Woven Composites Research Articles

Out‐of‐plane compression properties and failure mechanism of gradient 3D woven composites

AbstractGradient three‐dimensional (3D) orthogonal preforms with low‐ and high‐density regions were manufactured through the flexible oriented 3D woven process (FO3DWP) at different fiber volume fractions and z‐yarn contents. The layer porosity distribution of preforms was regulated by modifying fiber tension and measured using micro‐computed tomography (micro‐CT) technology. After impregnation with epoxy resin, the out‐of‐plane compression properties of gradient 3D woven composites were evaluated. The results indicated that the out‐of‐plane compression strength could be improved by the gradient design. In particular, the gradient composite with a fiber volume fraction of 0.46 and z‐yarn volume fraction of 0.05 exhibited the highest compression strength at 470 MPa. Furthermore, failure morphologies were analyzed using micro‐fracture photographs and scanning electron microscopy (SEM). The gradient design efficiently protected the interface between z‐directional fibers and the matrix by minimizing z‐yarn bending. However, the compression strength of 3D woven composites decreased as the z‐yarn content increased from 0.05 to 0.15, due to the increased bending of the z‐directional fibers during the compression test.

Numerical and Experimental Analysis of Mechanical Properties in Hybrid Epoxy-Basalt Composites Partially Reinforced with Cellulosic Fillers.

The current work is focused on numerical and experimental studies of woven fabric composites modified by hybridisation with biological (cellulosic) filler materials. The mechanical performance of the composites is characterized under tensile, bending and impact loads and the effect of hybridisation is observed with respect to pure and nonhybrid composites. Numerical models are developed using computational tools to predict mechanical performance under tensile loading. The computational prediction results are compared and validated with relevant experimental results. This research is aimed at understanding the mechanical performance of basalt-epoxy composites partially reinforced with micro-/nano-sized bio-fillers from cellulose and intended for various application areas. Different weave structures, e.g., plain, twill, matt, etc., were investigated with respect to the mechanical properties of the hybrid composites. The effects of hybridizing with cellulose particles and different weave patterns of the basalt fabric are studied. In general, the use of high-strength fibres such as basalt along with cellulosic fillers representing up to 3% of the total weight improves the mechanical performance of the hybrid structures. The thermomechanical performance of the hybrid composites improved significantly by using basalt fabric as well as by addition of 3% weight of cellulosic fillers. Results reveal the advantages of hybridisation and the inclusion of natural cellulosic fillers in the hybrid composite structures. The material developed is suitable for high-end applications in components for construction that demand advanced mechanical and thermomechanical performance. Furthermore, the inclusion of biodegradable fillers fulfills the objectives of sustainable and ecological construction materials.

Free vibration analysis of carbon-fiber plain woven reinforced composite conical-cylindrical shell under thermal environment with general boundary conditions

In this paper, the free vibration analysis of carbon fiber/epoxy resin and carbon/carbon plain woven conical-cylindrical shell under thermal environment with general boundary conditions using generalized differential quadrature (GDQ) is conducted. A two-step homogenization approach, in which 3D finite element method (3D FEM) based on 3D representative volume elements (3D RVE) are applied, is used to get the mechanical properties of the plain woven composites. According to first order shear deformation theory (FSDT) and Hamilton’s principle, considering a thermal environment, the governing equations of both the two shells are obtained. GDQ is applied during the solving procedure and general boundary conditions are considered through artificial springs. After several comparison studies focused on convergence, mechanical properties and thermal environment, the effects of boundary conditions, geometry, total fiber volume fraction and uniform, linear temperature field are studied comprehensively.

Uncertainty quantification and propagation in the microstructure-sensitive prediction of the stress-strain response of woven ceramic matrix composites

Hierarchical multiscale modeling of heterogeneous materials has traditionally relied upon a deterministic estimation of constitutive properties when making microstructure-sensitive predictions of effective response at each subsequent length-scale. Such an approach is wholly unsuitable for a variety of material classes, such as ceramic matrix composites, which exhibit large variability at multiple length-scales. This work demonstrates a framework for approaching two open problems towards improved microstructure-sensitive predictions, namely, (i) probabilistically calibrating complex constitutive models at the mesoscale to sparsely observed macroscale experimental data, and (ii) propagating this stochastic constituent behavior at the mesoscale towards low-cost homogenized predictions for unseen microstructures. The proposed stochastic scale-bridging framework displays a continuity of information flow where no portion of the experimental data is neglected out of convenience, facilitating the greatest information gain from oftentimes costly experiments. In this paper, suitable protocols were developed to address the challenges described above. The protocols were subsequently demonstrated on ceramic matrix composite’s uniaxial tensile stress–strain response, where constituent behavior at the mesoscale was described using continuum damage mechanics, and predictions encapsulating constitutive model parameter uncertainty were made for novel microstructures. The methodology presented in this work is broadly applicable to various material classes and constitutive models with high-dimensional parameter sets.

An extended full field self-consistent cluster analysis framework for woven composite

In this work, the self-consistent clustering analysis (SCA) framework is extended to include homogenization and full field analysis of 3D anisotropic woven composite Representative Unit Cell (RUC). The developed extended framework has two new features, namely, (i), to reconstruct the local field variables, a strain refinement stage is presented by solving full field Lippmann–Schwinger equations within 3D anisotropic woven composite RUC following the online predictive stage in SCA, and (ii), discrete Green’s operator based on finite difference is adopted to improve the accuracy of refined point-wise physical field variables. To demonstrate the accuracy and efficiency of the proposed method, benchmark problems are analyzed, and results are compared to directly numerical simulation (DNS). For the reproducibility of presented results, the developed code can be freely downloaded from https://github.com/Tong-RuiLiu/Extended-SCA-and-FFT-based-strain-refinement-method-.

Sinusoidally architected helicoidal composites inspired by the dactyl club of mantis shrimp

ABSTRACT The impact region of the dactyl club of mantis shrimp features a rare sinusoidally helicoidal architecture, contributing to its efficient impact-resistant characteristics. This study aims to attain bioinspired sinusoidally architected composites from a practical engineering way. Morphological features of plain-woven fabric were characterized, which demonstrated that the interweaving warp and weft yarns exhibited a sinusoidal architecture. Interconnected woven composites were thus employed and helicoidally stacked to achieve the desired structure. Quasi-static three-point bending and low-velocity impact tests were subsequently performed to evaluate their mechanical performance. Under three-point bending condition, the dominant failure mode gradually changed from fiber breakage to delamination with the increase in the pitch angle. Failure displacement and energy absorption of the helicoidal woven composites were, respectively, 43.89% and 141.90% greater than the unidirectional ones. Under low-velocity impact condition, the damage area of the helicoidal woven composites decreased by 49.66% while the residual strength increased by 10.10% compared with those of the unidirectional ones, exhibiting better damage resistance and tolerance. Also, effects of fiber architecture on mechanical properties were examined. This work will shed light on future design of the next-generation impact-resistant architected composites.

Assessing thermophysical properties of parameterized woven composite models using image-based simulations

Mesoscale simulations of woven composites using parameterized analytical geometries offer a way to connect constituent material properties and their geometric arrangement to effective composite properties and performance. However, the reality of as-manufactured materials often differs from the ideal, both in terms of tow geometry and manufacturing heterogeneity. As such, resultant composite properties may differ from analytical predictions and exhibit significant local variations within a material.We employ mesoscale finite element method simulations to compare idealized analytical and as-manufactured woven composite materials and study the sensitivity of their effective properties to the mesoscale geometry. Three-dimensional geometries are reconstructed from X-ray computed tomography, image segmentation is performed using deep learning methods, and local fiber orientation is obtained using the structure tensor calculated from image scans. Suitable approximations to composite properties, using analytical unit cell calculations and effective media theory, are assessed. Our findings show that an analytical geometry and sub-unit cell geometry provide reasonable approximations of the full-scale predictions for the effective thermal properties of a multi-layer production composite.

Numerical Modeling of Low-Velocity Impact on Composite Laminates

The response over the low-velocity impact of various shape impactors on a glass fiber reinforced polymer composite has been numerically analyzed with a hemispherical, flat, partially flat and truncated shaped impactor used to analyze the behavior of resistance of a GFRP composite at various speeds. The numerical analysis was carried out using finite element analysis software, ABAQUS (Dynamic/Explicit). To assess the response of the composite laminates while impacting, finite element models were developed. The Hashin failure criteria were used to represent braided glass-fiber reinforced composite plate damage. Regarding projectile shape, the impact reaction of the composite was examined. The results also show that the mechanical response of woven glass fiber polymer composite under low-velocity projectile impact largely depends on the impactor’s nose shape and the velocity of the impactor.

Thermally-induced responses of triaxially woven fabric composites

The article examines the thermal responses of one-ply triaxially woven fabric composites (TWFCs). A temperature change experimental observation is first conducted on plate and slender strip specimens of TWFCs. Computational simulations are then performed with analytical and simple, geometrically-similar model configurations to capture thereby offering insights into the anisotropic thermal effects of the experimentally observed deformation. It is revealed that the leading cause of the observed thermal responses is the advancement of a locally formed twisting deformation mode. Therefore, a newly defined thermal deformation description called the coefficient of thermal twist is then characterized for TWFCs for different loading cases.

Hierarchical multiscale analysis for 3D woven composite leaf spring landing gear

In this work, a hierarchical multiscale analysis method was used for 3D woven composite leaf spring landing gear. The structural finite element models at micro, meso and macro scales were established and discussed, respectively. The influence of weave patterns on the tensile properties of 3D woven composites were carried out by experiment and numerical simulation. Finally, the multiscale model was established to predict the mechanical properties of 3D woven composite leaf spring landing gear. The results showed that the maximum prediction error was 9.01% at the microscopic scale, 4.55% at the mesoscopic scale, and 5.61% at the macroscopic scale, thus verifying the effectiveness of the used hierarchical multiscale analysis strategy. The presence of stuffer yarn within the material and the yarn arrangement density were the key factors affecting the structural load-bearing capacity in the design of 3D woven composite leaf spring landing gear.

Low velocity impact failure mechanisms of carbon/UHMWPE 2.5D woven hybrid composites via experimental and numerical methods

This paper investigates the failure mechanisms of carbon/UHMWPE 2.5D woven hybrid composites under single and repeated low velocity impacts. Two types of specimens, carbon 2.5D woven composites (C-2.5DWC) and carbon/UHMWPE 2.5D woven hybrid composites (H-2.5DWC), were subjected to single and repeated impacts at 15 J/mm and 5 J/mm respectively. X-ray micro-computed tomography was employed to discuss the damage distribution. A meso-macro combination finite element model was proposed to analyze the failure mechanisms. The results demonstrated that, when compared to C-2.5DWC, H-2.5DWC has higher specific energy absorption and distinct toughness characteristic under 15 J/mm single impact, and exhibits a more dispersed damage distribution that primarily extends along the weft direction as the number of 5 J/mm repeated impacts increases, resulting improved damage tolerance. The simulation results agreed well with experimental data, and the synergistic effect of carbon and UHMWPE fibers allows uniform propagation of the impact stress within hybrid composites.

Influence of weaving parameters on thermal protection performance of gradient3Dwoven composite

AbstractA dual‐scale ablation model was developed to address the lack of research on the influence of weaving parameters of gradient 3D woven composites on the ablation performance. It consists of a mesoscale heat transfer model and a macroscale ablation model, and they are effectively connected by parametric conduction. By comparing with experimental results, the accuracy of the model was demonstrated. The effect of yarn spacing, recession resistant layer thickness on the thermal protection performance of gradient 3D woven composite was investigated. Furthermore, the effect of each weaving parameter on the integrated performance of ablation resistance, thermal insulation and light‐weight level is evaluated. The results show each weaving parameter has a substantial impact on thermal protection performance, with weft spacing and binder yarn spacing being the most significant influence. Reasonable design of these parameters can facilitate the comprehensive performance of composites. These results serve as a useful reference for refinement design of thermal protection materials.

On the use of the Combined Loading Compression fixture to estimate the intralaminar compressive fracture toughness of composites

This study reassesses the constraint effect provided by a Combined Loading Compression (CLC) fixture on notched specimens used to measure the compressive intralaminar fracture toughness of composite materials. An experimental campaign is carried out to determine whether a variation in the specimen gauge section length would result in a significant change in the nominal strength of Double Edge Notch CLC specimens. Following the testing of six sets of different specimen geometries for both a uni-directional thermoplastic and a bi-directional woven thermoset composite, the effect of the gauge length is analysed using the size-effect method. Results show that nominal notched strength variation is minimal, suggesting that the CLC clamp does not effectively constrain the gripped sections against in-plane deformations. This assessment proves that the correction factor used in the determination of the R-curve needs to be computed considering the entire specimen geometry, including the gripped regions. Furthermore, the results reveal that previous characterisation campaigns conducted using end-loaded Double Edge Notch Compression specimens could have led to a significant underestimation of the steady-state fracture toughness.

A geometric modeling method for an integrally stiffened panel with three-dimensional woven composites

In this article, we propose a geometric modeling method for an integrally stiffened panel using 3D woven composites. To observe the geometric shapes of the panel, we design weave patterns in which the skin and stiffener are integrated and manufacture the panel. Cross-sections of the manufactured panel are observed using a microscope, and paths and shapes of tows are modeled using weaving parameters and the obtained cross-sections. To verify the method, buckling analysis is performed on the panel and compared with test results. The proposed method can be effectively applied to the design of integrally stiffened panel using 3D woven composites.

Parametric modeling of 2.5D woven composites based on computer vision feature extraction

The aim of this paper is to develop a comprehensive modeling strategy for creating a realistic representative volume element (RVE) of 2.5D woven composites. The strategy consists of two main parts: the extraction of geometric feature parameters and the establishment of a parametric voxel-mesh full-cell model (VFM). Firstly, a neural network model is constructed to achieve an accurate segmentation of yarn cross-sections from X-ray computed tomography (XCT) images. Secondly, geometric feature parameters are then extracted from the segmentation results using image algorithms. Finally, a parametric modeling method is proposed to establish the VFM of the material. To evaluate the performance of the VFM, its structural sizes, overall fiber volume fraction (FVF), and stiffness prediction accuracy are assessed. The comparison results indicate that the VFM achieves a fine mesoscale characterization and a high stiffness prediction accuracy.

Effect of fabric structural stability on the tensile property of bidirectional angle-interlock woven composites

Three-dimensional bidirectional angle-interlock woven (3DBAW) composites exhibit the orthogonal high modulus, which has the potential to be used in load-bearing components. 3DBAW preforms prepared using the certain and uncertain cross-sectional yarns exhibit various structural characteristics, and the mechanical properties of composites show the high variation. To investigate the effect of fabric structural stability on the elastic properties of 3DBAW composites and broaden its application, contrast analysis of quasi-static tensile properties of composite specimens was proposed, and the failure mechanism was analysed. The results showed that the high tensile initial elastic modulus of 3DBAW composites was attributed to the low curvature of load-bearing yarns. For composites with stable fabrics, the tensile process was smooth and steady owing to the uniform fiber spacing, and the tensile elastic modulus and strength show the smaller coefficient of variation. The tensile crack surfaces of composites with stable structural fabrics were regular, and making the full use of the load-bearing yarns. 3DBAW preforms with stable structure can effectively reduce the fluctuation of changes at the initial stage of loading, and the translaminar fracture and adhesive matrix failure are the main failure modes without the obvious interlaminar fracture. The results provided the support for the application of 3DBAW composite in load-bearing components.

Experimental and numerical study on the mechanical properties of carbon/aramid intralayer hybrid composites

This study presents an investigation on the mechanical properties and failure mechanisms of composites made of plain woven fabrics reinforced with carbon fibers, aramid fibers, and their intralayer hybrids. The specimens were fabricated by hand lay-up method. Tension, compression, and shear tests were performed in accordance with the relevant standards to investigate the tensile, compression, and shear properties of carbon fiber, aramid fiber, and carbon/aramid fiber intralayer hybrid plain woven composites. Accurate strain field was obtained by digital image correlation (DIC) technology and compared with the results measured by the strain rosettes. Furthermore, a multi-scale modeling strategy was developed to predict the mechanical properties of the hybrid composites. The fiber monofilament model was used to calculate the effective properties of carbon and aramid yarns at the micro-scale level. Representative volume element (RVE) models of the hybrid composite were constructed considering the real fabric pattern at the meso-scale level. The predicted results agree well with the experimental data which validates the multi-scale modeling strategy. The presented information on the tensile, compressive, and shear properties and finite element simulation method of carbon/aramid intralayer hybrid composites should be useful in subsequent research as well as in designing new high-performance composites and structures.

Multiscale modelling of strongly heterogeneous materials using geometry informed clustering

Computationally efficient and numerically accurate modelling of heterogeneous materials with complex internal architectures at the macroscale is a current problem. For instance, in engineering materials such as 3D woven composites, retaining the description of material architectures is important to obtain an accurate prediction of stiffness. However, computational cost increases in proportion to the level of mesoscale details modelled. To enable efficient and accurate calculations on the structural scale, a multiscale method that can identify repeatable patterns in the mesoscale and represent them efficiently at the macroscale is proposed. This method has two important novelties, (i) a method to identify and store repeatable patterns during offline stage in the form of 3D Voronoi cells using a data compression algorithm, k-means clustering. This improves the identification with a minimum number of data clusters and minimises the effects of mesh sizes, and (ii) a method to select most similar Voronoi cells from the mesoscale database during online stage using image registration and k-d tree data structure. This enables computations being performed without explicitly modelling mesoscale details and reduces the computational cost that are otherwise required. The proposed method is validated against 3D woven unit-cell and three-point bending examples. Furthermore, the ability to find repeatable patterns is tested by analysing a woven architecture previously not stored in the database.

Study on impact resistance and parameter optimization of patch‐repaired plain woven composite based on multi‐scale analysis

AbstractPatch‐repaired plain woven composite structures were exposed to internal damage caused by impact during service, which reduced mechanical properties. A multi‐scale modeling strategy was proposed to study the impact resistance characteristics of patch‐repaired plain woven carbon‐fiber‐reinforced‐polymer (CFRP) laminates. The micro representative volume element (RVE) was extracted from the yarn; a local homogenization method was used to obtain the equivalent cross‐ply laminate (ECPL) cells corresponding to the mesoscale RVE. The finite element model (FEM) of patch‐repaired plain woven laminate was established by extending the ECPL cells. The FEM was checked by the low‐velocity impact (LVI) tests, and the impact parameter errors were within 10%. Furthermore, impact resistance of repaired specimens under different impact conditions (e.g., the impact energy was 3 ~ 20 J) was studied. Finally, patch parameters (patch thickness, patch size, off‐axis angle) of the repaired specimen were optimized by multi‐objective optimization based on the surrogate model and response surface method (RSM). After multi‐objective function optimization, the optimal patch parameter configuration (the thickness of the patch was 0.87 mm, the diameter was 66 mm, and the off‐axis angle was 44.2°) reduced the absorbed energy value of the repaired specimen from 4.9089 to 4.1640 J, and the delamination area of the repaired specimen from 605 to 280 mm2. All the results provide a reference for patch repair of plain woven composites.

Investigation on the effect of interface properties on compressive failure behavior of 3D woven composites through micromechanics-based multiscale damage model

In this paper, the effect of interface properties on the compressive failure behavior of 3D woven composites (3DWC) is investigated by incorporating a micromechanics-based multiscale damage model (MMDM). The correlation between the mesoscopic stress of yarns and microscopic stress of constituents is established by defining a stress amplification factor. With the microscopic stresses, the fiber breakage and matrix failure can be separately evaluated at the microscale, without assuming the yarns as transversely isotropic homogeneous materials. Especially, the interfacial debonding between yarns and matrix is also a dominant damage mode within 3DWC. Given that there is still a lack of studies on the influence of interfacial properties on the compressive failure behavior of 3DWC, it is meaningful to perform numerical parametric studies to reveal how the interface properties contribute to the damage mechanisms of 3DWC under compressions. The predicted results indicate that with the increase of interface strengths and fracture toughness, the compressive resistance of 3DWC can be significantly improved, resulting in higher strength and failure strain. Additionally, the studied 3DWCs with weak, medium and strong interfaces exhibit different damage development processes.