Iraqi journal of mechanical and material engineering

In this paper the FE simulation and experimental equipment and design of the system for deformation by single point incremental sheet metal forming are presented. The formability is executed at room temperature and needs the milling machine, the tool of hemispherical head and toroidal head applied to deform the sheet, whereas translates from the peripheral of the sheet to its focus that additionally driving the sheet down. The blank is distorted increment by increment into the required shape via hemispherical or toroidal nose instrument going along a circular way. In the present investigation, the deformation’s analyses were down on the aluminum 7075 compound with thickness (0.9mm) and various device nose are enormously impact on the contact region and its observed that the hemispherical apparatus gives the best outcome. Close to this investigation consequence of the impact of shaping instrument nose on the formability is displayed. The ANSYS results are comparison with results obtained experimentally and it\'s discovered the deviation about 8% and this is expected to the criteria of spring-back.

Smart materials have a growing technological importance due to their unique thermomechanical characteristics. Shape memory alloys belong to this class of materials being easy to manufacture, relatively lightweight, and able to produce high forces or displacements with low power consumption. These aspects could be exploited in different applications including vibration control. A dynamic vibration absorber (DVA) can be used as an effective vibration control device. It is essentially a secondary mass, attached to an original system via a spring and damper. The natural frequency of the DVA is tuned such that it coincides with the frequency of unwanted vibration in the original system. This work aims to develop a dynamic vibration absorber with the help of shape memory alloy (SMA) springs in order to attenuate the vibration for a range of excitation frequencies. The experimental apparatus consisted of low-friction cars free to move in a rail. A shaker that provides harmonic forcing excites the system. Special attention is dedicated to the analysis of vibration reduction that can be achieved by considering different approaches exploiting temperature variations promoted either by electric current changes or by vibration absorber techniques. The results established that adaptability due to temperature variations is defined by modulus of stiffness.

In this research, erosion wear rate and hardness shore D for polymer biocomposite materials were investigated. The present bio-composites made up of differing weight percentage of pistachio shell powder (0%, 5%, 7%, and 9%) with epoxy resin was prepared by hand layout method. The erosion wear rates for bio composites obtained with under constant factors (10 hours, 60º impingement angles, sand silica particles 850μm, standoff distance 23 cm, flow rate 45 L/min, room temperature, nozzle diameter 4mm and pump diameter 50 mm). Results show that the specimen (epoxy + 9% pistachio shell powder) has the best erosion wear rate resistance and hardness shore D compared with other specimens, also the specimen reinforced by 9% pistachio shell have the lower density and highest water absorption percentage and it is found that the improving percentage for the this specimen in hardness is (11.5%) and in erosion wear rate is (775%). The study reveals that the addition of pistachio shell powder to the epoxy reduces its erosion wear rate and semi ductile behavior.

One of the main sources of global air pollution is the undesirable gas emissions from diesel engines, as well as the accompanied particulate matters (PM). Consequently, the reduction of their amount and quality is highly recommended for clean environment. The present work includes an attempt to use diesel-water emulsion as a fuel on compression ignition (CI) engine emissions and to investigate its effect on these hurtful discharges. For this reason, tests are carried out on a single cylinder, 4-stroke CI engine with steady speed (1500 rpm) and different loads (0-100 %) operated with various proportions of diesel-water emulsions and compared it to the diesel fuel. Four samples of diesel-water emulsions are prepared at ratios of (5, 10, 15 and 20 %) by water volume in diesel and with help of Tween 20 and Oleic Acid as a surfactant to maintain its stability for long periods of time. Gas emissions of the engine are recorded for CO2, CO, HC, and NOX using an exhaust gas analyzer and smoke opacity using a device of smoke meter. Results reveal that the diesel-water emulsion significantly decreases the NOX emissions and smoke opacity. The highest reduction ratio for NOX and smoke opacity are found in case of fuel emulsion DW20, with values of 32.5 % and 39 % respectively, in comparison with that of diesel fuel.

Poly Methyl Methacrylate resin distinguished by its low impact and fatigue strength, there are many researches that will deal with these situations. In the current study the matrix was heat cured material powder of PMMA was reinforced with peanut and walnut Shells to PMMA base material, which commonly utilize in the applications of denture. these natural powders were added in various weights fraction (4%, 8%, and 12%), and with similar average particle size (53μm) and studied Density and water absorption properties. In this study the method used to prepare the specimens is Hand Lay-Up method. The results showed that the values of density are increased when the weight fractions of both reinforcing natural particles increased and the maximum value was obtained with adding peanut shells powder at (12 wt.%.) (1.206 gm/????????3) for the composite specimens, while the values of water absorption Tests was decreased by increasing the weight fractions of both reinforcing powders peanut and walnut Shells in PMMA resin and The lowest values was obtained by adding peanut shells powder at (12 wt.% P) (0.003 % ).

Recent experimental research has shown that when injecting diesel fuel at 5000 bar in a combustion chamber at 300 °K, shockwaves are induced. Such shockwaves have demonstrated their influence on improving combustion, however the mechanism behind this improvement isn’t fully understood. This paper takes recently published experimental work another step, using a CFD numerical solution. Graphical results and fluid mechanics theory was then used to explain the impact of such shockwaves on the liquid fuel’s droplets thermo fluid effects. Methodology involves building a CFD model capable of handling supersonic and subsonic fluid flows, and then generate graphic results. Graphical CFD results were validated against graphical experimental results, with regards to the presence of shockwaves. Confirming the induction of shockwaves in recent experimental research. It was concluded that shockwaves can influence fuel droplet evaporation rate by influencing; (a) the Nusselt and Prandtl numbers, as shown in Eq. (1) to (4), and subsequently (b) influencing the evaporation of a liquid fuel droplet as in equation (8). Shockwaves are energy carriers and therefor a fuel droplet can be influenced as it is crossed by the shockwave. High pressure fuel injection inducing shockwaves improves air/fuel combustion and not just what is traditional thought (finer droplets & turbulences).

The aim of this study to investigate the influencing factors of the lower suspension arm by integrating finite element technique with response surface methodology (RSM). Response surface methodology has been widely used to predict stress von Mises on lower arm systems models. Aluminum alloys (AA7075-T6) are selected as a suspension arm materials. The structural model of the suspension arm was developed utilizing the Solid works. The finite element model and analysis were performed utilizing the finite element analysis code. The finite element model is correlated with design of experiments (DOE) modal test. Influences of the various factors namely; mesh size, load are investigated using RSM. A mathematical prediction model has been developed based on the most influencing factors and the validation simulation analysis proved its adequacy. The results show that there is no abnormality in the methodology adopted (R2 =0.8406). Ratio greater than 4 is desirable; Model’s ratio of 8.183 indicates an adequate signal. The Model F-value of 5.65 implies the model is significant. RSM was used to design the experiments and analyzed the results obtained. RSM aimed towards prediction stress on lower arm through the various factors of the suspension arm geometrical construction.