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This study investigates the use of hemp/glass fiber reinforced epoxy composites for designing automotive front bumper beams, focusing on crashworthiness and pedestrian safety. The composite bumper beam model is evaluated through low- and high-velocity crash simulations and pedestrian leg form impact tests using LS-DYNA software. Optimal stacking sequences are analyzed, with high-strength glass fibers positioned on the outer layers to bear impact loads and low-density hemp fibers in the middle. The hybrid hemp (H)/glass (G) fiber composite laminate can absorb up to 90 % of the impact energy absorbed by a glass fiber composite, with a ± 45° fiber orientation, showing exceptional energy absorption capabilities. The [G(±45°) 4 , H(±45°) 4 ] S composite bumper beam offers superior impact performance, safety, and a weight reduction of 49.2 % compared to a commercial steel bumper beam. This study highlights the potential of natural fiber composites as sustainable alternatives in automotive design. [ABSTRACT FROM AUTHOR]

• The baking soda abrasive jetting method as a new surface material stripping method for glass fiber reinforced materials (GFRP) was studied. • The jetting effects of different abrasives were compared, and the advantage of low damage of baking soda abrasives was highlighted. • Chemical stripping method was used to compare cleanliness. • The surface material of GFRP stripping process was simulated using LS-DYNA. Glass fiber reinforced composites (GFRP) working in a specific environment require regular inspection and maintenance. It is necessary to remove the surface material of fiber reinforced composites to check the fracture of fibers and the damage to matrix that binds fibers in this process. In this paper, the baking soda abrasive jetting was utilized to strip the surface material of glass fiber reinforced epoxy resin (GFREP). The stripping effects of baking soda abrasive jetting technology under different jetting parameters (fiber orientation, jet angle, jet pressure) were explored, and the optimum stripping conditions were determined as parallel to the fiber, 30°, 0.4 MPa. Compared with the chemical stripping method (phenol-dichloromethane), baking soda abrasive jetting can better retain epoxy resin between glass fibers. The LS-DYNA was applied to simulate the erosion process of a single abrasive particle under the optimum stripping condition. The plastic deformation of the matrix and the slight bending deformation of the glass fiber under abrasive impact were observed. [ABSTRACT FROM AUTHOR]

• Mode I fracture process is characterized for GFRP-steel bi-material interface. • Double-cantilever beam experiments supplemented by detailed DIC measurement. • Accurate modeling of crack initiation, fiber bridging and propagation by new CZM. • Four-linear traction-separation law derived from DIC measurements and iterative FEA. Debonding is characterized as the governing failure mode in the innovative wrapped composite joints made with glass fiber composite material wrapped around steel hollow sections without welding. The prerequisite for predicting debonding failure of wrapped composite joints is to obtain fracture behavior of the composite-steel bonded interface. The mode I fracture behavior of the bonded interface was experimentally investigated using glass fiber composite-steel double cantilever beam (DCB) specimens. The crack length a and the crack tip opening displacement (CTOD) during the test were accurately measured by analyzing the digital image correlation (DIC) data while the strain energy release rate (SERR) was calculated through the extended global method (EGM). The cohesive zone modeling (CZM) was utilized in the finite element model with the proposal of a four-linear traction-separation law to simulate the mode I fracture process. An approach is introduced to determine the critical stages of the proposed four-linear cohesive law by combining accurate measurements of crack length a and CTOD, along with SERR values. The validity of the four-linear cohesive law and the introduced approach to determine the critical stages were confirmed by good agreement in both global and local behavior between the testing and the FEA results. [ABSTRACT FROM AUTHOR]

• Custom-built 3D weaving machine was used to weave 3D spacer glass fiber fabrics. • PU foaming was directly performed in the vacancies of 3D woven I-beam composites. • Up to 43 % compressive modulus increase was obtained via in-situ PU foaming. • Energy absorption was increased in LD-PUFFIC by 173 % under three-point bending. • Post-mortem mechanical test samples were monitored by fractography. 3D weaving of I-beam structures can potentially create delamination- and joint-free structures, expanding their use in engineering applications compared to metal or traditional laminated composite beams. In addition, polymeric foams can be utilized to fill the vacancies between the web and the flanges of I beams, improving the mechanical characteristics and the structural integrity with little to no weight penalty. Moreover, interposing an adhesive layer between the I beam and the foam structure can result in a more effective bonding which intensifies the structure's robustness. In this study, high-performance I-beam composites were produced by combining polymeric foams with 3D woven glass fiber composites. Low- and high-density polyurethane foams were successfully inserted between the web and the flanges of 3D woven glass fiber composites manufactured by the vacuum infusion process using the free-rise foaming method. Samples with adhesive films were also produced to assess and compare their effectiveness with the composites made solely of polyurethane foam and I beam. The increases in energy absorption capacity and compressive and flexural properties were analyzed under compressive and flexural (three-point bending) loading. The obtained results indicate that structural integrity under bending can be substantially improved with the in-situ foaming supported by adhesive layers. [ABSTRACT FROM AUTHOR]

High performance shape-adjustable structural batteries with both excellent electrochemical performances and mechanical properties, and compatible with conventional batteries and composite processing techniques, are highly attractive for next generation electrical vehicles and electrical aircrafts. Herein, a high-performance structural lithium-ion battery composite (SLBC) is developed by encapsulating commercial-available battery core materials with hybrid fiber reinforced epoxy composite laminate shells, which can be assembled into desired irregular shapes with the conventional vacuum bagging technique. Firstly, the laminate shell layout with the combination of glass fiber woven fabric (GFWF) and carbon fiber woven fabric (CFWF) is designed and optimized. Meanwhile, a PET film is employed to wrap the battery core materials, which enables processing of the SLBC with liquid electrolyte in ambient condition. The SLBC obtained demonstrates both prominent mechanical (flexural strength of 211.7 MPa and flexural modulus of 7.7 GPa) and electrochemical properties (an initial discharge capacity of 98.5 mAh/g at 0.2C, a high energy density of 314.5 Wh kg−1, and a good cycling performance) owing to the hybrid design of CFWF and GFWF as well as a sealed environment to guarantee the battery operate well. Impressively, the in-situ mechano-electrochemical measurements are assessed under the out-of-plane compressive stress and the flexural stress conditions. These results show that the SLBC under loading can maintain stable electrochemical performance even at a high out-of-plane compressive stress of 20 MPa and a high flexural stress of 150 MPa. Furthermore, the SLBC can also maintain the excellent discharge capacity when subjected to a high impact energy, which is promising in next generation electrical vehicles. Finally, the wave-like SLBC fabricated demonstrates the effectiveness in withstanding loads and driving electric fan simultaneously, which is promising in next generation electrical vehicles.. [ABSTRACT FROM AUTHOR]

Hard armour plates are used in body armour for protection against high-velocity threats. The strike face often consists of a single ceramic tile that is covered by a sheet material made of a high-tenacity fibre-composite material. During impact, the ceramic will fracture but at the same time cause erosion and fragmentation of the hard core of the projectile. The composite cover is there to improve the ballistic performance by partly maintaining the integrity of the fracturing ceramic. In this study, a new production method where glass fibre yarns were filament-wound around an alumina tile in a unidirectional 0°/90° lay-up, was investigated. Ballistic testing was conducted with a 7.62 mm armour piercing projectile. The new target design gave a remarkable increase in the V 50 ballistic limit velocity by as much as 16% compared to a traditional design where a glass fibre fabric was wrapped around the tile. A higher degree of fragmentation of the projectile steel core after perforation was also observed. The high degree of fibre alignment in the filament-wound composite, as opposed to the more wavy fibres in the fabric, is believed to be the main reason for the higher ballistic performance. [ABSTRACT FROM AUTHOR]

This paper describes the development of electrically insulating hybrid steel–composite cross-arm for medium-voltage overhead distribution power lines with three conductors. The main goal was to achieve substantial weight savings compared to a common steel cross-arm with three ceramic insulators widely used in the Czech Republic. The structure has been designed as a combination of two main composite components – a pultruded horizontal profile and a braided vertical conical tube. These components are connected by a steel locking component which also serves for attaching the whole cross-arm to common concrete utility poles. The hybrid cross-arm is conceived to insulate electrical current in the default configuration thanks to the properties of the glass fiber reinforced composite materials, yet additional insulating elements can be used to further increase the electrical insulation distance. The materials and components used for the construction are chosen by combining finite element simulations of mechanical and electrical behavior with experimental testing and verification of important characteristics on selected substructures. The final design of the cross-arm is then manufactured and subjected to long-term testing in real-life environmental conditions. The achieved reduction of weight exceeds 50% while maintaining the mechanical rigidity and strength of the steel solution as well as the required insulation properties. The future trend of the cross-arm development is aiming at the weight reduction and increase of manipulation capabilities resulting in lowering many additional costs. In this work the designed cross-arm has half the weight of the original one. [ABSTRACT FROM AUTHOR]

Hybrid carbon/glass fibers composites can possess pseudo-ductility of progressive failure through material design to achieve the function of load early warning. The printing design and forming thermal environment of parts have important influence on the pseudo-ductile behavior of hybrid fiber composites. In this paper, the hybrid continuous carbon/glass fibers reinforced nylon composites with progressive failure pseudo-ductility were prepared by additive manufacturing, and the effects of printing layer thickness, carbon/glass fibers layer ratio and forming thermal environment on the tensile properties and pseudo-ductility of hybrid fiber composites were investigated and characterized. The results indicate that the printing layer thickness has no significant impact on the tensile strength of hybrid fiber composites, the pseudo-ductility is obvious when the layer thickness of [G 5 C 2 G 5 ] is 0.075 mm and 0.125 mm. With the same material ratio, reducing the layers or setting the printing platform temperature (100 °C) can decrease defects generation to achieve the better pseudo-ductility. However, the pseudo-ductility immensely weakens using the annealing treatment of 120 °C for 3 h. The pseudo-ductility of the [G 5 C 2 G 5 ] 0.075 , [G 5 C 2 G 5 ] , [G 3 C 1 G 3 ] and [G 4 C 1 G 4 ] samples have been discovered successfully. [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]

• 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]

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]

In this work, the static and dynamic mechanical properties of glass fiber reinforced polypropylene (GRPP) laminated self-reinforced polypropylene (SRPP) composite structure were studied, which includes the influences of the SG (SRPP/GRPP) internal and external positions (with two SG positions which are S/G/S, G/S/G) and the SG thickness ratios (with three SG ratios which are 1: 1, 1: 2, 1: 3). Results show that the tensile modulus improvement of laminates was obvious compared with SRPP. A hypothesis is constructed based on the elementary flexural beam theory. The flexural responses of S/G/S and G/S/G are highly similar to SRPP and GRPP respectively, the flexural strength and modulus of S/G/S are less than 50% of G/S/G. The flexural modulus of G/S/G- SG1: 3 is 111 % of GRPP. The impact responses of S/G/S and G/S/G are similar to GRPP and SRPP respectively, but more energy was absorbed in S/G/S. With the increase of SG ratio, less damage and deformation were shown in two structures, which their modes converge. [ABSTRACT FROM AUTHOR]

Combined with GFRP composites stress corrosion experiments, the traditional virtual crack closure technique (VCCT) is improved, and a new WDN-VCCT method is proposed to calculate the stress intensity factor (SIF) at the crack tip of GFRP composites. Its calculation formula makes up for the deficiency of the traditional VCCT method. The calculation results of the WDN-VCCT method and the calculation results of the stress extrapolation method (SEM) are compared and analyzed, and the actual accuracy of the two methods is fully evaluated. The results show that the calculation accuracy of the WDN-VCCT method is higher than that of the SEM method, the calculation efficiency is faster, and the calculation results are closer to the real value. [ABSTRACT FROM AUTHOR]

In the paper, effect of quartz additions on the durability of a polymer composite was investigated. The tested material was based on a resin MC-DUR 1200VK with two layers of E-type glass fiber reinforcement of an area density 300 g/m2 with an emulsion binder. The quartz was added in form of powder of fraction 0.1–0.3 mm in different proportions. Durability was measured in terms of specific wear work obtained from the novel tribological tester TT-4. Its important feature was the application of friction belt instead of disc or plate, which made it possible to avoid undesirable impact of the used friction surface and wear debris on the measurement results. Apart from that, standard measurements of flexural strength, shear strength between the layers, tensile strength, proof resilience, and microhardness were performed. It was found that the examined polymer composite increased its wear resistance when it contained 1% of the quartz powder. Similarly, the best results were achieved for the composite with 1% addition of quartz for the shear strength and proof resilience. However, further increase of the addition content caused decrease of the wear resistance. On the other hand, in comparison to the composite with no quartz powder, all other properties worsened after the quartz powder was added in any proportion. Despite no clear trends in characteristics after quartz addition was present, important finding was that it was disadvantageous to increase above 1% addition of quartz powder in the composite of resin MC-DUR 1200VK reinforced with two layers of E-type glass fiber of a weight 300 g/m2 with an emulsion binder. Initial researches also demonstrated that quartz additions might have different effect on the similar composite with other sort of reinforcement. [ABSTRACT FROM AUTHOR]

This study presents experimental investigation and formulation of a new anisotropic nonlinear thermo-viscoelastic constitutive model to understand the time-dependent multi-axial responses of polyamide composites subjected to various histories of mechanical loading at several isothermal temperatures: 20 °C-100 °C. The composites were tested under uniaxial tension along 0° and 90° injection molding directions and the axial and lateral responses of the specimens were recorded. Experimental results indicate that composites exhibit pronounced time-dependent responses, even at low temperatures, and mechanical loadings, even at relatively low strain levels, cause permanent deformations and hysteretic responses. A new constitutive model that accounts for continuous microstructural changes under thermo-mechanical stimuli was formulated to describe the macroscopic anisotropic responses of the composites. The model was derived based on a multi-network approach and the microstructural changes are governed by the deformations of the composites. Elevated temperatures soften the polymers, making it easier to deform the composites, and thus accelerate the microstructural changes. The model is shown capable of describing mechanical responses of polyamide composites under various loading conditions, loading histories, and temperatures. [ABSTRACT FROM AUTHOR]

In recent years, natural fiber as a green and renewable resources have attracted much attention to be used as reinforcement in composites. The aim of this work is to assess mechanical properties and durability in harsh environments of epoxy-based flax and glass bio-hybrid fiber reinforced plastics (bio-HFRP) composites. With the same fiber mixing ratio, the flexural and dynamic mechanical properties of the bio-HFRP composites were studied by changing the stacking order. The pure flax FRP and bio-HFRP composites were exposed to hygrothermal at 20 °C, 40 °C, and 60 °C for 28 days, respectively. The water absorption and diffusion capacity, the bending and shear properties were analyzed. Compared with the pure flax FRP, the flexural strength of G 2 F 2 s group sample was increased by 2.2 times. When exposed to the hygrothermal environment, flexural strength loss rate of the G 2 F 2 s group sample is only reduced by 4.35%, 9.00% and 11.51%, and its flexural modulus decreases 15.48%, 15.90% and 23.89%. It shown that the addition of glass fiber effectively improves the water absorption of flax fiber composites. Hybridization of flax fibers with glass fibers was a practical approach to enhance FRP laminates in hygrothermal environmental conditions after synthesizing the stacking sequence, mechanical properties and aging resistance. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and modelling study that determined the influence of thickness on the softening-rate, composite damage initiation and propagation, and structural survivability of composite structures in fire. Fire-under-compression load tests were conducted using glass fibre reinforced vinyl-ester laminates of varying thicknesses to quantify the influence of thickness on fire structural survivability. The matrix softening and degradation rates decreased as the composite thickness increased. The laminate thickness variations had a strong influence on the fire-under-compression load performance and failure mode. The analysis reveals complex multi-mode failure mechanisms involving global buckling and transitioning into shear dominated failure as the composite thickness increased. A thermal–mechanical model that can predict the time-to-failure of glass fibre reinforced composite subjected to a combined compression and fire load was developed and its validity was assessed by comparing the theoretical predictions to the experimental data. [ABSTRACT FROM AUTHOR]

Fiber reinforced polymer composites have great potential to replace steel for bridge cables, underground oil extraction and ocean engineering owing to light weight, high strength and desirable corrosion and fatigue resistances. How to reduce the material cost and improve the durability through the reasonable material design is significant to promote the engineering application. In the present paper, two kinds of carbon/glass fiber hybrid plates were developed including the fiber random hybrid (RH) and core–shell hybrid (CH) modes. The exposure of sustained bending loading and water immersion as long as 360 days was conducted to investigate the effect of fiber hybrid mode and bending loading on the mechanical properties. The results showed the synergetic effects between the carbon and glass fibers can be fully developed through the random fiber hybrid mode. Furthermore, the incongruous bearing behavior and stress concentration of carbon/glass fiber/resin interface were largely relieved, which contributed to higher mechanical properties. Compared to CH plate, the maximum increase percentages of tensile and flexural strength for RH plate after 360 days were 51.3% and 39.7%, respectively. Higher bending loading level resulted in the fast formation of microcracks, which provided more storage space for the water molecule and accelerated the resin hydrolysis and interface debonding of fiber/resin. Finally, the long-term life prediction of hybrid plate in three typical bridge service environments showed the RH plate has superior corrosive resistance compared to CH plate. The retentions of tensile and flexural strength for the service time of five years were close to 30–40% and 50–60%, which provided the durability guideline based on fiber hybrid design for the engineering applications. [ABSTRACT FROM AUTHOR]

• Hygrothermal environment has a significant effect on the strength of glass fiber composites. • Hygrothermal environment has little effect on the tensile stiffness of glass fiber composites. • Hygrothermal environment shortens the damage process of glass fiber composites under tension. • Hygrothermal environment changes the failure diagram of glass fiber composites under tension. In this paper, a progressive damage model considering hygrothermal effect is established. Taking high strength glass fiber composite plate as an example, the progressive damage model of open-hole composite plate is established, and the ultimate tensile and compressive strength at room temperature, dry state and hygrothermal environment are predicted. The model was verified by comparing with the experimental results. The results of numerical simulation and experiment show that the hygrothermal environment has a significant effect on the ultimate strength of open-hole composite plate. The tensile ultimate strength of open-hole composite plate decreases about 39% and the compressive ultimate strength decreases about 35% at 70 °C and equilibrium moisture absorption. The results show that hygrothermal environment has little effect on the tensile stiffness of open-hole composite plate, and the tensile modulus decreases by 6% at 70 °C and equilibrium moisture absorption. According to the numerical results, the hygrothermal environment can shorten the damage propagation process of the open-hole composite plate under tensile load, but does not affect the damage propagation process under compression load. The hygrothermal environment can change the macro failure diagram of the open-hole composite plate under tension from "X" to "I", but does not affect the macro failure diagram of the open-hole composite plate under compression. [ABSTRACT FROM AUTHOR]

This work examines the influence of kerosene flame exposure on the residual mechanical behavior (tension and compression) of hybrid quasi-isotropic composite laminates consisting of carbon/glass fibers and a PEEK thermoplastic matrix. The influence of a kerosene flame exposure (116 kW/m2 and 1100 °C), on the composites structural integrity was examined as a function of exposure time (5–10-15 min). The changes in the tensile and compressive properties (axial stiffness and strength) were compared with respect to the virgin materials (experiencing no prior flame exposure). The discussions on fire- and mechanically-induced damage mechanisms are supported by fractographic analysis of specimens. It is therefore possible to better understand how the fire-induced damages within the laminates micro- and meso-structures modify the mechanical behavior of flame-exposed laminates. Regardless the exposure time, the kerosene flame exposure involves in-plane and through-thickness temperature gradients, which ultimately create two well defined areas within the laminates: an extensively delaminated one (the one close to the exposed surface) and a relatively well preserved one (close to the back surface). From the present work, it is possible to conclude that the mechanical properties in tension are severely affected (-50% in stiffness and −70% in strength) by prolonged exposures to kerosene flame (15 min) with respect to as-received specimens. When compared to the 5 min case, flame exposure time (ranging from 5 to 15 min) seems to have little very influence on tensile properties and the effect is moderate on compressive properties. The barrier formed by an extensive thermally-induced delamination contributes to relatively preserve the structural integrity of the plies close to the back surface. The mechanical loading is taken up by the 0° fibers in non-delaminated areas of the specimens, resulting in preserving the residual mechanical in tension and in compression. [ABSTRACT FROM AUTHOR]

Computational micromechanics analysis of short fiber reinforced polymer (SFRP) composites is of great significance to provide an understanding of the relationship between microstructures and complex mechanical behaviors of the materials. In this study, an innovative computational framework is proposed for the analysis of SFRP composites considering multiple constituents and different failure modes. Firstly, a unit cell model composed of fiber, matrix and interface is built up to analyze the nonuniform stress distribution around a fiber. Secondly, a reconstruction algorithm is proposed to provide geometrical information of fiber distributions with arbitrary orientation state and a wide range of fiber length and fiber volume fraction. With the help of embedded element method (EEM) and MATLAB script, RVE models embedded with numerous unit cells are established. The predicted properties of the RVE models of short glass fiber reinforced polypropylene (SGFRPP) are verified by an orientation average method and a modified rule of mixture, respectively. The progressive damage procedure of the material is predicted and the damage initiation and evolution are for the first time quantitatively characterized by the extent variables of different failure modes. An in situ microtomography tensile test are performed to prove the feasibility and accuracy of the proposed framework. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced composites have been used as a secondary barrier structure in LNG cargo containment systems (CCS) for their excellent strength and corrosion resistance. However, during LNG transport, the tanks experience periodic thermal and bending stress because of the cryogenic environment. These conditions degrade the mechanical properties of the composites in the CCS. In this study, finite element analysis was conducted using the mechanical properties of each composite. A quasi-static tensile test was carried out, and the coefficients of thermal expansion were used to obtain the mechanical properties. To verify the reliability of the numerical analysis, modeled structural unit specimens were manufactured, and 3-axis strain gauges were attached to measure thermal strain under cryogenic conditions. Validation of the strain between experiments and computation was performed, and the finite element analysis was conducted based on the observed mechanical properties and their reliability. [ABSTRACT FROM AUTHOR]

The fiber-reinforced composite (FRP) shaft need to consider vibration performance of the transmission system to improve work efficiency, comfort, service life and safety. The fiber materials and tubes containing metal connectors are important parts of the FRP shaft so that the study on the vibration performance of these two key components is of great significance for an in-depth understanding of the vibration performance of shafts. The finite element analysis (FEA), pulse vibration excitation technique (PVET) and formula computing were used to study the effect of the vibration characteristics of shafts. This study revealed that increasing the modulus of the fiber is one of the effective methods to increase the natural frequency of the FRP tube and the damping ratio of the carbon FRP tubes were slightly smaller compared with basalt and glass fiber. The FEA of FRP tube results were not distinct from the measured and calculated results so that these FEA results were relatively reliable. The damping of the tube with metal flanges at both ends were weaken compared the FRP tube. This work will be of great significance to the optimization design of the vibration performance of FRP shafts. [ABSTRACT FROM AUTHOR]

The GRP (Glass Reinforced Polymer) composite pipes produced by filament winding technique are used in many fields such as the transmission of pressurized chemical liquids, industrial liquids, oil and natural gas transmission and construction materials. GRP composite pipes may be subjected to low velocity impacts for various reasons both during installation and service. The impact on the GRP composite pipe wall may lead to some nonvisible damages such as matrix crack, fiber damage, delamination and inter-layer separation. Composite pipes suffered strength loss due to these damages caused by impact cannot support the expected strength values during service. Pipes with three different diameters (Ø54, Ø72 and Ø96 mm) were produced to investigate the damage caused by low velocity impact and to determine the effect of these damages on the strength losses of the composite pipe. In order to investigate the influence of low velocity impact damage, the produced pipes were subjected to impacts at the velocity of 1.5, 2, 2.5 and 3 m/s according to ASTM D 7136 and preliminary damage was formed. During low velocity impact tests, Force-Time, Force-Displacement and Energy-Time graphs were obtained and dynamic behavior of the pipes were examined. With the increase in diameter; it has been observed that the effect of low velocity impact is reduced and the damage after impact transformed into delamination damage rather than multiple damage. [ABSTRACT FROM AUTHOR]