Sugiman Sugiman

This research aims to study the effect of fiberglass layers of skin and core thickness of ethylene vinyl acetate (EVA) foam cored sandwich composites on its interlaminar shear strength. The sandwich composite consists of fiberglass woven roving reinforced unsaturated polyester resin skin and EVA foam core, where the skin serves to resist shear loads, and the core serves as a structural support and reduces the overall weight of the composite. This study varied the EVA foam core thickness to 5 mm, 8 mm, and 10 mm, and the number of fiberglass skin layers to 2, 4, and 6 layers. The tests were conducted with a 500 kN capacity Universal Testing Machine (UTM) in accordance with ASTM D2344 standard. The test results showed that the interlaminar strength increased significantly as the number of skin layers increased. However, an increase in core thickness leads to a decrease in interlaminar strength. The main failure mode observed was delamination within the fiberglass skin layers.

The incorporation of solid waste, tyre-derived rubber, into epoxy resin matrices presents a sustainable strategy for recycling end-of-life tyres while enabling the development of advanced composite materials and structural adhesives. This work examines the influence of microwave (MW) irradiation parameters, specifically power and exposure time, on the performance of ground tyre rubber (GTR)/epoxy composites. GTR particles were subjected to MW treatment at 630 W and 810 W for durations ranging from 20 to 120 s. The epoxy system was prepared using diglycidyl ether of bisphenol-A and cycloaliphatic amine (EPH 555). Mechanical behavior was characterized through tensile and fracture toughness testing, while physical properties were assessed via water absorption, fracture surface morphology, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and Fourier transform infrared (FTIR) analyses. Microwave treatment modified the carbon (C)–sulphur (S) bond of GTR without disrupting its primary chemical backbone. Compared with untreated GTR, MW-treated composites exhibited higher tensile strength (11-15%) and elastic modulus (12-15%), albeit at the expense of reduced fracture toughness. In comparison with neat epoxy, however, GTR incorporation improved fracture toughness, attributed to crack pinning mechanisms, while diminishing tensile properties. Furthermore, GTR addition lowered water absorption, with MW treatment imparting additional benefits, improving water resistance under tensile loading. These findings highlight the potential of recycled tyre rubber as an effective filler for epoxy-based composites, offering both environmental and performance advantages.

The growing demand for lightweight, high-performance structures in transportation and manufacturing has intensified research on hybrid weld-bonding as a joining method that synergizes the metallurgical strength of resistance spot welding (RSW) with the stress-damping capability of adhesives. However, the interaction between welding parameters, adhesive type, and adhesive thickness and their collective influence on nugget microstructure and joint integrity remains poorly understood. This study addresses these gaps through a systematic parametric investigation of hybrid spot weld–epoxy joints in AISI 1008 steel. Three commercial epoxy adhesives (Araldite 5 min, Araldite 90 min, and Devcon 90 min) were applied at thicknesses of 0.2, 0.6, and 1.0 mm under a fixed RSW schedule (50 A, 10 s), followed by a secondary factorial test varying welding current (50-80 A) and time (10-20 s) for Araldite 5 min at 0.6 mm. Mechanical performance was evaluated via lap shear testing, while fracture morphology and nugget chemistry were analyzed using optical microscopy, SEM, and EDX. Results revealed an optimal configuration at 60 A and 10 s with 0.6 mm Araldite 5 min adhesive, achieving the highest shear strength (~5.74 kN). Strength exhibited a non-monotonic dependence on adhesive thickness, indicating coupled thermo-mechanical effects of polymer decomposition and stress redistribution. Fractographic analysis showed transitions from interfacial to cohesive failure modes with increasing adhesive thickness, while excessive welding energy induced HAZ softening and porosity. The study advances mechanistic understanding by correlating adhesive curing kinetics and thermal degradation with nugget evolution and joint mechanics. These findings provide both scientific insight and practical guidance for optimizing hybrid joining parameters in thin-gauge steel structures.

The use of adhesive joints has been increasing in joining metallic and non-metallic materials due to advantages such as homogeneous stress distribution and a smooth surface appearance. This study aims to analyze the effect of support plates on the shear strength of aluminium and steel adhesively bonded joints. The position of the support plates was studied within the overlap area. Experimental testing was carried out using single lap joint specimens per ASTM D1002. Finite element modelling was also carried out using Abaqus software to analyze the stress distribution in the adhesive layer. The experiment results showed that the addition of the support plates did not increase the shear strength of the joint, but instead tended to decrease it. The strength of aluminium joints with support plates at a distance of 3.125 mm from the end of the lap of the joint decreased by 62%, while the strength of steel joints decreased by about 38%. Finite element modelling results show that von Mises stress at the end of the lap joint decreased with the addition of support plates.

The increase in environmental awareness worldwide has driven the design of environmentally friendly materials, making this research on the effects of alkali treatment on banana bunch fiber composites particularly significant. The detrimental environmental impact has shifted attention from synthetic fibers to natural fibers. Natural fiber composites have attracted the attention of material engineers due to their ability to decompose, abundant and sustainable availability, low density, and high specific strength. Many sources of natural fibers have been used for composite reinforcement, such as jute, kenaf, sisal, coconut fiber, pineapple fiber, and banana stem fiber. Fiber treatment is necessary to enhance the compatibility between polymer matrix and natural fibers. The most commonly used method is alkali treatment using a sodium hydroxide (NaOH) solution. This research, which investigates the effect of alkali concentration (NaOH) on the properties of unsaturated polyester reinforced with Kepok banana (Musa paradisiaca) bunch fiber, significantly contributes to the global shift towards environmentally friendly materials, a movement that you, as researchers and professionals, are actively part of. Banana bunch fibers were treated with alkali solutions at 2, 4, 6, and 8% concentrations for 2 hours. The fiber content in the matrix was 40%. The tests that were conducted included Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), tensile testing, and scanning electron microscopy (SEM). It was found that alkali treatment improved the tensile strength and elastic modulus of unsaturated polyester/banana bunch fiber composites. The 2% alkali treatment provided the highest tensile strength and elastic modulus, increasing by 92.13% and 273%, respectively. FTIR, XRD, and SEM analysis confirmed the optimal results of the 2% alkali treatment.

Cement mortar offers an excellent replacement for materials such as fine aggregate with tire rubber waste in the form of crumbs. It provides excellent environmental and technical benefits to concrete production using recycled materials. As such, it contributes to the sustainable development of the construction industry. This paper mainly emphasizes the strength of untreated and treated crumb rubber from waste tires in cement mortar. Crumb rubber that has been pre-treated with Silica fume (SF) and sodium hydroxide (NaOH) to improve the strength of the mortar mix. This research used a cement-aggregate mix ratio of 1:4 and a water-cement ratio of 1:2. Five different percentages of fine aggregate replacement (0, 3, 6, 9, and 12%) was selected. The compressive strength, density, and water absorption of the mortar were measured at 28 days to find optimum strength. The compressive strength of the cement mortar mixed with treated crumb rubber showed significantly higher values, with an increase of 92% for 12% treated crumb rubber by sodium hydroxide (TN12) compared to untreated crumb rubber. The density value of the mortar cube mixed with treated crumb rubber decreased when the percentage of replacement for treated crumb rubber increased. In the application of roof tiles, lower density values provide an advantage for workability during installation. For water absorption, the treated crumb rubber contributes to a lower percentage of water absorption (acceptable until 6% for SF and 9% for NaOH) compared to the control sample as untreated crumb rubber. Therefore, a mixture of mortar with treated crumb rubber, especially NaOH solution, is better than the untreated crumb rubber specimen.

Simulasi Pengaruh Jumlah Palang Rim Sepeda Motor Terhadap Equivalent von Mises stress dan Safety Factor Menggunakan Software Ansys

The present paper investigates the tensile properties of the hybrid of bamboo-coconut fibers (coir)/unsaturated polyester composites. Portland cement has been u The present paper investigates the tensile properties of the hybrid of bamboo-coconut fibers (coir)/unsaturated polyester composites. Portland cement has been u

The effects of volume fraction on the flexural characteristics of epoxy materials filled with cement, fly ash, and CaCO3 are discussed in this work. At a temperature of 50oC, water was used to soak the filled epoxies. It was discovered that the flexural modulus rose with the volume fraction for all fillers. However, the flexural strength of fly ash and CaCO3-filled epoxies tended to decrease with the increase in volume percent. The flexural strength of cement-filled epoxy somewhat improved with the increment volume fraction. According to those data, cement has a stronger interface than fly ash and CaCO3. In comparison to those in the dry condition, the flexural modulus and strength of all the epoxy systems dramatically decrease for the aged specimen. Epoxy that has been filled appears to lessen the reduction in flexural properties compared to that of neat epoxy. Again, the cement-filled epoxy performs better than fly ash and CaCO3. Halpin-Tsai and Pukánszky models have been successfully applied to model the flexural modulus and strength in the dry condition, respectively, but both models failed to predict those mechanical properties in wet condition.