Fatigue analysis for the first row of blades of a micro turbine under full loading cycle using transient modal analysis
, Pages: 145-156
Ali Soleimani Saeid Shahraki and Hosein Bisadi PDF (650K)
Abstract: In advanced modern turbines, the temperature of the turbine's first blade row which is called the turbine's hot part, increases almost as 1000℃. These blades must operate for long periods of time. Since, the main failure reason of the parts operating under high temperature and cyclic loading conditions is fatigue as well as creeping phenomena, acquiring an accurate estimate of these blades' lifetime under creeping and fatigue interactions is very necessary for theoretical and practical requirements. The fatigue of the first blade row of the micro turbine TRI60 is analyzed in this study. For the purpose of estimating the fatigue lifetime of turbine and motor, heat transfer of blades as well as thermal stress is analyzed at first via ABAQUS software. Consequently, a fatigue analysis under full cycle and within the interval of 2/3 v_max to v_max is performed using Smith-Watson-Taper algorithm and transient modal analysis via Fe-safe software.
Keywords: First row of blades, Micro turbine, Full loading cycle
Fatigue life prediction: A comparative study for a three layer EN45A parabolic leaf spring
, Pages: 157-166
Krishan Kumar and M. L. Aggarwal PDF (650K)
Abstract: There are literally several studies accomplished to predict the fatigue life of leaf springs but estimation of fatigue life of a parabolic leaf spring by using CAE tools has not yet been executed in the past. Parabolic spring is an important component in a vehicle suspension system. It needs to have excellent fatigue life and in today’s scenario manufacturers rely on constant loading fatigue analysis. The objective of this work is to perform the fatigue analysis of parabolic leaf spring by three different methods where CAE analysis is performed to observe the distribution of stress fatigue life and damage using Goodman approach. In this work, fatigue life of the parabolic leaf spring is determined as per SAE spring design manual and experimentally by testing on full scale fatigue testing machine. ANSYS is used for CAE solution for the prediction of leaf springs fatigue life considering stress theory. The fatigue life estimated by all three modes is then compared for the purpose of validation. The methodology used in this paper brings a practical approach to the professionals in the industries who are engaged for design of mechanical components.
Keywords: Parabolic leaf spring, Fatigue life, CAE analysis
Free vibration analysis of isotropic plate with stiffeners using finite element method
, Pages: 167-176
Devesh Pratap Singh Yadav, Avadesh K Sharma and Vaibhav Shivhare PDF (650K)
Abstract: This paper presents the free vibration analysis of stiffened isotropic plate by means of finite element method. Stiffeners are used in plates to increase the strength and stiffness. The effect of position of stiffeners on isotropic plate has been studied which involve the possible combination of clamped and free edge condition. The model has been discretized using a 20-node solid element (SOLID186) from the ANSYS element library. The natural frequencies are calculated using Block-Lanczos algorithm. The comparisons of stiffened plate with the available results are found to be in good uniformity. The effect of different boundary conditions, stiffeners location, thickness ratio, stiffener thickness to plate thickness and aspect ratio on the vibration analysis of stiffened plates has been studied.
Keywords: Stiffened plate, Stiffeners, Finite element method, Free vibration
Investigating the dynamic response of a punch to human head using finite element analysis
, Pages: 177-186
A.Tanbakoosaz, R. Azarafza, M. Saboni, M. Alinejad and A. Bahmani PDF (650K)
Abstract: Head injuries are among the dangerous injuries which are common in all sport types. In the present study, the dynamic response of a punch to the head of a Wushu fighter was simulated by modeling the human head in ABAQUS software. Moreover, the maximum displacement and the stress distribution in the helmet and head parts were analyzed by finite elements method. The obtained results showed a significant interval in the response of different tissues to the delivered blow. The maximum shear stress, normal stress and displacement in the helmet were 5.616 MPa, 5.755 MPa and 1.236 mm, respectively, while these magnitudes were respectively 3.199 MPa, 6.268 MPa and 0.0001867 mm in skull, 4.596 MPa, 3.691 MPa and 0.1180 mm in the head skin and 0.01098 MPa, 0.8779 MPa and 0.04993 mm in brain. The present model with its unique features can be a valuable and powerful instrument to gain a better insight into the injury mechanism for better diagnosing of injuries and to design protective helmets with higher efficiency and safety for various sport forms as well.
Keywords: Finite element analysis, Shear stress, Punch, Sanda protective helmet
Mathematical modeling of temperature during laser forming using bimodal beam
, Pages: 187-194
Masoud Sistaninia and Mahjoubeh Sistaninia PDF (650K)
Abstract: An analytical and numerical solution is developed for a transient heat conduction equation in which a plane slab is heated by a bimodal distribution beam over the upper surface. In laser heat treatment of steel few methods are used to produce a wider and nearly uniform average irradiance profile. This may be achieved by a bimodal (TEM11) shaped laser beam. In this paper, Green function method is employed to derive an analytical solution for thermal field distribution induced by laser forming process. Then 3-D finite element modeling of a slab in the ANSYS code is used to model the thermal field of laser forming with bimodal beam distribution. The results show that bimodal beam is useful for obtaining a uniform heat intensity distribution.
Keywords: Thermal modeling, Laser forming, Finite element, Bimodal beam
The influence of cutting conditions and cutting tool geometry on the atomistic modeling of precision cutting
, Pages: 195-206
Angelos P. Markopoulos, Nikolaos E. Karkalos, Kalliopi-Artemi L. Kalteremidou, Andreas Balafoutis and Dimitrios E. Manolakos PDF (650K)
Abstract: In this paper a molecular dynamics simulation of nano-metric cutting of copper with a diamond tool is presented. MD simulations require the determination of the interaction of the involved atoms through a function of potential for the materials involved in the analysis and the accurate topography of the studied area, leading to high demand of computational time. The models presented are taking into account the cubic lattice of copper, test two different potential functions and at the same time control the computational cost by introducing small models at realistic cutting conditions. This is realized by a novel code developed and allows focusing on the influence of several processes and modeling parameters on the outcome of the simulations. Models with and without thermostat atoms are investigated and the influence of cutting conditions and cutting tool geometry on chip morphology, cutting forces and cutting temperatures are studied.
Keywords: Molecular dynamics, Simulation, Nano-machining, Cutting forces, Morse potential
® 2010 GrowingScience.Com