182 research outputs found
Experimental study of fatigue age on SUP-9 leaf spring steel which received heat treatment and shot peening processes
No full textOne aspect of the technical defect of leaf springs that are subjected to dynamic loads is fatigue defects which cause failure, as a result of uneven road surface or impact. Then leaf springs are expected to have a higher fatigue resistance limit. To improve the mechanical properties of leaf spring steel by providing heat treatment and shot peening processes, which will provide compressive residual stress to the surface, thereby improving the fatigue resistance of the spring. In this study, SUP 9 steel specimen has dimensions of 7 mm and a width of 50 mm, the heat treatment process is carried out at an austenitizing temperature of 920⁰C and 480 ⁰C temper temperature, for shot peening it is carried out at a pressure of 5 kg / cm², a shot diameter of 0.8 mm, with a peening time of 15 seconds, 17 seconds and 20 seconds, and testing of tensile, hardness, fatigue, residual stress, and fractography. This study shows that for a long shot time, good results are obtained, namely, the fatigue life has increased 8.7 times from the fatigue life of the spring steel without shot peening with application stress of 217 N / mm², and the residual stress is -847.39 N / mm²
Crushing behavior of foam filled steel extrusion / Al Emran Ismail
No full textThe concern of vehicle structural integrity and safety is given highly considerable amount of research and development by engineers and scientist world wide. Weight reduction of structures without compromising the structural durability is the important aspect because weight is strongly related to fuel consumption. In this work, rigid polyurethane foam is used to fill into steel extrusions. Different foam density is used to reinforce the steel tubes and at the same time different steel wall thickness also adopted to study the crushing behavior under quasi-static compression loading loaded at different angles. Force versus displacement of each column condition is recorded automatically, compared and analyzed. The area under the curve represent the energy absorbed by the column and the column length is properly designed to prevent buckling which will be resulted catastrophic failure leading to low energy absorption capability. Then, the final crushed columns are analyzed to study the correlation with the crushing characteristics. It is found that the energy absorption increased when increasing the foam density but when the tube wall reached a maximum thickness, the foam density no longer affected to increase the energy absorption
Assessment of thermal energy storage integrated solar thermal collector system: a review
No full textRenewable solar energy is clean, abundant and globally available although intermittent in nature, thus requires storage ability whereby the solar radiation can be utilized and store simultaneously, the excess reuse during cloudy weathers and night time when there is no solar radiation. Continuous investigations by many researchers have shown that the integration of thermal energy storage (TES) to solar collector could improve the system performance and extend their utilization beyond solar radiation hours. Several studies utilizing different energy storage materials such as phase change materials (PCM), nanomaterials, PCM nanomaterials and hybrid PCM materials have reported improved heat transfer mechanism in solar thermal collectors. However, the demerits on weight, size and space increment, leakages and poor heat transfer mechanism caused by the PCM-TES incorporation with solar thermal collectors still persists despite the several research attempts on development of new smart PCM-TES materials and their incorporation. Thus far, the current mini-review paper attempts to bridge the literature gaps on past and recent PCM-TES integration techniques used for solar thermal collector systems. In addition, the performance analysis of existing designs, material fabrications and suggested improvement are discussed in this paper
Crack behavior of heat treated sintered steel under cyclic loading / Al Emran Ismail
No full textFatigue crack nucleation and initiation at particles or defects in materials have been the interest of many researchers over the past years . This is because the understanding of theses phenomena would provide a better understanding of production of new fatigue resistanc e materials. In this study a test was developed to evaluate the fatigue properties and to observe fatigue crack nucleation and initiation in sintered steel. The fatigue test was carried out on polished specimens which was based on plate bending gives balanced biaxial tension. The experimental results shows that there were mixed mode of crack nucleation and initiation such that most cracks initiated at the interface of particles and matrix especially at high stress values . Cracks were also observed to initiate at voids and beneath the surface. Quenched specimens which were tempered between temperature range of 300°C and 600°C shows similar crack initiation mechanisms. The significant differenc e between as-rece ived and tempered specimens was that the number of cycles to fail due to di fferences in material hardne ss and internal defect s. The result s of the experimentation are discussed in the light of possible micro crack toughening at the crack tip and the presence of residual stresses due, to temperature changes. It is believed that some effects of residual stresses at the surface and beneath playa role in the nucleation of crack in sinter ed steel
Mode III stress intensity factors of sickle-shaped surface cracks in round bars / Al Emran Ismail
No full textThe solutions of stress intensity factors (SIFs) of sickle-shaped surface crack in round bars are not currently available especially when the cracks are subjected to mode III loading. Mode I SIFs can be obtained in open literature however they are also insufficiently completed. Therefore, this paper develops numerically the sickle-shaped crack in round bars using AN SYS finite element program. In order to validate the model, the existing mode I SIFs are used and then compared with the present model. It is found that both models are well agreed with each other. There are two important parameters used such as the crack aspect ratio, a/b and the relative crack depth, a/D ranging between 0.2-1.2 and 0.1-0.6, respectively. SIFs based on J-integral are calculated along the crack fronts for various crack geometries. It is found that the SIFs are significantly affected by a/b and a/D. For the relatively straight-fronted crack (a/b £ 0.2), the SIFs are almost flattened along the crack front. When a/b increased (a/b > 0.2), the SIFs have decreased whereas they are increased when a/D increased. It is also found that the SIFs closed to the outer edge are higher than the SIFs at the deepest crack along the crack front. However when a/b³ 1.2, the role of SIFs along the crack fronts are inversed where lower SIFs are observed at the outer point compared with the middle point
Fatigue crack initiation in powder metallurgically-processed tool steel material under cyclic loading / Al Emran Ismail and Mohd Nor Berhan
No full textThe cyclic behavior of P/M steel has been evaluated at different tempering conditions. Heat treatment is found to significantly affect the hardness, micro structure and fatigue response of the material. Optimum tempering temperature is found to give the highest hardness and better fatigue life compare to as-received material. This heat treatment also characterizes the mechanisms of fatigue crack initiations. Three mechanisms are found in this material: (I) crack initiated from broken particle, (2) crack initiated from open pore and (3) crack initiated from interfacial debonding between particle and matrix. It has been observed that, by carefully designing the heat treatment this steel can be beneficially used in fatigue loaded components
Experimental studies on the quasi-static axial crushing behavior of foam-filled steel extrusion tubes
No full textThe concerns of automotive safety have been given special attention in order to reduce human fatalities or injuries. One of the techniques to reduce collisio
Crushing performances of axially compressed Woven Kenaf fiber reinforced cylindrical composites
No full textThis paper presents experimental investigations on the crushing performances of axially compressed woven kenaf fiber reinforced cylindrical composites. Based on the literature survey, there are tremendous amount of work are available on the crushing performances regardless whether the composite contained synthetic or natural fibers. However, lack number of work found in discussing the crushing capability for the composite tubes fabricated using woven kenaf mat reinforced composites. Kenaf fiber in the form of yarn is weaved into a woven mat before it is submerged into a resin bath prior the mats are shaped to form a cylindrical tube. There are two important parameters are used such as number of layers and fiber orientations. The composite tubes are then quasistatically compressed to obtain the force-displacement curves. Energy absorption capability and other crashworthiness parameters are calculated and discussed in term of number of layers and fiber orientations. According to the results, it is found that both number of layer and fiber orientations played an important role in an elastic region or the first region. On the other hand, in the second stage, it is insignificantly affected the plateau stage where the curves seemed not much different
On three classes of mesh for the solution of a singularly perturbed two-point boundary value problem
No full textThere are several mesh types on which the solutions of discretized governing equations are obtained in computational fluid dynamics. Main classes include uniform, piecewise-uniform, exponential expanding, and hybrid meshes. Despite of their successful stories, their unwitting applications often result in bad solutions which involve, for instance, spurious oscillations, over- or under-estimations, and excessive computation time. This paper pays attention on three mesh classes, namely the uniform mesh, the piecewise-uniform mesh as represented by Shishkin mesh, and Shishkin-exponential expanding mesh which signifies the hybrid mesh. In particular, we examine the comparative effectiveness of the meshes for the solution of a singularly perturbed two-point boundary value problem. This is done by employing an error model based on the singular perturbation parameter and mesh number, with the assumption that the spatial error grows with respect to space. It is found that the number of mesh is reduced by at least half if the Shishkin mesh is replaced by the uniform and the Shishkin-exponential expanding meshes, in order to prevent spurious oscillations. The finding serves as a guideline for the researchers and engineers in selecting appropriate meshes on which flow problems are numerically solved
Development of an aquaponic system using ablution greywater for recreational purpose
No full textThe ablution ritual consumes large quantities of water, especially in mosques and public prayer rooms, where the greywater is allowed to run free and drain away. In Malaysia, most ablution system consists of a line of water taps with a drainage trough to carry the greywater to main drains. Some decent water is lost in the process as the tap is left running. In view of unnecessary waste, a simple recycling system can be designed to collect, treat and reuse the ablution water within a close-loop system for non-drinking applications, such as toilet flushing, general washing, plants watering and flowerbed cultivation. Therefore, this study was conducted to recover and reuse the ablution greywater that produced from Masjid Sultan Ibrahim with an aquaponic system. The aquaponic system involves the use of fish as a source of nutrients for the plant's growth, while the plants filter the water for the fish. In addition, the aquatic system model has its own attraction value that is very compatible with the landscape of the Masjid Sultan Ibrahim and at the same time it also provides recreational activities
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