• Interaction and multiscale mechanics
• /
• 제5권3호
• /
• pp.287-318
• /
• 2012

We apply a partitioned-solution (iterative-staggered) coupling method based on a fixed Eulerian mesh with the level set function to a large-deformation fluid-structure interaction (FSI) problem where a large-deformable thin structure moves in a high-speed flow field, as an airbag does during deployment. This method combines advanced fluid and structure solvers-specifically, the constrained interpolation profile finite element method (CIP-FEM) for fluid Eulerian mesh and large-deformable structural elements for Lagrangian structural mesh. We express the large-deformable interface as a zero isosurface by the level set function, and introduce virtual nodes with level sets and structural normal velocities to generate the level set function according to the large-deformable interfacial geometry and enforce the kinematic condition at the interface. The virtual nodes are located in the direction normal to the structural mesh. It is confirmed that application of the method to unfolded airbag deployment simulation shows the adequacy of the method.

• 대한기계학회논문집 C: 기술과 교육
• /
• 제3권2호
• /
• pp.125-130
• /
• 2015

Using flexible multibody system dynamic method, the rigid-flexible coupling multibody dynamic analysis model of the drum brake system was developed, and the kinematic and dynamic simulation of the system was processed as its object of study. Simulations show that the friction will increase with the dynamic friction coefficient, but high dynamic friction coefficient will cause the abnormal vibration and worsen the stability of the brake system, even the stability of the whole automobile. The modeling of flexible multi-body can effectively analyze and solve complex three-dimensional dynamic subjects of brake system and evaluate brake capability. Further research and study on this basis will result in a convenient and effective solution that can be much helpful to study, design and development of the brake system.

• 한국정밀공학회지
• /
• 제26권5호
• /
• pp.128-134
• /
• 2009

This paper aims to design a variable-stiffness type economical safety joint for service robots. The safety joint was designed to have a passive shock absorbing mechanism for protecting human from a catastrophic collision under service condition of robots. A simple mechanism composed of two action disks for switching the load transfer, a spring and a screw for pre-load was proposed. In order to evaluate the performance of the safety joint a testing platform which can carry out the static and impact tests was also designed and fabricated. From the test results, the designed safety joint was proved to have a variable load-carrying capacity and about 42% impact absorption capacity with simple manipulation of the control screw.

• 제어로봇시스템학회논문지
• /
• 제5권2호
• /
• pp.208-219
• /
• 1999

Springs have been employed in a wide range of mechanical systems. This work deals with the concept of an adaptable spring mechanism which can arbitrarily modulate its spring characteristics. The adaptable spring is desired for enhancing performances of various mechanical systems employing springs. We demonstrate that such adaptable springs can be realized by adapting anthropomorphic musculoskeletal structures of the human upper-extremity, which possesses highly nonlinear kinematic-coupling among redundant muscles existing in its structures. This phenomenon has been explained by several human arm models. Based on the analysis results, we propose multi-degree-of-freedom spring mechanisms resembling the musculoskeletal structure of the human upper-extremity, and verifiy the applicability of these mechanisms through simulation.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 추계학술대회 논문집
• /
• pp.463-468
• /
• 2011

According to a quantum leap of the performances of automobile, environmental factors are important as functional factors, especially noise. BLDC motor, one of the part of automobile, is also no exception. In this paper, investigation of the sound sources of outer rotor type BLDC motor is performed. In order to reduce noise, it must be necessary knowing sound source. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. For structural analysis, modal experiment and 3D mode analysis are performed. On behalf of electromagnetic analysis, 2D finite element method is carried out. Finally, coupling analysis is performed in order to know about influence between two factors.

• Steel and Composite Structures
• /
• 제17권2호
• /
• pp.185-198
• /
• 2014

Carbon-manganese steel A42 (French standards) is used in steam generator pipes of nuclear center and subject to low cycle fatigue (LCF) loads. In order to obtain the material LCF behavior, the tests are implemented in a hydraulic fatigue machine. The LCF plastic deformation and cyclic stress in macroscope have been influenced by the accumulated low cycle fatigue damage. The constitutive kinematic and isotropic hardening modeling is modified with coupling fatigue damage to describe the fatigue behavior. The improved model seems to be good agreement with the test results.

• Nuclear Engineering and Technology
• /
• 제56권10호
• /
• pp.4412-4422
• /
• 2024

The CFETR multipurpose overload robot (CMOR) is a critical component of the fusion reactor remote handling system. To accurately calculate and visualize the structural deformation and stress characteristics of the CMOR motion process, this paper first establishes a CMOR kinematic model to analyze the unfolding and working process in the vacuum chamber. Then, the dynamic model of CMOR is established using the Lagrangian method, and the rigid-flexible coupling modeling of CMOR links and joints is achieved using the finite element method and the linear spring damping equivalent model. The co-simulation results of the CMOR rigid-flexible coupled model show that when the end load is 2000 kg, the extreme value of the end-effector position error is more than 0.12 m, and the maximum stress value is 1.85 × 10⁸ Pa. To utilize the stress-strain data of CMOR, this paper designs a CMOR morphology prediction control system based on Unity software. Implanting CMOR finite element analysis data into the Unity environment, researchers can monitor the stress strain generated by different motion trajectories of the CMOR robotic arm in the control system. It provides a platform for subsequent research on CMOR error compensation and extreme operation warnings.

• 대한의용생체공학회:의공학회지
• /
• 제23권3호
• /
• pp.171-179
• /
• 2002

운동 중에 있는 인체 무릎관절의 기능을 이해하기 위한 기구학적(Kinematic) 분석 과 동역학적(Kinetic) 분석을 행하는데 있어서 관절 표면의 기하학이 주요한 역할을 한다는 것은 잘 알려져 있다. 슬관절은 미끄러짐 (sliding)과 구름 (rolling) 운동을 고려하지 않고는 정확하게 모델 될 수 없다 본 연구에서는 미끄러짐 과 회전 운동 그리고 주요 인대 (ligament)를 고려한 3타원 인체 슬관절 모델을 제시한다 본 연구는. 슬관절의 전형적인측 평면 CT 영상의 확장으로부터 얻어진 두개의 캠 측면도를 이용하여 보다 실제에 가까운 관절의 기하학을 이용한 모델을 제시한다 개발된 모델은 보행 중 인체 슬관절을 통한 힘의 전달경로를 예측하는데 있어서 실험을 기초로 한 이전의 결과보고와 비교하여 볼 때 매우 잘 일치한다 대퇴골와 경골 사이의 접촉 점은 무릎의 굽힘이 진행되는 동안 전방에서 후방으로 이동하는데 이것은 무릎의 굽힘과 폄의 운동에 대한 전방/후방 운동의 커플링을 반영한 것이다. 본 연구에서 개발된 모델에 의하면 일회의 보행 사이클동안 경골 표면에 접촉 점의 전방/후방 이동변위는 바깥쪽 관절구 쪽이 약 16 mm 이고. 안쪽 관절구 쪽이 약 25 mm 이다 또한, 일회의 보행 사이클 동안 대퇴골 의 이동변위는 바깥쪽이 약 7 mm 그리고 안쪽이 약 10 mm 이다. 개발된 모델은, 관절의 퇴화를 진단 하는데 이용할 수 있는 가능성이 기대된다

• 한국소음진동공학회논문집
• /
• 제22권9호
• /
• pp.903-909
• /
• 2012

In elliptical vibration cutting(EVC) where the cutting tool traces a micro-scale 2-dimensional elliptical trajectory, the kinematical and vibrational characteristics of the EVC device greatly affect cutting performance. In this study, kinematical and vibrational characteristics of an EVC device constructed with two orthogonally-arranged stacked piezoelectric actuators were investigated both analytically and experimentally. The step voltage was applied to the orthogonal EVC device and the associated displacements of the cutting tool were measured to assess kinematical characteristics of the orthogonal EVC device. To investigate the vibrational characteristic of the orthogonal EVC, sinusoidal voltage was applied to the EVC device and the resulting displacements were measured. It was found from experiments that coupling of displacements in the thrust and cutting directions and the tilt of the major axis of the elliptical trajectory exists. In addition, as the excitation frequency is in vicinity of resonant frequencies the distortion in the shape of the elliptical trajectory becomes greater and change in the rotation direction occurs. To correct the shape distortion of the elliptical trajectory, the shape correcting procedure developed for the parallel EVC device was applied for the orthogonal EVC device and it was shown that the shape correcting method successfully corrects distortion.

• Coupled systems mechanics
• /
• 제2권1호
• /
• pp.53-83
• /
• 2013

Sea waves induce significant pressures on coastal surfaces, especially on rocky vertical cliffs or breakwater structures (Peregrine 2003). In the present work, this hydrodynamic pressure is considered as the excitation acting on a piezoelectric material sheet, installed on a vertical cliff, and connected to an external electric circuit (on land). The whole hydro/piezo/electric system is modeled in the context of linear wave theory. The piezoelectric elements are assumed to be small plates, possibly of stack configuration, under a specific wiring. They are connected with an external circuit, modeled by a complex impedance, as usually happens in preliminary studies (Liang and Liao 2011). The piezoelectric elements are subjected to thickness-mode vibrations under the influence of incident harmonic water waves. Full, kinematic and dynamic, coupling is implemented along the water-solid interface, using propagation and evanescent modes (Athanassoulis and Belibassakis 1999). For most energetically interesting conditions the long-wave theory is valid, making the effect of evanescent modes negligible, and permitting us to calculate a closed-form solution for the efficiency of the energy harvesting system. It is found that the efficiency is dependent on two dimensionless hydro/piezo/electric parameters, and may become significant (as high as 30 - 50%) for appropriate combinations of parameter values, which, however, corresponds to exotically flexible piezoelectric materials. The existence or the possibility of constructing such kind of materials formulates a question to material scientists.