• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.18 no.4 s.70
• /
• pp.453-458
• /
• 2005

This study deals with elasto-plasticity of granular micro-structures which recovers continuum elasto-plasticity in its counterpart. The theory is based on doublet mechanics that assumes particles of finite size and connecting linear springs, and it makes extensions to plasticity. The result shows that the micro model has one to one relationship with the continuum model in the simplest case. Micro-strain and micro-stress of two dimensional plane stress problem were calculated, which shows the behavior of the specimen and verifies the effectiveness of this model.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.2 s.233
• /
• pp.270-276
• /
• 2005

This paper develops the flexible computational model of a heavy truck by interfacing the frame modeled as a flexible body to the heavy truck's computational model composed of rigid bodies. The frame is modeled by the finite element method. Three torsional modes and three bending modes of the frame are considered for the interface of the heavy truck's computational model. The actual vehicle test is conducted off road with a velocity of 20km/h. The vertical accelerations at the cab and front axle are measured in the test. For the verification of the developed computational model, the measured vertical acceleration profiles are compared with the simulation results of the heavy truck's flexible computational model. E grade irregular road profile of ISO is used as an excitation input in the simulation. The verified flexible computational model is used to compare the vibration characteristics of a front suspension system having a multi-leaf spring and that having a tapered leaf spring. The comparison results show that the front suspension having a tapered leaf spring has a higher vertical acceleration at the front axle but a lower vertical acceleration at the cab than the suspension system having a multi-leaf spring.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.3
• /
• pp.95-100
• /
• 2002

Built-in Eccentric Bearing-Torsional Spring (BEBTS) type Automatic Belt Tension Unit (ABTU) is one of typical belt tension units. The BEBTS type ABTU system frequently experiences torsional vibration about its pivot due to the variation of belt tension. However, it is very difficult to analyze the rotational (or torsional) vibration of the ABTU because the exciting moment varies according to the change of belt tension. To get over this difficulty, in this paper. the ABTU was simplified as 1-DOF translational motion model in the tangential direction. Its equation of motion was derived and solved. The time history and frequency responses were computed and examined for three of BEBTS type ABTUs which are made by different manufacturers but the tame kind.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.1
• /
• pp.33-41
• /
• 2011

This study presents modeling technologies applicable to an unbonded post-tension system using a finite element software package. In this study, both direct modeling method and multiple spring method were used. The direct modeling method adopts tube-to-tube contact elements to represent the physical feature of a post-tension system. The multiple spring method uses virtual tendons attached to the real tendons using a number of rigid axial springs that freely rotate at the ends. Both modeling technologies provide accurate predictions. However, only the multiple spring method provides numerically stable and reliable responses with a consideration of concrete tension stiffening effects. Therefore, the multiple spring method turned out to be a generally applicable modeling technology for the unbonded post-tension system. Comparisons were made for the analytical and experimental results for the verification of the selected method, and parameter studies were carried out to confirm the appropriateness of the modeling assumptions and parameters adopted in the analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.11
• /
• pp.922-931
• /
• 2017

This research paper describes design procedures and those verification with multi-body dynamic analysis and an experiment for the development of an unprecedented type of canister cover, named as the separating cover. In order to overcome drawbacks from the precious rupture type and actuator driven cover, the separating cover was suggested. It has the simplest structure composed of the previously developed explosive bolt and a spring-lever driven system. First of all, mechanical feasibility with proposed design parameters based on mathematical modeling was confirmed through dynamic analysis and then its results showed good agreement with the followed empirical results acquired from a high speed camera. On top of that, a parametric study was conducted to identify the effect of each design parameter on separating performance. It is highly expected that this research contributes to provide military industries with a brand new canister cover having simplicity and cost efficiency and thus it will be very useful in MLRS(Multiple Launch Rocket System).

• Journal of the Korea Society of Computer and Information
• /
• v.28 no.9
• /
• pp.73-79
• /
• 2023

This paper describes a level of detail (LOD) based bending spring structure and damping technique that can reliably represent strain-based dynamics (SBD) on a triangular mesh. SBD models elastic energy using strain instead of energy based on the edge length of a triangular mesh. However, when a large external force occurs, the process of calculating the elastic energy based on edges results in a degenerate triangle, which stretches in the wrong direction because it calculates an unstable strain. In this paper, we introduce an LOD-based bending spring generation and energy calculation method that can efficiently handle this problem. As a result, the technique proposed in this paper can reliably and efficiently handle SBD based on bending springs, which can provide a stable representation of cloth simulation.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1996.04a
• /
• pp.108-116
• /
• 1996

본 논문에서는 하중부와 방법을 추(dead weight)와 공압(pneumatic)을 이용한 방법에서 스프링을 이용한 방법을 추가하였으며, 압축형 스프링을 선택적으로 사용하여 마찰시험기 수직방향에서의 강성을 큰 변화 폭으로 변화시켰다. 또한 선행된 연구를 통하여 수직하중의 변동량에 크게 영향을 미치는 것으로 알려진 바 있는 디스크 시편의 misaligment 효과를 상사하고 극대화 하기 위하여 본 논문에서는 경사진 디스크 시편을 추가로 사용하였다. 상기조건으로 마찰시험기 시스템의 각 하중부과 방법과 수직강성 변화가 마찰특성에 미치는 영향을 실험적으로 측정 평가하였으며, 마찰시험기 동특성계 모델의 이론적 해석을 통하여 마찰특성 변화를 고찰하였다. 또한, 미끄럼 접촉 시의 수직력과 마찰력을 측정하고, 데이터의 통계적 처리방법에 따른 마찰계수의 변화 특성도 평가하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.7 s.262
• /
• pp.725-731
• /
• 2007

An air spring which is a part of the suspension system of automobiles is used to reduce and absorb the vibration and the noise. Main components of the air spring are a cord reinforced rubber bellows, a canister and a piston. The performance of the air spring are depended on configurations of rubber bellows, the angle and elastic modulus of cord. The finite element analysis are executed to predict and evaluate the load capacity and the stiffness. The design variables of air spring are determined to adjust the required specifications of the air spring. Several samples of the air spring are manufactured and experimented. It is shown that the results by finite element analysis are in close agreement with the test results.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.405-408
• /
• 2007

Vestibular hair cells, the sensory receptors of vestibular organs, selectively amplify miniscule stimuli to attain high sensitivity. Such selective amplification results in compressive nonlinear sensitivity, which plays an important role in expanding dynamic range while ensuring robustness of the system. In this study, negative stiffness mechanism, a mechanism responsible for the selective amplification by vestibular hair cells, is applied to a simple mechanical system consisting of an array of inverted pendulums. The structure and working principle of the system have been inspired by gating spring hypothesis proposing that opening and closing of transduction channels contributes to the global stiffness of vestibular hair bundle. Parameter study was carried out to analyze the effect of each parameter on the compressive nonlinearity of suggested model.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.18 no.4
• /
• pp.67-72
• /
• 2010

In this study, performance analysis and design optimization is carried out for a multi-rate spring brake system, which is used in a cable ride to stop the arriving passengers in safe and comfortable manner. Mathematical model for the spring is developed toward the objective of minimizing the impact at the arrival while satisfying the constraint of limited distance at the stop. Matlab code is utilized to examine parameters affecting the performance of the brake system. The results are validated by a commercial software RecurDyn. Kriging meta model is used to reduce the computational cost of the analysis. Optimization is conducted by RecurDyn, from which the design parameters are determined that minimizes the impact at the stop.