Satin Weave Research Articles

Evolution of the strain energy release rate during ductile or brittle failure in woven‐ply reinforced thermoplastic laminates under high temperature conditions

Depending on laminates’ stacking sequence, the contribution of matrix behavior to the strain energy release rate is evaluated during failure in brittle and ductile composite laminates subjected to high temperature conditions (T > Tg) when matrix toughness is enhanced. The purpose of this work is therefore to investigate the strain energy released along with crack growth in 5‐harness satin weave carbon fabric reinforced polyphenylene sulfide (PPS) structures with a Single Edge Notch. The crack growth appears to be self‐similar in quasi‐isotropic (QI) laminates, and nonself‐similar in angle‐ply (AP) laminates. Based on fracture mechanics concepts, semianalytical representations of the translaminar failure are combined with an Acoustic Emission (AE) technique to correlate the cumulative AE energy to the strain energy release rate. The experimental results reveal that the fracture toughness increases with increasing precrack length in QI laminates, whereas the effect of increase in precrack length exhibits reduced fracture toughness in AP laminates. The energy released during a non‐self‐similar crack growth is all the more significant than the stress concentration factor is reduced. A small defect (e.g., precrack) means a larger portion of the mechanical energy brought to the specimen to be dissipated during failure by means of large plastic deformations. With respect to QI laminates, the contribution of PPS matrix toughness to the fracture energy released is more significant in highly ductile AP laminates, resulting in higher fracture toughness. POLYM. COMPOS., 40:121–131, 2019. © 2017 Society of Plastics Engineers

Uniaxial tensile tests and dynamic mechanical analysis of satin weave reinforced epoxy shape memory polymer composite

The utilization of epoxy shape memory polymer composite (SMPCs) as engineering materials for deployable structures has attracted considerable attention in recent decades due to high strength and satisfactory stiffness in comparison with shape memory polymers (SMPs). Knowledge of static and dynamic mechanical properties is essential for analyzing structural behavior and recovery properties, especially for new epoxy SMPCs. In this paper, a new weave reinforced epoxy shape memory polymer composite was prepared with satin weave technique and resin transfer molding technique. Uniaxial tensile tests and dynamic mechanical analysis were carried out to obtain basic mechanical properties and glass transition temperatures, respectively.The tensile strength and breaking elongation of warp specimens were comparable with those of weft specimens. The increment of elastic modulus and hysteresis loop areas became smaller with loading cycles, meaning that cyclic tests could obtain approximate stable mechanical properties. For dynamic mechanical properties, glass transition temperature (Tg) obtained from storage modulus curves was lower than that determined from tan delta curves and Tgs in the warp and weft directions were similar (29.4 °C vs 29.7 °C). Moreover, the storage modulus in response to Tg was two orders of magnitude less than that with respect to low temperature, which demonstrated the easy processibility of epoxy SMPCs near glass transition temperature. In general, this study could provide useful observations and basic mechanical properties of new epoxy SMPCs.

Determination of J-R curves by load separation criterion in highly ductile TP-based composites under high temperature conditions

This work was aimed at determining the J-integral in 5-harness satin weave carbon fabrics reinforced PolyPhenylene Sulphide (PPS) structures at 120°C>Tg (glass transition temperature). The use of the linear elastic fracture mechanics (LEFM) framework to investigate the fracture behavior is not relevant in C/PPS laminates whose angle-ply stacking sequence is characterized by a highly ductile behavior. Thus the corresponding strain energy release rate (denoted J) in angle-ply laminates can be evaluated by means of the J-integral to account for the elastic-plastic fracture mechanics (EPFM). To this aim, a particular attention was paid to determine ηel- and ηpl-factors which are key points in the evaluation of J. ηel is classically evaluated using the compliance method, whereas, ηpl is determined by means of the load separation method applied to both elastic and total displacements. The comparison between initial crack length calculated using plastic and total displacement allows us to conclude that ηpl-factor based on total displacement leads to more accurate results. Using the Sij parameter, it is therefore possible to estimate transverse crack growths for different initial notch lengths. The predicted crack growth is in a good agreement with the experimental evolution obtained using Digital Image Correlation (DIC). Finally, the present work provides the J-R curves of highly ductile composite systems for different initial crack length over width ratios (a/w).

Influence of matrix ductility and toughness on strain energy release rate and failure behavior of woven-ply reinforced thermoplastic structures at high temperature

Abstract The purpose of the present work is to investigate damage evolution in 5-harness satin weave carbon fabric reinforced PolyPhenylene Sulphide (PPS) structures with an initial edge notch. To understand how the physical properties of the constituents (e.g. matrix toughness and ductility) and the architecture of reinforcement (woven-ply) affect the fracture behavior of C/PPS laminates, it is useful to have analytical representation of the translaminar failure modes based on fracture mechanics concepts, the strain energy release rate G especially. Translaminar failure is determined by the combination of loading, location of defect and material heterogeneity (presence of matrix-rich regions at the crimp area in woven-ply laminates). When translaminar failure is initiated from an existing notch, a sequence of energy-absorbing events (fiber breakage, matrix cracking, fibers pull-out, fiber/matrix debonding) occurs in a region surrounding the notch tip. The knowledge of energy-absorbing processes is therefore important since they are responsible for the toughness of the composite. Depending on laminates' stacking sequence, the contribution of matrix behavior to strain energy release rate can be evaluated during damage in both brittle and ductile composite laminates subjected to high temperature conditions (T > T g ) when matrix ductility and toughness are enhanced. Depending on the initial notch orientation (0 or 45°), the failure mode is either a mode I or a mixed mode (I + II). The acoustic energy associated with translaminar failure was correlated with the strain energy release rate during translaminar failure. The total strain energy release rate in quasi-isotropic (QI) laminates is 6 times as low as in angle-ply (AP) laminates, suggesting that large plastic deformation (due to a matrix-driven behavior and an enhanced matrix ductility at T > Tg) are instrumental in dissipating a great portion of the mechanical energy brought to the specimen in AP laminates. The “material” effect is combined with a structural one (rotation of the fibers) at the crack tip, and leads to ductile failure. Both effects contribute to high fracture toughness in AP laminates.

Computational Homogenization of Mechanical Properties for Laminate Composites Reinforced with Thin Film Made of Carbon Nanotubes

Elastic properties of laminate composites based Carbone Nanotubes (CNTs), used in military applications, were estimated using homogenization techniques and compared to the experimental data. The composite consists of three phases: T300 6k carbon fibers fabric with 5HS (satin) weave, baseline pure Epoxy matrix and CNTs added with 0.5%, 1%, 2% and 4%. Two step homogenization methods based RVE model were employed. The objective of this paper is to determine the elastic properties of structure starting from the knowledge of those of constituents (CNTs, Epoxy and carbon fibers fabric). It is assumed that the composites have a geometric periodicity and the homogenization model can be represented by a representative volume element (RVE). For multi-scale analysis, finite element modeling of unit cell based two step homogenization method is used. The first step gives the properties of thin film made of epoxy and CNTs and the second is used for homogenization of laminate composite. The fabric unit cell is chosen using a set of microscopic observation and then identified by its ability to enclose the characteristic periodic repeat in the fabric weave. The unit cell model of 5-Harness satin weave fabric textile composite is identified for numerical approach and their dimensions are chosen based on some microstructural measurements. Finally, a good comparison was obtained between the predicted elastic properties using numerical homogenization approach and the obtained experimental data with experimental tests.

Unit cells of composites with symmetric structures for the study of effective thermal properties

Effective thermal properties of macro composites with symmetric structures can be efficiently calculated by a size-limited representative unit cell. In this paper, a general rule of such unit cell formulation is developed. Two key steps are involved, the identification of structure symmetries and the derivation of boundary conditions, in which the first step build a geometric model while the later one endows the model physical meanings to represent the original structure. The route from the experiment specimen to the unit cell model, especially the evolution of relevant boundary conditions is clarified. The macroscopic heat flux in experiments is defined as symmetric and antisymmetric thermal stimulus by its directions. For three typical translational, reflectional and 180° rotational symmetric structures, the temperature distribution disciplines under different macroscopic thermal stimuli are revealed and summarized as two equations, and can be used to derive boundary conditions of unit cells. An axial study of unidirectional fiber reinforced composite is conducted to demonstrate the difference between the derived and the inappropriate boundary conditions in the physical mechanism point of view. For the transverse direction of the composite, four unit cell models of reducing sizes are established, and the basic process of unit cell formulations and boundary conditions derivations is stated. Then, for more complex satin woven composites, structure symmetries indicated in the 4-, 5-, 6-, 7- and 8-harness textiles are investigated, two unit cells of different sizes are formulated and the corresponding boundary conditions are derived in a unified form, and the identical results obtained by multi-size unit cells validate the unit cell and the boundary conditions. The approach developed in this paper can be applied to thermal studies of any other composites with relevant structure symmetries.

Wear evaluation of three-dimensionally woven materials for use in a novel cartilage replacement

The wear behavior of three-dimensional woven materials is poorly understood and is of great concern for three-dimensional weaves intended for orthopedic use. This study focuses on the fiber material and weave pattern used at the bearing surface during accelerated life testing. Samples of polyester and ultra-high molecular weight polyethylene in orthogonal and satin weave patterns were subjected to pin-on-disk testing in a Deionized water bath while the mating surface was made from cobalt-chromium alloy. All samples showed steady wear except ones with a satin weave of ultra-high molecular weight polyethylene at the bearing surface. These fabrics exhibited wear rates at three million cycles comparable to bulk non-crosslinked polyethylene found in the literature. These results indicate that with a proper pairing of weave pattern and fiber material, three-dimensional woven materials have the potential to be used in orthopedic articulating surfaces.

Novel Heating Elements for Induction Welding of Carbon Fiber/Polyphenylene Sulfide Thermoplastic Composites

Conductive films of carbon nanofibers (CNFs) decorated/coated with metals, either silver (Ag) or nickel (Ni) are fabricated using a solution casting process and used as novel heating elements (HEs) for induction welding of carbon fiber/polyphenylene sulfide (CF/PPS) thermoplastic composites. Prior to making the films, the metal‐coated CNFs are prepared by an electroless plating method using Ag or Ni precursors. A solution of the metal‐coated CNFs is then casted onto a pure PPS film to give a robust conductive film upon solvent evaporation and annealing in an oven at 200 °C. SEM observation and electrical resistivity measurements reveal that the CNFs are successfully coated with the metals which result in a significant decrease of the films’ electrical resistivity. A third type of HE is also fabricated by solution mixing Ag‐coated CNFs and magnetic Fe3O4 nanoparticles. The welding efficiency of the fabricated films is assessed for induction welding of two different types of thermoplastic composites, that is, unidirectional pre‐impregnated 16 plies ​​of CF/PPS compression‐molded in a quasi‐isotropic stacking sequence and 8‐ply of satin weave fabric CF/PPS compression‐molded in a cross‐ply stacking sequence. The mechanical apparent lap shear strength (LSS) of the induction‐welded joints is evaluated for the fabricated HEs and compared with the LSS of joints welded using conventional stainless steel mesh susceptors. Under similar testing conditions, Ag‐coated CNFs HEs lead to the highest LSS with an average value of ≈31.5 MPa. In general, the new HEs result in superior LSS and higher heating rates when compared to the metallic mesh counterparts. The present work offers a new perspective to push the boundaries toward high quality welding of thermoplastic composites using nanomaterials‐based HEs.

Virtual curing of textile polymer matrix composites

A homogenization approach to simulate the curing process in textile composites is presented. Internal stresses build-up in a thermosetting polymer matrix during cure because of thermal expansion/contraction mismatch, chemical shrinkage and lack of uniformity in the thermal field. The matrix cures within the fiber tows as well as in the pockets outside the tows. Although the explicit modeling of each fiber and matrix is preferred, it is computationally prohibitive for tows containing large numbers of fibers. Instead, a homogenization approach that is presented here models the effective curing of the tow by extending the cure hardening instantaneously linear elastic (CHILE) model, originally developed for matrix curing. The possibility of damage and/or failure in the matrix during cure is modeled using the Bažant-Oh crack band model. Using cure parameters for the IM7-8552 material system, the effectiveness of the homogenization procedure is assessed by comparing the curing of a homogenized tow with the curing of discrete fiber–matrix tow, followed by the virtual curing of a 8-harness satin (8HS) weave. Subsequently, the 8HS weave mechanical response is computed. Lastly, the 8HS mechanical response when cure induced effects (manufacturing process) are not taken into consideration are assessed.

Dynamic properties of carbon nanotubes reinforced carbon fibers/epoxy textile composites under low velocity impact

Abstract In this study, the impact response of polymer composites containing a random distribution of carbon nanotubes (CNTs) has been investigated by considering energy profile diagrams and associated force-time curves. The composite consists of CNTs initially filled Epon 862 Epoxy resin and implanted between plies of T300 6k Carbon fiber with 5HS (satin) weave. Different mass fractions of CNTs were used: 0% as reference, 0.5%, 1%, 2% and 4%. Taylor impact test was used to obtain the impact response of specimens. Projectile manufactured from a high strength and hardened steel with a diameter of 20 mm and 1.5 kg of mass was launched by a compressed gas gun within the velocity of 7 m/s. Deformation histories and damage modes of specimens were recorded during impact using high-speed camera. The effect of CNTs amount on dynamic properties and damage process was discussed.

Effect of fabric weaves on the dynamic response of two-dimensional woven fabric composites

This study investigated the effect of two-dimensional fabric weaves (plain, twill, and satin) on the vibrational characteristics (natural frequency and damping) of woven carbon/epoxy composites. Natural frequencies of woven composites were measured by experimental modal analysis for plain weave, twill weave, and satin weave composites. The experimentally measured natural frequency results were compared with the ones predicted by numerical free vibration analysis. Numerical analysis was performed using a multiscale modelling approach. First, the impregnated fiber tow properties were predicted using periodic boundary conditions assuming that fibers are perfectly bonded. Then, the homogenized impregnated fiber tow properties and matrix properties were used to predict the natural frequencies of woven composite beams. The experimental and numerical results revealed that satin weave composites possess higher natural frequencies than plain weave composites. Flexural loss factor of woven composites was measured experimentally by dynamic mechanical analysis and half-power bandwidth method. Results from both analyses showed that plain weave composites have higher flexural loss factor as compared to satin weave composites.

A novel analytical curved beam model for predicting elastic properties of 3D eight-harness satin weave composites

Abstract An offset representative unit cell (ORUC) is introduced to predict elastic properties of three-dimensional (3D) eight-harness satin weave composites both analytically and numerically. A curved beam model is presented based on minimum complementary energy principle, which establishes an analytical solution for elastic modulus and Poisson’s ratio calculation. Finite element method is developed to predict engineering constants of composites. Modified periodic boundary conditions and load method for ORUC are also presented. Experiments of simulated material are performed under tensile test. Close correlation is obtained between experimental data and predictions. Sensitivity study is conducted and manifests that within a large variation of constitutive material properties, the curved beam model derives close predictions comparing to finite element model, which indicates the stability of the curved beam model. Parametric study is also conducted to discuss the effect of weave type and geometric dimensions on elastic properties. It is argued that the curved beam model could manifest fine predictions accurately and stably, and is recommended for the prediction of elastic properties of satin weave composite.

Fatigue of a 3D Orthogonal Non-crimp Woven Polymer Matrix Composite at Elevated Temperature

Tension-tension fatigue behavior of two polymer matrix composites (PMCs) was studied at elevated temperature. The two PMCs consist of the NRPE polyimide matrix reinforced with carbon fibers, but have different fiber architectures: the 3D PMC is a singly-ply non-crimp 3D orthogonal weave composite and the 2D PMC, a laminated composite reinforced with 15 plies of an eight harness satin weave (8HSW) fabric. In order to assess the performance and suitability of the two composites for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions simulating the actual operating conditions. In all elevated temperature tests performed in this work, one side of the test specimen was at 329 °C while the other side was open to ambient laboratory air. The tensile stress-strain behavior of the two composites was investigated and the tensile properties measured for both on-axis (0/90) and off-axis (±45) fiber orientations. Elevated temperature had little effect on the on-axis tensile properties of the two composites. The off-axis tensile strength of both PMCs decreased slightly at elevated temperature. Tension-tension fatigue tests were conducted at elevated temperature at a frequency of 1.0 Hz with a ratio of minimum stress to maximum stress of R = 0.05. Fatigue run-out was defined as 2 × 105 cycles. Both strain accumulation and modulus evolution during cycling were analyzed for each fatigue test. The laminated 2D PMC exhibited better fatigue resistance than the 3D composite. Specimens that achieved fatigue run-out were subjected to tensile tests to failure to characterize the retained tensile properties. Post-test examination under optical microscope revealed severe delamination in the laminated 2D PMC. The non-crimp 3D orthogonal weave composite offered improved delamination resistance.

Investigations on the mode I translaminar failure and determination of fracture toughness in woven-ply carbon fibers thermoplastic composites at high temperatures

The purpose of this study is to investigate the mode I translaminar fracture energy for initiation and propagation of 5-harness satin weave carbon fabrics reinforced PolyPhenylene Sulphide (PPS) laminates subjected to tensile loadings at T>Tg (glass transition temperature) when matrix toughness is significantly enhanced. Specimens with a quasi-isotropic stacking sequence and a single-edge-notch geometry are characterized by an elastic-brittle response resulting from transverse matrix cracking and fiber breakage near the notch tip. From the macroscopic response standpoint, crack initiation and propagation virtually occur at the same time corresponding to ultimate failure making therefore difficult the assessment of corresponding strain energy release rates. The values obtained for crack onset were determined by means of three different technics: (i) the Crack Tip Opening Displacement (CTOD) method based on the outer surface full-field measurements – (ii) cracking gauges bonded to the outer surface – (iii) monitoring of the Acoustic Emission (AE) activity associated with the prominent damage mechanisms (transverse matrix cracking and fibers breakage). Within the framework of Linear Elastic Fracture mechanics (LEFM), the initiation KI_init and critical KIc mode I fracture toughness were calculated from the strain energy release rate GI in the case of quasi-isotropic laminates. Through the comparison with the value calculated from semi-empirical solutions developed for isotropic materials, the capability of these methods to provide reproducible and accurate values was validated. Among the different techniques implemented in the present work, the monitoring of AE signals is particularly relevant as it provides a reliable approach to detect the crack onset at the microscopic scale.

Temperature Effects on Mechanical Properties of Woven Thermoplastic Composites for Secondary Aircraft Structure Applications

The effect of temperature on the mechanical behavior of 8-H satin woven glass fabric/polyethylene sulfide (GF/PPS) was investigated in this paper. Static-tensile tests were both conducted on notched and unnotched specimens at typical temperatures (ambient, 95°C and 125°C) based on the glass transition temperatures ( T g ) of the neat resin and composite, their strength and moduli were obtained and compared. The damage patterns of failed specimens of notched and unnotched were examined with the aid of high-definition camera and stereomicroscope. The results of stress-strain relationships showed that the slight nonlinearity of the curves were observed for these two specimens, which was associated with the plastic deformation of localized resin. The damage patterns of notched and unnotched specimens at different temperatures proved that damage and plastic deformation were two simultaneous mechanisms and it was prominent in the notched. It was the overstress accommodation mechanism that led to a relative high strength rentention for the notched and a reduction of the hole sensitivity. The results obtained in this paper indicated that GF/PPS can be used as secondary aircraft structures at elevated temperatures higher than its T g .

An experimentally validated computational model for progressive damage analysis of notched oxide/oxide woven ceramic matrix composites

The focus of this paper is to examine the effect of a notch on the failure response of an oxide/oxide ceramic matrix composite (CMC) subjected to room-temperature tensile loading. The CMC is made of aluminosilicate matrix reinforced by 3M Nextel™ 610 alumina fibers (AS/N610) that are woven into an eight-harness satin weave (8HSW) preform. Uniaxial tensile tests were carried out on both un-notched and single-edge-notched tensile (SENT) specimens of two different lay-ups, (0/90)S and (45/0/-45/0)S , using a hydraulically activated load frame. The digital image correlation (DIC) technique was utilized to map the deformation histories and identify the locations of strain concentration for both un-notched and SENT specimens. The experimental results were subsequently used to develop a lamina-level constitutive model for a single 8HSW ply that incorporates damage and fracture mechanics implemented through a finite element (FE) framework. A secant-modulus approach was employed to model the pre-peak nonlinear damage evolution, while the post-peak softening was modeled using the smeared crack approach (SCA). Utilizing the ply properties measured from the un-notched (0/90)S and (45/0/-45/0)S tension tests, the proposed computational model is able to predict the failure strength and strain localization in the SENT specimens. Such a predictive model can aid in the design of CMC structures and accelerate the development of CMCs for engineering applications.

Effect of structural parameters on thermal protective performance and comfort characteristic of fabrics

In an attempt to understand the influence of basic structural parameters of fabrics on thermal protection and comfort, present study mainly focuses on analyzing effect of fabric weaving pattern and fabric weight. Fabric samples of three basic weaving patterns (plain, twill, and satin) and three different weights were prepared. Air permeability of the developed fabric samples was measured. Thermal protective performance of fabrics against radiant heat and flame exposures of two different intensities were measured. Spectral transmission behavior of fabrics was also studied. It was observed that for same fabric weight, protective performance and air permeability of satin woven fabrics were better as compared to the fabrics of other patterns. Protective performance increased and air permeability decreased as fabric weight increased for each type of woven structure included in this study. A new structural parameter is proposed which primarily influences the protective performance of fabrics exposed to either radiant heat, flame, or combined convective/radiant heat exposure.

The Effect of Various Weave Designs on Mechanical Behavior of Lamina Intraply Composite Made from Kenaf Fiber Yarn

The development of lamina intraply composite is a novel approach that can be adopted to address the challenges of balance mechanical properties of polymer composite. This research will focuses on the effects of weave designs on the mechanical behavior of a single ply or also known as lamina intraply composite. The six (6) specimens of lamina intraply composites were made by kenaf fiber as a reinforcement and unsaturated polyester resin as a matrix in various weave designs which were plain, twill, satin, basket, mock leno and leno weave. The vacuum infusion technique was adopted due to advantages over hand lay-up. It was found that the plain, twill and satin weave exhibited better mechanical properties on tensile strength. The fiber content of the specimen was 40% and the result of the resin content of the specimen was 60% due to the higher permeability of natural fiber.

The Effect of Lamina Intraply Hybrid Composites on the Tensile Properties of Various Weave Designs

The topic of natural fiber is one of the most active areas in thermoset composite research today. This paper will focuses on the effect of weave designs on the mechanical behaviour of lamina intraply hybrid composites. Twelve specimens were used and they were made of kenaf fibre and glass fibre as a reinforcement and unsaturated polyester resin as a matrix in various weave designs which were plain, twill, satin, basket, mock leno, and leno weave. Vacuum infusion technique was used due to its superior advantages over hand lay-up. The specimens were produced in two types which were kenaf fibre in warp direction interlace with glass fibre in weft direction (WK-WG) and glass fibre in warp direction interlace with kenaf fibre in weft direction (WG-WK). Various weave designs were found to affect the tensile properties. Glass fibre in warp direction has a greater effect on tensile strength compared to kenaf fibre in warp direction. Mock leno weave exhibited better mechanical properties for WK-WG and WG-WK, about 54.74 MPa and 99.46 MPa respectively.

Automatic detection of fiber orientation on CF/PPS composite materials with 5-harness satin weave

The physical proprieties of composite materials are highly influenced by the fiber orientation. This characteristic becomes critical when we bring into question composite laminates materials with unidirectional or bidirectional fiber reinforcement, which exhibit an orthotropic behavior. In this work, we propose a simple, fast and very stable method for automatic detection of fiber orientation on carbon fiber (CF) polyphenylene sulfide (PPS) composite materials with 5-harness satin weave (5-H satin). Our approach is based on the analysis of a material picture, using image processing and computational geometry techniques such as edge detection, flood fill and minimum-area enclosing rectangle. The results obtained are very accurate with the same good stability for any picture/fiber orientations. Even the method was built around a specific composite material, i.e. CF/PPS 5-H satin CETEX from the TenCate Company, with some small parameters tuning, it can be successfully applied to other materials, some different examples being shown in this paper.