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Abstract Leaf springs are designed to bear loads as well as shocks in automotive vehicles. Two leaves of glass fiber-reinforced composites (GFRCs) of various shapes sandwiched between steel plates were analyzed for application in a minitruck. Computer-aided engineering analysis was performed for five different types of GFRC material leaf springs: flat leaf, flat and parabolic leaf, both parabolic leaf, both parabolic leaf springs with aluminium alloy bushes at the eye-end and spring steel multi-leaf springs. A silencer pad was used in the parabolic leaf spring to reduce delamination and vibration at contact points of the mating leaf. The various shapes and combinations of leaves provided varying parameters, namely, the deformation, maximum equivalent strain, maximum equivalent stress and fatigue life. The CAE results showed that compared with the other combinations, the flat leaf and parabolic leaf combinations provided the maximum equivalent strain, maximum equivalent stress and fatigue life.

Leaf springs are designed to bear loads as well as shocks in automotive vehicles. Two leaves of glass fiber-reinforced composites (GFRCs) of various shapes sandwiched between steel plates were analyzed for application in a minitruck. Computer-aided engineering analysis was performed for five different types of GFRC material leaf springs: flat leaf, flat and parabolic leaf, both parabolic leaf, both parabolic leaf springs with aluminium alloy bushes at the eye-end and spring steel multi-leaf springs. A silencer pad was used in the parabolic leaf spring to reduce delamination and vibration at contact points of the mating leaf. The various shapes and combinations of leaves provided varying parameters, namely, the deformation, maximum equivalent strain, maximum equivalent stress and fatigue life. The CAE results showed that compared with the other combinations, the flat leaf and parabolic leaf combinations provided the maximum equivalent strain, maximum equivalent stress and fatigue life. [ABSTRACT FROM AUTHOR]

In this work, the glass fiber reinforced plastic (GFRP) composite pipes used as sewerage pipes in oil and gas field environments were studied. The accelerated aging experiments were carried out under the simulated environments of three typical oil field media which including circulating air, simulated produced water and standard simulated oil. Scanning electron microscopy (SEM) was adopted to observe the microscopic morphology of the aged GFRP tubes under the three conditions. The microstructural characteristics of the aged tubes and the evolution process of internal defects were also analyzed and evaluated in combination with micro-CT technology. The attenuation pattern of the hoop tensile strength of the aged pipes was measured via the separation disk method, and the service life prediction was carried out based on the Arrhenius theory with the hoop strength as the life index. The results show that the accumulation of aging time and continuous heat input will aggravate the expansion of internal pores and cause the aggregation of small-volume defects into large-volume defects. Especially in the simulated oil environment, which has the highest sensitivity to defects. The maximum porosity reaching 1.5 % and the maximum volume of individual defects exceeding 106 μm3 after aging for 4000 h at 95 °C. The thermal aging process under the three environmental conditions had similar aging characteristics, and interfacial damage of the glass fibers was observed in all of them. The variability of hydrothermal aging is related to the hydrolytic behavior of the glass fibers, which is associated with the progressive dissolution damage of the SiO 2 network in the glass fibers, as well as the breaking of silane bonds. Thus, the hydrothermal environment had the most significant effect on the hoop tensile strength decay. Ultimately, 75 % strength retention was taken as the end-of-life indicator. The predicted service life based on the Arrhenius model for the three environments of thermo-oxygen, hydrothermal and simulated oil were 23.5, 23.1 and 28.5 years at 20 °C, and 12.2, 4.9 and 10.3 years at 40 °C, respectively. [ABSTRACT FROM AUTHOR]

Glass fiber reinforced polymer-based composites prepared by photocuring technology offer notable advantages. However, the traditional UV curing technology faces challenges in balancing curing efficiency, penetration depth, and mechanical properties when producing high-thickness fiber-reinforced composites. This study introduced a new method for crafting thick glass fiber reinforced composites via upconversion particle-assisted near-infrared photopolymerization (UCAP). Near-infrared (NIR) radiation had superior penetration in glass fiber composites system, effectively curing of specimens exceeding 20 mm in thickness. Through micro-CT and atomic force microscopy, it was verified that UCAP specimens had fewer interfacial defects and a wider interphase, making contribution to enhanced interlaminar and interfacial shear strength. Additionally, uniform curing effectively alleviated stress concentration under external forces, resulting in a 78.5 % increase in flexural strength and a 32.1 % increase in impact toughness for UCAP specimens compared to UV-cured ones. This approach facilitated rapid outdoor curing of large-sized glass fiber composites with sustained structural stability, showcasing the potential application of UCAP in high-performance glass fiber composites rapid prototyping. • Photo curing of high-thickness glass fiber composite using high penetration NIR. • NIR cured composites exhibit enhanced interfacial performance and reduced internal defects compared to UV curing ones. • NIR cured specimens exhibit uniform stress distribution compared to UV curing specimens. • Composites cured by NIR demonstrate higher flexural strength compared to those cured using UV. [ABSTRACT FROM AUTHOR]

The behavior of composite materials under tensile and bending loading differs, and material designs optimized for tensile loading may not be suitable for applications subjected to bending loading. In this study, the bending behavior of two different composite materials, namely glass and carbon fiber-reinforced composites, was analyzed under a three-point bending load. The output from the analysis of these two materials was compared, revealing that, in addition to longitudinal direction strength, transverse and through-thickness directional strength, as well as shear strength in all planes of the composite, are essential to minimize deformations, normal stress, and shear stress. In the study, under the same loading and boundary conditions, the carbon epoxy composite exhibited 84% more deformation than the FR-4 composite at the maximum load considered for the study. Furthermore, the strength of the FR-4 composite in the loading direction was 2.4 times greater than that of the carbon epoxy composite. The present work is used for the effective design of the composite material under bending loading.

Objectives The aim of this study was to evaluate the in vitro biocompatibility and in vivo osseointegration of three novel bioactive glass fiber reinforced composite (GFRC) implants and to compare these with metal (Ti6Al4V) implants. Methods The surfaces of these experimental substrates were characterized by scanning electron microscopy (SEM), a 2D profilometer and by contact angle measurement. In vitro biological performance was assessed using MG-63 human osteoblast-like cell morphology, cell proliferation assays and the alkaline phosphatase (ALP) activity testing. Furthermore, in vivo osseointegration performance was examined by installing samples into rabbit femurs and evaluated the results using micro-CT, histology and histomorphometrical analysis; these assessments were carried out after 1, 2, 4 and 8 weeks of healing. Results The results showed that moderate surface roughness, moderate hydrophilic exposure and moderate homogenous exposure of bioactive glass fibers were present for all of the GFRC substrates. Furthermore, MG-63 cells, when cultured on all of the GFRC substrates, grew well and exhibited a more differentiated phenotype than cells grown on titanium alloy (Ti6Al4V) substrate. Histological evaluation revealed more newly-formed bone regeneration within the thread of the GFRC implants during the initial healing period. In addition, the novel GFRC implants with a bioactive Bio-fiber structure and glass particles within the epoxy resin matrix showed better bone volume/tissue volume (BV/TV) values at 4 weeks and this was accompanied by bone-implant contact (BIC) values at 8 weeks comparable to the Ti6Al4V group. Significance These findings demonstrated that novel GFRC implants seem to show improved osteogenesis and osseointegration functionality and have potential as a substitute for Ti6Al4V, or other metal-based materials, when used for clinically dental and orthopedic applications. [ABSTRACT FROM AUTHOR]

This study assesses the progression of damage occurring on glass fiber reinforced polyester composite specimens using acoustic emission (AE) parameters. Its aims are to improve understanding of the particular characteristics of AE signals; and also to determine the relationship between AE signals and the failure of the material. Time and frequency domain trends were analysed at four different applied loads (60.97, 67.75, 74.52 and 81.30 MPa) representing 45–60% of the ultimate tensile strength of material. The relevant AE parameters were analysed both in the early stages of the test and as the material neared the fracture zone. The results showed a high degree of correlation between the root mean square and number of hits AE values and the number of cycles to failure, of 92.99 and 92.19%, respectively. This correlation, as well as AE basic parameters, suggests that AE can be a valuable tool to predict the fatigue life and detect the onset of damage in such composite materials. [ABSTRACT FROM AUTHOR]

This work describes the composition of the products from solvolysis of thermoset polyester in an acetone/water mixture. A qualitative and quantitative evaluation of the compositions of the aqueous and oil phases was achieved by the combination of liquid chromatography with electrospray ionization mass spectrometry (LC-ESI-MS/MS), gel permeation chromatography (GPC), and total organic carbon (TOC). Close to 100% of the organic carbon in the aqueous phase was explained by the monomers phthalic acid and dipropylene glycol, co-solvent acetone, and a secondary reaction product, isophorone. In the oil, the most abundant compounds were isophorone, 3,3,6,8-tetramethyl-1-tetralone, and dihydroisophorone. While the first two compounds were intermediates in the self-condensation of acetone, dihydroisophorone has not been reported previously as the by-product of the conventional acetone self-condensation reaction pathway. The quantification results have shown that solvolysis can be successfully used to close the loop in the polymer life cycle while producing a broad spectrum of high-value products that could be recycled for production of polymers, used as a building blocks, or as fine chemicals. [ABSTRACT FROM AUTHOR]

2,3-Epoxypropyl-3-(2-furyl) acrylate (EPFA) was synthesized from 3-(2-furyl) acrylic acid (FAA) and epichlorohydrin, followed by copolymerization of EPFA with methyl methacrylate (MMA) by varying the mole ratio of EPFA:MMA at different reaction times using benzoyl peroxide as an initiator at 80°C in toluene. The FAA, EPFA and copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (1H NMR) spectroscopy, viscosity measurement, gel permeation chromatography (GPC) as well as epoxy equivalent weight (EEW). Mechanical properties, electrical properties and chemical resistance of the selected glass fiber reinforced composites were determined according to the ASTM method and discussed in light of copolymer composites. [ABSTRACT FROM AUTHOR]

Restoration of primary maxillary incisors severely damaged by caries or trauma is a clinical challenge in pediatric dental clinics. Early childhood caries is observed in approximately half the child population. In the past, the only treatment option would have been to extract the affected teeth and replace them with prosthetic substitutes. With the introduction of new adhesive systems and restorative materials, alternative approaches in treating these teeth have been proposed. The purpose of this paper was to describe the rehabilitation of primary anterior teeth in a 5-year-old patient using glass fiber reinforced composite resin as an intracanal post. [ABSTRACT FROM AUTHOR]

Aiming for obtaining flame-retardant vinyl ester resins (VER) and the composite, a kind of liquid 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-containing 1-vinylimidazole salt (called VIDOP) was conveniently synthesized through the neutralization of the DOPO-derived acid and 1-vinylimidazole to be applied as flame-retardant crosslinking agents of VER. Curing behaviors, flame retardancy, thermal decomposition behaviors, thermal-mechanical properties, and mechanical performance of VER materials were investigated. With 25 wt% addition of VIDOP, the modified resin (VIDOP25/VER) and their glass fiber reinforced composites (VIDOP25/VER/GF) achieved UL 94 V-0 rating with a limiting oxygen index value of 32.1% and 38.3%, respectively. Both heat release and smoke release of VIDOP25/VER and VIDOP25/VER/GF decreased compared to those of the reference sample in the cone calorimetry test. VIDOP showed flame-retardant activities in both gaseous and condensed phases for the resin, while they didn't work well in the condensed phase for the composite. VIDOP/VER presented a little lower a glass transition temperature than VER with a relatively low crosslinking density, in which 1-vinylimidazoles covalently linked with the VER chain and the DOPO-derived group attached to the resin via ionic bonds. VIDOP/VER and the composite had better mechanical properties than the unmodified sample and outperform other systems in well-balanced performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly(ether-imides) were prepared by two simultaneous reactions, that is, Diels-Alder reaction and nitro displacement reaction. Thus 3-nitrophthalic anhydride was reacted with furfuryl amine and the resultant amic acid was then reacted with three bismaleimides (2a–c) and disodium salt of bisphenol–A. The obtained polymers were treated with acetic anhydride to form cyclic imide, as well as aromatization of Diels-Alder adduct. The poly(ether-imide)s were characterized by IR spectral studies and theromgravimetry. A “in situ” polymerization on glass fibers was also carried out and the laminates were characterized by physical, mechanical, and chemical properties. [ABSTRACT FROM AUTHOR]

We investigated the feasibility of a transversely isotropic approach to assess the strength properties during the design of a composite leaf spring. A modified Arcan test setup was developed to test the strength properties of the used non-crimp fabric based material in all orthotropic directions. Through comparisons with standardized coupon test methods for fiber-reinforced materials, a notch stress factor for tensile and shear load was derived. Our results indicate that fabric influences the material's strength, and the assumption of transverse isotropy behavior is invalid. The measured transverse tensile strength was lower by a factor of 2.2 in the out-of-plane direction than in the in-plane direction, possibly leading to a lower resistance of leaf springs against delamination. Process induced differences did not significantly affect the measured strength in the tested directions. These findings will be useful in developing leaf springs with increased fatigue resistance. [ABSTRACT FROM AUTHOR]

Polymer matrix composites have established themselves in the materials family due to their improved properties like high specific stiffness and strength, durability etc. Recycled polyethylene terephthalate (RPET) is being used as matrix material in a variety of polymer matrix composites. Composite materials based on RPET matrix, in addition to being cost effective, are also environment friendly. Use of RPET as matrix material not only reduces the consumption of virgin materials, but it also simultaneously addresses the concern regarding environmental pollution due to post consumer PET waste. This review compiles and critically analyses the efforts of various researchers regarding the influence of; different types of reinforcing materials such as synthetic and natural fibers, micro and nano fillers, blending of RPET with various virgin polymers, on the properties of composite materials based on RPET. [ABSTRACT FROM AUTHOR]

• A neural network can be trained by both experimental and theoretical data. • Experimental input data ensures better defect identification than modeling data. • Automated procedure provides characterization accuracy up to 15% by defect depth. • Experimental TSR profiles provide low scattering of characterization results. The paper describes the concept of an automated defect characterization procedure by using infrared nondestructive testing of glass fiber reinforced composite. The proposed algorithms have allowed determination of defect depth, lateral dimensions and area, as well as coordinates of defect centers. The algorithms are based on the use of the neural network trained on both experimental and theoretical temperature profiles. An acceptable for practice accuracy of defect characterization has been obtained on the experimental data (0–15% by defect depth and 26–139% by defect area). [ABSTRACT FROM AUTHOR]