JOURNAL OF SIMULATION AND ANALYSIS OF NOVEL TECHNOLOGIES IN MECHANICAL ENGINEERING (JOURNAL OF SOLID MECHANICS IN ENGINEERING)
Year:2010 | Volume:2 | Issue:2|Papers Count:8

Tolerance analysis of mechanical assemblies is an important tool in reliable design of products at low cost and good quality. Using this tool, it is possible in manufacturing stage to observe the effect of parameters on assembly requirements. The direct linearization method is a useful method which runs based on vector loop analysis. In this research, the DLM method is used to analyze the tolerance chain in triggering mechanism assembly. Furthermore the percent contribution of various manufacturing dimensions on the design requirement of the assembly in determined.

The main purpose of this article is calculating forces and moments of each of the process rolls for designing and manufacturing of ring rolling machine to be used for airplane engine cases. Axial redial ring rolling process was simulated by finite element method. To validate the results, output of simulation of rolling a simple ring made of Ti-6Al-4V alloy was compared to experimental results. Comparing results show good accuracy of simulation. Also in this article, a new method for simulating of guide rolls proposed, that is more simple and efficient than the previous methods.

Meshfree Collocation Method is used to solve linear two-dimensional problems. This method differs from weak form methods such as Galerkin method and no cellular networking and no numerical integration. Therefore, this method has no constraints such as the integration accuracy and the integration CPU time, and equations can be isolated directly from the strong form of governing PDE. The fundamental problem of this method is unstable solution especially in the case, including derivative boundary conditions. In this paper hermite type shape functions are used to impose boundary conditions. These shape functions have improved the solution accuracy. also, In this paper  effects of various parameters such as type weight functions, order based vector, dilation parameter, distribution nodal on the solution accuracy have been studied.

Hot ring rolling is a highly nonlinear, unsteady-state and asymmetry process which is affected by many parameters. The friction coefficient between the ring, the driver roll and the idle roll is one of the problems, which has significant effect on the quality of final product. In this study, the effect of these two parameters on hot ring rolling was investigated based on a 3D coupled-thermo mechanical FE model. The 3D model of ring rolling process was built in ABAQUS including ring, driver roll, idle roll and guide roll. The value of fishtail defect was measured for different friction coefficients between ring and driver roll and also ring and idle roll. The results show that the value of the fishtail defect decreases with the increase of the friction coefficient between the ring and the idle roll or the decrease of friction coefficient between the ring and the driver roll. Furthermore the value of the fishtail defect increases with the decrease of the friction coefficient between the ring and the idle roll or the increase of friction coefficient between the ring and the driver roll. Also the value of these two parameters must be restricted in a specific range, upper and lower values are not allowed. The obtained results may provide a guide for process optimization.

Twist extrusion process is a rather new route to produce highly strained materials. In this process, severe plastic deformation is applied by large shear strains. In current article, required energy for twist extrusion by use of admissible velocity field together with the upper bound technique is predicted. The proposed model is capable of considering the effect of various parameters such as die geometry and friction conditions. In addition, the model anticipates the critical die design parameters. To verify the proposed model, the predictions were compared with the results of a finite-element analysis and reasonable consistency was observed.

In this study, a novel numerical method is proposed for determination of mode-I interlaminar fracture toughness, GIc, in multi-directional (MD) double cantilever beam (DCB) specimens using fracture properties of unidirectional DCB specimens. Two factors, b and Dc are defined to minimize the undesirable effects on strain energy release rate. b describes the difference between maximum and average of SERR along the delamination front. Dc shows the bending-bending coupling of laminated composites. b and Dc factors are not independent factors because both of them affect on distribution of SERR. As a result, by 3D modeling of DCB specimen in ANSYS software, limitation of b is determined so that the fracture toughness of MD DCB specimen with 0//0 interface can be predicted from toughness of unidirectional DCB specimen. Numerical results shows that fracture toughness predicted with the proposed approach is in good agreement with available experiments in the literature for b<20%.

Automobile manufactures are persistently trying to develop comfort of passengers by improving different specification such as decrease of sound level in engine compartments. There is a main problem that the noise generated in air intake systems may be disgusting. Statistical energy analysis is a suitable method for acoustical-vibration analysis of structures in high frequency range. In this paper, the air intake system of an engine compartment is modeled using SEA. The transmission loss through the intake duct is calculated with importing CAD model and creating subsystems at high frequency range. In addition, comparing the results of fully modeled of intake systems with current experimental data, shows a good accuracy of results especially in high frequency range. Furthermore, the influence of inserting porous material is studied.

In this investigation‚ the fracture toughness of A356 containing 15% SiC composite was studied. Al/SiC composites have been considered because of their mechanical and erosion properties .Low fracture toughness in Al/SiC as compared with Aluminium alloys is one of its disadvantage. In this study at first A356 alloy was melted in a smelting electrical furnace then poured into the mould. A356-15% SiC were composed by melting method and mixing continuously (in order not to precipitate SiC to the bottom) in the presence of a nature gas. The melt was poured in a metallic mould, then specimens were cut from the products bars in order to calculate fracture toughness according to ASTM. Obtained results for different specimens compared together. In this study Crack Opening Displacement (COD) is used to determine fracture toughness rate. KIc was calculated in composites and compared with that of base alloy. As a result KIc in composite samples were decreased significantly, debris, cracks, gas cavity.