International Journal of Advanced Design and Manufacturing Technology
Volume:3 Issue: 4, 2010

In this paper the critical strain energy release rate for T300/913 carbon-epoxy laminated composites has been studied using ANSYS finite element software based on virtual crack closure technique (VCCT). Compact Tension (CT) specimen has been used for numerical analyses and the geometrical dimensions have been extracted from the existing references. The results obtained from the finite element analysis are compared with the existing experimental results in literature. There is good agreement between the critical energy release rate obtained from finite element analysis and the experimental results. Accuracy and simplicity of presented model make it appropriate for predicting the experimental results and improving experimental techniques. The innovation of the present research is the simplicity of the model for simulation of the critical strain energy release rate of the laminated composites.

In this paper, a new combined power and refrigeration cycle is proposed, which combines the Rankin power cycle and the Ejector refrigeration cycle. This combined cycle produces both power output and refrigeration output simultaneously. This cycle is driven by the flue gas of gas turbines, industrial waste heats, solar energy and geothermal energy. An exergy analysis is performed to guide the thermodynamic improvement for this cycle and a parametric analysis is conducted to evaluate the effects of the thermodynamic parameters that are significant on the performance of the combined cycle. The results indicate that the biggest exergy loss is due to the irreversibilities. The ejector causes the most effect on exergy loss. It is also shown that the turbine inlet pressure, the turbine back pressure, the condenser temperature and the evaporator temperature have significant effects on the turbine power output and exergy efficiency of the combined cycle.

Effect of methanol concentration and channel depth of bipolar plates on the performance of single direct methanol fuel cell was investigated experimentally. The membrane used in this experiment was Nafion117. Dimension of the single cell were 10cm 10 cm. Methanol concentrations of 0.50, 1.0, 1.5, 2.0, 3.0 molar were used. Channel depth of the bipolar plates were chosen to be 1.0, 1.5, 2.0 mm, and in order to investigate the effect of channel depth, anode channel depth and cathode depth were changed simultaneously. Optimized methanol concentration for the single cell were 0.5-1.5 molar. Based on different experiments, as channel depth is decreased, mass transfer is improved and removal of carbone dioxide takes place easier. The results indicate that the best channel depth for this kind of single cell is 1.0 mm.

This work presents the heat transfer characteristics of a new type of porous radiant air heater that operates on the basis of effective energy conversion method between flowing gas enthalpy and thermal radiation. At each layer, the gas and solid phases are considered in non-local thermal equilibrium, and combustion in the porous radiant burner is modeled by considering a non-uniform heat generation zone. The homogeneous porous media, in addition to its convective heat exchange with the gas, may absorb, emit, and scatter thermal radiation. In order to determine the thermal characteristics of the proposed porous radiant air heater, a two-dimensional model is used to solve the governing equations for porous medium and gas flow, moreover discrete ordinates method is employed to obtain the distribution of radiative heat flux in the porous media. In order to validate the applied numerical method at the present analysis, the results are compared with some reported theoretical and experimental results of other investigators, where good agreement is observed.

Hydroforming process in one of the most effective production method, for improving the drawing ratio in sheet metal forming process. This is due to the fact that in hydroforming process, forming takes place using a punch which drives the part forward via a controlled fluid pressure. In this paper, deep drawing hydroforming for circular punch is investigated. Different pressure paths are tested using ABAQUS 6.7 software, in order to determine practical pressure constraint via simulation. Finally, drawing ratio effect on practical pressure constraint is investigated. In order to evaluate simulation accuracy, the obtained results are compared with some experimental results. Results indicate that by increasing drawing ratio, rupture curve is dropped significantly, and allowed zone area is reduced. Moreover, with increasing time, allowed zone area is expanded, and with increasing drawing ratio, allowed zone distance is reduced.

In this paper, Ultrasonic assisted cutting (UAT) process has been investigated. The cutting technique is among the advanced machining techniques which improve cutting capability of materials. Vibratory tool is made under longitudinal mode with 10 micron amplitude and 20 KHz frequency, in such a way that vibration is applied in cutting speed direction. Experiment carried out on Al7075; using ultrasonic assisted turning has lead to reduction in the cutting force, versus traditional cutting process. Moreover, further experiments were done aiming at investigating effective parameters in UAT machining process on Al7075 parts. These parameters include cutting speed, feed rate, depth of cut, and vibration amplitude. Statistical analysis on the experiment results were carried out, and different mathematical models for forecasting cutting force and optimizing machining parameters are presented in order to achieve minimum cutting force. At the end, cutting forces were compared for two machining processes namely ultrasonic assisted cutting (UAT) process, and traditional machining.

Premixed combustion is widely used for reducing pollutant emission from combustion chambers. However, these systems may be sensitive to complex phenomena such as flashback. In the present study flame, flashback and structure of premixed laminar flames are investigated theoretically. The mathematical model includes the axi-symmetric continuity, Navier Stocks, energy, and species equations. Combustion is modeled as one-step overall reaction using experimental relation with Arrhenius finite rate model. Flashback is examined as a function of wall velocity gradient, tube radius, and fuel concentration in mixture. The analysis is done in two stages. In the first stage, analysis is done traditionally where the value of flashback criteria is calculated and the unstable region of combustion is obtained. In the second stage, flame is kept to propagate into the region of investigation to study the flame structure. Because of complexity of flame flashback, difficulties of performing the experiments confronting flashback phenomena, and fire hazard, the numerical simulation of this phenomenon is strongly recommended.

One of the most important parts of power transmission in automotives is C.V. joint, which consists of four components where exterior bowl is one of them. Due to its complexity, and importance in automobile and existence of high stresses, forging process is the only cost effective method of production. Hence, the best method of production of this part is forging process. The exterior part of C.V. joint is produced through two subsequent stages. First, forward extrusion is applied followed by backward extrusion. In this research hot forward and backward extrusion of C.V. joint of PRAID with pre-heating while heat loss has taken into account, were simulated using finite element method. The Arbitrary Lagrangian-Eulerian method was employed to improve element distortions. Dies were considered as solid and elastic to investigate the thermal interactions of dies and the work piece. Deformation behavior, die contact pressure and punch force have been discussed by using the numerical results. Force diagrams during forging process according to die displacement and related results are discussed. Numerical results are compared with theoretical results for validation, meanwhile the comparison results are in good agreement.