The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Haifeng Zhang - One of the best experts on this subject based on the ideXlab platform.
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dynamic behaviors of the Crankshafts in single cylinder and twin cylinder rotary compressors
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Ang Chen, Jianhua Wu, Haifeng Zhang, Yanzhong LiAbstract:Abstract Refrigeration rotary compressors are widely used in air-conditioners. A rotary compressor has a special rotor-bearing system, since the elastic cantilevered crankshaft is under dynamic transverse forces on different planes. The large deformation of the crankshaft would affect the thickness of the oil film, wear the bearings down or even induce the rotor-to-stator rubs. It is considered as a non-linear fluid–structure interaction problem. To ensure the compressor operating well, the dynamic behaviors of both single-cylinder and twin-cylinder compressors' Crankshafts at various speeds are analyzed. The influence of configuration of balancers on the reliability of rotor system is investigated for the further. Calculation results suggest that the vulnerable sections of crankshaft vary with the rotational speed. It is also found that 80% of the dynamic balance is the optimum design condition to reduce the transverse forces on crankshaft and the wear-out of journal bearings.
K S Choi - One of the best experts on this subject based on the ideXlab platform.
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simulations of stress distributions in crankshaft sections under fillet rolling and bending fatigue tests
International Journal of Fatigue, 2009Co-Authors: K S ChoiAbstract:Abstract The residual stresses due to fillet rolling and the bending stresses near the fillets of crankshaft sections under bending fatigue tests are important driving forces to determine the bending fatigue limits of Crankshafts. In this paper, the residual stresses and the bending stresses near the fillet of a crankshaft section under fillet rolling and subsequent bending fatigue tests are investigated by a two-dimensional plane strain finite element analysis based on the anisotropic hardening rule of Choi and Pan [Choi KS, Pan J. A generalized anisotropic hardening rule based on the Mroz multi-yield-surface model for pressure insensitive and sensitive materials (in preparation)]. The evolution equation for the active yield surface during the unloading/reloading process is first presented based on the anisotropic hardening rule of Choi and Pan (in preparation) and the Mises yield function. The tangent modulus procedure of Peirce et al. [Peirce D, Shih CF, Needleman A. A tangent modulus method for rate dependent solids. Comput Struct 1984;18:875–87] for rate-sensitive materials is adopted to derive the constitutive relation. A user material subroutine based on the anisotropic hardening rule and the constitutive relation was written and implemented into ABAQUS. Computations were first conducted for a simple plane strain finite element model under uniaxial monotonic and cyclic loading conditions based on the anisotropic hardening rule, the isotropic and nonlinear kinematic hardening rules of ABAQUS. The results indicate that the plastic response of the material follows the intended input stress–strain data for the anisotropic hardening rule whereas the plastic response depends upon the input strain ranges of the stress–strain data for the nonlinear kinematic hardening rule. Then, a two-dimensional plane-strain finite element analysis of a crankshaft section under fillet rolling and subsequent bending was conducted based on the anisotropic hardening rule of Choi and Pan (in preparation) and the nonlinear kinematic hardening rule of ABAQUS. In general, the trends of the stress distributions based on the two hardening rules are quite similar after the release of roller and under bending. However, the compressive hoop stress based on the anisotropic hardening rule is larger than that based on the nonlinear kinematic hardening rule within the depth of 2 mm from the fillet surface under bending with consideration of the residual stresses of fillet rolling. The critical locations for fatigue crack initiation according to the stress distributions based on the anisotropic hardening rule appear to agree with the experimental observations in bending fatigue tests of crankshaft sections.
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testing and modeling of frequency drops in resonant bending fatigue tests of notched crankshaft sections
SAE transactions, 2004Co-Authors: W Y Chien, K S Choi, Jwo Pan, D CloseAbstract:Resonant frequencies of a resonant bending system with notched crankshaft sections are obtained experimentally and numerically in order to investigate the effect of notch depth on the drop of the resonant frequency of the system. Notches with the depths ranging from 1 to 5 mm, machined by an EDM (Electrical-Discharging Machining) system, were introduced in crankshaft sections at the fillet between the main crank pin and crank cheek. The resonant frequencies of the resonant bending system with the crankshaft sections with various notch depths were first obtained from the experiments. Three-dimensional finite element models of the resonant bending system with the Crankshafts sections with various notch depths are then generated. The resonant frequencies based on the finite element computations are in good agreement with those based on the experimental results. The information on the frequency drop for a given notch depth from the results in this investigation can be used as a guidance to infer the extent of fatigue crack depths in the resonant bending fatigue tests of crankshaft sections.
Yanzhong Li - One of the best experts on this subject based on the ideXlab platform.
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dynamic behaviors of the Crankshafts in single cylinder and twin cylinder rotary compressors
International Journal of Refrigeration-revue Internationale Du Froid, 2014Co-Authors: Ang Chen, Jianhua Wu, Haifeng Zhang, Yanzhong LiAbstract:Abstract Refrigeration rotary compressors are widely used in air-conditioners. A rotary compressor has a special rotor-bearing system, since the elastic cantilevered crankshaft is under dynamic transverse forces on different planes. The large deformation of the crankshaft would affect the thickness of the oil film, wear the bearings down or even induce the rotor-to-stator rubs. It is considered as a non-linear fluid–structure interaction problem. To ensure the compressor operating well, the dynamic behaviors of both single-cylinder and twin-cylinder compressors' Crankshafts at various speeds are analyzed. The influence of configuration of balancers on the reliability of rotor system is investigated for the further. Calculation results suggest that the vulnerable sections of crankshaft vary with the rotational speed. It is also found that 80% of the dynamic balance is the optimum design condition to reduce the transverse forces on crankshaft and the wear-out of journal bearings.
Young Hoon Moon - One of the best experts on this subject based on the ideXlab platform.
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Coupled electromagnetic and thermal analysis of induction heating for the forging of marine Crankshafts
Applied Thermal Engineering, 2016Co-Authors: Min Churl Song, Young Hoon MoonAbstract:The induction heating of heavy marine crankshaft preforms has been analyzed to evaluate the temperature distribution prior to forging. The preform has a cylinder shape with a ring groove region and is heated in sections by induction. Each section is then forged to produce a crankshaft pin journal and a web region with continuous grain flow using vertical and horizontal compressions. Since induction heating of the preform needs precise temperature control to prevent process-induced defects such as overheating or insufficient heating, an equivalent circuit model was adopted in conjunction with a coupled electro-magnetic and thermal analysis to evaluate the coil current induced in preforms with various dimensions, power levels, and frequencies. The magnetic permeability, which depends on temperature and magnetic field, was evaluated in an iterative manner and also considered in the analysis. The temperature distribution of the preform was numerically predicted and compared with experimental values. The experimental validation confirms that the suggested analysis method can be a practical tool to predict the temperature distribution in the induction heating for the forging of heavy marine Crankshafts.
Simon Ho - One of the best experts on this subject based on the ideXlab platform.
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assessment of bending fatigue limit for crankshaft sections with inclusion of residual stresses
International Journal of Fatigue, 2007Co-Authors: Paul V Spiteri, Simon HoAbstract:Abstract The fatigue limit of rolled, ductile cast iron crankshaft sections under bending was investigated experimentally and analytically. The relationship of different failure criteria – specifically, surface crack initiation, resonant shifts, and two-piece failures – on the fatigue limit of the Crankshafts was explored from testing. A comparison showed that using the surface crack failure criterion decreased the apparent fatigue limit of the crankshaft significantly. This result supported the theory of crack arrest in the fillet area of Crankshafts and raises a significant challenge to the use of the surface crack failure criterion due to its inconsistent correlation to two-piece failure. Also an engineering practice for residual stress simulation and fatigue limit estimation due to a fillet rolling process on a crankshaft was explored. The complete analytical process was validated by the resonant bending fatigue test results. The normal stress distribution from the fillet surface-to-depth of a crankshaft section under bending was first obtained by a three-dimensional elastic finite element analysis. The residual stress distribution near the crankshaft fillet induced by a fillet rolling process was then determined by a three-dimensional elastic–plastic finite element analysis. A resultant normal stress distribution along any possible crack growth plane originating from the fillet surface and extending into the component was defined by superimposing the normal stress components due to the bending moment and the rolling load. Based on these calculated normal stresses, two fatigue models (such as the SWT equivalent stress and the effective stress intensity factor range) used to estimate the fatigue limits on surface cracks and in-depth cracks were examined by the experimental data. The results showed that the SWT equivalent stress was not a good fatigue damage parameter for surface cracks and the effective stress intensity factor range derived on the technique of crack modeling did correlate reasonably to the experimental data.