JOURNAL OF SIMULATION AND ANALYSIS OF NOVEL TECHNOLOGIES IN MECHANICAL ENGINEERING (JOURNAL OF SOLID MECHANICS IN ENGINEERING)
Year:2013 | Volume:5 | Issue:2 (12)|Papers Count:6

In this paper, experimental results of a deep drawing process to produce a cylinder of high strength steel with a spherical head were compared with it’s simulation results and three proposal design types. Meanwhile, the amount of limiting draw ratio in some stages was determined. Accuracy and precision of the results of a finite element software to predicting the multi stage deep drawing process of high-strength thin steel sheets was measured. ABAQUS version 6-9-3 was used to simulate the process.In this research, the raw material was a circular blank of annealed steel AISI-4130 with 2 mm thickness that in experimental test, subjected to one drawing stages, three redrawing stage and two heat treatment stages. The uni-axial tensile test was performed to determine the mechanical properties of the steel sheet.Numerical thickness distribution was compared with the experimental results in different stages of deep drawing and the accuracy was good (about 2.55%). Base on this results the proposal designs were simulated to introduce the properties of the most suitable design types.

The aim of this paper is modeling and sensitivity analyzing of full toroidal continuously variable transmission (CVT). The dynamic analysis of CVT is implemented and contact between the disk and the roller is modeled via elastohydrodynamic (EHL) lubrication principles. Then, a computer model is created to determine traction coefficient, spin losses and the efficiency of CVT.Results of the model are compared with other models to confirm its validity. Then, an optimization is accomplished using Genetic Algorithm, and maximum efficiency of full toroidal CVT is achieved 88.15%. Finally, sensitivity of power transmission efficiency to optimization parameters at their optimum values is calculated. It is shown that efficiency of CVT has maximum sensitivity to dimensionless parameter k and curvature radius of the roller.

Carbon nanotubes have an important role in reinforcing nanocomposits. Many experimental observations have shown that in the most nanostructures such as nanocomposites, carbon nanotubes (CNTs) are often characterized by a certain degree of waviness along their axial direction. In the present paper, the effects of initial curvature, influence of surrounding medium that is modeled as Winkler elastic foundation on behavior of slightly curved carbon nanotubes are investigated. To capture the small size effects, nonlocal elasticity theory is implemented. Bending governing equations are derived using the principle of minimum total potential energy and these nonlinear equations are solved by Newton Raphson method. It is shown that the larger the initial curvature, the higher deflection can occur. Furthermore, neglecting the effect of initial curvature of CNTs can lead to incorrect results.

In this study, effects of lacing rods location on natural frequencies of last stage of a Steam Turbine Blades (STBs) have been investigated. STBs are critical and important elements in a turbine as well as power plants. One of the most important parameters in turbine blades is lacing rods location. In this paper, first, a three dimensional (3D) scan was used to produce the geometrical model of the blade. Then, last stage of a low pressure turbine have been produced and simulated by assembling of the one-blade model. There are two rows of lacing rods in the last stage of turbine. In this paper, effecting the lacing rods location on natural frequencies of system has been studied. According to the Campbell diagrams, the results showed there is no resonance in the last stage blades of the steam turbine for different locations of the lacing rods.

In this paper, effects of ply orientation of adjacent plies with ( f//q) interfaces on mode II critical strain energy release rate (fracture toughness) of multidirectional (MD) laminate has been studied. Ply orientation of adjacent plies is one of the most important parameters affects the modeII critical strain energy release rate (IIc G) in the initiation of the delamination. To study this parameter, End Notch Flexure (ENF) specimen has been used for measuringIIc G of laminated composites. Eventually, the purpose is to predict ofIIc G of MD composite specimen, without direct experimental tests and finite element modeling using the results of unidirectional (UD) ply. First, IIc G of unidirectional composites will be studied and by the results obtained, the behavior of multidirectional laminated composites is predicted. In this context, a comprehensive method was proposed that combines prediction methods, and analytical modeling. The obtained IIc G of multidirectional laminated composites with (f//q)interfaces can be used for design purposes. Results obtained using this method has been compared with the results of numerical and theoretical methods. This prediction method reduces the calculation costs of FE and analytical models, and also the costs of experiments significantly.

This paper studies the nonlinear vibration analysis of a simply supported Euler-Bernoulli beam resting on a nonlinear elastic foundation under compressive axial load using nonlinear normal modes concept in the case of three-to-one (3: 1) internal resonance. The beam’s governing nonlinear PDE of motion and also its boundary conditions are derived and then solved using the method of Multiple Time Scales. Under three to-one-internal resonance condition applying nonlinear normal modes the steady state stability analysis of the beam’s vibrations is performed.Then the effect of changing the value of different parameters on the beam’s dynamic response and the steady state stability analysis is investigated.