Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Transactions of the Korean Society of Mechanical Engineers A
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
Editor in Chief :
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
Selecting the target year
Structural Analysis of Floating Offshore Wind Turbine Tower Based on Flexible Multibody Dynamics
Park, Kwang-Phil ; Cha, Ju-Hwan ; Ku, Namkug ; Jo, A-Ra ; Lee, Kyu-Yeul ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1489~1495
DOI : 10.3795/KSME-A.2012.36.12.1489
In this study, we perform the structural analysis of a floating offshore wind turbine tower by considering the dynamic response of the floating platform. A multibody system consisting of three blades, a hub, a nacelle, the platform, and the tower is used to model the floating wind turbine. The blades and the tower are modeled as flexible bodies using three-dimensional beam elements. The aerodynamic force on the blades is calculated by the Blade Element Momentum (BEM) theory with hub rotation. The hydrostatic, hydrodynamic, and mooring forces are considered for the platform. The structural dynamic responses of the tower are simulated by numerically solving the equations of motion. From the simulation results, the time history of the internal forces at the nodes, such as the bending moment and stress, are obtained. In conclusion, the internal forces are compared with those obtained from static analysis to assess the effects of wave loads on the structural stability of the tower.
Biomimetic Actuator and Sensor for Robot Hand
Kim, Baek-Chul ; Chung, Jinah ; Cho, Hanjoung ; Shin, Seunghoon ; Lee, Hyongsuk ; Moon, Hyungpil ; Choi, Hyouk Ryeol ; Koo, Jachoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1497~1502
DOI : 10.3795/KSME-A.2012.36.12.1497
To manufacture a robot hand that essentially mimics the functions of a human hand, it is necessary to develop flexible actuators and sensors. In this study, we propose the design, manufacture, and performance verification of flexible actuators and sensors based on Electro Active Polymer (EAP). EAP is fabricated as a type of film, and it moves with changes in the voltage because of contraction and expansion in the polymer film. Furthermore, if a force is applied to an EAP film, its thickness and effective area change, and therefore, the capacitance also changes. By using this mechanism, we produce capacitive actuators and sensors. In this study, we propose an EAP-based capacitive sensor and evaluate its use as a robot hand sensor.
Integrated Risk Management System for Intelligent Vehicle
Yi, Kyongsu ; Choi, Jaewoong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1503~1510
DOI : 10.3795/KSME-A.2012.36.12.1503
This paper presents an Integrated Risk Management System (IRMS), which is designed to integrate longitudinal and lateral collision avoidance systems. Indices representing longitudinal and lateral collision risks are designed. From the designed indices, an integrated control strategy is designed. A collision avoidance algorithm is designed to assist the driver in avoiding collisions by using a vehicle-driver-controller integrated linear model. The performance of the proposed algorithm is investigated via computer simulations conducted using the vehicle dynamics software CARSIM and Matlab/Simulink.
Flaw Detection in Pipe-Welded Zone by Using Wavelet Transform and SH-EMAT
Lee, Jin-Hyuk ; Kim, Dae-Hyun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1511~1519
DOI : 10.3795/KSME-A.2012.36.12.1511
Pipe structures contain many welded zones, and ultrasonic tests are increasingly being performed by using automated testing devices in order to evaluate the weld integrity. An electromagnetic acoustic transducer (EMAT) is a noncontact transducer that can transmit or receive ultrasonic waves without a couplant. Furthermore, it can easily generate specific guided waves such as SH (shear horizontal) or Lamb waves by altering the design of the coil and magnet. Therefore, an EMAT should be useful for application to an automated ultrasonic inspection system. In this study, SH waves generated using an EMAT were applied to inspect the pipe-weld zone. To analyze the specific SH mode (SH0) from the SH wave signals, wavelet transform was applied. It was found that flaws could be detected precisely because the intensity of the
mode-frequency, which is analyzed by using wavelet transform, is proportional to the length of the flaw.
Estimates of Elastic Fracture Mechanics Parameters for Thick-Walled Pipes with Slanted Axial Through-Wall Cracks
Han, Tae-Song ; Huh, Nam-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1521~1528
DOI : 10.3795/KSME-A.2012.36.12.1521
The present paper provides the elastic stress intensity factors (SIFs) and the crack opening displacements (CODs) of a thick-walled pipe with a slanted axial through-wall crack. For estimating these elastic fracture mechanics parameters, systematic three-dimensional elastic finite element (FE) analyses were performed by considering geometric variables, i.e., thickness of pipe, reference crack length, and crack length ratio, affecting the SIFs and CODs. As for loading condition, the internal pressure was considered. Based on the FE results, the SIFs and CODs of slanted axial through-wall cracks in a thickwalled pipe along the crack front and the wall thickness were calculated. In particular, to calculate the SIFs of a thick-walled pipe with a slanted axial through-wall crack from those of a thick-walled pipe with an idealized axial through-wall crack, a slant correction factor representing the effect of the slant crack on the SIFs was proposed.
Tensile Tests for Copper Thin Foils by Using DIC Method
Kim, Chung Youb ; Song, Ji Ho ; Park, Kyung Jo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1529~1534
DOI : 10.3795/KSME-A.2012.36.12.1529
In this study, tensile tests for 12-
-thick copper thin foils were performed by using the DIC method. The DIC method provided precise stress-strain curves for thin film materials, and a commercial inkjet printer can be simply and effectively used for printing speckle patterns on the specimen of Cu thin films whose surface contrast is too low to apply the DIC method. The mechanical properties of Cu thin foils obtained in this study are as follows: elastic modulus E = 89.2 GPa, 0.2% offset yield stress
= 232.8 MPa, tensile strength
= 319.2 MPa, elongation at fracture
=16.8 %, and Poisson's ratio
Study on Safety Design of Vertical-Type Heat Recovery Steam Generator Based on Large-Scale Analysis
Ryu, Tae-Young ; Yang, Sang-Mo ; Jang, Hyun-Min ; Choi, Jae-Boong ; Myung, Ki-Chul ; Lee, Dong-Yun ; Choi, Shin-Beom ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1535~1542
DOI : 10.3795/KSME-A.2012.36.12.1535
A Heat Recovery Steam Generator(HRSG) is the main component of a Combined Cycle Power Plant(CCPP). It is a very large structure that is made from relatively thin metal sheets. Therefore, the structural integrity of an HRSG is very important to ensure safe operation during plant lifetime. In particular, thermal deformation and thermal fatigue have been revealed as the main causes of the mechanical degradation of an HRSG. In order to prevent unexpected damage, safety evaluation based on a large-scale analysis is necessary. Therefore, this study aims to improve the safety of HRSG by using Finite Element Analysis(FEA) results derived from large-scale analysis. Furthermore, the modified design is verified by comparing it with the original one. This result will be used as basic data for improving the safety of a vertical-type HRSG.
Modeling and State Observer Design for Roll Slip in Cold Cluster Mills
Kang, Hyun Seok ; Hong, Wan Kee ; Hwang, I Cheol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1543~1549
DOI : 10.3795/KSME-A.2012.36.12.1543
This study focuses on the state space model and the design of a state observer for the slip dynamics between rolls in STS cold cluster mills. First, a mathematical model of the roll slip is given as a nonlinear differential equation. Then, by using a Taylor series expansion, it is linearized as a state space model. Next, by using Gopinath's algorithm, a minimal-order state observer based on the state space model is designed to estimate the angular speed of all idle rolls except for an actuated roll that is measureable. Finally, a computer simulation is used to validate that the proposed state space model very well describes slip dynamics between, and moreover, the state observer very well estimates the angular speed of the idle roll.
Study of Structural Design of Polyethylene Pleasure Boat
Cho, Seok Swoo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1551~1561
DOI : 10.3795/KSME-A.2012.36.12.1551
Boat or yacht hulls are mainly built using FRP composite materials. FRP boat hull manufacturing has been restricted since 2000 under international regulations on ocean environment safety. FRP composite materials cannot be recycled and require more than 100 years to biodegrade. Therefore, alternatives to FRP have been proposed by many boat builders. Steel, aluminum, and FRP are commonly used as boat hull materials. Their design specifications are proposed as Korean register of shipping. However, the design specifications for inexpensive materials for a small boat have not yet been studied. Small shipbuilders manufacture and sell HDPE canoes or HDPE kayaks. In this study, a hull form was designed based on actual boats. The thickness of an HDPE boat hull was determined based on ISO 12215-5 structural design specifications.
Alignment Patterns and Position Measurement System for Precision Alignment of Roll-to-Roll Printing
Seo, Youngwon ; Yim, Seongjin ; Oh, Dongho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1563~1568
DOI : 10.3795/KSME-A.2012.36.12.1563
Printed electronics is a technology used for forming electronic circuits or devices, and it is used in the manufacture of many products such as RFID tags, solar cells, and flexible display panels with a much lower cost than in the case of semiconductor process technology. Web-guide-type printing such as roll-to-roll printing is a method used to produce printed electronic devices in a large volume. To commercialize such products, highly precise alignment between printed layers is required. In this study, a highly precise alignment system is proposed, and some experimental results are compared with those obtained using a laser surface vibrometer to illustrate the reliability of the proposed system. The robustness of the proposed system to web deformation is also considered experimentally.
Numerical Simulation of Steel/Kevlar Hybrid Composite Helmet Subjected to Ballistic Impact
Jo, Jong Hyun ; Lee, Young Shin ; Jin, Hai Lan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1569~1575
DOI : 10.3795/KSME-A.2012.36.12.1569
In this study, ballistic impact effects on a helmet were investigated using the AUTODYN-3D program. Two types of materials were used for manufacturing the helmet: single Kevlar and Steel/Kevlar hybrid composites. Furthermore, two types of bullets were used in the simulation: steel spherical and 7.62 mm full-jacketed. In the simulation, the shape deformation of the projectile and internal energy were calculated. From the results, impact velocities above 655 m/s and 845 m/s were required to perforate the Steel/Kevlar helmet with steel spherical and 7.62 mm full-jacketed bullets, respectively. The results show that there was a large difference between the ballistic resistance of the Kevlar and Steel/Kevlar helmets. For the simulation on an NIJ-STD-0106.01 Type II helmet, a 7.62 mm fulljacketed bullet with a striking velocity of 358 m/s was used. Simulation results show that the Steel/Kevlar helmet could resist a 7.62 mm full-jacketed bullet traveling at 358 m/s.
Numerical Simulation of Failure Mechanism of PELE Perforating Thin Target Plates
Jo, Jong Hyun ; Lee, Young Shin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1577~1583
DOI : 10.3795/KSME-A.2012.36.12.1577
Penetrator with enhanced lateral effect (PELE) is a novel projectile that does not require dynamite and a fuse. It comprises a high-density jacket that is closed at its rear end and filled with a low-density filling material. To study the explosion characteristics of PELE using AUTODYN-3D code, the calculation models of the projectile body and the bullet target were developed and the process of penetrating an aluminum-2024 alloy target using PELE was simulated. The scattering characteristics after PELE penetrated the aluminum-2024 alloy target were studied for different filling materials. The explicit finite element analysis of PELE fragmentation was implemented with the stochastic failure criterion in AUTODYN-3D code. As the filling expanded, the fragments gained velocity and dispersed laterally, increasing the damage area considerably. The number and shape of PELE fragments differed depending on the impact pressure of the filling that fragmented during the penetration and lateral dispersion processes.
Dynamic Characteristics of Plastic Materials for Automobile Cockpit Module
Woo, Chang Su ; Park, Hyun Sung ; Jo, Jin Ho ; Kim, Ji Hoon ; Choi, Ju Ho ; Kim, Yeoung Kuk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1585~1590
DOI : 10.3795/KSME-A.2012.36.12.1585
Engineering plastics are used in instrument panels, interior trim, and other vehicle applications, and the thermomechanical behaviors of plastic materials are strongly influenced by many environmental factors such as temperature, sunlight, and rain. As the material properties change, the mechanical parts create unexpected noise. In this study, the dynamic mechanical property changes of plastics used in automobiles are measured to investigate the temperature effects. Viscoelastic properties such as the glass transition temperature and storage modulus and loss factor under temperature and frequency sweeps were measured. The data were compared with the original ones before aging to analyze the behavior changes. It was found that as the temperature increased, the storage modulus decreased and the loss factor increased slightly.
Effect of Surface Properties on Adhesive Strength of Joint of Glass Fiber/Polyester Composite Panels
Nhut, Pham Thanh ; Yum, Young Jin ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1591~1597
DOI : 10.3795/KSME-A.2012.36.12.1591
Adherend samples were made from unsaturated polyester and woven and mat glass fibers by the hand layup and vacuum methods. The mechanical properties of the adhesive, composite adherends, and terminal-joint and secondary-joint specimens were determined experimentally. Combinations of the experiment results and the bonding theory were used in this study. The maximum and average shear stresses were calculated based on the maximum tensile force and geometry parameters of the joint specimens. The results of the maximum and average shear stresses were compared and evaluated for six joints. The results showed that the grinding and grind/acetone joint had the highest strength among three types of terminal-joints. Similarly, the mat-mat and mat-woven joints had the highest strength among three types of secondary-joints with the same value. Conversely, no treatment and woven-woven bonding had very low strength. In each case, failure occurred always at two ends and then moved toward the middle area of the overlap length.
Analysis of Impact Behavior of Al-Alloy Castings Considering Internal Defects
Jo, Seong-Woo ; Kwak, Si-Young ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1599~1604
DOI : 10.3795/KSME-A.2012.36.12.1599
In general, internal defects, such as shrinkage in casting, cause stress concentration and can be a starting point for cracks. Therefore, it is important to understand the effects of internal defects on the mechanical properties including the impact behavior. This study aim is to evaluate the effects of internal casting defects on the impact performance of Al-alloy castings. Both an experimental method and computational analysis were used to achieve the research objective. The internal defects in the casting were scanned using an industrial CT scanner, and their shape was simplified using ellipsoidal primitives for impact analysis. The good agreement between the experimental and computer simulation results verified the reliability of the proposed computational method for the FEA of casting components with internal defects.
Akaike Information Criterion-Based Reliability Analysis for Discrete Bimodal Information
Lim, Woochul ; Lee, Tae Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1605~1612
DOI : 10.3795/KSME-A.2012.36.12.1605
The distribution of a response usually depends on the distribution of the variables. When a variable shows a distribution with two different modes, the response also shows a distribution with two different modes. In this case, recently developed methods for reliability analysis assume that the distribution functions are continuous with a mode. In actual problems, however, because information is often provided in a discrete form with two or more modes, it is important to estimate the distributions for such information. In this study, we employ the finite mixture model to estimate the response distribution with two different modes, and we select the best candidate distribution through AIC. Mathematical examples are illustrated to verify the proposed method.
Distortion Analysis for Outer Ring of Automotive Wheel Bearing
Lee, Seung Pyo ; Kim, Bong Chul ; Lee, In Ha ; Cho, Young Geol ; Kim, Yong Chan ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1613~1618
DOI : 10.3795/KSME-A.2012.36.12.1613
The wheel bearing is one of the important parts in a vehicle for translating power and bearing weight. When it is mounted on the knuckle by using bolts, the distortion of the outer ring including the seal mounting point and raceway occurs. In this study, a numerical analysis was performed to analyze the distortion of the outer ring by using a finite element method. The commercial software MSC.MARC was used for this purpose. Elastoplastic and contact analysis were carried out to compute the clamping behavior of the outer ring, bolts, and knuckle. Because the concavity on the flange of the outer ring affects the deformation, its effect was considered. To verify the reliability of this study, the roundness of the outer ring was measured. The experimental results were comparatively in agreement with the computational results.
Finite Element Analysis of Edge Fracture of Electrical Steel Strip in Reversible Cold Rolling Mill
Byon, Sang Min ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1619~1625
DOI : 10.3795/KSME-A.2012.36.12.1619
An electrical steel strip is commonly used as a core material in all types of electric transformers and motors. It is produced by a cold rolling process. In this paper, a damage-mechanics-based approach that predicts the edge fracture of an electrical steel strip during cold rolling is presented. We adopted the normal tensile stress criterion and the fracture energy method as a damage initiation criterion and a damage evolution scheme, respectively. We employed finite element analysis (FEA) to simulate crack initiation and propagation at the initial notch located at the edges of the strip. The material constants required in FEA were experimentally obtained by tensile tests using a standard and a notched sheet-type specimen. The results reveal that the edge crack was initiated at the entrance of the roll bite and that it rapidly evolved at the exit. The evolution length of the edge crack increased as the length of the initial notch as well as the front tension reel force of the strip increased.
Optimum Design of Underwater Connector Hole Arrangement for Deep-sea Pressure Vessel Cover Plate
Lee, Minuk ; Park, Soung-Jea ; Yeu, Tae-Kyeong ; Ki, Hyong-Woo ; Hong, Sup ; Cho, Su-Gil ; Jang, Jun-Yong ; Lee, Tae Hee ; Choi, Jong-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1627~1633
DOI : 10.3795/KSME-A.2012.36.12.1627
A deep-sea pressure vessel needs to protect the internal electrical equipment from the high external pressure. Thus, the pressure vessel should be designed to be watertight and structurally safe. In this study, a cylindrical-type pressure vessel comprising a hollow cylinder and cover plates at both ends is investigated. For communication between the internal electronic equipment and the external device, holes are bored on the cover plate to install underwater connectors. Considering the type of internal equipment and underwater connector specifications, multiple holes may be required. These holes can affect the structural safety of the pressure vessel cover plate. In this study, the optimum design of the hole arrangement in consideration of the structural safety of the cover plate was performed.
Dynamic Property Identification of Structural Systems with Hinge Joint Using Equivalent Stiffness
Won, Junho ; Lim, Che Kyu ; Lee, Doo-Ho ; Choi, Joo-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1635~1642
DOI : 10.3795/KSME-A.2012.36.12.1635
The identification of the dynamic properties of structural joints is important for predicting the dynamic behavior of assembled systems. However, the identification of the properties using analytical or experimental approaches is extremely difficult or even impossible. Several studies have proposed hybrid or synthesis methods that simultaneously used analytical and experimental approaches to identify the dynamic properties of a joint. However, among the many types of joints, only the bolt joint was treated as a practical example in these studies. In this study, for a simple assembly system comprising two plates and one hinge joint, a simple methodology involving the use of the static-based subpart analysis method to identify the dynamic properties is proposed. Finally, the proposed method is applied to a glove box in a passenger vehicle that includes hinge joints.
Numerical Study of Design of Micro Bubble Generation Nozzle
Kim, Hyun-Il ; Lee, Sang Min ; Shin, Myung Sun ; Lee, Jong Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1643~1651
DOI : 10.3795/KSME-A.2012.36.12.1643
Recently, with increasing standards of living and income, environmental pollution has attracted increased interest. On account of a revision to water pollution regulations, the improvement of sewage disposal efficiency was studied. One of the ways to improve the sewage disposal efficiency is to increase the dissolved oxygen content of water in the water treatment tank. In this study, we suggest a nozzle design using a spiral and a crash mode for generating micro bubbles and thus increasing the dissolved oxygen content of water. The micro bubbles through the spiral and crash flows are generated in the nozzle. In the design of the crash mode, the development goal with regard to the bubble size was not achieved. On the other hand, a bubble size of
accounted for 79.3% of all bubbles in the spiral mode. This study should contribute toward increasing the sewage disposal efficiency.
Pressure Drop Variations and Structural Characteristics of SMART Nuclear Fuel Assembly Caused by Coolant Flow
Jin, Hai Lan ; Lee, Young Shin ; Lee, Hyun Seung ; Park, Nam Gyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1653~1661
DOI : 10.3795/KSME-A.2012.36.12.1653
In this study, the pressure drop changes and structural characteristics of a SMART rod bundle under the effect of a coolant were investigated. The turbulence model of the BSL Reynolds stress model was used to model the coolant flow, and a fluid solid interaction simulation was conducted. First, fuel rod vibration analysis was performed to confirm the natural frequency of the fuel rod, which was supported by spacer grid assemblies, and this was compared with experimental results. From the experimental results, the natural frequency was found to be 48 Hz, and the error compared with the simulation results was 2%. The pressure drop at the rod bundle was calculated and compared with the experimental data; it showed an error of 8%, demonstrating the simulation accuracy. In the flow analysis, the flow velocity and secondary flow at different domains were calculated, and vortex generation was also observed. Finally, through the fluid solid interaction analysis, the fuel rod displacements caused by flow-induced vibrations were calculated. Then, calculated displacement PSD at maximum displacement happed point.
Lateral Crush Strength of Nuclear Fuel Spacer Grid Considering Weld Properties
Song, Kee Nam ; Lee, Sang Hoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1663~1668
DOI : 10.3795/KSME-A.2012.36.12.1663
A spacer grid, which is one of the structural components in a PWR fuel, is an interconnected array of slotted grid straps that are welded at the intersections to form an egg-crate structure. The spacer grid is required to have sufficient lateral crush strength to enable nuclear reactor shut-down during abnormal operating environments. Previous studies on the lateral crush strength analysis of the spacer grid were performed using only the base material properties. In this study, to investigate the effect of the lateral crush strength of the spacer grid when using the mechanical properties in the weld zone instead of the base material properties, lateral crush strength analysis by considering the mechanical properties in the weld zone as obtained from the instrumented indentation technique was performed, and the results were compared with those of previous studies.
Tearing Test for Automotive Vibroisolating Rubber and Formulation of Tearing Energy
Moon, Hyung-Il ; Kim, Heon Young ; Kim, Min Gun ; Kim, Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1669~1674
DOI : 10.3795/KSME-A.2012.36.12.1669
A commonly analytical estimation of fatigue life on rubber components is using fatigue life equation based on various fatigue test results. However, such method has very restricted applicability in actual designing processes because performing fatigue tests requires a lot of time and money. In addition, non-standard rubber materials and their randomness make it hard to make databases. In this paper, the other fatigue life estimation method using tearing energy was suggested. We performed static and dynamic tearing test about automotive vibration rubber materials and a finite element formulation using a virtual crack to calculate the tearing energy of rubber components with complicated shapes. To using the suggested method, fatigue life of an automotive motor mount has been estimated and verified the reliability of this method by using comparison between the estimated values and the actual fatigue life.
Analysis of Tube Extrusion Process Conditions Using Mg Alloy for Automotive Parts
Park, Chul Woo ; Kim, Ho Yoon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1675~1682
DOI : 10.3795/KSME-A.2012.36.12.1675
Weight reduction is increasingly being considered very important in light of air pollution and the exhaustion of resources. As a result, many automotive components are being replaced by Al and Mg alloys, and studies are increasingly focusing on the same. However, the use of Mg alloys is limited because they have higher material cost and lower productivity owing to the difficult forming conditions compared with Al alloys. In this study, the tube extrusion process conditions of an automotive bumper back beam were analyzed using FEA. Material tests were performed to determine the properties, and experiments and analyses for a simple shape were performed to define the data for heat generation during plastic deformation. Then, the analyses of the product were carried out by considering various temperatures and ram speeds. The conditions were then established, and a product without surface defects was extruded successfully.
Lightweight Design of a Vertical Articulated Robot Using Topology Optimization
Hong, Seong Ki ; Hong, Jung Ki ; Kim, Tae Hyun ; Park, Jin Kyun ; Kim, Sang Hyun ; Jang, Gang-Won ;
Transactions of the Korean Society of Mechanical Engineers A, volume 36, issue 12, 2012, Pages 1683~1688
DOI : 10.3795/KSME-A.2012.36.12.1683
Topology optimization is applied for the lightweight design of three main parts of a vertical articulated robot: a base frame, a lower and a upper frame. Design domains for optimization are set as large solid regions that completely embrace the original parts, which are discretized by using three-dimensional solid elements. Design variables are parameterized one-to-one to the material properties of each element by using the SIMP method. The objective of optimization is set as the multi-objective form combining the natural frequencies and mean compliances of a structure for which load steps of interest are selected from the multibody dynamics analysis of a robot. The obtained results of topology optimization are post-processed to designs favorable to manufacturability for casting process. The final optimized results are 11.0% (base frame), 12.0% (lower frame) and 10.0% (upper frame) lighter with similar or even higher static and dynamic stiffnesses than the original models.