Iranian Journal of Mechanical Engineering Transactions of the ISMEIranian Journal of Mechanical Engineering Transactions of the ISME
http://jmee.isme.ir/
Tue, 11 Dec 2018 19:42:53 +0100FeedCreatorIranian Journal of Mechanical Engineering Transactions of the ISME
http://jmee.isme.ir/
Feed provided by Iranian Journal of Mechanical Engineering Transactions of the ISME. Click to visit.Effect of temperature on free vibration of functionally graded microbeams
http://jmee.isme.ir/article_33305_5307.html
Modified couple stress theory is applied to study of temperature effects on free vibration of Timoshenko functionally graded microbeams. Due to the interatomic and microstructural reactions of the structures in micro scale, the dynamic behavior of the microbeam is predicted more accurate applying the couple stress theory. Both of the simply supported and clamped boundary conditions are assumed to obtain the natural frequencies of the beam. The natural frequencies are obtained by minimization of the Lagrange function and applying the Ritz method. Finally, effects of various parameters such as; temperature change, power law index, height to length scale parameter ratio and height to length ratio on natural frequencies of the microbeam are presented and discussed in detail. The results obtained in this work is validated against numerical data given in the literature search.Fri, 30 Nov 2018 20:30:00 +0100Thermo-economic analysis of absorption chiller integrated with a GE-F5 gas turbine for power ...
http://jmee.isme.ir/article_33314_5307.html
The efficiency and output power of gas turbine power plants are heavily affected by ambient air temperature. To compensate this defect, some cooling technologies and technics are applied. In this paper, the effect of applying an absorption chiller by recovering waste heat from gas turbine flue gas has been investigated. For this purpose, the behavior of a GE-F5 gas turbine was modeled by coding in MATLAB software, and the code was in relation to a complete full-scale monitor and measurement on an operating unit, in Yazd Zanbagh power plant located in IRAN, Coordinates 31.9318° N and 54.3184° E .The results show that by decreasing the inlet temperature to near dew point temperature, the output power would increase about 3.135 MW, which is considerable amount in comparison with the power capacity equals 25 MW. The payback period for the project was obtained to be estimated 11 years, whereas no subsiding considerations, the payback time would be shorter nearby 45% at all. By considering social cost of carbon, payback period decreases to 7 years and 6 months.Sat, 01 Dec 2018 20:30:00 +0100Parametric optimization of cylindrical grinding process through hybrid Taguchi method and RSM ...
http://jmee.isme.ir/article_33315_5307.html
The present investigation proposes a hybrid technique: Taguchi method, response surface methodology (RSM) and genetic algorithm (GA), to analyze, model and predict vibration and surface roughness in traverse cut cylindrical grinding of aluminum alloy. Experiments have been conducted as per L9 orthogonal array of Taguchi methodology using several levels of the grinding parameters. Analysis of variance has been done to identify the influential process parameters on output variables. RSM has been applied to develop relationship between output responses with input parameters. Multi-objective overlaid contour plots have been made to study the interaction effects on both the responses simultaneously. Developed models are then solved individually, first and then combinedly by GA, for process optimization. Predicted output responses are then confirmed by confirmatory experiments.Wed, 28 Feb 2018 20:30:00 +0100Design and Modification of One Arm Driven Manual Hemiplegic Wheelchair
http://jmee.isme.ir/article_33316_5307.html
This paper presents design modification to the existing standard wheelchair by incorporating an improved propulsion system and also braking and tilting systems that allow its full control with only one hand. The proposed design has the propulsion system with a chain drive powered through a four-bar linkage driven by the main handle. The desired direction of motion is obtained by moving the lever in opposite directions. Disk brakes mounted on each of the wheels are operated through a brake lever attached to the handle near the main propulsion lever. The design involves a detachable lever operated lead screw that can be fitted to a wide range of wheelchair models. The leadscrew operated lifting mechanism helps to raise the seat cushion and tilt the backrest that facilitates easy shifting of the patient to bed or stretcher. The design of wheelchair mechanism is based on the anthropometric data for transfer of clients to bed. The proposed design has the merits of mechanical advantage of requiring lesser force to operate and improved speed of operation due to velocity ratio of the chain drive.Wed, 28 Feb 2018 20:30:00 +0100Cracked piezoelectric layer bounded between two orthotropic half-planes
http://jmee.isme.ir/article_33317_5307.html
This paper deals with the behavior of anti-plane shear crack in a piezoelectric layer bounded between two orthotropic half-planes within the framework of linear electroelasticity. The crack surfaces are assumed to be permeable or impermeable. The analysis is based on the stress fields caused by Volterra-type screw dislocation in the medium. Fourier transforms are used to reduce the dislocation problem to the solution of Cauchy-type singular integral equations, which are solved numerically for the dislocation density on the cracks. The dislocation densities are then employed to derive field intensity factors at the crack tips. The results show that the stress and the electric displacement intensity factors at the crack tips depend on the lengths and orientation of the cracks. It is also shown that, for a fixed value of the mechanical load, the field intensity factor can be either enhanced depending on the magnitude and direction of the applied electrical load. Furthermore, the interaction between the two cracks is investigated.Wed, 28 Feb 2018 20:30:00 +0100Effect of Insulated Up and Down Lid Motion on the Heat Transfer of a Lid-Driven Cavity with an ...
http://jmee.isme.ir/article_33318_5307.html
This study investigates the effect of lid motion on the optimal characteristics a thin rectangular fin attached on the hot wall of a square lid-driven cavity with active vertical walls. The optimal fin position is studied for Richardson numbers of 0.1-10. The effect of mounting a rectangular fin with a thermal conductivity of 1 and 1000 on minimization and maximization of heat transfer through such cavity is explored. Mixed convection equations are solved using the control volume method with the help of the SIMPLER algorithm. The Particle swarm optimization algorithm is used to determine the fin characteristics that minimizes or maximizes the heat transfer to the cold wall. The results show that optimal fin length and position is influenced by the position of the lid driven on the top or bottom of the cavity as well as lid velocity direction. The greatest reduction and increase in the Nusselt number are related to Richardson number of 0.1 with the bottom lid moving in the negative direction and Richardson number of 10 with the bottom lid moving in the positive direction, respectively.Wed, 28 Feb 2018 20:30:00 +0100