Search

This study proposes a process for the preparation of composite laminates using the shear thickening fluid (STF) impregnated aramid fabric and presents some fabric panel configuration strategies. Firstly, this study prepared two kinds of STF using 20 nm and 500 nm silica particles. Then, the STF‐impregnated Kevlar fabrics were laminated and hot‐pressed to form the fabric panels. After that, the ballistic performance of the fabric panels was evaluated by firing the 9 mm steel core projectile using a gas gun. The ballistic tests showed that the ballistic performance of the hybridized configuration panels using STF‐20 treated fabrics as the front panels and STF‐500 treated fabrics as the backing panels was superior, with a reduction of 36.1%–37.6% in the number of perforated layers (4.7–5 layers) compared to a single STF‐treated panel. This study provides a new idea and method for applying STF in protective equipment. Highlights: Shear thickening fluid (STF) and aramid fabric are better combined by hot pressing lamination process;The ballistic properties of fabric panels are significantly improved by hybrid configuration;The ballistic performance enhancement mechanism of composite bulletproof plate was revealed. [ABSTRACT FROM AUTHOR]

The increase in aerospace composites usage for structural components demands advanced repair analysis. Overlay repairs of carbon fiber-reinforced polymer laminates offer an alternative that is easier to perform and less time-consuming to produce than the widely used tapered scarf repair and stepped lap. Composite specimen manufacturing was based on both twill carbon/epoxy prepreg and wet layup. The repair was performed with both prepreg and wet extra plies to the parent prepreg structure. However, the design of overlay joints must be carefully investigated to avoid generating stress concentration regions at free edges. This study examined specific extra ply terminations' impact on peak stresses in the adhesive bond line. Linear finite element analysis was performed to conduct a maximum principal stress study with a focus on three joint design parameters: ply material, overply effect, and stacking sequence. FEA accurately predicted experimentally observed responses and provided further insight into the failure behavior of the structure. Results showed that overlay joints have a strong sensitivity to ply material type, the number of overply, and stacking sequence. The introduction of overplies provided protection and stiffness at joint tips, and an overply material behavior was identified. The location of 0̊plies in the composite laminates was highlighted as an important factor. The analysis was then extended to three-dimensional FE models for verification. In conclusion, results showed that high-stress concentration in overlay joints can be mitigated with the introduction of overplies and appropriate changes in joint design parameters to reduce stress peaks at joint tips and corners. [ABSTRACT FROM AUTHOR]

In recent years, researchers have made efforts to promote the thermal protection capabilities of firefighting suits in response to frequent fire accidents. In this paper, a novel silica/aramid nonwoven fabric (SiO 2 /AF) aerogel composite was prepared by combining AF and SiO 2 aerogel using the sol-gel method and dip coating technology. Polyimide (PI) and zeolitic imidazolate framework-L (ZIF-L) were used as insulation reinforcement materials to fabricate four types of laminated fabrics, namely, the outer layer + waterproof breathable layer + different insulation layers (AF, SiO 2 /AF, 0.8 % SiO 2 /AF/PI and 0.12 % SiO 2 /AF/ZIF-L, respectively). In addition, the fireman uniform was taken as the control group. The results showed that the insulation performance of the composite fabrics was better than that of the control group, and the outer layer + waterproof breathable layer+0.12 % SiO 2 /AF/ZIF-L laminated fabric exhibited the lowest thermal conductivity (0.038 W/(m·K)), best thermal radiation protective performance (RPP) (246.04 kW/m2) and excellent wear resistance (mass loss rate 0.46 %). This significant work will open up broad prospects for the applications of SiO 2 /AF composites in the area of heat-resistant clothing. [ABSTRACT FROM AUTHOR]

In this research, a laminate was produced by assembling five textile layers. These layers were a coated double-sided knitted structure, a non-woven fabric, a hydrophilic membrane that was thermally assembled to a surface veil, and an open-work knitted fabric. The laminated textile's breathability, windproofness, and waterproofness were evaluated. The multi-layered fabric was windproof, and its water vapor permeability was 347.297 g m-2 s-1 (CV= 8.902%). Its resistance to water penetration was equal to 117.68 Schmerber (CV = 7.81%). The assembled fabric's mechanical properties were also evaluated. Young's modulus values were equal to 2 MPa (CV= 8.613%) and 1.6 MPa (CV= 8.349%) for both fabric directions. Its flexural rigidity was 5056.659 mg cm and its surface total deformation was lower than 450 µm when measured under 20, 40, 60, and 80 mN loads. Based on the results obtained, it was concluded that the developed multi-layered fabric could be used to produce raincoats and jackets to protect the wearer from light rain and drizzle. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to fabricate a multifunctional electromagnetic interference (EMI) shielding composite fabric with simultaneous high-efficiency photothermal conversion and Joule heating performances. Design/methodology/approach: A multifunctional polypyrrole (PPy) hydrogel/multiwalled carbon nanotube (MWCNT)/cotton EMI shielding composite fabric (hereafter denoted as PHMC) was prepared by loading MWCNT onto tannin-treated cotton fabric, followed by in situ crosslinking-polymerization to synthesize three-dimensional (3D) conductive networked PPy hydrogel on the surface of MWCNT-coated cotton fabric. Findings: Benefiting from the unique interconnected 3D networked conductive structure of PPy hydrogel, the obtained PHMC exhibited a high EMI-shielding effectiveness vale of 48 dB (the absorbing electromagnetic wave accounted for 84%) within a large frequency range (8.2–12.4 GHz). Moreover, the temperature of the laminated fabric reached 54°C within 900 s under 15 V, and it required more than 100 s to return to room temperature (28.7°C). When the light intensity was adjusted to 150 mW/cm2, the PHMC temperature was about 38.2°C after lighting for 900 s, indicating high-efficiency electro-photothermal effect function. Originality/value: This paper provides a novel strategy for designing a type of multifunctional EMI shielding composite fabric with great promise for wearable smart garments, EMI shielding and personal heating applications. [ABSTRACT FROM AUTHOR]

In high-velocity projectile impacts, the contact duration is very short and the response of the target is governed by the local behavior of the material in the impact zone. On impact, a compressive stress wave is generated in the target, which travels in the thickness direction. This compressive stress wave plays a significant role in the failure of thick composite targets. In conventional laminates, the out-of-plane (transverse) compressive strength of composite resists the generated compressive stress wave which is not efficient since out-of-plane compressive strength is significantly lower than the fiber direction strength value. In the current numerical study, a non-conventional approach has been adopted by orienting the fibers in the impact direction to utilize the high compressive strength in the fiber direction to resist the projectile impact. In this regard, unidirectional composite rod segments are considered with fiber aligned in the projectile impact direction. The resulting effect on the impact energy absorption and the overall mechanical impact response is numerically studied and compared with conventional woven fabric laminates. Several configurations of these unidirectional fiber rod segments and the role of lateral confinement are also studied to understand their effect on the impact energy absorption. The numerical simulation results indicate an advantage for the proposed arrangement of composite (segments) rods with fiber in impact direction over the conventional woven fabric laminates. [ABSTRACT FROM AUTHOR]

Laminated fabrics offer a unique combination of properties and are widely used in various applications, including as moisture barriers in firefighters' protective clothing. Tearing is a common testing method used to evaluate the mechanical performance of laminated fabrics. However, limited information is available on the tearing behavior of laminated fabrics using the trapezoidal procedure. Using high‐speed imaging, this study examined the tearing process of three moisture barriers commonly used in firefighters' protective clothing. The results revealed that the tearing process varied depending on factors such as the structure of the base fabric, the presence of an extra coating on top of the membrane, and the continuous or discontinuous nature of the adhesive layer. This study provides insight into the effect of each component of a laminated fabric on the tearing process, and can inform the design of better performing moisture barriers. Highlights: Study of trapezoidal tearing behavior of moisture barriers.Analysis by high‐speed imaging and field emission scanning electron microscope.Influence of base fabric, adhesive configuration, presence of extra coating.Cyclic tearing pattern for woven base fabric and dot adhesive.Continuous tearing for nonwoven base fabric and continuous adhesive. [ABSTRACT FROM AUTHOR]

To develop continuous fibre compos laminates and fabrics in the aeronautics and aerospace industry, a thorough understanding of the behaviour of these materials under various loading conditions is required. The purpose of this work aims to assess the failure of different composite materials subjected to a bending load, using the progressive damage approach. Puck's failure criteria and gradual degradation model have been used to simulate the initial and the successive damage, respectively. A user-defined material (UMAT) subroutine has been developed and implemented through finite element software Abaqus. Moreover, the effect of geometrical parameters is performed and identified by the experimental protocol. The predicted results obtained by this numerical modelling show a good correlation with the findings of the experimental test. [ABSTRACT FROM AUTHOR]

Multi-layer fabrics are commonly used in ballistics shields with a lower bulletproof class to protect against pistol and revolver bullets. In order to additionally limit the dynamic deflection of the samples, layers reinforced with additional materials, including non-Newtonian fluids compacted by shear, are additionally used. Performing a wide range of tests in each case can be very problematic; therefore, there are many calculation methods that allow, with better or worse results, mapping of the behavior of the material in the case of impact loads. The search for simplified methods is very important in order to simplify the complexity of numerical fabric models while maintaining the accuracy of the results obtained. In this article, multi-layer composites were tested. Two samples were included in the elements subjected to shelling. In the first sample, the outer layers consisted of aramid fabrics in a laminate with a thermoplastic polymer matrix. The middle layer contained a non-Newtonian shear-thickening fluid enclosed in hexagonal (honeycomb) cells. The fluid was produced using polypropylene glycol and colloidal silica powder with a diameter of 14 µm in the proportions of 60/40. The backing plate was made using a 12-layer composite made of Twaron® para-aramid fabrics with a DCPD matrix—not yet used in a wide range of ballistics. Then, numerical simulations were carried out in the Abaqus/Explicit dynamic analysis. The Johnson–Cook constitutive strength model was used to describe the behavior of elastic–plastic materials constituting the elements of the projectiles. For the non-Newtonian fluid, a Up-Us EOS was used. The inner layers of the fabric were treated as an orthotropic material. Complete homogenization of the sample layers was carried out, thanks to which each layer was treated as a homogeneous continuum. As a parameter of fracture mechanics for shield components, the strain criterion was used with the smooth particles hydrodynamics method (SPH). Then, the results of simulations were compared with the results of the ballistic test for both samples placed next to each other, which resulted in the formation of a multi-layer composite in one ballistic test subjected to impact loads during firing with a 9 × 19 mm Parabellum FMJ projectile with an initial velocity of 370 ± 10 m/s. The results of numerical tests are very similar to the ballistic tests, which indicates the correct mapping of the process and the correct conduct of layer homogenization. The applied proportions of the components in the non-Newtonian fluid allowed a reduction in the deflection compared to previous studies. Additionally, the proposal to use a DCPD matrix allowed to obtain a much lower deflection value compared to other materials, which is a novelty in the field of production of ballistic shields. [ABSTRACT FROM AUTHOR]

This research investigated the use of electrospun nanofibers as reinforcing laminates in textiles to enhance their mechanical properties for use as smart and technical textile applications. Crimping plays a crucial role in textiles. Because of crimp, fabrics have extensibility, compressibility, and improved quality. Although crimping is inevitable for fabrics used in smart textiles, it is also a disadvantage as it could weaken the fibers and reduce their strength and efficiency. The study focused on preparing laminated textile composites by electrospinning a polyacrylonitrile (PAN) polymer onto textile fabric. The research examined the effect of electrospun nanofibers on the fabric by using a tensile testing machine and scanning electron microscopy. The results revealed that the prepared laminated textile was crimp-free because of the orientation of the nanofibers directly electrospun on the fabric, which exhibited perfect bonding between the laminates. Additionally, the nanofiber-reinforced composite fabrics demonstrated a 75.5% increase in the elastic moduli and a 20% increase in elongation at breaking. The study concluded that the use of electrospun nanofibers as laminates in textile composites could enhance the elastic properties, and prepared laminated composites will have the advantages of nanofibers, such as crimp-free elastic regions. Furthermore, the mechanical properties of the laminated textile composite were compared with those of the micromechanical models, providing a deeper understanding of the behavior of these laminated composites. [ABSTRACT FROM AUTHOR]

Five samples of the nylon fabric laminated rubber bearing were manufactured with different rubber layer thickness and nylon cloth specifications. The compression and compression shear tests were conducted to evaluate the mechanical properties of the bearings. Results show the novel bearings' vertical stiffness is significantly lower than that of laminated steel rubber bearings, but their vertical damping ratio can reach 7%. The effective horizontal stiffness decreases with increasing shear strain due to rollover deformation. The bearings do not get seriously damaged when the shear strain is 300%. The equivalent damping ratio of the bearings varies in the range of 9%–13%. [ABSTRACT FROM AUTHOR]

In the paper, a detailed experimental and numerical investigation of compression after impact (CAI) behavior of hygrothermal aged T300 985LV carbon/epoxy composites is presented. Rectangular fabric laminates are damaged by low‐velocity impact, and moisture absorption conditioning is carried out. The moisture absorption curves agree with Fick's law, with a moisture equilibrium rate of 0.84% at 1392 h. Then, CAI experiments are carried out on moisture saturated specimens at different temperatures. The effects of hygrothermal environments on CAI strength are obtained with an interpretation of corresponding mechanism. Furthermore, finite element analysis based on hygrothermal mechanics formulation and incremental Newton–Raphson mixed iteration equation is established. The numerical results are in good agreement with the experimental ones, with an accuracy of up to 92%, which demonstrates the effectiveness of the established numerical model. The results show that the CAI strength of 85 RH% hygroscopic saturated laminates is decreased by approximately 12% at 85°C and 17% at 128°C. Additionally, the allowable compression value of 3546 μɛ is obtained for T300 985LV composite laminates, which is useful for applications in civil aircraft design. [ABSTRACT FROM AUTHOR]

Textile composites owe their desirable mechanical properties to the intricate fabric architecture. However, manufacturing deviations can influence these attributes, significantly affecting their mechanical performance. Thus, ensuring the quality and structural integrity of fabric architectures has become pivotal, leading to the advancement of ultrasonic non-destructive testing techniques. However, existing techniques, primarily tailored for unidirectional laminates, often struggle with weave pattern extraction, given the complex features of fabric laminates. To address this gap, a pulse-echo ultrasound coupled to a 2D analytic-signal analysis is proposed. The 2D analytic-signal methodology autonomously discerns the complex ultrasound features from fabric laminates, streamlining weave pattern analysis. The study showcases ply-by-ply reconstruction of local weave patterns of fabric laminates with nominal layups of [ # (0 / 90) ] 8 and [ # (+ 45 / − 45) # (0 / 90) ] 5 s , respectively. The efficacy of the methodology is ascertained through quantitative metrics, highlighting its innovative potential for through-depth extraction of local weave patterns in a swift and automated manner. [ABSTRACT FROM AUTHOR]

This study focuses on the fatigue and static response of noncrimp fabric laminates modified with electrospun nanofiber veils; thus, the cross-ply was engaged in performing the test program. The results of static flexural tests and short-beam shear tests initially exhibited significant improvement in the flexural and interlaminar shear strength of the nanofiber modified (NM) samples due to different mechanisms. Further, the fatigue tests were conducted under the load-control fatigue condition, and the NM configuration exhibited high deflection and low stiffness decrease rate during the progressive damage. Notably, the fatigue strength of the NM configuration was 1.7 times higher than the virgin configuration, and the run-out point analysis revealed that the nanofiber veil has excellent potential to extend the material fatigue strength range and optimize the fatigue energy absorption capability of composite material. Finally, although the residual strength of the pre-cycling specimens reduced with an increase in load level, the stiffness reduction could not accurately predict the residual strength of the sample. [ABSTRACT FROM AUTHOR]

Failure mechanisms of curved cross-ply laminates under static and fatigue loading have been studied extensively, but the examination of fabric laminates which are the most commonly used ply type in curved supports in airplane wing structures is lacking. In this study, unidirectional (UD) and fabric carbon fiber reinforced polymer (CFRP) laminates are examined to elucidate the failure initiation mechanisms of laminated composites under fatigue and static loading. The crucial point of the research is applying the analyses using fabric laminate with a currently used stacking sequence in commercial airplanes. In addition to the fabric laminate, UD laminate is also included in the research to compare the real complex stacking with the simplest stacking. In the experiments, it is observed that both static and fatigue failures initiate roughly at the maximum radial stress location (approximately 35% of the thickness from the inner radius). For UD laminates, there is no visible difference between the failure mechanisms under static and fatigue loadings. However, for fabric laminates, fatigue failure is observed to occur as a single major crack at the maximum radial stress location as in UD laminates, whereas static failure is observed to occur as multiple diffusive cracks at the maximum radial stress location. Additionally, cracks grow mostly as intralaminar cracks connected with regions of occasional interlaminar cracks. [ABSTRACT FROM AUTHOR]

The reinforcement of natural and artificial fiber-oriented woven fabrics with thermosetting polymers is getting popularity nowadays. The hybridization of natural hemp with glass could facilitate the developed composite panels to be a potential candidate for automotive parts. Both hemp and glass-woven fabrics were treated with greenly synthesized silver nanoparticle (AgNPs) obtained from Tilia cordata leaf extracts and then composited by using thermosetting epoxy resin. Three composite panels were developed from five consecutive layers of glass- and hemp-woven fabrics (sequence is glass, hemp, glass, hemp, glass); in two of them the fabrics were loaded with 1% and 5% AgNPs, respectively, the third one was prepared without any nanosilver loading. The presence of green AgNP was tested and confirmed by using XRF (X-ray fluorescence) and ICP OES (inductively coupled plasma optical emission spectroscopy) test. The developed hybrid composites were characterized for thermal, mechanical, physical, and morphological performance and found satisfactory results. Statistical analysis of the test results also confirmed the positive influence of nanosilver loading on hybrid composites. However, the developed biocomposite panels could facilitate the industrial production units with most advanced, feasible, and multi-functional laminated products. [ABSTRACT FROM AUTHOR]

In this study, the comfort properties of water-proof but breathable (water vapour permeable) textile fabrics having the composite structure containing a membrane layer or a coating layer are examined. In the present study, parameters such as ambient conditions, the air gap between body and garment, thickness of materials used in the production of garments and composite structure affecting the comfort properties of the structures mentioned above were examined. After the selection and obtaining the samples; water vapour permeability, air permeability, waterproofness tests were respectively applied and the results were interpreted in a way that producers and related scientists could benefit. The most important results achieved here are that the water vapour permeability decreases as the thickness of the membrane/coating in which the fabrics are coated/laminated increases, the air gap between the body and the garment reduces the water vapour permeability greatly, the membrane character (microporous / non-porous) has different effects on the water vapour permeability in different ambient conditions. These results sound promising for future studies. [ABSTRACT FROM AUTHOR]

Impact experiments of thick fabric carbon/epoxy laminate specimens, with small thickness ratio, are conducted at distinct energy levels and thicknesses to characterise the damage process. These specimens and loading conditions are representative of a new generation of critical structural components in aviation, such as wing spars, landing gear beams and fittings, that are increasingly being made entirely from composites. The tests address the need to better understand the damage process for specimens with a small thickness ratio since existing experimental impact data for large thickness ratio (thin laminates) may not be directly applicable. Two energy levels, two different fabric layups and two impact methods (drop-weight and gas-cannon) were used. Data from high-speed cameras were processed in a novel way, providing the force during impact. C-scans and micrographs were used to characterise damage. The results show that specimens with a thickness ratio of 5 (20 mm thick) experience more bending compared to specimens with a ratio 2.5 (40 mm thick). For gas-cannon impacts, this results in a higher delaminated area. The drop-weight impacts show almost no differences in damage size for the thickness range analysed. The influence of layup on the global impact response is negligible, but locally it can result in significant variations in dent depth. The dent depth scales linearly with the impact energy and the delaminated area linearly with the impact velocity. There is no clear correlation between the compression-after-impact failure mechanisms and the residual strength. Impact damage, at the current energy levels, showed a minimal reduction of residual strength. [ABSTRACT FROM AUTHOR]

The compressive strength of fiber reinforced composites is typically limited by a shear localization phenomenon known as microbuckling and is very sensitive to local imperfections of fiber alignment. Local misalignments act as randomly distributed flaws and introduce a dependence of the compressive strength on the size of material volume element under consideration. For homogeneously loaded material elements, weakest-link theory in combination with a Weibull power law is a frequently employed statistical model for microbuckling strength. This implies a dependence of strength on the size of volume under consideration. The present contribution investigates the strength–size relation for a non-crimp fabric via a numerical approach. Characteristics of the misalignment flaws used in simulations are derived from a comprehensive data set collected via large-scale measurements of roving dislocations on dry fiber material. Predictions resulting from the weakest-link Weibull theory are compared against strength–size statistics gathered by numerical analysis. In this manner, the size effects in single plies and laminates are quantified. The main findings are that weakest-link Weibull theory is well suited to predict size related strength loss in individual plies. However, it is also found that when plies are bonded to form laminates, misalignments in individual plies are mitigated in a way that is inconsistent with the weakest-link assumption. In all situations considered here, the strength loss expected from weakest-link Weibull theory was outweighed by a strength increase due to the mitigation effect when the volume was increased by adding extra layers to a laminate. [ABSTRACT FROM AUTHOR]

Recently, due to environmental and sustainability issues, the scientific community has been attracted to renewable natural resources, even for the development of materials intended for structural applications. This work deals with the pre‐treatment of a flax fiber fabric by exploring the effects of the exposure time to nitrogen plasma on the ultimate performance of polypropylene matrix composite laminates potentially usable for the realization of internal parts in the naval sector. Flax fabrics were treated with three different exposure times (5, 10, and 15 min) with the aim to improve the adhesion between the hydrophilic fibers and the hydrophobic matrix. At first, transverse and longitudinal wicking tests were carried out on the treated fabrics in order to evaluate the improvement of the absorption constants after the formation of reactive groups on their surface. The results collected so far in terms of fabric water uptake, tensile, and flexural properties as well as morphological aspects (SEM analysis) and damage evolution (ESPI technique), have indicated that the optimal pre‐treatment time of the reinforcing fabrics is equal to 15 min. Compared to the laminate with untreated fabrics, the specimen with flax fibers treated for 15 min displays higher tensile properties with an increase of 6.8% and 22.31% in ultimate strength and modulus, respectively. More in general, the achievements of this research might be useful to extend the current range of applications of flax fibers even in industrial fields still dominated by conventional fibers. [ABSTRACT FROM AUTHOR]

Continuous real-time human motion and heart-rate monitoring systems can provide vital clinical information for disease diagnosis, preventive healthcare and rehabilitation care. However, it is still a challenge to design wearable pressure/strain sensors with great flexibility and sustainable power for motion detection and physiological signal monitoring. Here, a self-powered laminated fabric sensor based on Schottky contact was successfully fabricated. This laminated fabric sensor was constructed by sandwiching the polypyrrole (PPy)-coated fabric with the Ni-coated fabric and Al plastic film. The electrical outputs under strain were attributed to the single Schottky contact between PPy and Al. This fabric sensor exhibited excellent stability under continuous quick cycling operation and at high relative humidity, which could be adapted to different human body parts for continuous motion detection and heart-rate monitoring. This work is of great significance to demonstrate a promising strategy toward self-powered wearable pressure sensors used for human motion detecting and hear-rate monitoring. [ABSTRACT FROM AUTHOR]

Carbon fiber fabrics have been largely used in composite structures as they provide high mechanical strength and potential weigh reduction, allowing more efficiency in product design. However, the production of the parts generates scraps that is discarded as a waste, becoming a challenge to recycle the carbon fiber with predictable mechanical strength. Within this context, this research analyzed strategies of laying up carbon woven fabrics based scraps, in order to reach a desirable mechanical properties in bending loading. Three types of laminates were manufactured using varied fabric size and number of discontinuities in the layup combined with polyethylene terephthalate (PET) film as a matrix. The obtained composites were tested under four-point-bending test and an energy-strength based analysis was conducted. This analysis explained a strategic position of fabric scrap to maximize the bending strength: providing a value of 106.33 MPa for a composite with high number of discontinuities against 83.11 MPa for another with less discontinuity. [ABSTRACT FROM AUTHOR]

In the design of composite materials, the properties and failure modes/mechanisms are always of the main concern. In this work, the mechanical properties and failure mechanisms of composite laminates with classical fabric stacking patterns ([(0, 90)]8 and [(0, 90)/(± 45)]4) were systematically investigated through mechanical experiments and FEM (finite element method) numerical simulations. The results show that the tensile modulus and bending modulus of the laminates were reduced by 22.2% and 37% after partially changing the stacking angle to ± 45°, but corresponding elongation and bending displacement were increased by 8.8% and 11.7%, respectively. Bending failure mode changes from complete fracture to partial fracture. Meanwhile, the delamination damage and tow peeling from the matrix increase significantly. FEM simulations on tensile and bending processes of the composites indicate that the ± 45° stacking angle leads to the change of the axial stress direction from SX (0°) to SY (± 45°), which is difficult to be observed from mechanical experiments. The FEM simulation provides a cost effective and efficient way for the structural visual optimization design and failure prediction of the actual composite materials. [ABSTRACT FROM AUTHOR]

Fabrics which can keep people cool in a hot climate have attracted considerable attention in recent years. Among various cooling strategies, fabric cooling by water evaporation is proved to be very safe, simple and sustainable. Here, a tri-layer laminated fabric (TLF) inspired by perspiration is designed to realize passive cooling of human body. An interlayer fabric which is coated with crosslinked sodium polyacrylate can absorb and store a large amount of water. A moisture-absorbing and quick-drying fabric is used as the outer layer while a waterproof breathable fabric is used on the inside of the laminate in contact with skin. The prepared TLF shows decent evaporative cooling performance under dry heat conditions. The water absorbency of TLF is about 400% higher than that of pristine cotton after 1 h soaking in water. Under a 1 sun irradiation (1000 W m.2), the indoor temperature of a simulated room can be reduced by ≈.5.7 °C compared with the other without a cooling system. Meanwhile, the evaporative cooling effect can be maintained up to 5 h. This cooling fabric shows broad application prospects in the fields of thermal cooling to human and buildings. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel ML based inverse framework for predicting elastic properties of carbon fiber. • Predicts transverse and shear modulus that are challenging to obtain experimentally. • Homogenized RVE with random fiber distribution used to generate input data. • Multiscale framework to evaluate elastic properties of woven fabric laminates. Evaluating the transverse and shear modulus of carbon fibers experimentally is challenging and are usually obtained by an inverse approach using a micromechanical model. This paper presents an inverse approach for predicting the fiber properties from experimentally evaluated properties of the unidirectional (UD) lamina, using a machine learning (ML) based surrogate model. The ML framework is based on Gaussian process regression (GPR), which also provides a measure of uncertainty in the predictions. The ML model is trained using synthetic data generated using Finite Element (FE) homogenization considering different fiber and matrix properties, volume fractions, and fiber distribution. The proposed inverse framework is demonstrated to predict the elastic properties of polyacrylonitrile (PAN)-based fibers used in carbon-epoxy composites that have significant variations (low to high modulus) in its properties (T300-M60J). The fiber properties predicted using the GPR surrogate shows good agreement with the values reported in the literature, with a difference of less than 1.5%. The computational framework is further extended to predict the elastic properties of the woven fabric laminate using multi-scale homogenization. In summary, the results show that the GPR-based surrogate model offers an accurate and computationally efficient alternative to FE-based forward model for predicting the properties of the fiber. [ABSTRACT FROM AUTHOR]

During the late Miocene the Mediterranean experienced a dramatic intensification of opaline accumulation, recorded by the deposition of diatomaceous sediments. The fine lamination of these deposits potentially records annual to sub‐annual palaeoceanographic processes that occurred during a critical phase of the geodynamic evolution of the Mediterranean basin, which eventually led to the Messinian salinity crisis. The diatomaceous facies has been interpreted by previous researchers as the product of intensified upwelling currents and of bottom anoxia formation in the Mediterranean basin. However, until now, no efforts have been made to unravel the sedimentological and micropalaeontological content of these deposits at the lamina‐scale. This paper presents the first case study of a systematic scanning electron microscope‐based morphological investigation of the diatomaceous sediments deposited during the late Miocene at the northernmost offshoot of the Mediterranean basin (Piedmont Basin, north‐west Italy). Using a non‐invasive analytical approach, six faciological components (laminae, laminated packets, non‐laminated intervals, burrows, opal‐rich aggregates and mixed pelletal structures) and their relationships are described and interpreted herein. Following the lamina‐scale study of these sediments, an annual sedimentary cycle could be identified and an accumulation rate (ca 50 cm kyr−1) inferred that is atypical for a setting actively influenced by upwelling. The role played by the entanglement of diatom valves in creating a physical barrier to the bioturbation is here emphasized as the main process responsible for the preservation of the laminated fabric of diatomaceous sediments, challenging the supposed role of deep anoxia. These results suggest that the late Miocene diatomaceous deposition in the Piedmont Basin cannot be univocally considered as a by‐product of upwelling intensification and seafloor oxygen depletion. [ABSTRACT FROM AUTHOR]

Flexible fabrics have been widely used in body armor designs. Here we report ballistic impact damage of stacked cross-plied composite fabric and cross-plied laminated panels. The ballistic impact behaviors of stacked cross-plied composite fabric and cross-plied laminated panel have been tested with fragment-simulating projectiles under the strike velocity 550–600 m/s to explore the influence of the layers combination of fabric target on ballistic impact. Two types of macroscopic anisotropy continua finite element models based on fabric targets structures are established to analyze the ballistic mechanism of stacked cross-plied composite fabric and cross-plied laminated panels. The impact damage morphologies and energy absorptions have also been compared between the tests and finite element analysis results. We have found the stacked fabric construction absorbed more energy than their counterpart cross-plied laminated panel, while the laminated panel shows better structural integrity and stability during ballistic penetration. [ABSTRACT FROM AUTHOR]

This paper describes the development of laminated fabrics that contain a silver grid for electromagnetic shielding (EMS) applications. The silver grid was constructed with 0.3, 0.4, and 0.5 mm wire diameters and spacings. To reduce material costs, a solvent‐based polytetrafluoroethylene (PTFE) film, cotton woven fabric, and conductive silver paste were used to fabricate a cost‐effective EMS conductive laminated fabric successfully. Using a coaxial transmission line holder, the electromagnetic shielding effectiveness (EMSE) of various conductive laminated fabrics was measured in the 30 to 3000 MHz frequency range. The variation in the EMSE of the conductive networks with different grid shapes, grid densities, fineness values for the conductive lines, and concentrations of the silver paste on the PTFE films was evaluated. Based on optical microscopy observations and analysis, it was found that the conductive silver paste that was diluted by a high boiling point solvent comprising a mixed dibasic acid ester (DBE) could be printed on the PTFE film using a 300‐mesh screen to obtain a clear and complete mesh wire structure that was easy to coat. The results indicated that the proposed conductive laminated fabrics with the 0.3 mm silver wire dimension and spacing had a higher EMSE and electrical conductivity than those of the 0.4 and 0.5 mm wire dimensions and spacings. The results also showed that the fabrics with a 0.3 mm wire diameter and spacing with DBE dilution had a slightly lower EMSE and electrical conductivity than those of the bare PTFE films with a 0.3 mm wire diameter and spacing in the 120 to 2450 MHz frequency range. The conductive laminated fabrics with a 0.3 mm wire diameter and spacing silver electronic coating could be used for electromagnetic interference shielding applications. The conductive silver‐laminated woven fabric could also be applied to curtains, wall coverings, bedspread sets, maternity clothes, work bibs, microwave ovens, induction cookers, protective clothing, and antielectromagnetic mobile phone sets. [ABSTRACT FROM AUTHOR]

In this work, the statistical distribution of mechanical properties and energy absorption at break of laminated cotton fabric reinforced epoxy composites was determined. The static mechanical tests showed that the cotton fabric significantly influenced the mechanical performance of epoxy resin, where tensile strength, tensile modulus, tensile elongation at break, flexural modulus, and impact strength increased significantly, while flexural strength decreased. The energy absorption behaviors in the tensile tests were investigated, where more energy at tensile break was absorbed when cotton fabric was incorporated, as shown by the 684% to 2707% increase. The similar increases were observed in the flexural and impact tests, which were 92% to 355% and 309% to 833%, in different directions, respectively. The statistical distribution patterns of the mechanical properties parameters in variously direction of cotton fabric reinforced laminate were mapped. The results showed the distribution patterns of tensile modulus, flexural modulus, tensile strength, flexural strength, and energy absorption before maximum stress in the flexural test correlated with fiber angle in the laminate, while the distribution patterns of tensile elongation, impact strength, and energy absorption in the flexural and tensile tests agreed well with distribution of fiber content in the test cross section. With the incorporation of cotton fabric, the breakage behavior of epoxy transitioned from brittle fracture to toughened fracture as shown in distribution patterns of fracture energy absorption. The viscoelastic properties of the cotton fiber‐reinforced laminates were investigated via DMA. The cotton fiber‐reinforced laminates possessed higher transition temperatures, the storage modulus (E') and loss modulus (E"), compared to epoxy. [ABSTRACT FROM AUTHOR]

This article presents the studies on the launderability of conductive fabrics with four types of metal coatings (Cu, Ag, Ni/Cu, or Ni/Cu/Co), respectively, which are laminated to three common fabrics (spandex, nylon, and denim) using thermoplastic urethane (TPU) film. The electrical resistance as a function of laundry cycles is used to characterize the performance of these conductive materials. The laundry procedure follows the AATCC M6 test standard by using the AATCC compliant washer and dryer with control factors such as detergent, temperature, agitation speed, and spin speed. After the intended wash and dry cycles, the electrical resistance of the conductive fabrics is measured using a four-point probe method. The resistance stability over the laundry cycles is compared between these conductive fabrics with four metal coatings, respectively. In general, all the conductive fabrics show an increase in electrical resistance with laundry cycles, and the extent of the increase depends on the metal coating and the base fabrics to which the conductive fabrics are laminated. Further, the soaking test reveals that the AATCC certified detergent does not have a measurable effect on the performance of the conductive fabrics. To obtain an insight on the degradation of the conductive fabrics during laundry, further inspection and analysis are performed, including 3-D optical microscopy, scanning electronic microscopy (SEM), cross sectioning, and X-ray fluorescence (XRF). A significant peeling and fracture of metal coating layers, due to mechanical tumble or agitation stresses during laundry, are observed for the conductive fabrics with Cu, Ni/Cu, and Ni/Cu/Co coatings, leading to electrical resistance increase or even electrical open, whereas the conductive fabrics with Ag coating show a metal scratch instead of peeling and fracture, possibly due to silver’s superior flexibility, ductility, and adhesion with the base fiber. Besides metal coatings, the mechanical properties of the base fabrics appear to significantly affect the laundry performance of the conductive fabrics, in which the more rigid base fabric causes higher mechanical stresses on the metal coating, leading to more damages and accordingly higher increases in resistances. [ABSTRACT FROM AUTHOR]

The use of kevlar fabric laminates in the structural repair and retrofitting of reinforced concrete members becomes a great deal of research work nowadays. Many research works have been done on the performance of Fibre-Reinforced Polymer (FRP) laminates on reinforced concrete structural members. Some studies have been done on the performance of kevlar fabric laminates on reinforced concrete structural members and only few contributions are available for self-compacting concrete structural members. Hence, in this research work, an attempt is made to study the performance of reinforced concrete and self-compacting beams laminated with various numbers of kevlar fabric layers by an epoxy bonding agent under a two-point concentrated loading system. The experimental data of ultimate load, mid-span deflection and mode of failure was collected and discussed. Theoretical and analytical studies were also conducted and compared with experimental results. When applying the kevlar fabric as an external reinforcement, the flexural strength of two-layer U-shape kevlar fabric-laminated beams has been increased by 88% and 82%, respectively, compared to unlaminated reinforced concrete and self-compacting beams. [ABSTRACT FROM AUTHOR]

In this article, chip-on-fabric (COFa) assemblies using anisotropic conductive films (ACFs) and metal-laminated fabric substrates were investigated. To fabricate the metal-laminated fabric substrates, electroless nickel–immersion gold (ENIG) metal-finished Cu circuits were fabricated on the B-stage nonconductive films (NCFs), followed by laminating onto the fabrics. Then, the 50- $\mu \text{m}$ -thick Si chip was bonded onto the fabric substrates using ACFs with a thermocompression (T/C) bonding method. First, the ACFs’ joint properties, such as electrical resistances and adhesion strengths, were evaluated and compared with conventional chip-on-flex (COF) assembly. To enhance static bending flexibility without chip fracture, chip-in-fabric (CIFa) assemblies were developed after optimizing the thickness of a cover layer on the Si chip. Finally, mechanical and moisture-related reliability of the CIFa packages was evaluated through dynamic bending, 85 °C/85% relative humidity (RH), and washing reliability. [ABSTRACT FROM AUTHOR]

Fabrication of multifunctional materials via incorporation of the third component into structural composite laminates is of great interest, especially for manipulating surface properties. However, achieving a uniform, well‐dispersed surface microstructure in ternary composites is quite challenging by using the traditional fabrication processes. In this article, a novel cascaded suspension deposition method is presented to introduce well‐dispersed short fibers into the molded laminates, allowing the control of the surface properties of the resulting ternary composite. Towards this goal, the micron‐sized, nickel‐coated carbon (NiC) fibers are uniformly deposited on a glass fabric surface by the proposed method. The deposited fabric is then used to fabricate NiC/glass/epoxy composite laminate by vacuum assisted resin transfer molding (VARTM). The deposition morphology on the glass fabrics and the fabricated laminates is investigated by assessing: (i) spatial uniformity of fiber volume fraction; (ii) degree of dispersion; and (iii) process‐induced orientation and degree of alignment. To demonstrate the flexibility of the proposed method, the effects of fiber concentration, fabric architecture, and resin flow are studied. The experimental results reveal that, in all fabrication cases, the cascaded suspension deposition technique is capable of depositing short fibers on the fabric surface with a uniform fiber volume fraction and excellent dispersion with random orientation. In addition, it is observed that the resin flow during VARTM does not considerably disturb the deposition‐induced microstructure of the NiC fibers, which allows the successful fabrication of ternary composites by VARTM. [ABSTRACT FROM AUTHOR]

Cu pattern-laminated fabric substrates using epoxy-based B-stage adhesive films were demonstrated. Fine-pitch Cu electrical patterns were fabricated on B-stage adhesive films and then laminated to fabrics. As a result, fabric substrates having minimum Cu line width of $80~\mu \text{m}$ were successfully fabricated without any Cu lines displacement and fabric damages. First, the effects of the curing properties of adhesive films on fine-pitch Cu patterning were investigated by Fourier transform infrared (FTIR) spectroscopy and a 90° peel adhesion test. In addition, the morphology of the Cu pattern-laminated fabric substrates was observed depending on the viscosity of epoxy laminating adhesive film. Finally, the effects of film moduli on the dynamic bending fatigue properties were investigated experimentally and theoretically. [ABSTRACT FROM AUTHOR]

This paper proposes a new hybrid layout to retrofit and repair timber beams by means of carbon composite material. It is based on the combination of a carbon laminate strip attached on the tension side, and a carbon fabric discontinuously wrapping the timber element. This layout has been experimentally validated by means of a study involving large-scale timber beams with many years in service. Results demonstrate not only that the bending load capacity of the broken beams can be totally recovered, but that it may even be increased by 70% with respect to the non-broken ones. [ABSTRACT FROM AUTHOR]

Out-of-plane ply wrinkling is a major quality issue for carbon fiber reinforced prepreg parts. Its triggers are numerous and not every influencing parameter is fully understood, yet. The research presented in this paper aims at providing a better insight into ply wrinkling generated during autoclave compaction using caul plates. A detailed description of the experimental set-up and the applied methodology is provided. Statistical analyses of varying influencing factors such as part thickness, geometry, tool–part interaction, and laminate lay-up are presented. This, in turn, generates a better understanding of their impact on fiber wrinkling risk and size. Part geometry and compaction deformation show the most significant influence on wrinkle size. However, for the given manufacturing concept, tool–part interaction also plays a significant role. It influences both the dimension and location of the wrinkles, as well as the existence and size of a critical flange length of the part. A noteworthy effect on wrinkle generation and size can also be observed when adding unidirectional plies to an otherwise fabric laminate. [ABSTRACT FROM AUTHOR]

A novel low-melting, low-viscosity, one-part bismaleimide resin based on m -xylylene bismaleimide has been developed and examined for application in vacuum-assisted resin infusion. The resin is a fully formulated system comprising a ternary eutectic BMI mixture blended with bis-(o -propenylphenoxy)benzophenone and 2,2'-bis(3-allyl-4-hydroxyphenyl)propane as co-monomers. The resin offers enhanced properties for melt processing techniques. The formulation strategy and chemistry is presented and discussed in detail. For resin infusion and/or resin transfer molding technologies, the melt processing temperature of the resin is in the range of 90–110℃. Processing data of the uncured and mechanical properties of cured neat resin are provided. The resin shows a T gof 285℃ when post-cured at 250℃ for 6 h. Finally, a 400 × 500 mm2carbon fabric laminate was successfully molded for demonstration by a VARI process. The microscopic study reveals no voids and no laminate surface imperfections. The VARI processing details are presented and discussed. [ABSTRACT FROM AUTHOR]

With aeronautic industries focussing on thinner structures and reducing manufacturing costs, recent research has been dedicated to the impact and post impact response of thin laminates (<2 mm) made of textile fabric composites. A recent study revealed that thin laminates based on thin plies exhibit extensive fibre failure and a reduced compression after impact strength. To mitigate this weakness, we propose a novel laminate concept based on combining plies of different thicknesses in an unsymmetrical configuration (intermediate grade plies are located only at the bottom of the laminate, i.e., the non-impacted face). C-scan inspection on impacted and quasi-statically indented specimens, allowed the damage sequence of the proposed unsymmetrical hybrid laminate to be compared with that of the thin-ply baseline. The hybrid laminate with intermediate plies at the bottom, delayed and reduced the fibre damage, decreased the projected delamination area and led to a 30% increase in the compression after impact strength in contrast to the thin-ply baseline laminate. [ABSTRACT FROM AUTHOR]

The need for multifunctional carbon fibre composite laminates has emerged to improve the reliability and safety of carbon fibre composite components and decrease costs. The development of an electrical selfsensing system for woven fabric carbon fibre composite laminate panels which can detect and locate damage due to impact events is presented. The electrical sensing system uses a four probe electrical resistance method. Two different sensing mats are investigated, the main difference between them are the surface area of the electrodes and the distance between the electrodes. To investigate the damage sensitivity of the sensing system for woven fabric carbon fibre composite laminate panels, panels are produced with various thicknesses from 0.84 to 3.5 mm and are impacted at energies from 1 to 10 J to generate barely visible impact damage. Damage is detected using global electrical resistance changes, the changes in electrical resistance vary depending on carbon fibre volume fraction, spacing distance between the sensing electrodes in the sensing mats, the surface area of the electrodes, damage size, and damage type; it is found that the thicker the panel, the less sensitive the electrical resistance system is. The effect of the surface area of the sensing electrodes is high on the electrical resistance baseline, where the baseline increases by up to 55% when the surface area of the sensing electrodes increases from 100 mm2 to 400 mm2; while spacing distance between electrodes has a greater effect on damage sensitivity of the electrical resistance sensing system than the surface area of the sensing electrodes. [ABSTRACT FROM AUTHOR]

During recent years, crude material costs and increasing environmental concerns have led to the search for new reinforcement materials for composites. Consequently, interest on natural fiber reinforced polymer composites has increased significantly owing to their easy availability, light weight, and low price. In this study, surface modification effects were investigated on the mechanical properties of woven jute fabric reinforced laminated composite plates, experimentally. The woven jute fabrics were retained at the rates of 0%, 5%, 10%, and 15% NaOH solution for 15 days at room temperature for surface modification process. Then, woven jute/epoxy (WJE), woven jute/polyester (WJP), and woven jute/vinylester (WJV) laminated composite plates having six layers were produced using modified woven jute fabric. The mechanical properties of woven jute reinforced laminated composites, such as tensile, compression, and shear properties, were determined at room temperature. The experimental results were analyzed statistically with Weibull distribution having 85% reliability level. The statistical results showed that the surface modification process and type of matrix material have dramatically affected the mechanical properties of woven jute fabric reinforced laminated composites. [ABSTRACT FROM AUTHOR]

This study presents a new approach method for instrumented drop weight tests, with a central spherical impactor and a circular sample support. The tests were carried out on glass fiber reinforced polymer (GFRP) laminates with three types of reinforcement: plain-woven fabric, stitched plain-woven fabric and 3D non-crimp fabric (NCF). It was found that the plain-woven fabric reinforced laminate showed a more violent destruction mode (a massive fracture crack) in comparison with the other two. The stitched and the 3D NCF reinforced laminates exhibited a better impact resistance manifested by a higher stress at the failure initiation point, and a slower or totally arrested fracture crack growth. The applied methodology proved effective for the evaluation of materials under impact loading conditions. A novel element is the use of fast-frame camera images to measure the displacement of the specimens during the impact. It strongly improved the obtained results and enabled a reliable analysis of the strain-stress progress. [ABSTRACT FROM AUTHOR]

Wearable heaters have attracted growing attention for maintaining a relatively constant temperature of the human body in cold environments with near zero energy consumption. Herein, we developed a multifunctional laminated fabric with fascinating electro/solar-thermal conversion, thermal energy storage and thermal insulation properties. With cotton fabric as the substrate, MXene/polydimethylsiloxane (PDMS) conductive network was decorated on the upper layer, and carbon nanotube (CNT)/cellulose nanofiber (CNF)/paraffin (PA) aerogel phase change composites were assembled on the bottom layer. Attributed to the strong conductivity and light absorption of MXene and the light/thermal response of CNT and PA components, this wearable laminated fabric broke the limitation of intermittent solar photothermal heating, and integrated multiple heating modes to precisely heat the human body. Meanwhile, the low thermal conductivity of aerogel retarded heat loss. The laminated fabric can help people better adapt to a variety of complex and changeable environments such as cold winter, rainy days and nights. This study provides a promising and energy-efficient avenue for the development of all-day personal thermal management fabrics. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, porous SiC f /SiC composites are prepared by chemical vapor infiltration of SiC matrix on stitched fibrous preforms with different fabrics laminate structure. The microstructure of the fibrous preforms before and after infiltration of SiC matrix and the permeability and the regeneration efficiency of the porous SiC f /SiC composites with different laminate structure have been determined. Experimental results show that the porous SiC f /SiC composites with twill fabrics laminate structure exhibits a higher permeability with a higher volume porosity and mean pore diameter. In comparing the regeneration ability of two types laminate structure filter medium, as expected, the twill fabrics laminate structure exhibits a better regeneration efficiency than the plain fabrics laminate structure due to its higher air permeability. [ABSTRACT FROM AUTHOR]

The development of impact resistant hybrid composites for ballistic applications is a recent trend. The increased energy absorption and reduced weight are some of the advantages for using these composites. Hybrid composites constituted of ultra-high molecular weight polyethylene (UHMWPE) laminates and aramid fiber fabrics were obtained by autoclave molding. The dynamic compression test was performed using a Split Hopkinson pressure bar with a standard deformation rate. The V50 ballistic limit test was carried out following the military standard MIL-STD-662F. The ballistic table NIJ Standard 0108.01 was taken as a reference and 9 mm Luger FMJ and.44 Mag Lead SWC EXPP ammunition were used. The dynamic-mechanical properties of the hybrid composites were evaluated. The composites exhibited an areal density of 5.30 ± 0.05 kg.m−2, meeting the required criteria in NIJ 0108.01. The V50, maximum stress, tenacity, storage modulus and tan delta peak height depended on the proportion of UHMWPE used in the hybrid composites: the best results were obtained for the composites with 75% UHMWPE and 25% aramid. [ABSTRACT FROM AUTHOR]

In today's scenario, numerous studies have shown a great interest on 3D woven structures like 3D warp interlock fabric as a fibre reinforcement for composite material to provide a better impact than 2D laminated fabrics with unlinked structures in the thickness. The impact energy absorption capacity depends on different and independent parameters, including the shape and speed of the projectile, the type of fibrous structure (geometry), the type and nature of the threads (raw material, linear density, and twisting value), and the type of impregnation of the composite material. As part of our research work on hard impact protection solutions, the interest of textile composite structures, in particular those integrating 3D warp interlock fabrics, has been revealed. Based on the result, protection solutions with such fabric structure revealed larger dynamic deformation capacity for absorbing the impact energy as compared with not only a ceramic material facing a 12.7 mm ammunition (mass 43 g) at 610 m/s but also those solutions made with metallic materials facing a FSP (diameter 20 mm, mass 54 g) at 630 m/s and 1600 m/s. For each of these different threats, a specific type of composite material has to be used. These composite material solutions are mainly defined to respond to the appropriate mode of impact behaviour. [ABSTRACT FROM AUTHOR]

Laminated fiber reinforced composites are increasingly being used in various load-bearing applications including for instance aerospace and wind energy power industries. Understanding the mechanical behavior of a unidirectional lamina as the basic part of a laminated composite is of great interest from a design perspective and also for the analysis of composite structures. At the micro-level, mechanical behavior of a lamina including stiffness and strength is studied based on the mechanical properties of individual constituents. This study focuses on micromechanical approaches such as strength of materials, elasticity, semi-empirical, and numerical methods for the prediction of the stiffness and strength of a unidirectional lamina. To assess the accuracy of these models, results of each model are compared against experimental results available in the literature for unidirectional composites with different fiber volume fractions. Moreover, recent studies on micromechanical modeling of unidirectional composites are reviewed. [ABSTRACT FROM AUTHOR]

Shales are commonly anisotropic in nature due to layering and natural fractures which consequently impact the mechanical behavior of shale in terms of stress-strain distribution, fracture initiation, propagation and fracture pattern. The classical method of strain measurement with strain gauges can not reveal the complex process of strain accumulation and fracture propagation in such anisotropic rocks. Therefore, we applied optical techniques along with image processing to measure strain on the surface of laminated Green River shale samples with various lamination angles under indirect tensile testing conditions. Full-field strain development was monitored over time and fracture patterns were identified utilizing digital image correlation (DIC) technique. A load-strain nature were established as a function of lamination angles incorporated with DIC generated horizontal, vertical and shear strain maps which results in better understanding of sequences in strain development and fracture pattern due to laminations. Variation in indirect tensile strengths are evaluated and reported with applied energy which shows that sample with higher tensile strength required higher applied energy to fail it. Fracture pattern obtained from DIC visualization are characterized which show that shear failure is dominant when failure occurred through laminations and tension for central failure samples. Finally, the measured axial strain from load frame is compared with DIC and achieved a considerable agreement in both measurement. The knowledge of this study can help in evaluating fracture behavior of laminated formations which can be important for energy-related activities including fracturing, fluid injection and extraction. [ABSTRACT FROM AUTHOR]

• Asymmetric S2-glass/aramid woven fabric hybrid laminates with different mixing ratios and impacting sides are studied. • Different single fibre and hybrid laminate designs are evaluated using multi-criteria decision-making analysis. • Areal density, deformation and absorbed energy were selected as design criteria. • FE simulation was performed considering non-linear material constitutive behaviour and interlaminar and intralaminar failure modes. Hybrid composites have gained a lot of attention due to their superior mechanical performance and energy absorption capacity compared to single-fibre counterparts, but studies on the hybridization of aramid and S2-glass fabrics are still scarce. This paper presents a multi-criteria decision-making analysis and numerical simulation applied to the study of the performance of asymmetric inter-ply hybrids of plain-weave aramid and satin-weave S2-glass fabrics/epoxy laminates subjected to low-velocity impact. Different aramid/glass fibre ratios, impact sides and impact energies (19 J, 37 J and 72 J) were investigated. A multi-criteria decision-making analysis was performed to identify the best laminate design based on the technique for order of preference by similarity to the ideal solution which considered areal density, deformation and absorbed energy as design criteria. A novel numerical FE model based on continuum damage mechanics was developed considering non-linear material constitutive behaviour and different interlaminar and intralaminar failure modes. The material model was implemented in Abaqus/Explicit solver using a user-defined material model, and the non-linear material behaviour in the normal direction is considered by defining instantaneous stiffnesses using third-degree polynomials. The results identified single fibre laminates as the worst designs and hybrid laminates with aramid on the impact side as the best design. Besides, for similar fibre ratios, the total delamination area was larger for the impact on aramid layers. [ABSTRACT FROM AUTHOR]

• A metal-free daytime radiative cooling film fabricated using a tandem approach of selecting materials that emit in the atmospheric window (8 µm -13 µm) shows high cooling efficiency of 7.8 °C with respect to ambient temperatures. • The film with the emissivity of 0.87 in the atmospheric window consists of silica and silicon nitride microparticles embedded in poly(methyl methacrylate) matrix. • Owing to the high bandgap of the particles, the film doesn't absorb solar radiation. • The observed cooling effect is attributed to forward scattering, high bandgap, and phonon-polariton resonances associated with the microparticles dispersed in the polymer. • A prototype, an umbrella fabric laminated with the film, exhibits a sub-ambient cooling of 7.6 °C and 5.4 °C in controlled and field conditions, respectively. Achieving sustainable and clean energy in a completely passive manner is conceivable through radiative cooling process that pumps heat from the terrestrial objects deep into the cold outer space. Various designs of radiative coolers, multilayer, and photonic radiators, have been explored in the past, but most of them require optimization for up-scaling and cost-reduction. Herein, we report a facile method of preparing a radiative cooling film using a one-step solution processing technique. The concept relies on the choice of materials that emit in the atmospheric window (8 µm -13 µm) using the tandem approach to maximize the thermal radiation without incorporating any metallic reflective components. The film prepared by dispersing silicon dioxide and silicon nitride microparticles in a polymer matrix shows excellent emission spanning the entire atmospheric window, resulting in efficient light management and thus daytime radiative cooling. The cooling efficiency of the system is studied by varying the ratio of the particles and comparing it with those prepared using individual particles dispersed in the matrix. The film, thus optimized with an equal ratio of particles in the matrix, devoid of any reflective layer, exhibits a maximum cooling of 7.8 °C below ambient temperatures with an average cooling of 6.2 °C, on par with the cooling efficiencies obtained from conventional architectures. The observed effect is attributed to forward scattering, high bandgap, and phonon-polariton resonances associated with the microparticles dispersed in the polymer. As a prototype, an umbrella fabric laminated with the film exhibits a sub-ambient cooling of 7.6 °C and 5.4 °C in controlled and field conditions, respectively, during daytime. Thus, radiative cooling metal-free films that employ a tandem approach via a facile solution processing technique are highly scalable and effective for daytime cooling applications. [ABSTRACT FROM AUTHOR]