International Journal of Advanced Design and Manufacturing Technology
Volume:2 Issue: 3, 2009

In the present paper, the deformation zone of the ECAE (Equal Channel Angular Extrusion) process was investigated using the upper bound theorem. For this purpose, the shape of the streamlines in the deformation zone was assumed to be cubic Bezier curves. Then, the force required for the ECAE process was optimized with regard to the parameters defining the shape of streamlines by the upper bound theorem. By using of these streamlines, equivalent stain induced through one pass of the ECAE was calculated and the shape of the dead metal zone was determined. The influence of different friction conditions on the deformation field was studied. The force applied through the process was determined by optimizing an upper bound solution and was compared with other works including experimental and theoretical data. Also using this comparison, it was seen that the difference between the theoretical and experimental value for the force was reduced in the present method.

In this study, the effective factors on warpage in short fibre reinforced thermoplastic composites has been studied. First of all, the effective factors in manufacturing process were detected and then in order to decrease the number of experiments, the approach of Design of Experiments has been applied. By using micromechanics theory in composites and coefficients of thermal expansion models, a dedicaded code has been used to set up the experimnts. Then the effect of each significant parameter drived and the most effective parameter on warpage phenomenon is detected. At last by using Taguchi's optimization method, warpage of short fibre reinforced thermoplastic composites has been minimized.

In recent years, the application of composite materials in aircraft and space vehicle structural components has become increasingly popular. Preventing failure of composite structural systems has been an important issue in engineering design. Due to the lack of through-the-thickness reinforcement, structures made from laminated composite materials and adhesively bonded joints are highly susceptible to failure caused by interfacial crack initiation and growth. The delamination phenomenon in a laminated composite structure may reduce the structural stiffness and strength and redistribute the load in a way that the structural failure is delayed or may lead to structural collapse. As the most application of these materials is in space structures, the failure of a composite structure component can lead to a catastrophic failure of the structure as whole, thus, an accurate quantitative measurement and understanding of damage and determination of remaining useful service life plays a vital role in prediction of failure of such structures. To do so, first, the fracture properties of material should be determined. To calculate these properties, there are several experimental methods. Among them, the modified Arcan test is one of the most apposite methods for in-plane mixed-mode loading condition. In this investigation, a new specimen has been introduced to reduce cost and problems concerning utilization of adhesively. The critical fracture parameters of carbon-epoxy woven laminated composite material, which is of paramount materials in industry, in room temperatures is calculated both with experimental and numerical methods. These parameters include the critical stress intensity factors and critical strain energy release rate on crack tip. The geometric correction factors for modified Arcan test are calculated with a 2D finite element analysis. Finally, the values of critical fracture properties are calculated using these geometric modification factors and critical loads generated via experimental procedure

Cold roll-forming is a process in which the roll of sheet is formed by passing continuously through the set of rotary rollers without changing thickness in a cool way until it is formed to the desired profile. In this paper a parametric study on the section twist angle in roll-forming the non-symmetric channel is presented, using finite element simulation. At first finite element simulation results are validated by comparing the computed longitudinal strain, near the flange edge, with previously published experimental strains, for a special symmetric channel section. Here symmetric channel section was considered for verifying the finite element results, because of the lack of previous researches on non-symmetric channel section. Then by repeating the finite element simulation for similar section but with different flange width and changing the geometrical parameters such as flange width difference, sheet thickness and profile angle the effect of these parameters on twist angle is investigated. Investigating the results show that section twist angle is increased by decreasing the profile angle and sheet thickness and by increasing the flange width difference. All simulations were carried out using the commercial software ABAQUS 6.7.

Sheet metal components design and manufacture need a great deal of experience and know-how. Strip layout design is usually done with trial and error until best design for strip layout is finally achieved. Knowledge for the system is formulated from plasticity theories, experimental results, and the empirical knowledge of field experts. In this paper, an algorithm which can automatically design the bending sequence for progressive dies is described. A computer program is developed based on the algorithms and it composed of several modules, namely: feature recognition and design advisory module, flat pattern layout module and strip layout module. In the feature recognition module, all of the features of a 3-D component can be recognized automatically and checked against some manufacturability rules. In the second module, the flat pattern layout of the component is created automatically. In the strip layout module, the bending sequence is determined using fuzzy set theory. The system is developed in Visual Basic on a Solid Works platform. The software can also be used as an advisory system for die designers.

According to recent achievements in Nano technology we can see its effects in different engineering fields. In Nano manufacture process the first essential step is modeling coordinately in order to make it available different software are developing for this propose. In this paper Nano modeling for two papers is developed first understanding structure in Nano and micro size and second simulations of molecular movements in Nano size. In this paper fundamental concepts of both methods are discussed and MATLAB based software is developed for this purpose. In first step cubic and cylindrical shapes are modeled by the software then some simulations in which temperature’s effect modeled are presented. In second part a 2D model based on molecular dynamics is presented wit using this model we can find effects of force on AFM cantilever’s tip which has a great important in different Nano manufacture areas

After springs production, different residual stresses are created in the inner and outer surfaces of spring wires. Some of these stresses for example compressive residual stresses are useful and some are harmful. The effects of vareation of these stresses are caused spring relaxation and decrising in their free length when they are loaded intermittently. For review this phenomena in this research, first a test device with 0.5 Hz operational frequency was made. Then with the idea of operation mechanism of milling machines dividing attachment and cams mechanism and performance, a fixtures was designed and manufactured in order to apply displacement and preload to springs. In the next step manufactured springs were stress relieved under different temperatures and times.After that they were loaded intermittently and their free lengths after 10,000 cycles were measured. Investigation on tests results showed the effects of changes in temperature and time of stress relieving on springs free length decreasing. Two approximate equations with first and second degree were extracted from experimental data. Finally, optimal operation of stress relieving was obtained

The purpose of this research is to analyze the bevel gear forge process with finite element method by means of Super forge software and to compare it with the experimental results. Also a comparison between the microstructure of machining gears and forge gears after applying heat treatment on them is done. After committing the metallography experiments, we observe that the microstructure of forged gears has tinier martensites with short distances in gears surface, but machining gear has greater martensites with long distances.The obtained results show that the method of pieces production just before applying the heat treatment process will have a high effectiveness on the microstructure. Also, increasing in billet diameter that results billte’s heigh deduction, will cause pressure tonnage increasing. The obtained results of the simulation process show at the end of this paper.