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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 33, Issue 12 - Dec 2009
Volume 33, Issue 11 - Nov 2009
Volume 33, Issue 10 - Oct 2009
Volume 33, Issue 9 - Sep 2009
Volume 33, Issue 8 - Aug 2009
Volume 33, Issue 7 - Jul 2009
Volume 33, Issue 6 - Jun 2009
Volume 33, Issue 5 - May 2009
Volume 33, Issue 4 - Apr 2009
Volume 33, Issue 3 - Mar 2009
Volume 33, Issue 2 - Feb 2009
Volume 33, Issue 1 - Jan 2009
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Enhanced Spherical Indentation Techniques for Rubber Property Evaluation
Hwang, Kyu-Min ; Oh, Jopng-Soo ; Lee, Hyung-Yil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1357~1365
DOI : 10.3795/KSME-A.2009.33.12.1357
In this study, we enhance the numerical approach of Lee et al.
to spherical indentation technique for property evaluation of hyper-elastic rubber. We first determine the friction coefficient between rubber and indenter in a practical viewpoint. We perform finite element numerical simulations for deeper indentation depth. An optimal data acquisition spot is selected, which features sufficiently large strain energy density and negligible frictional effect. We then improve two normalized functions mapping an indentation load vs. deflection curve into a strain energy density vs. first invariant curve, the latter of which in turn gives the Yeoh-model constants. The enhanced spherical indentation approach produces the rubber material properties with an average error of less than 3%.
A Numerical Study on Mechanical Behavior with Cyclic Deformation of Anterior Cruciate Ligament
Ban, Yong ; Choi, Deok-Kee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1366~1374
DOI : 10.3795/KSME-A.2009.33.12.1366
Anterior cruciate ligament(ACL) of human body experiences a large deformation. May during everyday when large deformation is repeated by various activities such as outdoor activity, ACL easily get damaged. In order to acknowledge the effect of the cyclic large deformation to ACL, the constitutive equations for ACL are derived from experiment data. The concept of the objective stress rate plays a important role wherever large deformation occurs. In order to obtain the objective stress rates the eigenprojection technique is used. A comparison is made for four different cases: Jaumann rate, Green-Naghdi rate, logarithmic rate and twirl tensor of Eulerian triad rate for an isotropic material subject to cyclic deformation, such as simple shear motion. Four different materials are studied to compare the behavior of the materials for ACL using different objective rates. Finally, more complicated model with fibers for soft tissues is used to calculate the behavior subjected to cyclic large deformation.
Calculation of the Crack Length for a Pipe Specimen using the Modified Load Ratio Method
Choi, Jung-Hun ; Huh, Yong ; Koo, Jae-Mean ; Seok, Chang-Sung ; Park, Jae-Sil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1375~1382
DOI : 10.3795/KSME-A.2009.33.12.1375
The objective of this paper is to apply the load ratio method to the measurement of the crack length of the real scale pipe specimen. The load ratio method was modified and finite element analyses were performed to derive the relationship between the normalized compliance and the normalized crack length for the pipe specimen. In order to measure the crack length, the direct current potential drop method and the modified load ratio method were applied to the pipe test. The applicability of the modified load ratio method was confirmed by comparing the calculated crack length with the measured crack length from the pipe experiment.
Optimal Wear Design for a Hypotrochoidal Gear Pump without Hydrodynamic Effect
Kwon, Soon-Man ; Sim, Mu-Yong ; Nam, Hyoung-Chul ; Shin, Joong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1383~1392
DOI : 10.3795/KSME-A.2009.33.12.1383
A disadvantage in the design of a hypotrochoidal gear pump as in a gerotor pump is a lack of parts that can be adjusted to compensate for wear in the rotor set, and as a consequence, it causes a sharp reduction of volumetric efficiency. In this paper, an attempt has been made to reduce the wear rate between the rotors of a hypotrochoidal gear pump. Using the knowledge of shape design on the rotors, the contact stresses without hydrodynamic effect between the rotors` teeth are evaluated through the calculation of the Hertzian contact stress. Based on the above result and the sliding velocity between the rotors, a genetic algorithm (GA) is used as an optimization technique for minimizing the wear rate proportional factor (WRPF). The result shows that the wear rate or the WRPF can be reduced considerably, e.g. approximately 12.8% in this paper, throughout the optimization using GA.
Validation of a Local Failure Criteria Using the Results of Wall-Thinned Pipe Failure Tests
Kim, Jin-Weon ; Lee, Sung-Ho ; Park, Chi-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1393~1400
DOI : 10.3795/KSME-A.2009.33.12.1393
The objective of this study is to validate local failure criteria, which were proposed based on the notched-bar specimen tests combining with finite element (FE) simulations, using the results of real-scale pipe failure tests. This study conducted burst test using wall-thinned pipe specimens, which were made of 4 inch Sch.80 ASTM A106 Gr.B carbon steel pipe, under simple internal pressure at ambient temperature and performed associated FE simulations. Failure pressures were estimated by applying the failure criteria to the results of FE simulations and were compared with experimental failure pressures. It showed that the local stress based criterion, given as true ultimate tensile stress of material, accurately estimated the failure pressure of wall-thinned pipe specimens. However, the local strain based criterion, which is fracture strain of material as a function of stress tri-axiality, could not predict the failure pressure. It was confirmed that the local stress based criterion is reliably applicable to estimation of failure pressure of local wall-thinned piping components.
Preliminary Study on Linear Dynamic Response Topology Optimization Using Equivalent Static Loads
Jang, Hwan-Hak ; Lee, Hyun-Ah ; Park, Gyung-Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1401~1409
DOI : 10.3795/KSME-A.2009.33.12.1401
All the forces in the real world act dynamically on structures. Design and analysis should be performed based on the dynamic loads for the safety of structures. Dynamic (transient or vibrational) responses have many peaks in the time domain. Topology optimization, which gives an excellent conceptual design, mainly has been performed with static loads. In topology optimization, the number of design variables is quite large and considering the peaks is fairly costly. Topology optimization in the frequency domain has been performed to consider the dynamic effects; however, it is not sufficient to fully include the dynamic characteristics. In this research, linear dynamic response topology optimization is performed in the time domain. First, the necessity of topology optimization to directly consider the dynamic loads is verified by identifying the relationship between the natural frequency of a structure and the excitation frequency. When the natural frequency of a structure is low, the dynamic characteristics (inertia effect) should be considered. The equivalent static loads (ESLs) method is proposed for linear dynamic response topology optimization. ESLs are made to generate the same response field as that from dynamic loads at each time step of dynamic response analysis. The method was originally developed for size and shape optimizations. The original method is expanded to topology optimization under dynamic loads. At each time step of dynamic analysis, ESLs are calculated and ESLs are used as the external loads in static response topology optimization. The results of topology optimization are used to update the design variables (density of finite elements) and the updated design variables are used in dynamic analysis in a cyclic manner until the convergence criteria are satisfied. The updating rules and convergence criteria in the ESLs method are newly proposed for linear dynamic response topology optimization. The proposed updating rules are the artificial material method and the element elimination method. The artificial material method updates the material property for dynamic analysis at the next cycle using the results of topology optimization. The element elimination method is proposed to remove the element which has low density when static topology optimization is finished. These proposed methods are applied to some examples. The results are discussed in comparison with conventional linear static response topology optimization.
Stability Analysis of Cracked Beams with Subtangential Follower Force and Tip Mass
Son, In-Soo ; Yoon, Han-Ik ; No, Tae-Woo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1410~1416
DOI : 10.3795/KSME-A.2009.33.12.1410
In this paper, the purpose is to investigate the stability and variation of natural frequency of a cracked cantilever beams subjected to follower force and tip mass. In addition, an analysis of the flutter instability(flutter critical follower force) of a cracked cantilever beam as slenderness ratio and crack severity is investigated. The governing differential equations of a Timoshenko beam subjected to an end tangential follower force is derived via Hamilton`s principle. The two coupled governing differential equations are reduced to one fourth order ordinary differential equation in terms of the flexural displacement. Finally, the influence of the slenderness ratio and crack severity on the critical follower force, stability and the natural frequency of a beam are investigated.
A Study on the Dynamic Characteristics of Free-Friction Stroke Damper by Finite Element Method
Ku, Hi-Chun ; Lee, Jae-Wook ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1417~1426
DOI : 10.3795/KSME-A.2009.33.12.1417
Various types of damper are usually applied to reduce noise and vibration for mechanical systems. Especially, for washing machines, the free-friction stroke damper is installed. The behavior of the free-friction stroke damper has nonlinear characteristics such as hysteresis and viscoelastic properties because of its foam material. First of all, the dynamic experiments were carried out by using a MTS machine to find characteristics of the free-friction stroke damper. And the simulation model of the free-friction stroke damper and characteristics of a foam material were evaluated by using optimization technique. To make a good simulation model which can show the dynamic characteristics, it is important to understand the working mechanism of the damper. The Finite Element Method (FEM) technique can help us instinctively understand the damping phenomenon under operating conditions, because we can observe the condition of damper at every step in the simulation by using it. Also, by changing factors, we can comprehend the variation of characteristics of damper. So, in this paper, a study on the dynamic characteristics of free-friction stroke damper by FEM is focused on. Finally, the possibility which physical experiments can be replaced into simulations is shown.
The Melnikov Analysis of the Pitch Dynamics of a Gravity Gradient Satellite
Lee, Mok-In ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1427~1432
DOI : 10.3795/KSME-A.2009.33.12.1427
The pitch motion of a generic gravity gradient satellite is investigated in terms of chaos. The Melnikov method is used for detecting the onset of chaotic behavior of the pitch motion of a gravity gradient satellite. The Melnikov method determines the distance between stable and unstable manifolds of a perturbed system. When stable and unstable manifolds transverse on the Poincare section, the resulting motion can be chaotic. The Melnikov analysis indicates that the pitch dynamics of a generic gravity gradient satellite can be chaotic when the orbit eccentricity is small.
A Study on the Real-Time Analysis of a 6×6 Autonomous Vehicle
Cho, Du-Ho ; Lee, Jung-Han ; Yi, Ki-Chang ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1433~1441
DOI : 10.3795/KSME-A.2009.33.12.1433
In multibody dynamic analysis, one of the most important problems is to reduce computation times for real-time simulation. This paper presents the derivation procedure of equations of motion of a 6
6 autonomous vehicle in terms of chassis local coordinates which do not require coordinates transformation matrix to enhance efficiency for real-time dynamic analysis. Also, equations of motion are derived using the VT(velocity transformation) technique and symbolic computation method coded by MATLAB. The Jacobian matrix of the equations of motion of a system is derived from symbolic operations to apply the implicit integration method. The analysis results were compared with ADAMS results to verify the accuracy and approve the feasibility of real time analysis.
Transient Characteristics Analysis of Structural Systems Undergoing Impact Employing Hilbert-Huang Transformation
Lee, Seung-Kyu ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1442~1448
DOI : 10.3795/KSME-A.2009.33.12.1442
Transient characteristics of a signal can be effectively exhibited in time-frequency domain. Hilbert-Huang Transform (HHT) is one of the time-frequency domain analysis methods. HHT is known for its several advantages over other signal analysis methods. The capability of analyzing non-stationary or nonlinear characteristics of a signal is the primary advantage of HHT. Moreover, it is known that HHT can provide fine resolution in high frequency region and handle large size data efficiently. In this study, the effectiveness of Hilbert-Huang transform is illustrated by employing structural systems undergoing impact. A simple discrete system and an axially oscillating cantilever beam undertaking periodic impulsive force are chosen to show the effectiveness of HHT.
Statistical Performance Estimation of a Multibody System Based on Design Variable Samples
Choi, Chan-Kyu ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1449~1454
DOI : 10.3795/KSME-A.2009.33.12.1449
The performance variation of a multibody system is affected by a variation of various design variables of the system. And the effects of design variable variations on the performance variation must be considered in design of a multibody system. Accordingly, a variation analysis of a multibody system needs to be conducted in design of a multibody system. For a variation analysis of a performance, population mean and variance which are called statistical parameters of design variables are needed. However, an evaluation of statistical parameters of design variables is impossible in many practical cases. Therefore, an estimation of statistical parameters of the performance based on sample mean and variance which are called statistic of design variables is needed. In this paper, the variation analysis method for a multibody system based on design variable samples was proposed. And, using the proposed method, a variation analysis of the vehicle ride comfort based on sample statistic of design variables was conducted.
Crack Tip Creep Deformation Behavior in Transversely Isotropic Materials
Ma, Young-Wha ; Yoon, Kee-Bong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1455~1463
DOI : 10.3795/KSME-A.2009.33.12.1455
Theoretical mechanics analysis and finite element simulation were performed to investigate creep deformation behavior at the crack tip of transversely isotropic materials under small scale creep (SCC) conditions. Mechanical behavior of material was assumed as an elastic-
creep, which elastic modulus ( E ), Poisson`s ratio (
) and creep stress exponent ( n ) were isotropic and creep coefficient was only transversely isotropic. Based on the mechanics analysis for material behavior, a constitutive equation for transversely isotropic creep behavior was formulated and an equivalent creep coefficient was proposed under plain strain conditions. Creep deformation behavior at the crack tip was investigated through the finite element analysis. The results of the finite element analysis showed that creep deformation in transversely isotropic materials is dominant at the rear of the crack-tip. This result was more obvious when a load was applied to principal axis of anisotropy. Based on the results of the mechanics analysis and the finite element simulation, a corrected estimation scheme of the creep zone size was proposed in order to evaluate the creep deformation behavior at the crack tip of transversely isotropic creeping materials.
Reliability-Based Design Optimization Using Kriging Metamodel with Sequential Sampling Technique
Choi, Kyu-Seon ; Lee, Gab-Seong ; Choi, Dong-Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1464~1470
DOI : 10.3795/KSME-A.2009.33.12.1464
RBDO approach based on a sampling method with the Kriging metamodel and Constraint Boundary Sampling (CBS), which is sequential sampling method to generate metamodels is proposed. The major advantage of the proposed RBDO approach is that it does not require Most Probable failure Point (MPP) which is essential for First-Order Reliability Method (FORM)-based RBDO approach. The Monte Carlo Sampling (MCS), most well-known method of the sampling methods for the reliability analysis is used to assess the reliability of constraints. In addition, a Cumulative Distribution Function (CDF) of the constraints is approximated using Moving Least Square (MLS) method from empirical distribution function. It is possible to acquire a probability of failure and its analytic sensitivities by using an approximate function of the CDF for the constraints. Moreover, a concept of inactive design is adapted to improve a numerical efficiency of the proposed approach. Computational accuracy and efficiency of the proposed RBDO approach are demonstrated by numerical and engineering problems.
Process Analysis and Test for Manufacturing the Sleeve Spring Type-Torsional Vibration Damper
Hwang, Beom-Cheol ; Bae, Won-Byong ; Jang, Young-Jun ; Kim, Chul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1471~1481
DOI : 10.3795/KSME-A.2009.33.12.1471
In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, the closed form equations to predict the spring constant of a sleeve spring and the torsional characteristics of the torsional vibration damper are proposed to calculate stiffness of the damper and verified their availability through the finite element analysis and experiments. And the stability of the sleeve spring torsional vibration damper is verified by analyzing the inner star and outer star, which are the core parts of the damper, and 2-roll bending process is proposed to manufacture sleeve spring. The program to calculate the initial radius including spring-back effect is developed, and the FEA method to analyze elasto-plastic problem was verified through analysis of 90
bending process. The results of the analysis are in good agreements with those of the experiments. The newly proposed method can be used as an advanced technique that remarkably curtails cost of production and replaces the conventional forming.
Statistical Analysis for NDI Results of Aircraft Engine Component for Determining Crack Initiation Period
Choi, Jae-Man ; Kwon, Young-Han ; Choi, Hwan-Seo ; Yang, Seung-Hyo ; Woo, Sang-Wook ; Cho, Soon-Mi ; Lee, Seung-Joo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 33, issue 12, 2009, Pages 1482~1487
DOI : 10.3795/KSME-A.2009.33.12.1482
In this study statistical analysis was performed for NDI(Non-Destructive Inspection) results of F100 engine front seal support assembly. NDI results can be statistically considered as Quantal Response Data. It is found that the suitable probability distribution to the failure data is normal distribution through MLE(Maximum Likelihood Estimation) of the Quantal Response Data. Moreover, Cumulative Distribution Function, failure rate function and B-Life are calculated on the supposed distribution.