• Title/Summary/Keyword: Contact Simulation

Search Result 1,045, Processing Time 0.03 seconds

Determination of Contact Area of Cylindrical Nanowire using MD Simulation (MD 시뮬레이션을 이용한 실린더 형태 나노와이어의 접촉면적에 관한 연구)

  • Kim, Hyun-Joon
    • Tribology and Lubricants
    • /
    • v.32 no.1
    • /
    • pp.9-17
    • /
    • 2016
  • Contact between solid surfaces is one of the most important factors that influence dynamic behavior in micro/nanoscale. Although numerous theories and experimental results on contact behavior have been proposed, a thorough investigation for nanomaterials is still not available owing to technical difficulties. Therefore, molecular dynamics simulation was performed to investigate the contact behavior of nanomaterials, and the application of conventional contact theories to nanoscale was assessed in this work. Particularly, the contact characteristics of cylindrical nanowires were examined via simulation and contact theories. For theoretical analysis, various contact models were utilized and work of adhesion, Hamaker constant and elastic modulus those are required for calculation of the models were obtained from both indentation simulation and tensile simulation. The contact area of the cylindrical nanowire was assessed directly through molecular dynamics simulation and compared with the results obtained from the theories. Determination of the contact area of the nanowires was carried out via simulation by counting each atom, which is within the equilibrium length. The results of the simulation and theoretical calculations were compared, and it was estimated that the discrepancy in the results calculated between the simulation and the theories was less than 10 except in the case of the smallest nanowires. As the result, it was revealed that contact models can be effectively utilized to assess the contact area of nanomaterials.

Optimization of Ground Contact Model of Ankleless Lower Exoskeleton Robot for Gait Simulation (보행 모의 실험을 위한 발목 없는 하지 외골격 로봇의 지면 접촉 모델 최적화)

  • Gimyeong Choi;Sanghyung Kim;Changhyun Cho
    • The Journal of Korea Robotics Society
    • /
    • v.18 no.4
    • /
    • pp.481-486
    • /
    • 2023
  • The purpose of this study is to optimize parameters of a contact model to obtain similar ground contact force of human walking. Dynamic walking simulation considering ground contact is performed to determine load specifications when developing walking assist robots. Large contact forces that are not observed in actual experimental data occur during the simulation at the initial contact (e.g., heel contact). The large contact force generates unrealistic large joint torques. A lower exoskeleton robot with no ankles is developed with the Matlab simscape and the nonlinear hyper volumetric contact model is applied. Parameters of the nonlinear hyper volumetric model were optimized using actual walking contact force data. As a result of optimization, it was possible to obtain a contact force pattern similar to actual walking by removing the large contact force generated during initial contact.

Analysis of Dynamic characteristic of 2-DOF Contact Slider (2자유도 Contact Slider 모델의 동특성 해석)

  • Park, Kyoung-Su;Chun, Jeong-Il;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2001.05a
    • /
    • pp.924-929
    • /
    • 2001
  • The flying height of contact slider is determined by vertical and pitching motions of slider. This paper performed the computer simulation for flying height change of contact slider. It is changed by many parameters, contact stiffness, contact damping, air bearing stiffness ratio, a location of mass center, and so on. Computer simulation is performed for knowing for what change of these parameters influences in flying height of contact slider. Disk surface is modeled in harmonic wave with from 10㎑ to 600㎑. Tri-pad slider is modeled in that contact slider has 2-DOF motion (vertical motion, pitching motion). Tri-pad contact slider is analyzed by numerical analysis method in computer simulation.

  • PDF

Contact Pressure Analysis of a Windshield Wiperblade (와이퍼 블레이드의 누름압 해석)

  • Lee, Byoung-Soo;Shin, Jin-Yong
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.14 no.3
    • /
    • pp.51-57
    • /
    • 2006
  • The contact pressure distribution between a rubber wiper blade and a glass windshield is a major factor for wiping performance. A modeling and simulation method has been developed to forecast the contact pressure distribution on a wiper blade. For modeling multi-body dynamics of an wiper linkage system and flexible nature of wiper blade, ADAMS and ADAMS/flex are employed. A simulation study has been also conducted to obtain contact pressure distribution. Comparison between simulation and measurement is provided to ensure fidelity of the model and the simulation method.

Effects of sizes and mechanical properties of fuel coupon on the rolling simulation results of monolithic fuel plate blanks

  • Kong, Xiangzhe;Ding, Shurong;Yang, Hongyan;Peng, Xiaoming
    • Nuclear Engineering and Technology
    • /
    • v.50 no.8
    • /
    • pp.1330-1338
    • /
    • 2018
  • High-density UMo/Zr monolithic nuclear fuel plates have a promising application prospect in high flux research and test reactors. The solid state welding method called co-rolling is used for their fabrication. Hot co-rolling simulations for the composite blanks of UMo/Zr monolithic nuclear fuel plates are performed. The effects of coupon sizes and mechanical property parameters on the contact pressures between the to-be-bonded surfaces are investigated and analyzed. The numerical simulation results indicate that 1) the maximum contact pressures between the fuel coupon and the Zircaloy cover exist near the central line along the plate length direction; as a whole the contact pressures decrease toward the edges in the plate width direction; and lower contact pressures appear at a large zone near the coupon corner, where de-bonding is easy to take place in the in-pile irradiation environments; 2) the maximum contact pressures between the fuel coupon and the Zircaloy parts increase with the initial coupon thickness; after reaching a certain thickness value, the contact pressures hardly change, which was mainly induced by the complex deformation mechanism and special mechanical constitutive relation of fuel coupon; 3) softer fuel coupon will result in lower contact pressures and form interfaces being more out-of-flatness.

A Contact Algorithm in the Low Velocity Impact Simulation with SPH

  • Min, Oak-Key;Lee, Jeong-Min;Kim, Kuk-Won;Lee, Sung-Soo
    • Journal of Mechanical Science and Technology
    • /
    • v.14 no.7
    • /
    • pp.705-714
    • /
    • 2000
  • The formulation of Smoothed Particle Hydrodynamics (SPH) and a shortcoming of traditional SPH in contact simulation are presented. A contact algorithm is proposed to treat contact phenomenon between two objects. We describe the boundary of the objects with non-mass artificial particles and set vectors normal to the contact surface. Contact criterion using non-mass particles is established in this study. In order to verify the contact algorithm, an algorithm is implemented in to an in-house program; elastic wave propagation is an analysed under low velocity axial impact of two rods. The results show that the contact algorithm eliminates the undesirable phenomena at the contact surface; numerical result with the contact algorithm is compared with theoretical one.

  • PDF

Modeling of the Centerless Infeed (Plunge) Grinding Process

  • Kim, Kang
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.7
    • /
    • pp.1026-1035
    • /
    • 2003
  • A computer simulation method for investigating the form generation mechanism in the centerless infeed (plunge) grinding process is described. For a 3-D simulation model of form generation, contact points are assumed to be on least squares contact lines at the grinding wheel, regulating wheel, and work-rest blade. Using force and deflection analyses, the validity of this assumption is shown. Based on the 2-D simulation model developed in the previous work and the least squares contact line assumption, a 3-D model is presented. To validate this model, simulation results were compared with the experimental works. The experiments and computer simulations were carried out using three types of cylindrical workpiece shapes with varying flat length. The experimental results agree well with the simulation. It can be seen that the effect of flat end propagated to the opposite end through workpiece reorientation.

A Molecular Dynamics Simulation for the Moving Water Droplet on Atomistically Smooth Solid Surface (원자적으로 균일한 평판 위에서 움직이는 물 액적에 대한 분자동역학 시뮬레이션)

  • Hong, Seung-Do;Ha, Man-Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.33 no.8
    • /
    • pp.559-564
    • /
    • 2009
  • The variation in the shape of water droplet moving on atomistically smooth solid surface in the presence of a constant body force is simulated using molecular dynamics simulation. We investigated how the advancing and receding contact angle of the moving water droplet changes on a solid surface having various characteristic energies. From the MD simulation results, we obtained the density profile defined as the number of water molecules at a given position. Then, assuming the water droplet periphery to be a circle, we calculated the contact angles by using a nonlinear fitting of the half-density contour line. The present simulation clearly shows the different profile of the advancing and receding contact angle for these three different interaction potential between the water droplet and the solid surface.

Kinematics of Grasping and Manipulation of Curved Surface Object with Robotic Hand (로봇 손에 의한 자유곡면 물체의 파지 및 조작에 관한 운동학)

  • Hwang Chang-Soon
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.29 no.1 s.232
    • /
    • pp.1-13
    • /
    • 2005
  • Kinematics of grasping and manipulation by a multi-fingered robotic hand where multi-fingertip surfaces are in contact with an object is solved. The surface of the object was represented by B-spline surfaces in order to model the objects of various shapes. The fingers were modeled by cylindrical links and a half ellipsoid fingertip. Geometric equations of contact locations have been solved for all possible contact combinations between the fingertip surface and the object. The simulation system calculated joint displacements and contact locations for a given trajectory of the object. Since there are no closed form solutions for contact or intersection between these surfaces, kinematics of grasping was solved by recursive numerical calculation. The initial estimate of the contact point was obtained by approximating the B-spline surface to a polyhedron. As for the simulation of manipulation, exact contact locations were updated by solving the contact equations according to the given contact states such as pure rolling, twist-rolling or slide-twist-rolling. Several simulation examples of grasping and manipulation are presented.

Finite Element Analysis of Forming Processes With Free Surface Contact Algorithm (성형공정의 자유 경계면 접촉에 관한 유한요소 해석)

  • 한영원;임용택
    • Transactions of Materials Processing
    • /
    • v.4 no.1
    • /
    • pp.48-58
    • /
    • 1995
  • In this study, a contact algorithm for the finite element analysis of free surface contact problem in materials forming is presented. The proposed contact algorithm consists of two parts. The first is the contact searching part, and the second, the constraint part. The contact searching algorithm does not require any a priori knowledge of the pairs of contact nodes or segments and the impenetrability constraint is satisfied using the penalty function scheme. void colsure in open-die forging was simulated to verify the accuracy and capability of the currently developed contact algorithm. The simulation results, obtained from ABAQUS simulation, were compared well to the experimental data available in the literature.

  • PDF