Papers by Keyword: Glass Fiber

Abstract: Glass fiber-reinforced composites (GFRC) are widely used in structural applications due to their high strength-to-weight ratio and excellent fatigue resistance. Nevertheless, the mechanical integrity of adhesive joints remains a critical challenge in composite structural engineering. This study aims to investigate the influence of varying epoxy resin mixing ratios on the lap shear strength of glass fiber-reinforced composite joints. Two experimental schemes were conducted by varying the resin-to-hardener composition in the range of 10:50 to 70:50 (by weight). Single-lap joint specimens were fabricated and tested in accordance with ASTM D5868-95. The results demonstrated that a resin-to-hardener ratio of 50:50 yielded the maximum lap shear strength, reaching 5.71 MPa for resin system A and 5.28 MPa for resin system B. This ratio indicated a stoichiometric balance between epoxy groups and active amine groups, resulting in optimal curing with maximum cross-linking density. Deviations from this optimal ratio, either due to excess or deficiency of one component, led to a significant reduction in joint strength, as indicated by brittle fracture or weak adhesive bonding. These findings highlight the importance of precise control over epoxy adhesive formulations to ensure reliable mechanical performance in composite structures. The implications of this research contribute to the development of more durable and efficient adhesive systems, particularly for GFRC applications in the automotive, aerospace, and marine industries.

Abstract: Steel is the most used material for concrete reinforcement; however, it performs poorly in aggressive environments (e.g. coastal areas) owing to corrosion (moisture and chlorides). This study aims to analyse the tensile strength of steel and glass fibre-reinforced polymer (GFRP) bars through laboratory testing to assess their feasibility and application in construction. Steel bars were tested by ASTM E8/E8M–22, obtaining values of 606.61 MPa (Ecuador) and 676.46 MPa (Peru), whereas GFRP bars were tested following ASTM D7205/D7205M–21 (1,000 MPa). The analysis indicated that GFRP bars offer structural advantages (suitable for elements in coastal zones with low to moderate seismic activity), environmental benefits (lower CO₂ emissions during production), and enhanced durability (corrosion resistance).

Abstract: The study used KH560 coupling agent to modify chopped glass fibers for reinforcing glass fiber/epoxy resin composites. As the glass fiber mass fraction increased, tensile, bending, and impact strength initially rose and then declined. Optimal mechanical reinforcement occurred at a 10% fiber mass fraction. SEM analysis revealed a well-integrated interface between glass fibers and the resin matrix, facilitating stress transfer and crack resistance. However, excessive fiber content led to diminished mechanical properties due to poor dispersion. Short-term UV aging significantly altered the composite's color, attributed to UV-induced photooxidation, though glass fibers' chemical stability mitigated deeper oxidation. Water exposure induced resin hydrolysis over time, further reducing mechanical properties. This research provides foundational insights for developing high-performance glass fiber reinforced epoxy resins as alternatives to metal power fittings.

Abstract: This study investigates the water absorption characteristics of epoxy-based hybrid composites reinforced with natural sisal fibers and synthetic glass fibers. Four different stacking sequences of fiber layers: SSSS (four sisal layers), SSSG (three sisal layers and one glass layer), SSGG (two sisal layers and two glass layers), and SGGG (one sisal layer and three glass layers), were fabricated to assess their influence on moisture absorption properties. The water absorption percentages determined during testing of the compositions are averaged, showing a trend of decreased water absorption with an increase in the number of glass fiber layers. The SGGG configuration exhibits the lowest water absorption at 3.18%, while the SSSS configuration has the highest at 6.63%. This trend highlights the absorbent nature of sisal fibers and confirms the role of glass fibers in enhancing water resistance. Hybrid fiber reinforcements can therefore improve not only the mechanical properties of epoxy composites but also make them more environmentally friendly. Such materials provide a viable alternative to conventional plastics. Additionally, understanding the effect of stacking sequences on moisture absorption may enable future composite designs tailored for specific environmental conditions.

Abstract: Machining processes on hybrid composite materials involve activities such as surface cutting, hole drilling and other cutting processes to achieve final shape and dimension of the composite product. There were several unexpected situations during the process, such as ununiform vibrations due to inconsistent of natural fiber structures and nonideal cutting conditions lead to progressive tool wear and low quality of the cutting surface. In this study, an experimental approach was conducted on the milling process of polyester matrix-based composites reinforced with abaca and glass fibers, produced through the press molding process. The milling process was utilized by a 10 mm diameter 4-flute carbide end mill cutter with a 45-degree helix angle. The study aimed to investigate the influence of cutting conditions (spindle speed, feed, and depth of cut) on vibration during the milling process of abaca-glass fiber composites. Three levels of each cutting parameters were determined based on cutting tool working capabilities, i.e. the spindle speed = 2000, 3000 and 5000 rpm, the feed = 0.004, 0.007 and 0.10 mm/tooth, and depth of cut = 1, 1.5 and 2 mm. The Design of Experiment (DOE) was constructed by Box-Behnken technique of Response Surface Methodology. The down milling process were conducted for all scenario of DOE, and the vibration was measured using a digital accelerometer. The results of the study indicated that vibration increased with the increase of spindle speed, feed, and depth of cut. The results show that the maximum vibration value (0.0206 m/s²) was obtained at a spindle speed of 5000 rpm with a feed of 0.07 mm/tooth and a depth of cut 2 mm. Meanwhile, the minimum vibration value (0.0143 m/s²) was obtained at the spindle speed 2000 rpm, feed 0.04 mm/tooth and depth of cut 1.5 mm.

Abstract: In this study, the low energy impact properties of flax/epoxy, glass/epoxy and hybrid flax-glass/epoxy laminates are evaluated for two different stacking sequences: a unidirectional [0]₈ and a cross-ply [0/90]_2s. For flax laminates, the base reinforcement is made of the combination of a unidirectional flax layer and a flax mat layer, where the mat phase consisted of short flax fibers used as a binder for the unidirectional phase. All laminates were tested under uniaxial tension both before and after impact and were molded at a fiber volume fraction of 40%. The results indicate that the specific stiffness of the flax fiber composite is approximately 7% higher than that of the glass fiber composite, regardless of the stacking sequence used. Concerning low-energy impact resistance, the cross-ply laminate demonstrates superior performance with higher impact resistance and less permanent deformation compared to the unidirectional laminate. The study also explores the hybridization of flax and glass fibers, suggesting a promising approach that leverages the synergistic effects of employing two different types of fibers in the composite. The comparison of energy absorption during impact shows that the hybrid fibers/epoxy composite has a higher energy absorption capacity than the glass fiber/epoxy composite. Additionally, hybridization helps mitigate the degradation of tensile properties caused by impact, representing an effective strategy to enhance the mechanical properties of the flax fiber composite post-impact.

Abstract: Soil stabilization is crucial for enhancing the engineering properties of soil and constructing durable infrastructure, such as highways, airports, and roadways. The study's constituents were previously employed separately, and the soil's strength improved when they were coupled with other ingredients. Experimental investigations were conducted to assess the effects of varying proportions of C&D waste, CCR, and molasses on key soil characteristics, including compaction, shear strength, and plasticity. A series of crucial tests, including Atterberg limits, compaction characteristics, differential swell index, unconfined compressive strength (UCS), California Bearing Ratio (CBR), and Scanning Electron Microscope (SEM) analysis, were conducted to evaluate the performance of the stabilized soil. Test results indicated marked improvements in the Atterberg limits, reduced swell potential, and elevated values of UCS and CBR, demonstrating the effectiveness of the proposed stabilization method. CDW, CCR, and molasses enhance Unconfined Compressive Strength (UCS) by improving strength and cohesion. The addition of these chemicals significantly improved the performance of the soil, as seen by the decreased settling, enhanced strength, and greater infrastructure durability. Molasses served as an effective natural binder, while glass fibers improved tensile strength and durability by distributing stress evenly. This approach addresses waste management issues and promotes sustainable construction practices, offering a cost-effective solution for enhancing soil performance and paving the way for resilient infrastructure development.

Abstract: The tensile behavior of an injection mold glass fiber reinforced polyamide matrix composite was determined between 10^-6-10^-1 s^-1 strain rates at 25, 65 and 90°C for the loading axis 0^o, 30^o and 90^o to the fiber plane. Microscopic studies were conducted to identify typical fracture mechanism involved at different temperatures. The composite exhibited the highest flow stress and elastic moduli sensitivities on the strain rate in the 0^o specimens, followed by the 30^o and 90^o specimens. The highest rate sensitivity was detected in the specimens tested at 25°C and the rate sensitivity declined as the test temperature increased from 25°C to 65 and 90°C. The observed rate sensitivity of the composite was ascribed to the rate sensitivity of the matrix while the elevated temperatures enhanced the fiber-matrix bonding.

Abstract: Tendons (cables or rods) are commonly employed as tension members in civil infrastructure, as well as buildings and offshore engineering structures. This study focuses on reliability evaluation of composite rods consisting of polymer matrix (carbon fiber/glass fiber hybrid thermoplastic composite rods (hybrid composite rods) and basalt fiber/polypropylene composite rod (BF/PP composite rod)). Optical and gravimetric methods were used to characterize the morphologies, including constituent volume fractions, of the composite rods. The hybrid composite rods are braided structures with varying diameters and braid angles. The BF/PP composite rod exhibits slight twisting. The volume fractions of the constituent elements (carbon fiber, glass fiber, basalt fiber, matrix, and void) were evaluated. Tensile and flexural tests were conducted under static and fatigue loadings. During the static tensile test, the stress applied to the composite rods was almost linearly proportional to the strain. The fiber-dominant behaviors of the composite rods were observed. During the static flexural test, the stress-strain relationship was initially linear, but as the stress approached its maximum, deformation became non-linear, and finally, the fibers fractured rapidly. During the fatigue tensile and flexural tests, the regression lines of the full-logarithmic curves showed good agreement with the fatigue test data. In addition, data was collected and statistical analyses were performed to assess the effects of environmental factors, such as temperature, on the static properties of the composite rods.

Abstract: The usage of laminated glass fiber reinforced polyester composites in aerospace applications helps to reduce overall weight of the aerospace structures. The flexural strength of the laminated glass fiber reinforced composites becomes more important when they are employing for aeroplane wings. In this work, a laminated glass fiber polyester composite with two distinct sets of six different woven lamina stacking sequences is manufactured via hand layup technique. The effect of stacking sequence over the total ply failure load are investigated through universal testing machine. Finally, the progressive failure of the lamina in composites is also examined using ANSYS software.