strength was evaluated by following compression test. The results show a substantial decline in compression after impact properties after thermal ageing. After aging at 180℃ for 32 days, the compression after impact stress and modulus retention rates of three-dimensional woven composites are 59% and 82.2%, respectively. Such degradation is attributed to interface damage and matrix degradation. The fracture morphologies observed by microscopy revealed that the failure of the original specimen was dominated by matrix crack, while for long time aged specimens interface degradation became main damage mechanism. The numerical study was used to unveil the influence of matrix crack and interface degradation on failure developments of composites. The results indicate a variation from a brittle failure mode to a progressive failure model after long time ageing.

Tension–tension fatigue behavior of layer-to-layer 3-D angle-interlock woven composites

The tension–tension fatigue behavior of (the layer-to-layer) three-dimensional angle-interlock woven composite (3DAWC) was investigated using the acoustic emission (AE) technique, examination of damaged regions via light microscopy and micro-CT, and finite element analysis (FEA). AE events occurred during the entire fatigue process, and damage modes were determined based on cumulative fatigue damage of the 3DAWC undergoing tension-tension cyclic loading. FEA was employed to determine stress distribution and specific regions of stress concentrations within the composite structure. Debonding occurred at the warp tow-matrix-weft tow interface where the warp tows exhibited a maximum in amplitude of undulation. In addition, interrupted tests were performed to investigate fatigue damage modes of the 3DAWC at specific points in the fatigue life. Fatigue damage occurred in three distinct stages with characteristic damage modes.

Ballistic impact damages of 3-D angle-interlock woven composites based on high strain rate constitutive equation of fiber tows

This paper reports the ballistic impact damage of three-dimensional angle-interlock woven composite (3DAWC) under a hemispherical rigid projectile penetration on the basis of high strain rate constitutive equations of fiber tows and multi-scale geometrical model of the 3DAWC. The constitutive equations of the Twaron® fiber tows (poly paraphenylene terepthalamide, PPTA) under high strain rates have been established to characterize the mechanical behaviors under impact loading. The Twaron® fiber tows were assumed as transversely isotropic viscoelastic material to derive the constitutive equations. The maximum strain failure criterion was adopted for defining the failure of the PPTA fiber tows. A user-defined subroutine UMAT (FORTRAN user-material subroutine) was written for combining both the constitutive equations and the failure criterion in numerical calculation. Based on a micro-scale geometrical model of the 3DAWC, the UMAT for the PPTA fiber tows was combined with a commercial available finite element method (FEM) software package LS-DYNA to calculate the ballistic impact damage when the 3DAWC panel penetrated under a hemispherical–cylindrical steel projectile. It was found that the FEM simulation agrees well with the experimental results. The impact damage morphologies and damage propagations, the energy absorptions and the stress distributions in the 3DAWC panel were presented to elucidate the ballistic penetration damage mechanisms for optimizing the ballistic protection capacity of the 3-D woven composite material.

Finite Element Model Analysis of 3-D Angle-Interlock Woven Composite under Quasi-Static Tensile Loading

The tensile response of three-dimensional angle-interlock woven composite (3DAWC) under quasi-static loading was investigated in experimental and finite element model (FEM) analysis. The FEM analysis was based on micro-structure at yarn level and connected with commercial FEM software ABAQUS/Explicit (ver. 6.10) to calculate the tensile property under quasi-static loading. The experimental and FEM stress-strain results were compared. Good agreement proved that the FEM method based on micro-structure was reasonable and effective and could be used to design 3-D woven structural composite.

Drop-weight impact damage of three-dimensional angle-interlock woven composites

The drop-weight impact behavior of three-dimensional angle-interlock woven glass fiber/unsaturated polyester resin composites was investigated with a drop-weight impact tester (Instron Dynatup 9250 impact tester). A unit cell model based on the maximum stress failure criterion and critical damage area failure theory was established to define the material properties and stiffness degradation of the three-dimensional angle-interlock woven composites. A user-defined subroutine vectorized user-material was developed to connect with the commercial finite element analysis package ABAQUS/Explicit. The drop-weight impact damage and impact load-displacement curves were calculated and compared with those in the experimental. Good agreements between the experimental and finite element analysis results proved the validity of the unit cell model and the subroutine vectorized user-material. The unit cell model is expected to be extended for the study of the impact damage of three-dimensional angle-interlock woven composites structures.

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.

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.

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.