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Abstract This paper presents an experimental study of the quasi-static and fatigue load performance of a pultruded GFRP (glass fiber-reinforced polymer) deck panel that can be used to furnish the roadway surface of temporary detour bridges. The flanges of the GFRP deck panel were reinforced with uniformly spaced steel wires to increase the flexural stiffness of the panel. A total of nine full size GFRP deck panel specimens were tested under static and fatigue loadings. The load-deflection behavior and ultimate strength of the deck specimens were compared with those of the unreinforced specimens. The test results were also compared with the results of finite element analysis. The steel reinforcement of the steel reinforced GFRP panels was only 2.5% of the cross-sectional area of the GFRP composite. The test results indicated that, at the design load level, the flexural stiffness of the steel reinforced GFRP panels was approximately 12.3% greater than that of the unreinforced GFRP panels. The test results further revealed that the fatigue loading up to 120% of the design load did not influence the stiffness of the steel reinforced GFRP deck panel. [ABSTRACT FROM AUTHOR]

Abstract The precast concrete sandwich panel (PCSP) is a popular structural type used for prefabricated construction. In this study, three kinds of glass fiber reinforced polymer (GFRP) connector, including a flat plate, a corrugated plate, and a hexagonal tube connector, were investigated for potential use in PCSPs. In-plane direct shear tests were conducted to evaluate the performance of the connectors based on a typical push-out configuration (i.e., three concrete wythes linked with connectors and two rigid foam layers in between). Twenty-five specimens were tested, and the parameters investigated consisted of GFRP laminate thickness, projected length, and shear force direction. The shear force vs. relative slip relationships and failure modes of all types of connector were compared and are discussed in detail in this paper. Meanwhile, finite element (FE) analysis was conducted to reproduce the test results. All three types of GFRP connector exhibited a progressive failure manner in spite of the linear brittle nature of the FRP materials; the corrugated plate connector achieved higher deformability than the flat plate connector, particularly when the GFRP laminate thickness was small; and the hexagonal tube connector exhibited similar behavior along two orthogonal directions, making them well suited for use as two-way connectors. The developed FE model was able to well predict the peak shear load and stiffness of all types of connector based on comparisons with the test results. [ABSTRACT FROM AUTHOR]

Abstract The effect of impact load with low velocity in thin-walled plates and profiles has been investigated. The paper deals with the relation between damage propagation, size and shape as a function of boundary conditions, layer arrangements and impact energy. The structures under consideration were made of eight-layer Glass Fiber Reinforced Polymer (GFRP) laminate with a quasi-isotropic, quasi-orthotropic and angle ply arrangement of layers. The standardised plates predefined to CAI tests and channel section profiles have been subjected to impact load. Based on the performed tests, the impact characteristics have been obtained and compared with the theoretical model (one degree of freedom mass-spring system). Further, despite it not being mentioned in the ASTM 7136 standard, characteristic curves were identified. It was noted that the impacts introducing matrix damages and the partial fracture of the fibres significantly change the course of the Force-Time histories, particularly after the maximum impact force is reached. [ABSTRACT FROM AUTHOR]

Abstract This paper studies the feasibility of improving structural performance of composites in the presence of stress concentrators. Matrix grading through local deposition of additive-enhanced matrices and fibre steering by varying fibrous architecture are examined independently and in combination on a glass-fibre triaxial braided composite subjected to open hole tensile test. Stiffened and toughened matrices were incorporated through precise point-wise injections of liquid reactive resin into dry preforms (Liquid Resin Printing). Fibre steering was implemented by varying the braiding angle along the length of the braided sleeve. It has been shown that these novel forms of architecture modification enable a significant improvement in composite strength through a variety of deformation mechanisms. This includes local stiffening of composite in the direct vicinity of the stress concentrator and damage accumulation away from the stress concentrators. The experimental observations are explained by using simple finite-element models. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new technique to reconstruct fiber architecture from tomography is presented. • Determines 3D fiber architecture from supervised reconstructed stacks of 2D data. • Approach is suitable for complex morphologies and high volume fractions of fibers. • Technique enables fiber tracking to incorporate with in situ mechanical loading. Abstract The recent ubiquitous utilization of short fiber reinforced composites (SFRCs) in applications that require complex shape conforming, light-weight materials with good strength properties, calls for in-depth studies to understand the underpinning physics behind SFRCs response to load and consequently damage. Since the accuracy of such studies is contingent on successful sub-volume characterization, the intricate sub-volume architecture of SFRCs requires conscientious methodology that addresses complex morphologies like fiber cross-overs, which is by no means a trivial endeavor. This paper proposes a novel framework that hinges on the synergy between robust 2D segmentation and 3D volume reconstruction techniques to faithfully reconstruct the fiber architecture of 3D X-ray tomograms of SFRCs. The implications of this framework not only include a platform that fully characterizes the complex sub-volume, but also provides a convenient means of incorporating tracking algorithms necessary for the in-situ characterization of the reconstructed fibers, if desired. [ABSTRACT FROM AUTHOR]

Abstract The experimental and numerical assessment of different aerospace grade composite materials under high-velocity impact is treated in this study. Characterisation of the materials, including thermosets (epoxy) and thermoplastics (PEEK) with carbon (unidirectional and woven fabric) and glass fibres, was conducted using high-velocity impact experiments. The test results indicate the glass fibre composites' superiority in the domain of classical composites in terms of weight-specific impact performance. The different carbon fibre composites have very similar ballistic limits but differ in terms of delamination behaviour. Subsequently, materials models are developed which reproduce interlaminar failure through the usage of surface-based cohesive contact formulations. By these means efficient and reliable simulation methods for impact events are developed. [ABSTRACT FROM AUTHOR]

Abstract The use of composite structures is increasing constantly in the last years, pushed by advantages of reduced weight and high strength. Moreover, the recent scenario points out a great attention on thermoplastic matrix composites due to their intrinsic recyclability as well for their possibility to re-use and re-manufacturing. However, the adoption of these materials can be further appreciated considering the secondary material workability as far as by demonstrating the possibility to re-manufacture the thermoplastic composite. The proposed work presents an experimental analysis carried out to investigate the downstream workability of a thermoplastic composite by one of the most versatile and flexible process. Glass fiber reinforced Polyamide 6 is the investigated material and the Single Point Incremental Forming is the implemented manufacturing approach. Since the composite matrix is characterized by a glass transition temperature higher than 50 °C, an external heating source has been necessary to perform the process in " hot" conditions. The process feasibility was fully demonstrated as well as the same was optimized in order to derive proper guidelines that can drive the process designer in the method star-up. [ABSTRACT FROM AUTHOR]

Abstract In this study, the influence of a novel intumescent flame retardant (IFR) on the mode I interlaminar fracture toughness and flame retardant properties of continuous glass fibre reinforced polypropylene (CGF/PP) composites is presented. The novel IFR system that consists of ammonium polyphosphate/poly (ethanediamine-1, 3, 5 triazine-o-4-amion-2, 2, 6, 6- tetramentylniperidine) (APP/PETAT) was introduced into the CGF/PP unidirectional prepregs (UD) composites by hot-melt impregnation process. Double cantilever beam (DCB) tests were performed to evaluate the mode I interlaminar fracture toughness (G IC) by using modified beam theory (MBT). It was found from the experimental results that compared to the neat CGF/PP composite, the mode I fracture toughness initiation toughness (G IC init.) and propagation toughness (G IC prop.) of CGF/PP/12.5 wt% IFR composites were increased by an average of 99.7% and 119.11% respectively. Meanwhile, samples with 12.5 wt% IFR could self-extinguish with an oxygen concentration of 32.4% and exhibit lower fire spread speed in UL-94 test. Furthermore, the peak of heat release rate (PHRR), total heat release (THR), fire performance index (FPI), and mass loss rate (MLR) tests indicated that IFR could dramatically enhance the flame retardancy of the composites. [ABSTRACT FROM AUTHOR]

Abstract The compressive kinking behavior of non-slender unidirectional glass fiber-reinforced polymer (GFRP) specimens has been analyzed by finite element (FE) models. The experimentally observed imperfections, including the initial fiber waviness throughout the entire specimen volume and the scattered resin/interface defects, were taken into account in the FE models. The birth-and-death method was employed to simulate the progressive damage to the material. The consideration of the coexistence of initial fiber waviness and initial resin/interface defects was found to be essential for accurate modeling of the kinking failure process. Kinking was initiated due to the disproportional increase of the fiber microbuckling at the locations of initial defects. The numerically obtained peak load, fiber microbuckling amplitudes, kink band angle and width, and compressive strain concentrations at the kink band edges were well predicted compared to the experimental results. The number of defects was less significant than the fact that defects existed that served as initiation points of the kink band formation. [ABSTRACT FROM AUTHOR]

Abstract This research evaluates, at microscopic level, the failure mechanisms of pultruded glass fibre reinforced polymers (GFRP) column elements after they have been subjected to temperature stress and compressive load. A scanning electron microscope (SEM) performed the investigation, with the GFRP samples cut into small sized specimens and treated with specific coatings. The analysed samples exhibited particular features, which have been interpreted with the support of fractography. The results suggest that the GFRP composite failure, under the combined duress of temperature and compression load, is mostly dominated by microbuckling. SEM analysis shows how the temperature treatment affects the resin-fibre interaction, how temperature interacts with the compression load and which failure mechanisms developed as a result. [ABSTRACT FROM AUTHOR]

Abstract Glass fiber-reinforced polymer (GFRP) panels have been increasingly used for structural applications due to their light weight, corrosion resistance and construction-easiness. This study evaluates the seismic performance of GFRP wall panels based on comprehensive shaking table tests and Finite Element Analysis (FEA). A GFRP wall panel is experimentally subjected to harmonic ground motions of frequencies ranging from 10 to 15 Hz. A mass is attached to the top of the panel to simulate gravitational weight. The panel remains undamaged under a peak base acceleration of 2.1 g. Its FEA is conducted using Abaqus based on Rayleigh damping. There is a good correlation between the experimental and FEA results. Another FEA model is developed to study the seismic behavior of a Reinforced Concrete (RC) wall, which is validated by results from an existing study. The two FEA models are then used to compare the seismic performance of GFRP wall panels versus RC walls in terms of drift ratio and hysteretic behavior. It is found that while GFRP wall panels cannot replace RC walls in multi-story buildings due to their low stiffness, their performances are comparable to RC walls for low-rise buildings. Therefore, GFRP wall panels can be potentially used in low-rise buildings in seismic regions. [ABSTRACT FROM AUTHOR]

Abstract The adoption of glass fiber reinforced polymer (GFRP) bars is becoming an interesting solution for different structural application, as a replacement of ordinary steel reinforcement, mainly for durability performance. The behavior of GFRP reinforcement, after high temperature exposure, is of critical importance for applications in concrete structures potentially subjected to fire. Accordingly, the aim of this study is the experimental evaluation of the residual behavior of GFRP bars subjected to different temperatures treatments, ranging between 100 and 700 °C. In particular, tensile tests on E-CR Glass FRP bars with nominal diameter of 14 mm were carried out after thermal treatment in an electric muffle, in order to characterize the degradation of the material residual properties after high temperature exposure. Young’s modulus and tensile strength decay were recorded. The experimental results are discussed with reference to practical structural applications as tunnel segmental lining. [ABSTRACT FROM AUTHOR]

Abstract A method of connecting precast concrete walls with Glass Fiber Reinforced Polymer (GFRP) composite sheets is investigated. The method can be used either as a seismic retrofit of existing welded steel plate connections or in new construction. The specimens consisted of two precast concrete wall panels connected with either two or four layers of unidirectional GFRP composite sheets. Eight specimens were subjected to quasi-static cyclic loads to explore the effect of the following variables on the connection capacity: concrete surface preparation; application of surface pressure to the GFRP laminate; number and orientation of GFRP composite layers; and use of carbon fiber reinforced polymer (CFRP) spike anchors. The performance of the composite connection was acceptable in terms of lateral load, lateral displacement, and shear transfer capacity. Application of surface pressure during curing of the GFRP laminate and the use of CFRP spike anchors improved the lateral load and displacement capacity of the composite connection significantly. An empirical expression is proposed to determine the capacity of the composite connection. [ABSTRACT FROM AUTHOR]

Abstract Fiber reinforced polymer (FRP) composites are commonly used in the chemical industry for storage tanks and pipelines, since most metallic alloys suffer from corrosion and result in costly maintenance and safety hazards. E-glass fiber is commonly used because of its low cost, but it is extremely susceptible to rapid degradation in low-pH environments. C-glass is an acid-resistant substitute, and while not as durable as carbon, it is much cheaper. Nevertheless, durable fibers are not the only key aspect of designing corrosion-resistant composites, as various degradation mechanisms must be considered. In this study, plain-weave laminates of C-glass and amine-cured epoxy are exposed to water and sulfuric acid solutions, and the relationship between diffusion kinetics and strength-loss is discussed. Results show that both solutions attack the fiber surface to some degree, but more importantly sulfuric acid increases the saturation uptake of water in the material, causing high swelling stresses that significantly reduce mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract In the present research work, the Generalised Local Model (GLM) is employed to characterize the failure of a commercial Fibreglass by determining the Primary Cumulative Distribution Function of Failure (PCDFF) through an experimental campaign and numerical computations. Four criteria used to define the failure condition are based on the following Generalised Parameters (GPs): (i) Maximum Principal Stress; (ii) von Mises Stress; (iii) Tsai-Hill GP; (iv) Hoffman GP. For each GP adopted, the PCDFF is derived in two different ways: (a) by examining data obtained from tension tests only (GLM single application); (b) by collecting data, determined through tension tests and three-point bending tests, into a unique set (GLM joint application). Finally, a comparison between the obtained PCDFFs and the experimental failure results is presented. [ABSTRACT FROM AUTHOR]

Abstract This paper presents experimental and numerical investigations about the effects of thermal cycles on adhesively bonded joints between pultruded glass fibre reinforced polymer – unsaturated polyester (GFRP) adherends used in civil engineering structural applications. Single lap bonded joints were produced with two commercial polymeric adhesives – epoxy (EP) and polyurethane (PUR) – and exposed to a mild (Mediterranean) range of thermal variations (−5 °C–40 °C) for up to 350 cycles in a dry condition. The mechanical performance of the adhesively bonded joints was assessed by means of single lap shear tests. Regardless of the inherent differences between both adhesives, results obtained show that the global effect of thermal cycles on the load vs. displacement response of EP-GFRP and PUR-GFRP joints was similar. For both adhesives, thermal cycles caused considerable reduction of joint stiffness and strength, with maximum reductions of 18% and 22% for EP-GFRP joints, respectively, and 19% and 11% for PUR-GFRP joints. The degradation of performance was influenced by post-curing effects, more relevant in the PUR adhesive. Before exposure to thermal cycles, both types of specimens exhibited similar failure mechanisms, which generally (80–90% of cases) involved light fibre tear and fibre tear modes, attesting the effectiveness of the adhesion process and material compatibility. Exposure to thermal cycles did not influence the failure modes of the PUR-GFRP joints; however, EP-GFRP joints became more prone to adhesive failure after being subjected to thermal cycles. Three-dimensional finite element models were used to estimate the magnitude of the internal stresses developed during the thermal cycles. For both types of bonded joints, the numerical results showed a relatively low magnitude of both shear and normal stresses developed due to the mismatch of the coefficients of thermal expansion (CTE) of the adherends and the adhesives. Overall, the results obtained indicate that thermal cycles degrade bonded joints between pultruded GFRP adherends and this degradation seems to be due mostly to detrimental effects on the constituent materials, namely the adhesives; however, for the conditions used in this study, this degradation seems to be compatible with the structural use of this type of joints in civil infrastructure. [ABSTRACT FROM AUTHOR]

Abstract The aim of this work to investigate the effect of glass fiber (GF) on the thermal properties of sugar palm (SP)/thermoplastic polyurethane (TPU) hybrid composites. Sugar palm/glass fiber hybrid composites at the different weight fraction of 0/40, 10/30, 20/20 and 30/10 were prepared by using melt-mixing compounding followed by hot pressing machine. Thermal properties of hybrid composites carried out by using Dynamic mechanical analyzer (DMA) and thermo-gravimetric analyzer (TGA). The storage modulus (E′), loss modulus (E″) and damping factor (tan δ) were evaluated as a function of different relative sugar palm/glass fiber weight fraction. Also, the peak height was investigated for tan δ curves. At higher glass fiber loading exhibited the highest storage and loss modulus while the lowest damping factor was observed for higher sugar palm fiber loading. Thermogravimetric analysis (TGA) demonstrated that the amount of residue decreased as the glass fiber loading decreased. Overall, the hybridization of glass fiber with sugar palm/TPU composites enhances the thermal properties of the hybrid composites for automotive applications. [ABSTRACT FROM AUTHOR]

Abstract The current work is concerned with ageing behaviour of sandwich composites constituted of E-glass fibre-reinforced vinylester bonded to PVC foam core being in service near the sea as a reference and basis for materials selection. In order to simulate the properties evolution of sandwich composites as real as possible, the sandwich composites were exposed to the two accelerated synergistic environmental conditions: solar radiation in conjunction with water vapour (condition A) and hygrothermal atmosphere alternating thermal cycling (condition B) for 1680 h, and the weight change and mechanical properties degradation were carried out. The results show that the sandwich composites lost weight in the condition A while gained weight in the condition B, and shear strength of sandwich composites fell finitely, revealing that PVC foam core was insensitive to the two ageing conditions. Meanwhile, the core fracture, interface-core fracture, interface debonding, and piles peel were observed as the increase of exposure time in the flatwise tension test, indicating debonding properties between skin and foam as well as between piles of composites skin were influenced by the two synergistic ageing conditions. [ABSTRACT FROM AUTHOR]

Abstract The apparent density, flexural modulus and strength of hybrid laminated composites were investigated through a full-factorial Design of Experiment (DoE) approach. Laminates were manufactured by hand lay-up using nine layers of glass fibre cross-ply fabric with an epoxy matrix phase reinforced with Portland cement microparticles. A first experiment investigated the effect of the inclusion site (particles in upper four layers, lower four layers, all layers or none), curing time (7 and 28 days) and compaction method (vacuum or uniaxial pressure). The fibre–matrix volume fraction and the particle mass fraction were fixed at 48.6/51.4% and 10% respectively. A second experiment investigated two distinct fibre–matrix volume fractions (48.6/51.4 and 29.6/70.4%) and five particle mass fractions (0, 2.5, 5.0, 7.5 and 10 wt%). Particle inclusions were restricted to the upper four layers, with 28 days of curing time and uniaxial compaction. The results were analysed via Analysis of Variance (ANOVA). A significant increase in flexural modulus and strength was observed at 28 days of curing time. Enhanced mechanical properties were obtained for laminates with particle inclusions only in the upper half of the structure, manufactured with 48.6/51.4% fibre-matrix volume fraction and uniaxial pressure. Higher flexural strength was achieved for composites manufactured with 51/49% fibre–matrix volume fraction and 2.5% of particle mass fraction. These fibrous-particulate hybrid composite laminates can be considered for future secondary structural parts in lightweight engineering applications. [ABSTRACT FROM AUTHOR]

Abstract The present paper aims to provide further understanding of the low-velocity impact behaviour of glass fabric cloth reinforced epoxy composite panels embedded with wire nets (WN-GF/epoxy). WN-GF/epoxy hybrid panels with six layer modes were manufactured by vacuum-assisted injection process. Low-velocity impact tests with various incident velocities were performed, and the perforation thresholds of the designed specimens were found out. Scanning electron microscope was carried out to study the microstructure of the composites after impact. Experimental results show that perforation threshold velocity of the specimens appears a bi-linear increasing tendency with increase of the embedded wire nets, and the increase ratio has an inflection point. Damage pattern observation results show that the enhanced energy abortion ability is mainly due to the increased delamination area of the specimens during the impact events. 3D finite element models were developed in ABAQUS/Explicit to analyze the damage behavior of WN-GF/epoxy composites, and a user subroutine was compiled. The contact load and change of kinetic energy absorption characteristics have been used to validate the finite element results. The penetration process and damage modes of WN-GF/epoxy interply hybrid composites under low-velocity impact are further discussed with the assistant of numerical results. [ABSTRACT FROM AUTHOR]

Abstract Dry carbon and glass fibre bundles were inserted into a ROHACELL® 71HERO Polymethacrylimide (PMI) foam core under a specific inclination angle and pin pattern in order to improve the impact damage tolerance and the fracture toughness of foam core sandwich. Impact tests were performed on pin-reinforced foam core sandwich panels with different pin-configurations at impact energies between 35 J and 70 J. X-ray computed tomography and ultrasonic C-scan were used to determine the damages in the foam core. At room temperature no cracks were observed in the foam core. Using carbon fibre pins led to the creation of thermally induced cracks in the foam core after impacts at −55 °C, which is critical for the integrity of the structure. The modification of the manufacturing process parameters and the use of glass fibre pins are two solutions to improve the impact behaviour at −55 °C by delaying the thermal cracks to higher impact energies. [ABSTRACT FROM AUTHOR]

Abstract Glued-in-rods (GiR) represent a class of joints being used in timber engineering that are mostly used to transfer axial loads in structural members with Glass Fibre Reinforced Polymers (G-FRP) increasingly being considered as rod material in substitution for the usually considered metallic rods. The primary objective of the research presented herein was to apply a probabilistic capacity prediction method to timber joints with G-FRP GiR. Necessary secondary objectives were to mechanically characterise the involved components (adhesive, rods, and timber) and to numerically investigate the stress state inside the tested joints. The methodology shall be applied to a recently reported in literature Zhu et al. (2017) that was specific in two ways: firstly, G-FRP rods were bonded into both ends of the timber block with both ends being tested to failure—a deviation from common practice; and secondly, as opposed to most previous studies exhibiting stiff adhesives, a ductile Polyurethane with markedly non-linear behaviour was used. All material characterisation was performed with methods that can be reproduced by any standard laboratory equipment, to provide parameters for the subsequent numerical analyses. Based thereupon, a probabilistic method was used and provided reasonably accurate predictions of the joint capacities of 25 different geometrical GiR configurations. The probabilistic method was extended for realistic estimations of the experimental capacity scattering in form of upper and lower percentiles. [ABSTRACT FROM AUTHOR]

The aim of the work was to assess the compressive strength of Fibre Metal Laminates after impact. The main objective of the evaluation of the compression after impact assessment of FMLs was the deep analysis of damage growth range, size and mechanisms during load from various initial damage states and final post-impact strength. The glass fibre/titanium and carbon fibre/titanium Fibre Metal Laminates were tested and analysed. Laminates previously subjected to impact energies ranging from 5 to 35 J were tested. Based on the research, three load bearing states of fibre-metal laminates were identified and characterized on the basis of an analysis of force reduction characteristics. In addition, it was found that the strength reduction of FMLs in relation to impact energy does not decrease significantly. One of the most crucial grounds for the above is the protective role of the elastic–plastic metal layers against rapid local buckling of the strength-carrying composite component. [ABSTRACT FROM AUTHOR]

[Display omitted] We tested the quasi-static tension behavior of the high-strength glass fiber four-Harness stain woven composite, Kevlar fiber plain woven composite, and their laminated hybrid composite. Their representative volume element models are established based on mesoscopic cross-section photographs combined with voxel mesh. A progressive damage model for predicting the damage initiation and evolution of the 2D woven composites is proposed. The crimping effect of plain-woven composites has been considered. The 3D Hashin and the maximum stress criterion are used as the fiber yarn and matrix's damage initiation criterion, respectively. The exponential model is used as the damage evolution model of the fiber yarn. A combination of exponential and reverse tangential damage models has been proposed to describe the damage evolution of the matrix. The proposed damage model is realized using user-defined subroutine UMAT and VUMAT. Abaqus/Standard performs the uniaxial tensile simulation of the two kinds of 2D woven composites with UMAT. Abaqus/Explicit solver simulates the laminated hybrid composite with VUMAT. The simulation results highly agree with the experiment results. [ABSTRACT FROM AUTHOR]

• This paper proposes a damage-resistant Hybrid Fiber Reinforced Polymer Composites (HFRP) design method based on the interface properties. • The microscopic interface properties of composites are introduced into the investigation of interlayer interface properties. • The influence of different hybrid interlayer interfaces on the delamination damage behavior of composites is clarified. • The 3D printing technology was used to prepare specimens of the hybrid fiber-reinforced composites. In this work, the poor impact damage resistance of carbon fiber-reinforced plastic (CFRP) composites was improved by mixing carbon fibers with ductile fibers (glass fibers/Kevlar fibers). The damage behavior of five interfaces of the prepared hybrid fiber-reinforced plastic (HFRP) composites was investigated through mode-I and mode-II interlaminar fracture toughness tests and micro-droplet debonding tests. On this basis, a numerical model for predicting the impact damage of HFRP composites was established. Through a comprehensive evaluation of the impact damage resistance indexes obtained from the numerical simulations, the hybrid fiber type, hybrid ratio between different fibers, and hybrid lay-up sequence could be optimized. The specimens with optimized lay-ups were prepared by 3D printing, and the effectiveness of the numerical model was verified through low-velocity impact and compression after impact (CAI) tests. The results show that the introduction of glass fiber layers in CFRP composites can significantly improve the damage resistance of the composites. Compared with CFRP composites, when the volume fraction of the glass fibers is 25%, HFRP composites have a smaller delamination damage area (reduced by 74.08%), furthermore, the pit depth is reduced by 43.01%, the CAI is increased by 17.29%, and the strength retention rate is increased by 31.94%. [ABSTRACT FROM AUTHOR]

[Display omitted] Recently, methods for determining interlaminar shear properties have been continuously developed to achieve homogeneous stress states and avoid edge effects. In this regard, the torsion test on tube specimens represents a setup with many advantages. Therefore, fibre composites made by a winding of glass and flax fibres were produced at a new type of mandrel, resulting in tubes with a wall thickness between 370 µm (glass) and 640 µm (flax). A new method for determining the shear strain is described in the context of the torsion test. The results are in line with analogous investigations, proving the validity of the new methodology. [ABSTRACT FROM AUTHOR]

A combined experimental and numerical study was performed to investigate the influence of multi-axial stress states and reinforcement type on the constitutive response of fibre reinforced epoxy polymers. The constitutive behaviour of unidirectional and cross-ply layups of carbon and glass fibre reinforced epoxy resin, IM7/8552 and S2/8552 respectively, was investigated. Prismatic short block specimens at different off-axis angles were tested under quasi-static through-thickness compression. The experiments were simulated with an enhanced non-linear material model based on shear localisation planes and pressure dependency, which represents the elastic and plastic experimental behaviour better than other formulations. The results show that the overall constitutive response is highly dependent on the fibre reinforcement type and multi-axial stress state on the mesoscale. In order to obtain an accurate description of the material behaviour, measurement aspects such as determining the correct orthotropic elastic constants, especially the Poisson's ratios, are highlighted. Furthermore, particular focus is also drawn on important modelling aspects such as material non-linearity and pressure effects. [ABSTRACT FROM AUTHOR]

• Hybrid continuous carbon/glass fiber composites based on different laminated design have been 3D printed. • The prepared hybrid fiber composites have excellent balance of impact resistance and tensile resistance. • The tensile strength prediction model considering hybrid effect with good applicability is established and verified. Material extrusion has been applied to the preparation of continuous fiber reinforced resin composites successfully. However, due to the limitations of the characteristics of a single fiber material, the prepared composites usually can only obtain the reinforcement of a single properties. In this study, the effects of the content ratio and arrangement mode of carbon/glass fiber layers in the 3D printed composites on tensile and impact properties were investigated, and the influence of mixed fibers was analyzed by failure morphology. The hybrid continuous carbon/glass fiber reinforced nylon composite parts with good balanced tensile and impact properties were obtained in the experiment, compared with single carbon fiber reinforced nylon composites, the impact strength increased to 250% of the original, while the tensile strength lost only 7%. Tensile strength and impact strength of the printed hybrid composites with the same fiber content and different arrangement are different by 20% and 35%, respectively. The tensile strength of 3D printed hybrid continuous fiber composites was accurately predicted by establishing a model considering hybrid effect. [ABSTRACT FROM AUTHOR]

Fibre hybridisation is used to balance the high cost of carbon fibres and the low durability performance of glass fibres. This study investigates the residual compressive mechanical properties of filament-wound hybrid glass/carbon Fibre Reinforced Polymer (FRP) tubes after exposure to elevated temperatures. Effects of temperature exposure and fibre orientation on compressive properties have been investigated. Tubes were exposed to temperatures ranging from ambient to 350 °C. Two fibre orientation configurations, including hoop (89°) and cross-ply (20% at 15°, 40% at 40°, and 40% at 75°) were used to study the effect of fibre orientation. Compression tests were carried out to study the compressive mechanical properties of FRP tubes, while Digital Scanning Calorimetry and Thermal Gravimetry Analysis were conducted to study the thermomechanical characteristics of the specimens before and after exposure to the elevated temperatures. Finally, the level of damage and its mechanisms were investigated using Scanning Electron Microscopy. The experimental test results indicate that hybrid carbon/glass FRP (C/GFRP) tubes exhibit a performance closer to the weaker tube type, i.e. CFRP tubes rather than GFRP tubes. Moreover, when subjected to elevated temperature, tubes with cross-ply fibre orientations showed slightly better compressive performance compared to the tubes with a hoop fibre orientation. [ABSTRACT FROM AUTHOR]

This study aims to improve the web crippling performance of pultruded glass fibre-reinforced polymer (GFRP) C sections using fibre-reinforced epoxy composite (FEC). The strengthened GFRP C sections were subjected to two loading conditions: interior-two-flange (ITF) and exterior two-flange (ETF). The parameters considered were bearing lengths, FEC strengthening length and thicknesses. Two failure modes, namely web-flange junction failure and web buckling failure were observed for the pultruded GFRP C sections under ETF loading conditions as the bearing length changed. While the combination of the web-flange junction and FEC crushing failures were observed under ITF loading conditions at 20 mm and 50 mm bearing lengths. Furthermore, the average web crippling capacity of strengthened GFRP C sections improved by up to 426 % and 488 %, in comparison to control samples under ETF and ITF loading conditions, respectively. The average web crippling capacity of pultruded GFRP C sections increased up to 45 % when the bearing length increased from 20 mm to 50 mm. The finite element (FE) outcomes showed an agreement with experimental results in the context of failure patterns, load-displacement profiles and web crippling capacities. Finally, equations were proposed to estimate the web crippling capacity of pultruded GFRP C sections strengthened with FEC. [ABSTRACT FROM AUTHOR]

A numerical investigation was carried out in order to simulate experimental results previously obtained concerning two-dimensional (2D) in-plane crack propagation in laminated glass fiber-reinforced polymer (GFRP) plates. The laminated plates were designed with an embedded circular pre-crack and subjected to quasi-static out-of-plane loads. In order to study the transition from standard fracture mechanics tests, where the crack propagates only in one dimension (1D), to 2D scenarios, additional double cantilever beam (DCB) experiments were carried out on the same material system. Three-dimensional finite element models were developed for the simulation of the experimental fracture responses and cohesive elements were used to take into account the fracture mechanisms acting on the fracture process zone. Compared to the 1D DCB specimens, a much higher value of the total strain energy release rate (SERR) was obtained for the 2D plates, which was correlated to their higher flexural stiffness and to the stress stiffening effect caused by the stretching of their deformed part. Furthermore, and based on the numerical results, it was proved that the area of the fully developed fiber-bridging in the plates can be directly obtained from the experimental compliance vs crack area curves. [ABSTRACT FROM AUTHOR]

Using a FEA homogenization technique, this study presents the influence of interphase region on composites. Numerical models using Abaqus ™ are developed in order to predict the mechanical behavior of a unidirectional composite (E-glass fibers/epoxy) under monotonic transverse traction. A Representative Volume Element description with a random distribution of the fibers is used. Linear elastic constitutive materials and Kinematic Uniform Boundary Conditions are considered. A numerical/experimental comparison is made in order to validate the model. The thickness and the modulus of the interphase have been determined by experimental measurements based on Atomic Force Microscopy and introduced in the numerical simulation, the effect of these properties as well as the effect of the interphase Poisson’s ratio, on the effective elastic properties of the composite is discussed. The obtained results are in good agreement with the experimental values previously measured by tensile test on macroscopic samples. The fact of considering the interphase improves the accuracy of the prediction of the composite's mechanical elastic behavior. [ABSTRACT FROM AUTHOR]

Understanding the failure mechanisms of the buckling process of glass fiber composites based on acoustic emission (AE) signals is a challenging task. In this work, a method combining AE with digital image correlation (DIC) was used to monitor compressive buckling behaviors of delamination composites. The analysis of AE signals is based on the k-means algorithm and principal component analysis (PCA). According to PCA, three characteristic parameters of AE signals like amplitude, peak frequency, and RA value (rise time divided by amplitude), are selected for cluster analysis by k-means algorithm. The results show that the AE signals of the compression process can be divided into three clusters. The three clusters correspond to three kinds of damage modes such as matrix cracking, fiber/matrix debonding, delamination and fiber breakage. The characteristic frequency of each mode is found by cluster analysis. Besides, the size and position of delamination defects result in the reduction of mechanical properties of the glass fiber composites. The complementary technology combining AE with DIC is effective for damage monitoring of the composites. Clear changes of the displacement fields can accurately detect the damage location and degree of the specimen. [ABSTRACT FROM AUTHOR]

Synergistic effects on shear resistance of ultra-high-performance hybrid-fiber-reinforced concrete (UHP-HFRCs) at high strain rates was investigated using a new shear test setup. Two UHP-HFRCs: L05S10 (containing 0.5 vol-% long and 1.0 vol-% short fiber) or L10S05; and, two ultra-high-performance mono-fiber-reinforced concretes (UHP-MFRCs): L15S00 (containing 1.5 vol-% long fiber) or L00S15, were tested. The L05S10 generated high synergy in shear resistance whereas the L10S05 did little. Synergies were significant for shear strength, shear peak toughness, but not for shear strain capacity. Moreover, the L00S15 produced the highest rate-sensitivity although the shear response of both UHP-MFRCs and UHP-HFRCs was generally sensitive to the applied strain rates. The experimental shear strengths were well-matched with the theoretical calculations. [ABSTRACT FROM AUTHOR]

This paper aims to present a methodology to predict the anisotropic and non-linear behaviour of glass fibre reinforced plastics using finite element methods. A material model is implemented in order to remedy the need of multiple material definitions, and to control the local plastic behaviour as a function of the fibre orientation. Injection moulding simulations traditionally provide second order orientation tensors, which are considered together with a homogenization scheme to compute local material properties. However, in the present study, fourth order tensors are used in combination with traditional methods to provide more accurate material properties. The elastic and plastic response of the material model is optimized to fit experimental test data, until simulations and experiments overlap. The proposed material model can support design engineers in making more informed decisions, allowing them to create smarter products without the need of excessive safety factors, leading to reduced component weight and environmental impact. [ABSTRACT FROM AUTHOR]

Composite pipes have become a viable alternative to metallic pipes in several applications. Flow-accelerated erosion and internal surface attack often result in thickness thinning that may compromise the structural integrity of the pipe and lead to its failure. In this paper, we investigate how the internal surface damage is reflected on the vibration behavior of a composite pipe conveying fluid. The defected pipe-fluid system is modeled using the extended Hamilton’s approach and discretized using the wavelet-based finite element method. The modal characteristics of the pipe vibrations have been obtained by solving the generalized eigenvalue problem. The developed model was validated and some benchmark solutions are presented to highlight the effects of the internal wall-thinning on the vibrational behavior of composite pipes conveying fluid. The obtained results facilitate the future research by revealing the potential of using the vibration signature as a basis for detection of erosion-induced internal defects in pipelines. [ABSTRACT FROM AUTHOR]

The elastic orthotropic behavior of thin woven composites is studied combining a numerical and experimental strategy. For thin materials, in-plane properties are measured by classical tensile tests and digital image correlation. The out-of-plane properties are derived performing finite element simulations at the level of the internal structure of the laminate. Indeed, the glass fiber arrangement in the yarn and the weaving pattern are defined based on microtomography and SEM observations. So a representative unit cell is found. A statistical approach is further proposed to derive the behavior of the warp and fill yarns, since the fiber position may fluctuate between yarns. For the considered laminate, the matrix (resin and ceramic inclusion) behavior is unknown and difficult to measure. Therefore an inverse method is proposed. By comparing with measured in-plane elastic moduli, behaviors of the matrix, of yarns and of the laminate are defined. The present homogenization strategy is exemplified by laminates used in printed circuit boards for high frequency applications. This approach has also been applied to investigate the evolution of the elastic moduli of the laminate with temperature. Those information, usually not available in the literature, are important when dealing with reliability of printed circuit boards during thermal cycles. [ABSTRACT FROM AUTHOR]

The use of glass fiber reinforced polymer (GFRP) composite bars as internal reinforcement for concrete is rapidly increasing especially in structures exposed to aggressive environments. A proper bond mechanism between GFRP bar and concrete is essential to ensure proper functioning of such structures. The slippage between the concrete and reinforcement has usually been ignored in numerical modeling of reinforced concrete (RC) structures. In this study, the effect of the bond action in flexural behavior of GFRP RC slabs was investigated. The analysis was first performed by considering a perfect bond between the concrete and reinforcement and ignoring any slippage. Next, an experimentally obtained bond-slip relation was used to replace the unrealistic perfect bond assumption. The predicted flexural load-deflection response of the slab was compared to the experimental data. The result obtained by incorporating the bond-slip model showed a better agreement with the experimental data. Hence, considering the slippage between the GFRP and concrete may be necessary when accurate deflection estimate is required under the service condition. Additionally, it was shown that the perfect bond assumption was sufficiently safe for the design of the GFRP RC slabs. [ABSTRACT FROM AUTHOR]

Conventional fiber-reinforced polymer (FRP) rod stirrups are characterized by at least one side overlap, where premature bond slip failure is likely to occur, resulting in low confinement efficiency. To overcome this shortcoming, an innovative closed-type winding glass FRP (CW-GFRP) stirrup was proposed by winding continuous filaments on the mould. This paper also presented an experimental study on the axial compressive behavior of 16 large-scale columns (300 × 300 × 900 mm), which were reinforced longitudinally with identical steel bars and transversely with different stirrups, namely steel, CW-GFRP or conventional GFRP rod stirrups. The confinement efficiency of these stirrups was compared regarding the failure modes, axial load capacity and ultimate axial strain. Test results indicated that columns reinforced with conventional GFRP rod stirrups exhibited bond slip failure after spalling of concrete cover, while CW-GFRP confined columns avoided this failure. The proposed CW-GFRP stirrups performed best in improving the ductility of columns. When stirrup spacing was 75 mm, an increase of 95% and 180% in ultimate axial strain was achieved for CW-GFRP confined columns compared with their steel and GFRP rod stirrup counterparts. Columns with CW-GFRP stirrups spaced at 50 mm exhibited monotonically ascending load–strain responses and achieved the ultimate strain up to 5.51%. [ABSTRACT FROM AUTHOR]

Microvascular channels in fiber-reinforced composites offer various functional enhancements such as damage monitoring and self healing. As an adverse effect, presence of such channels can harm the mechanical behavior of composites. In the present study, 3D models are generated to investigate the stress concentrations in the resin-rich pocket and failure behavior considering different stacking configuration and vascule sizes. Similar results were obtained for [0/90] 4s and [90/0] 4s stacking configuration in spite of having different layer just above the channel and different resin pocket dimensions. The effect of changing the vascule diameter is mostly observed in UD 0 configuration. Utilizing elliptical channels results in reduced stress concentrations compared to the circular ones with the same diameter. While the staking configuration affect the failure in the resin rich zone, it does not affect the failure from the laminate region. [ABSTRACT FROM AUTHOR]

This paper studies failure behaviors of glass fiber/PC resin thermoplastic composites under transverse tension and shear loads using explicit finite element method. Microscopic long fiber/matrix composite representative volume elements with randomly distributed fibers and periodic boundary conditions are established by ABAQUS-PYTHON script language. The finite-deformation viscoplastic Gurson model is used for predicting the plastic deformation and void growth of thermoplastic glassy polymer matrix, which is implemented using ABAQUS-VUMAT explicit subroutine. The bilinear cohesive model with finite-thickness interface element is used to simulate the fiber/matrix debonding. Three important issues are explored: first, effects of the cohesive interface strength on the plastic deformation and void growth of composites are studied using three mesh models and three fiber distributions. Second, failure surface under different tensile and shear displacement ratios is obtained, compared with the predictions using the Hashin and Puck failure criteria developed mainly for thermoset composites. Finally, the influence of the plastic softening effect of matrix on the strain concentration or localization behaviors is discussed. Results show the tension/shear load ratio and the cohesive interface strength produce large effects on the void growth and failure surface of composites, but fiber distribution shows a small effect on transverse load-bearing ability of composites. [ABSTRACT FROM AUTHOR]

This study investigates the impact behavior of fiber-metal laminates (FMLs) (Carbon FMLs and Glass FMLs), which were fabricated by using high-stiffness steel, carbon prepreg, and glass prepreg through autoclave molding. The mechanical behavior of the FMLs was evaluated by performing tensile, compressive, in-plane shear, and low-velocity impact tests. Drop-weight impact tests were conducted to induce cracking of the FMLs, and the crack initiation along with crack propagation behavior of the different laminate sequences ([0/0], [0/90], [0/90/0], [90/0/90] and [0/90/90/0]) were also studied. The results show that the fabricated FMLs have higher strength and stiffness than conventional FMLs. Their impact strengths increased, and weights decreased simultaneously. The absorption energy was proportional to the crack length that was induced by the low-velocity impact. Moreover, it was found that the fiber orientation mainly affected the direction of crack propagation in the FMLs. This investigation facilitates the design of high-stiffness and lightweight FMLs for automotive parts. [ABSTRACT FROM AUTHOR]

this paper analyses the numerical and experimental results to evaluate the dynamic properties of pultruded GFRP (Glass-Fiber Reinforced Polymers) buckled columns. The profiles are made of glass fiber reinforcement and thermosetting vinylester matrix with thin-walled open or closed cross section. The buckling phenomena of the column with fixed ends were evaluated with a non-destructive method based on experimental modal data through dynamic identification procedure. Numerical analysis has been carried out through Finite Element models calibrated considering two consecutive stages that involve the local and global scale: i) parametric natural frequencies analysis to model the different cross sections taking into account the sti f fness of the rotational constraint between the wall segments of the thin walled pultruded profiles; ii) buckling analysis to identify the inaccuracies in the specimen or in the experimental apparatus through global flexural displacements which increase continuously with the axial load. Experimental, theoretical and numerical results were compared in order to know the wall segment effects of GFRP columns in free vibration field when affected by buckling phenomena. The results allow to investigate the significant role that the manufacturing imperfections of pultruded material play in the structural performance of GFRP buckled columns. [ABSTRACT FROM AUTHOR]

This paper experimentally investigates the lightning strike response of a fiberglass/carbon woven hybrid laminate ([(0/90)g(45/0 2 /−45 2 /90 2 )c]s) under dry and hygrothermal conditions. Damage characteristics are evaluated using various inspection methods and possible damage mechanisms are discussed. Observations demonstrate that as the increase of lightning amplitude, notably enlarged carbon fiber breakage and fiberglass delamination areas as well as fiber bulging are presented in the in-plane and in-depth directions. Compared to a [45 2 /0 2 /−45 2 /90 2 ]s carbon woven specimen, the carbon fiber damage area, internal delamination area and damage depth for the hybrid one are 4.94 times, 2.26 times, 3.21 times greater under 22 kA lightning strike and 3.34 times, 1.97 times, 1.67 times greater under 32 kA strike, respectively. Hygrothermal aging significantly intensifies lightning strike damage on the hybrid specimen with complete detachment of fiberglass layer and massive internal delamination. The possible mechanism for the present damage behavior is analyzed. These results suggest that the fiberglass layer is not expected to protect the integrity of the carbon fiber reinforced polymer structure from lightning strike damage. [ABSTRACT FROM AUTHOR]

The knowledge of impact behaviour of heat exposed composites is very limited, even though this could be one of the critical issues for many practical applications. Therefore, the current study was conducted to investigate the effect of preheating on the impact performance of glass and flax fibre reinforced composite laminates by a comprehensive set of experiments. The composite laminates were partially damaged by heat convection (using a fan assisted furnace) and their impact properties, such as force and energy absorption, were measured under a low velocity (1.85 m/s) impact loading situation. The impact test results showed that the heat exposure at 300 °C increased the energy absorption of the glass fibre composites but reduced those of the flax fibre composites. Furthermore, an addition of ammonium polyphosphate, as a flame retardant, also incremented the absorbed energy of the heat exposed composites and significantly reduced the heat release rate, resulting in an acceptable vertical burning behaviour, that meets the aviation standard requirements. [ABSTRACT FROM AUTHOR]

The structure and interfacial shear strength (IFSS) of polypropylene-glass fiber/carbon fiber hybrid composites fabricated by a new method called direct fiber feeding injection molding (DFFIM) process were investigated based on the skin-core-skin structure and modified Kelly-Tyson equation, respectively. The fiber dispersion state was evaluated qualitatively by scanning electron microscopy (SEM) and quantitatively by the fiber distribution index (FDI). Carbon fiber agglomeration is more likely to occur in hybrid composites and was present in the core layer of DFFIM composites in this study. However, glass fiber has shown relatively uniform dispersion in hybrid composites with a greater tendency to be distributed in the skin layers. This is attributed to the difference in feeding method, where glass fibers were fed through the hopper while carbon fibers were inserted from the vent hole. The IFSS between fibers and polypropylene of different composites in different layers is discussed by considering fiber length and orientation distributions in the core and skin layers, respectively. [ABSTRACT FROM AUTHOR]

This paper focuses on the experimental characterization and modeling of the impact behavior of a multi-functional dual core sandwich panel designed for the rehabilitation of hydroelectric turbines. The studied sandwich panel consists of glass fiber reinforced epoxy (GFRE) facesheets and a dual core composed both of alumina trihydrate-filled epoxy (ATH/epoxy) and extruded polystyrene foam (XPS). Low-velocity impact tests are conducted at different impact energies to take into account the presence of debris in the water flow. A 3D numerical model is developed to simulate the impact tests and particularly the energy distribution within the sandwich constituents. A good correlation is achieved between the experimental data and numerical predictions. The dual core sandwich construction placed on a rigid foundation undergoes both local and global deformation under impact loading. The experimental results show that for the tested impact energy range, the sandwich panel absorbs approximately 50% of the impact energy. Although the top facesheet and the ATH/epoxy core govern the initial impact behavior, the recoverable compression deformation of the XPS foam core is the major energy absorption mechanism. This statement is well supported by the numerical simulation. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of homogenous and super hybrid external patches based on plain weave woven glass fabric and aluminium alloy sheet (2024) on low velocity impact and quasi-static tensile after impact (TAI) response of adhesively bonded external patch repairs in damaged glass/epoxy composite laminates. The intent of using super hybrid external patches is to combine the excellent high displacement to failure property of aluminium as a ductile reinforcement with the superior mechanical property of glass fiber as a brittle reinforcement. The undamaged normal specimens were taken as the standard specimen for evaluation of residual mechanical properties. Four various types of external patches with different contents of glass (100%, 50% with two different lay-up configuration, and 0%) were used for performing the repair. In all hybrid patches, the proportion of aluminium and glass fiber were equal (i.e. 50% of aluminium and 50% of glass by volume fraction), while lay-up configuration were different. This further allows studying the associated effects of hybridization and lay-up configuration on low velocity impact and TAI response of the repaired laminates. The effect of glass/aluminium content on impact response and TAI response was investigated at various nominal impact energy levels, namely 2, 4, 6 and 8 J. Results show that super hybridization and lay-up configurations of the external patches play a significant role on low velocity impact and post impact response (i.e. absorbed energy, peak contact force, ultimate load, stiffness, residual deformation, displacement to failure and damage pattern) of the repaired specimens. Results indicate that repaired specimens having external patches with outer layer of aluminium and inner layer of glass fiber exhibited better impact properties and damage tolerance capability than that of the specimens conventionally repaired using homogeneous glass patches. Damage profile analysis was in a good correlation with the experimental results. [ABSTRACT FROM AUTHOR]

A review of computational modelling and simulation of pultrusion processes is presented including such aspects as: resin flow and pressure distribution in a forming die; impregnation of reinforcing fibers; heat transfer and resin reaction; pulling force, stresses and strains development; methods for numerical optimization of the process. Development of models provides deeper knowledge concerning the mechanisms behind the process as well as the influence of constituent materials’ properties and manufacturing parameters. Consequently, accelerated development of pultrusion process, allowing for the manufacturing of geometrically complex profiles is promoted. [ABSTRACT FROM AUTHOR]

The study concerns glass-polyester laminates, i.e. polyester resin reinforced with E-glass balanced plain weave fabric and/or E-glass mat. Experimental 3-point bend tests were carried out on homogeneous laminate beams reinforced with glass fabric or glass mat and on mixed laminate beams and plates reinforced with a glass fabric/glass mat ply sequence. In order to select the adequate failure criteria, bend tests on homogeneous laminate beams were modelled numerically and simulated using MSC.Marc finite element code. In relation to laminae reinforced with glass fabric the Hashin Fabric failure criterion was selected, and in reference to laminae reinforced each with glass mat the Max Strain failure criterion was selected. The adequacy of the selected failure criteria was validated experimentally by bend tests on mixed laminate beams and plates. Good qualitative and quantitative agreement of the simulated pressure force vs. deflection charts with those of the experimental tests was obtained. [ABSTRACT FROM AUTHOR]