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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 36, Issue 12 - Dec 2012
Volume 36, Issue 11 - Nov 2012
Volume 36, Issue 10 - Oct 2012
Volume 36, Issue 9 - Sep 2012
Volume 36, Issue 8 - Aug 2012
Volume 36, Issue 7 - Jul 2012
Volume 36, Issue 6 - Jun 2012
Volume 36, Issue 5 - May 2012
Volume 36, Issue 4 - Apr 2012
Volume 36, Issue 3 - Mar 2012
Volume 36, Issue 2 - Feb 2012
Volume 36, Issue 1 - Jan 2012
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Finite Element Simulation of Fatigue Crack Growth: Determination of Exponent m in Paris Law
Chu, Seok-Jae ; Liu, Cong-Hao ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 713~721
DOI : 10.3795/KSME-A.2012.36.7.713
The finite element simulations of fatigue crack growth are carried out. Using only the mechanical properties usually obtained from the tensile test as input data, we attempted to predict the fatigue crack growth behavior. The critical crack opening displacement is determined by monitoring the change in displacements at the node close to the crack tip. Crack growth is simulated by debonding the crack tip node. The exponent in the Paris law was determined and compared to the published exponent. Plotting with respect to the effective stress intensity factor range yielded more consistent results.
Study on Dimensional Change in Wire Product During Wire-Drawing Process
Moon, Chang-Sun ; Kim, Nak-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 723~730
DOI : 10.3795/KSME-A.2012.36.7.723
During the cold wire-drawing process, the diameter of a wire is reduced and the length of the wire is increased as the wire passes through the die. The pressure and sliding motion at the interface between the wire and die cause elastic recovery of the workpiece and friction and wear on the die. In addition, wire deformation and frictional heating raise the temperature of the wire and die, resulting in difficulty in manufacturing the drawn products according to a designated inner diameter of the die, deviating from the designated dimension or the inner diameter of the die. In this study, considering the die temperature distribution, the effects of dimensional changes of the drawn products were analyzed quantitatively; these changes are caused by the elastic deformation of the die, the elastic recovery of the workpiece, and the thermal deformation of both the die and the workpiece. It was confirmed that the elastic recovery of the workpiece influenced these changes the most. The initial dies considering these factors could avoid deviation from the designated dimension, and the desired drawn products were obtained by using the designed initial drawing dies.
Evaluation of Aerodynamic Characteristics of NREL Phase VI Rotor System Using 2-Way Fluid-Structure Coupled Analysis Based on Equivalent Stiffness Model
Cha, Jin-Hyun ; Song, Woo-Jin ; Kang, Beom-Soo ; Kim, Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 731~738
DOI : 10.3795/KSME-A.2012.36.7.731
In this study, the evaluation of the aerodynamic characteristics of the NREL Phase VI Rotor System has been performed, for the 7 m/s upwind case using commercial FEA and CFD tools which are ANSYS Mechanical 12.1 and CFX 12.1. The initial operating conditions of the rotor blade include a
tip pitch angle. A numerical simulation was carried out on only the rotor parts, excluding the tower structure based on the equivalent stiffness model, to consider the aeroelastic effect for the numerical simulation using the loosely coupled 2-way fluid-structure interaction method. The blade root bending moment was monitored in real time to obtain reasonable results. To verify the analysis results, the numerical simulation results were compared with the measurements in the form of the root bending moment and the pressure distributions of the NREL/NASA Ames wind tunnel test.
Nano-Aperture Grating Structure Design in Ultra-High Frequency Range Based on the GA and the ON/OFF Method
Song, Sung-Moon ; Yoo, Jeong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 739~744
DOI : 10.3795/KSME-A.2012.36.7.739
The genetic algorithm (GA) is regarded as one of the best ways for determining a global solution. Because it does not require calculating the design sensitivity differently from the ordinary gradient-based method, it is appropriate for the design problem in the ultra-high frequency range; the ordinary gradient-based method has difficulty in calculating the sensitivity in this range. This paper deals with nano-aperture grating topology optimization based on the GA and the ON/OFF method. The objective of this study is to maximize the transmittance in the measuring area. The simulation and optimization processes are carried out by using the commercial package COMSOL associated with Matlab programming. The final optimal design gives around 21% performance improvement, compared with the initial model.
Topology Design of Rigid-String Mechanism Using Constraint Force Design Method
Heo, Jae-Chung ; Yoon, Gil-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 745~750
DOI : 10.3795/KSME-A.2012.36.7.745
This study extends the constraint force design method allowing topology optimization for planar rigid-link and string mechanisms. To our best knowledge, by applying conventional machine and mechanism design theories, it is likely that it is possible to find out optimal locations of joints and lengths of rigid-links but somewhat difficult to find out optimal topology of rigid-links. To achieve optimal topology of rigid links, there is our previous contribution so called the new constraint force design method with the binary design variables determining the existence of the auxiliary forces imposing apparent lengths among unit masses. By adding new binary design variables, this research extends the constraint force design method to find out optimal mechanism consisting of stringy links as well as rigid links that seems impossible in the conventional machine and mechanism design theories.
Study on Acceleration Factor Model with Accelerated Stress Interactions
Kim, Hyoung-Eui ; Kang, Bo-Sik ; Cho, You-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 751~757
DOI : 10.3795/KSME-A.2012.36.7.751
An accelerated life test (ALT) is a test method that forces components to fail more quickly than they would under use conditions by applying higher overstresses. When two or more accelerating stresses are involved in an ALT, an interaction effect may occur. In previous studies, mostly ALTs without considering an interaction of accelerated stresses and accelerated life models were proposed. The life data obtained are extrapolated using a life-stress relationship to estimate the life distribution at use conditions. We use the general log-linear relationship to model the dependence of life in the Weibull distribution on stress. Therefore, this study suggests the acceleration factor model between the lives at use conditions and accelerated conditions by using mechanical component life data considering an interaction effect. Further, the accelerated life test method and acceleration factor model proposed in this paper will be the basis for adopting an accelerated life test with accelerated stress interactions.
Method to Determine Elastic Follow-Up Factors to Predict C(t) for Elevated Temperature Structures
Lee, Kuk-Hee ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 759~768
DOI : 10.3795/KSME-A.2012.36.7.759
This paper proposes a method to determine the elastic follow-up factors for the
-integral under secondary stress. The rate of creep crack growth for transient creep is correlated with the
-integral. Elastic follow-up behavior, which occurs in structures under secondary loading, prevents a relaxation of stress during transient creep. Thus, both the values of
and creep crack growth increase as increasing elastic follow-up. An estimation solution for
was proposed by Ainsworth and Dean based on the reference stress method. To predict the value of
using this solution, an independent method to determine the elastic follow-up factors for cracked bodies is needed. This paper proposed that the elastic follow-up factors for
can be determined by elastic-plastic analyses using the plastic-creep analogy. Finite element analyses were performed to verify this method.
Finite Element Damage Analysis for Cast Stainless Steel (CF8M) Material Considering Variance in Experimental Data
Jeon, Jun-Young ; Kim, Nak-Hyun ; Kim, Yun-Jae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 769~776
DOI : 10.3795/KSME-A.2012.36.7.769
The damage analysis method in this paper needs a material property and failure criteria. The material properties and the failure criteria could be easily obtained from the results of notched bar tensile tests carried out on other materials studied previously. However, for the cast stainless steel (CF8M) material in this paper, because of the variance in the results from notched bar tensile tests under the same conditions, the material property and the failure criteria could be obtained differently, depending on the analyzer. Therefore, a proper procedure that can confirm the material property and failure criteria are needed. In this work, the averaged material property was obtained from the notched bar with a 16-mm notch radius, and three failure criteria for CF8M material by finite element analysis were obtained. Applying the material property and the failure criteria, FE damage analysis for the J-R fracture toughness test was conducted. For validation, the simulated results were compared with the experimental results.
Fast Simulation of Output Voltage for High-Shock Piezoresistive Microaccelerometer Using Mode Superposition Method and Least Square Method
Han, Jeong-Sam ; Kwon, Ki-Beom ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 777~787
DOI : 10.3795/KSME-A.2012.36.7.777
The transient analysis for the output voltage of a piezoresistive microaccelerometer takes a relatively high computation time because at least two iterations are required to calculate the piezoresistive-structural coupled response at each time step. In this study, the high computational cost for calculating the transient output voltage is considerably reduced by an approach integrating the mode superposition method and the least square method. In the approach, data on static displacement and output voltage calculated by piezoresistive-structural coupled simulation for three acceleration inputs are used to develop a quadratic regression model, relating the output voltage to the displacement at a certain observation point. The transient output voltage is then approximated by a regression model using the displacement response cheaply calculated by the mode superposition method. A high-impact microaccelerometer subject to several types of acceleration inputs such as 100,000 G shock, sine, step, and square pulses are adopted as a numerical example to represent the efficiency and accuracy of the suggested approach.
Underwater Structure-Borne Noise Analysis Using Finite Element/Boundary Element Coupled Approach
Lee, Doo-Ho ; Kim, Hyun-Sil ; Kim, Bong-Ki ; Lee, Seong-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 789~796
DOI : 10.3795/KSME-A.2012.36.7.789
Radiated noise analysis from a ship structure is a challenging topic owing to difficulties in the accurate calculation of the fluid-structure interaction as well as owing to a massive degree of freedom of the problem. To reduce the severity of the problem, a new fluid-structure interaction formulation is proposed in this paper. The complex frequency-dependent added mass and damping matrices are calculated using the high-order Burton-Miller boundary integral equation formulation to obtain accurate values over all frequency bands. The calculated fluid-structure interaction effects are added to the structural matrices calculated by commercial finite element software, MSC/NASTRAN. Then, the impedance and underwater radiation noise due to an excitation of structure are calculated. The present formulation is applied to a ship to calculate the underwater radiated noise.
Auto Tuning of Position Controller for Proportional Flow Control Solenoid Valve
Jung, Gyu-Hong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 797~803
DOI : 10.3795/KSME-A.2012.36.7.797
Proportional solenoid valves are a modulating type that can control the displacement of valves continuously by means of electromagnetic forces proportional to the solenoid coil current. Because the solenoid-type modulating valves have the advantages of fast response and compact design over air-operated or motor-operated valves, they have been gaining acceptance in chemical and power plants to control the flow of fluids such as water, steam, and gas. This paper deals with the auto tuning of the position controller that can provide the proportional and integral gain automatically based on the dynamic system identification. The process characteristics of the solenoid valve are estimated with critical gain and critical period at a stability limit based on implemented relay feedback, and the controller parameters are determined by the classical Ziegler-Nichols design method. The auto-tuning algorithm was verified with experiments, and the effects of the operating point at which the relay control is activated as well as the relay amplitude were investigated.
Improvement of the Convergence Capability of a Single Loop Single Vector Approach Using Conjugate Gradient for a Concave Function
Jeong, Seong-Beom ; Lee, Se-Jung ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 805~811
DOI : 10.3795/KSME-A.2012.36.7.805
The reliability based design optimization (RBDO) approach requires high computing cost to consider uncertainties. In order to reduce the design cost, the single loop single vector (SLSV) approach has been developed for RBDO. This method can reduce the cost in calculating deign sensitivity by elimination of the nested optimization process. However, this process causes the increment of the instability or inaccuracy of the method according to the problem characteristics. Therefore, the method may not give accurate solution or the robustness of the solution is not guaranteed. Especially, when the function is concave, the process frequently diverges. In this research, the concept of the conjugate gradient method for unconstrained optimization is utilized to develop a new single loop single vector method. The conjugate gradient is calculated with gradient directions at the most probable points (MPP) of previous cycles. Mathematical examples are solved for the verification of the proposed method. The numeri cal performances of the obtained results are compared to those of other RBDO methods. The SLSV approach using conjugate gradient is not greatly influenced by the problem characteristics and improves its convergence capability.
Condition Monitoring of an LCD Glass Transfer Robot Based on Wavelet Packet Transform and Artificial Neural Network for Abnormal Sound
Kim, Eui-Youl ; Lee, Sang-Kwon ; Jang, Ji-Uk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 813~822
DOI : 10.3795/KSME-A.2012.36.7.813
Abnormal operating sounds radiated from a moving transfer robot in LCD (liquid crystal display) product lines have been used for the fault detection line of a robot instead of other source signals such as vibrations, acoustic emissions, and electrical signals. Its advantage as a source signal makes it possible to monitor the status of multiple faults by using only a microphone, despite a relatively low sensitivity. The wavelet packet transform for feature extraction and the artificial neural network for fault classification are employed. It can be observed that the abnormal operating sound is sufficiently useful as a source signal for the fault diagnosis of mechanical components as well as other source signals.
A Study on Parameters of Soft Recoil Mechanism for Reduction of Recoil Force
Yang, Tae-Ho ; Lee, Young-Shin ; Lee, Kyu-Sub ; Jun, Sang-Bae ; Kang, Kuk-Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 7, 2012, Pages 823~828
DOI : 10.3795/KSME-A.2012.36.7.823
The soft recoil mechanism was an effective mechanism for reducing the recoil force by forwarding momentum. There were some parameters such as the fire angle, firing position, and initial pressure of the recuperator, which influenced the forwarding momentum. These parameters affected the generation of the forwarding momentum in the soft recoil mechanism. To design for the mechanism, the parameters affecting momentum were studied to consider some reasonable conditions. Among the various parameters, the initial pressure of the recuperator and firing position was confirmed as a key factor to have affected the momentum. It was determined that the recoil force had a minimum value when the initial pressure of the recuperator was 180.