Woven Reinforcement Research Articles

Diffuse manifold learning of the geometry of woven reinforcements in composites

When attempting to build mesoscale geometric models of woven reinforcements in composites based on X-ray microtomography data, we frequently run into ambiguous situations due to noise, particularly in contact zones between fiber tows, resulting in inadmissible cross-sectional shapes. We propose here a custom-built shape-manifold approach based on kernel PCA, k-means classification and Diffuse Approximation to identify, “repair” such badly segmented shapes in the feature space, and finally recover admissible shapes in the original space.

Viscoelastic Modeling of Responses in the Whole Compaction Process for Woven Fiber Reinforcements

Compaction and the corresponding viscoelastic behaviors of woven fiber reinforcements are essential to determine the mechanical properties of composite components. Current reported works separately studied the viscoelastic behaviors in partial stage of the compaction process. In contrast, here, we propose a uniform viscoelastic model that can describe the viscoelastic responses in all stages. Systematical experiments of carbon and glass woven fiber reinforcements demonstrate the effectiveness of this viscoelastic model. Moreover, the significances of the model parameters and their underlying relations are clearly revealed. The time constants are not equal in different stages due to different roles of fiber friction played. The relationship among time constants in different stages is found and is experimentally demonstrated. Stress constants strongly depend on the initial stress and types of fiber reinforcements. The relationships between stress constants in all stages are also obtained. The proposed theoretical model here provides a potential and promising approach to understand the viscoelastic responses of woven fiber reinforcements in compaction process.

Development and mechanical properties of adaptive fiber-reinforced plastics

Textile-based lightweight structures offer various possibilities for the design of tailored structures by the selective choice of materials and their processing into textile semi-finished products and fiber-reinforced plastics. Lightweight structures with a high mechanical load capacity are feasible by developing fiber-reinforced plastics with adaptive properties that are able to adapt their characteristics, e.g. geometry or stiffness, to external influences. Thus, the application potential of fiber-reinforced plastics can be further expanded. In this paper, we present novel adaptive fiber-reinforced plastics based on textile semi-finished products with integrated shape memory alloys and their mechanical characterization. The shape memory alloy is textile technically integrated and converted into friction spun hybrid yarn. Next, the produced hybrid yarn is integrated with plain, twill and satin woven reinforcement fabric in the weft direction during the shedding operation in weaving. Adaptive fiber-reinforced plastics are developed by infusing textile semi-finished products. Subsequently, the mechanical characterization of the adaptive fiber-reinforced plastics is carried out. Results show that, by integrating shape memory alloys into adaptive reinforced fabrics, the mechanical performance of fiber-reinforced plastics can be tailored.

Study of the internal confinement of concrete reinforced (in civil engineering) with woven reinforcement

Concrete is generally the most used material in the field of construction. Despite its extensive use in structures, it represents some drawbacks related to its properties including its low tensile strength and low ductility.To solve this problem, the use of steel reinforcement in concrete structures is possible. Another possibility is the introduction of different types of continuous fibre / staple in the concrete, such as steel fibres or synthetic fibres, to obtain ″Concretes bundles″.Many types of fibre concrete, which have been developed and for many of them, the gain provided by the fibre was rather low and no significant improvement in tensile strength was really reaching. By cons, the ductility was higher than that of ordinary concrete.The objective of this study is to examine concrete reinforcement by inserting reinforcements woven polyester. These are either woven bidirectional (2D) or three-dimensional woven (3D). So we will report the properties of each type of reinforcement and the influence of the method of weaving on the strength reinforcements and on the strength of concrete in which they are incorporated. Such influence should contribute to improving the sustainability and enhancement of reinforcement

Image‐based model reconstruction and meshing of woven reinforcements in composites

SummaryA method based on dual kriging is proposed to process X‐ray microtomographic scans of textile composites in order to construct a 3D representation of the fiber architecture with a regulated level of details. The geometry is optimized by using the curvature energy of fiber tow profiles in order to determine the best discretization scheme; then the nugget effect is applied in kriging to smooth the outward surface of fiber tows. This approach allows creating 3D models of variable resolution ranging from the X‐ray scan level to geometric representations with surface meshes required for numerical simulation. The method is applied to a glass fiber textile laminate embedded in a thermoplastic matrix, and preliminary results for the estimation of the local permeability of the fiber tows are presented. Copyright © 2017 John Wiley & Sons, Ltd.

Flexural and interlaminar shear study of hybrid woven kenaf/recycled GFRP (rGFRP) composites subjected to bending load

Delamination known as the failure at the interface between different layers is one of critical failure mechanism for laminates composites. Hybrid laminate composites comprised of unique ply material and structure, unwanted interlaminar shear stresses may occur between ply laminate due to different material behavior and properties. The aim of this research is to study structural integrity effect of interleaf glass mat and recycled GFRP waste (rGFRP) in woven kenaf reinforcement polyester composite. The properties of composites on ILSS and flexural behavior subjected to bending load were measured by flexural and short beam test (SBT). Span length to thickness ratio varies for both tests are 16: 1 and 4: 1 for flexural test and SBT respectively. Compression molding method was selected for composite fabrication; the fiber weight percentage ratios are constant at 35% of all samples. Results revealed that the flexural stress and flexural shear measured by flexural test is comparable for kenaf and kenaf/glass composites however, kenaf/rGFRP shows significant improvement, increased in maximum flexural stress up to 47.5%. Interlaminar Shear Strength (ILSS) calculated from SBT shows comparable value for all samples with slightly increased about 10% for both hybrid composites. Failure analysis observed by Scanning Electron Microscopic (SEM) and Optical Microscope shows severe interlaminar shear failure occur on glass mat hybrid composites for both tests. From the results, it can be conclude that hybridization of glass mat and rGFRP particulate improved flexural and ILSS properties. It also can be concluded rGFRP is potential to replace glass fiber as reinforcement.

Micromechanical modeling of plain woven polymer composites via 3D finite‐volume homogenization

In this article, an anisotropic version of 3D finite‐volume direct averaging micromechanics (FVDAM) has been developed, enabling efficient and accurate analysis of composites with woven reinforcements. The formulation is based on a local/global stiffness matrix procedure, with the equilibrium equations in conjunction with continuity of displacements and tractions imposed in an average sense. The present 3D FVDAM admits arbitrary anisotropic constituent materials, whereas the 2D FVDAM permits orthotropic subvolume materials at most. On this basis, an FVDAM‐based two‐step approach, which is expected to provide more accurate predictions than the traditional one‐step homogenization, is employed to homogenize the repeating unit cell of a plain weave. The performance of the proposed method is assessed by comparison with other analytical, numerical, and experimental data found in literature. The generated results demonstrate that the FVDAM is capable of modeling plain woven polymer composites reasonably, making FVDAM an attractive alternative to other numerical and analytical techniques for analysis of composites with periodic internal microstructures. POLYM. COMPOS., 39:3022–3032, 2018. © 2017 Society of Plastics Engineers

Characterisation of the mesoscopic and macroscopic friction behaviours of glass plain weave reinforcement

Friction at different levels of the multi-scale structure of textile reinforcements is one of the most significant phenomena in the forming of dry fabric composites. This paper investigates the effect of the test conditions on fabric/fabric and yarn/yarn friction. Friction tests were performed on a glass plain weave and its constitutive yarns, varying the pressure and velocity. The results showed that the friction behaviours at the two scales were highly sensitive to these two parameters. An increase in pressure led to a decrease in the friction coefficients until steady values were reached, while an increase in velocity led to an increase in the friction coefficients. At each scale, the frictional behaviour of the material was significantly influenced by the structural reorganisation of the lower scale.

Study to evaluate the Effect of Silane Treatment and Three Different Woven Fiber Reinforcement on Mechanical Properties of a Denture Base Resin

Study to evaluate the Effect of Silane Treatment and Three Different Woven Fiber Reinforcement on Mechanical Properties of a Denture Base Resin

Nonconformal mesh-based finite element strategy for 3D textile composites

A finite element procedure is developed for the computation of the thermoelastic properties of textile composites with complex and compact two- and three-dimensional woven reinforcement architectures. The purpose of the method is to provide estimates of the properties of the composite with minimum geometrical modeling effort. The software TexGen is used to model simplified representations of complex textiles. This results in severe yarn penetrations, which prevent conventional meshing. A non-conformal meshing strategy is adopted, where the mesh is refined at material interfaces. Penetrations are mitigated by using an original local correction of the material properties of the yarns to account for the true fiber content. The method is compared to more sophisticated textile modeling approaches and successfully assessed towards experimental data selected from the literature.

Interlaminar and Intralaminar Fracture Behavior of Carbon Fiber Reinforced Polymer Composites

Interlaminar and intralaminar fracture behavior of carbon fiber reinforced composites have been experimentally studied. Unidirectional, woven reinforcement and thermoplastic and thermoset polymer matrix laminates have been characterized using double cantilever beam (DCB) and end notch flexure (ENF) specimens for Mode-I and Mode-II fracture toughness, respectively and compact tension (CT) specimens for intralaminar fracture. AS4/PEEK, AS4/8552 and AGP193PW/8552 laminates have been characterized in this study. The fracture toughness determined from the experimental data could be related to the constituents and reinforcements. It has been observed between the two UD laminates, AS4/PEEK exhibit higher fracture resistance under both interlaminar and intralaminar fracture. Woven reinforcement is found to show higher mode-II interlaminar fracture toughness.

Continuum and discrete models for unbalanced woven fabrics

The classical models used for describing the mechanical behavior of woven fabrics do not fully account for the whole set of phenomena that occur during the testing of such materials. This lack of precision is mainly due to the absence of energy terms related to the microstructural properties of the fabric and, in particular, to the bending stiffness of the yarns. The importance of the bending stiffness on the overall mechanical behavior of woven reinforcements, if already essential for the complete description of balanced fabrics, becomes even more important in the case of unbalanced ones. In this paper it is shown that the unbalance in the bending stiffnesses of the warp and weft yarns produces macroscopic effects that are extremely visible: we mention, for example, the asymmetric S-shape of a woven interlock subjected to a Bias Extension Test. We propose to introduce a constrained micromorphic model and, simultaneously, a discrete model that are both able to account for (i) the angle variation between warp and weft tows, (ii) the unbalance in the bending stiffness of the yarns and (iii) the relative slipping of the tows. The introduced constrained micromorphic model is rigorously framed in the spirit of the Principle of Virtual Work for the study of the equilibrium of continuum bodies. A suitable constraint is introduced in such micromorphic model by means of Lagrange multipliers in the strain energy density and the resulting constrained model is seen to be a particular second gradient one. The main advantage of using such constrained micromorphic model is that the kinematical and traction boundary conditions that can be imposed on some sub-portions of the boundary of the considered body take a natural and unique meaning. The discrete model is set up by opportunely interconnecting Euler–Bernoulli beams with different bending stiffnesses in the two directions by means of rotational and translational elastic springs. The main strength of such discrete model is that the slipping of the tows is described in a rather realistic way. Suitable numerical simulations are presented for both the continuum and the discrete models and a comparison between the simulations and the experimental results is performed showing a definitely good agreement.

On the multiscale tribological signatures of the tool helix angle in profile milling of woven flax fiber composites

The present study is focused on tribological and multiscale analysis for the machined surfaces of bi-directional flax fibers reinforced polypropylene composites. This is to track the multiscale effect of the helix angle of the cutting tool, related to its kinematic, on the cutting mechanisms. The results show that the helix angle has significant effect on the tribological performances which affect the tribo-contact interaction between the flax fibers and the cutting edge. The fibers orientation in the woven reinforcement has significant effect on the surface quality. The multiscale analysis reveals the pertinent scales that activate the helix angle effect.

Characterization of 3D woven reinforcements for liquid composite molding processes

Compaction and permeability characterization of fibrous reinforcements is fundamental to liquid composite molding (LCM) processes, given that these fabric properties determine the part thickness, fiber volume content and mold filling time and patterns. In this study, the permeability of three different 3D woven carbon fiber reinforcements (orthogonal, angle interlock and layer-to-layer) was studied, each having a different weave style and z-binder pattern. For all reinforcements, single-cycle and multiple cycle compaction experiments were conducted on dry and saturated samples. The orthogonal preforms were more difficult to compact to the target fiber volume fraction of 0.65, with peak stresses reaching up to 2.3 MPa. Cyclic compaction tests were conducted to highlight the importance of permanent deformation in the reinforcements, when higher fiber volume content is desired via manufacturing using an LCM process. Unsaturated in-plane radial and saturated through-thickness permeability data were obtained at several fiber volume fractions. The orthogonal and layer-to-layer fabrics exhibited greater levels of anisotropy in the plane of flow. The rate of change of in-plane permeability with increasing fiber volume content was lower compared to through-thickness values. The effect of cyclic compaction on permeability was greater in the orthogonal and angle interlock reinforcements. Micrographs of infused samples showed significant permanent deformation of the z-binder yarns, an effect that reduced permeability at high fiber volume contents.

Particularities of Modelling the Mechanical Properties of Woven Composite Fabrics

The mechanical properties of composite fabrics rely on a fabric made by a textile weaving process. In order to use their special ability of being drapeable, instead of just plain weave fabrics, satin or twill reinforcement can be selected. Although some other advantages of the resulting composite, such as good impact resistance or damage tolerance are similar to all woven reinforcement composites, the superior drapeability of satin is a major reason to favour this type of textile reinforcement. This paper is focused on the modelling procedures of stiffness characteristics, specific to satin reinforced laminated composites, using a semi-discrete approach. This method is a compromise between the continuous and pure discrete approaches and is associated with a mesoscopic analysis of the repetitive unit cell (RUC). The elastic properties of the textile reinforced epoxy composite, namely longitudinal modulus and transverse modulus, in case of carbon and fibre glass based 5-harness satin reinforcement, are determined. The differences between the two resulting composite materials and the influence of the various geometric and material parameters involved are studied.

A Parametric Study on Compression Molding of Reference Parts with Integrated Features Using Carbon Composite Production Waste

Compression molding of near net-shaped rib-stiffened plates has been performed for a parametric investigation on the filling behavior of chopped woven flake reinforcements. The experimental investigation showed that different aspect ratios of ribs can be filled completely within the tested maximum ratio of flake size to rib opening width of 6.25 and a maximum consolidation pressure of 15 bar. However, defects such as voids, non-impregnated regions and fiber matrix separation may arise depending on the combination of parameters and a mechanical jamming effect caused by the woven architecture of the flakes. A tendency for a limiting consolidation pressure is observed based on the fiber matrix separation. The ability to re-use thermoplastic prepreg cutting waste has been demonstrated.

Study of Mechanical Properties of Natural and Hybrid Yarns Reinforcements

The present work was focused on development and studies of mechanical properties that natural fibres have in the woven reinforcements made from hemp and flax as well as hybrid yarns of hemp and glass fibres. Natural fibres such as hemp and flax are biodegradable, have low weight and show good flexibility. Glass fibre is widely used in the industry when low cost and good performance is required. The hemp yarns (100 Tex and 1186 Tex), the flax yarns (678 Tex) and the hybrid yarn of hemp and glass fibres (1644 Tex) were used to develop woven reinforcement structures. Average surface density for reinforcements of hemp yarns is 83- 529 g/m2 and for reinforcements of hybrid yarns 738- 741 g/m2.

Numerical modelling of forming of a non-crimp 3D orthogonal weave E-glass composite reinforcement

A hyperelastic constitutive model is implemented to study the formability on three-dimensional complex shapes of a single layer E-glass non-crimp 3D orthogonal woven reinforcement. Experimental measurements of the main deformation modes have been used to identify the strain energy density function of the constitutive model. The comparison of the finite element simulations and experimental results of tetrahedron and double-dome shaping processes demonstrated the adequacy of the adopted hyperelastic model to describe the deformation mechanisms involved during draping and the efficiency to predict the global behaviour of the non-crimp 3D woven reinforcement during complex shape forming.

A quantitative comparison of the capabilities of in situ computed tomography and conventional computed tomography for damage analysis of composites

The so called in situ computed tomography is a powerful non-destructive testing method to study the damage phenomenology while a material is loaded. However, the difference in the detected amount of damage compared to conventional CT scans after unloading of the specimen has not been reported so far and is therefore the focus of this study. Three different textile-reinforced composite materials have been experimentally investigated for that purpose. Carbon fibre reinforced epoxy composites with multi-layered flat bed weft-knitted fabrics and multi-axial non-crimp fabrics were uniaxially loaded in tension. In situ CT scans were taken at different load levels and conventional CT scans after unloading. The experiments have shown that the observed crack lengths and delaminated areas are significantly larger while the load is applied because of crack closure effects during unloading. Any damage diagnosis should therefore be performed under load. A ceramic C/C composite with woven reinforcement was taken as a third example. This composite was loaded by compression in thickness direction. It was found that the decrease of total porosity with increasing load can only be predicted by in situ CT measurements.

Impact behaviour of woven coir-epoxy composite: Effects of woven density and woven fabric treatment

Several approaches have been implemented to enhance the impact performance of natural fibre-reinforced composite structures. The control of reinforcement structure and fibre modification through treatment are among the approaches. The objective of this study was to evaluate the impact behaviour of woven coir-epoxy composite as a function of fabric density and fabric modification using alkalisation treatment. Samples were subjected to low-velocity impact penetration tests and image analysis technique was used to measure the area and perimeter of the damaged samples under impact. A multi-level full factorial design was implemented in this study as a systematic and efficient way to distinguish the interactions of more than one factor. Two levels of woven density (Type 1 and Type 2) were investigated and four levels of treatment percentage (0%, 6%, 9% and 12%) were examined. Moreover, analysis of variance (ANOVA) was employed to determine the significant factors that predominantly influence the impact behaviour of woven composites. It was found that the differences in woven density and woven treatment significantly affect the maximum impact load and deflection of woven coir-epoxy composites. Impact energy absorption, however, was only affected by woven treatment. Factor interactions were also apparent for maximum impact load, initiation energy and deflection. The results showed that woven reinforcement with denser structure was less stiff in nature. The deformability of the composites was also found to reduce with the increase of treatment percentage. Furthermore, poor damage resistance was observed in denser woven structure.