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Machinery

In Machinery, Machinery General, Research

Auto-positioning of sliding planes based on virtual force

Auto-positioning of sliding planes based on virtual force

Eun Ho Kim, Kyung Woon Kwak, Young Kook Kim, Soohyun Kim, Byung Man Kwak, In Gwun Jang, Kyung Soo Kim, International Journal of Control, Automation and Systems, August 2013, Volume 11, Issue 4, pp 798-804.

Abstract

In this paper, an auto-positioning algorithm for sliding planes is newly proposed in two different forms: the General Virtual Force Algorithm (GVFA) and the Applied Virtual Force Algorithm (AVFA). The proposed algorithm is then applied to an auto-positioning spreader which can slide on the top surface of a container with 3 degrees of freedom (DOF). This enables the spreader to handle containers even on a wavy open sea, where the inevitable swinging motion of a spreader leads to significant misalignment from the container during landing. With numerical simulation and experiments using a 1/20 scale model, it is verified that the proposed algorithms provide a robust and reliable solution for in-plane path-finding. Considering the limited space and cost for sensor equipment, however, using AVFA with 8 sensors can be a better solution for an actual application regardless of the slight sacrifice in performance in terms of operation time and energy consumed.

How Multibody Dynamics Simulation Technology is Used

A newly proposed auto-positioning algorithm for sliding planes was tested using RecurDyn and scale testing. Scale testing was able to validate the RecurDyn model. RecurDyn simulations were able to prove that the algorithms provide a robust and reliable solution for path finding.

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Dynamic Analysis of Needle Roller Bearings on Torque Loss

Dynamic Analysis of Needle Roller Bearings on Torque Loss

Atsushi Suzuki, Hideki Sugiura, Miki Mizono, Mizuho Inagaki, Tsune Kobayashi, Journal of System Design and Dynamics, 2013, Volume 7, No. 4, pp 405-415.

Abstract

Automatic transmissions consist of several planetary gear sets that are utilized to change gears. Needle roller bearings are widely employed in planetary gears used under high-load and high-speed conditions, and thus the torque loss of these bearings is an important issue in designing high-efficiency transmissions. In this paper, a dynamic analysis is conducted using a multibody dynamics model to investigate friction losses in the needle roller bearings that support pinions. This numerical model takes into consideration the detailed conditions of contact and friction between the needle rollers and other parts. A discrete sphere model is used in the contact analysis to simulate the load distribution for the needle rollers. The friction coefficient is defined as a function of sliding velocity, and is used to describe the experimentally determined relationship between the skew angle and thrust force of needle rollers. The measurements obtained for the axial force of a pinion validate the predictions of the numerical model. A numerical analysis is conducted to evaluate the radial and cage pocket clearances of needle roller bearings, and it is found that the cage pocket clearance is a dominant factor affecting the friction loss of pinion. An increase in loss is caused by the thrust force generated by the skew of the needle rollers. Consequently, the cage pocket clearance needs to be small so as to lessen the friction loss of the bearing.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to analyze the design of needle roller bearings in the planetary gears of an automatic transmission. Dynamic analysis in RecurDyn yielded the mechanisms of skew motion, the thrust force of the needle rollers, the axial force of the pinion and the friction torque. As a result, the design could be changed to reduce torque loss in the needle roller bearings.

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In Machinery, Machinery with Belts/Chains/Cables, Research

Modelling of Gear Meshing: A Numerical Approach for Dynamic Behavior Estimation of Thin Gears

Modelling of Gear Meshing: A Numerical Approach for Dynamic Behavior Estimation of Thin Gears

Francesca Cura, Carlo Rosso, Topics in Nonlinear Dynamics, April 2013, Volume 35, Conference Proceedings of the Society for Experimental Mechanics Series, pp. 319-333.

Abstract

The paper deals with the numerical analysis of thin gears. In particular, a brief overview of literature modeling techniques is reported in order to understand the best way for analyzing the dynamic behavior of gears. Then a multibody commercial software is used for implementing different complexity levels of models. The study starts with a simplified model that considers rigid the gears and concentrates the stiffness in the contact between teeth. The second, and more complex, model considers the stiffness in the contact and adds the compliance of the teeth. Stiffness of tooth is depicted as a rotational stiffness placed at the tooth root. Then, the third model increases the complexity, in fact the second model is complicated introducing the compliance of the gear body. In order to do that, a modal analysis of the gears is conducted and the synthetized modal shapes of the gears are introduced in the multibody model. The comparison highlights how the dynamic behavior of thin gears is really important in the meshing force estimation, in fact the transmission error becomes more irregular and the contact forces increase. As a second aspect, this analysis emphasizes the influence of the contact damping and the contact friction in the backlash phenomenon.

How Multibody Dynamics Simulation Technology is Used

The transmission dynamics of very thin gears is studied using a fully rigid model, RFlex and FFlex. It is concluded that the compliance of the gear bodies could deeply affect the transmission behavior. These dynamics could easily be missed if the gears were assumed to be rigid bodies.

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Numerical modeling of journal bearing considering both elastohydrodynamic lubrication and multi-flexible-body dynamic

Numerical modeling of journal bearing considering both elastohydrodynamic lubrication and multi-flexible-body dynamic

J. Choi, S.S. Kim, S.S. Rhim, J.H. Choi, International Journal of Automotive Technology, February 2012, Volume 13, Issue 2, pp 255-261.

Abstract

This study uses an elastohydrodynamic lubrication model coupled with multi-flexible-body dynamics (MFBD) to analyze dynamic bearing lubrication characteristics, such as pressure distribution and oil film thickness. To solve the coupled fluid-structure interaction system, this study uses an MFBD solver and an elastohydrodynamics module. The elastohydrodynamics module passes its force and torque data to the MFBD solver, which can solve general dynamic systems that include rigid and flexible bodies, joints, forces, and contact elements. The MFBD solver analyzes the positions, velocities, and accelerations of the multi-flexible-body system while incorporating the pressure distribution results of the elastohydrodynamics module. The MFBD solver then passes the position and velocity information back to the elastohydrodynamics solver, which reanalyzes the force, torque, and pressure distribution. This iteration is continued throughout the analysis time period. Other functions, such as mesh grid control and oil hole and groove effects, are also implemented. Numerical examples for bearing lubrication systems are demonstrated.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is coupled with an elastohydrodynamic module to analyze dynamic bearing lubrication characteristics, such as pressure distribution and oil film thickness. The elastohydrodynamic module transmits pressure, force, and torque data into RecurDyn. The FFlex module in RecurDyn allows for compliance effects to be analyzed while solving the dynamics of the system. These results agreed with experimental results and can now be used to improve the design.

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In Machinery, Machinery General, Research

Coupled simulation of gas flow and dynamic analysis for stroke calculation in circuit breaker

Coupled simulation of gas flow and dynamic analysis for stroke calculation in circuit breaker

Y.S. Lee, H.S. Ahn, S.W. Park, J.H. Lee, 1st International Conference on Electric Power Equipment – Switching Technology (ICEPE-ST), Xi’an, October 2011, pp 203-206.

Abstract

Electrical energy transmission and distribution devices are becoming more sophisticated and diversified in design, and also higher in its capacity due to rising in electricity usage. In direct response to demands of more reliable GIS (Gas Insulated Switchgear) from customers, computer simulations such as dynamics, structural, and fluid dynamics analysis are becoming more incorporated into the design process. Among the many types of simulations in GIS are low current interruption, SLF interruption, and BTF interruption. In the simulations, a stroke profile measured under loaded condition is required, and it leads to reduction in time and cost required towards the product development. In the paper, first, the actuator and interrupter of GIS is modeled using dynamics simulation program called RecurDyn. Second, SF6 gas pressure change in the interrupting chamber is made into a sub-routine using house code. Finally, with consideration of ODP (Oil Dash Pot) and friction forces of actuator, stroke profile under actual loaded condition is calculated.

How Multibody Dynamics Simulation Technology is Used

The actuator and interrupter of a gas insulated switchgear are modeled using RecurDyn. The results of this study are expected to be helpful to improve the efficiency and structural reliability of ultrahigh-voltage GIS circuit breakers early in development. This is expected to shorten the period of research and development and reduce test costs.

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In Machinery, Machinery General, Research

Optimal Control of passive Locking Mechanism for Battery Exchange Using Pontryagin’s minium principle

Optimal Control of passive Locking Mechanism for Battery Exchange Using Pontryagin’s minium principle

Wonsuk Jung, Jongwon Park, Seungho Lee, Kyungsoo Kim, Soohyun Kim, 8th Asian Control Conference (ASCC), Kaohsiung, May 2011, pp 1227-1232.

Abstract

Mobile robot market and its importance are rapidly increasing. Mobile robots usually mount batteries to extend operating time and workspace. For that, robot has to charge the battery while stopping at a station or exchange the battery. Charging battery is too slow to restart robots. Therefore, battery exchanging method is encouraged. Until now, this method needs expensive sensors such as laser range finder and vision sensors to align and is very complex mechanism which including battery removal from robot, moving to the station, docking mechanism and exchange mechanism. Thus, we proposed a new complete passive battery docking and exchange mechanism. This mechanism uses no actuators at whole actions. And it simplifies the process that unifies the docking and exchange mechanism using key and housing system. This system reduces the docking and exchange operating time and compensates wide range of offset between battery and charge station. But this mechanism needs optimal control of robot moving, because this system is composed of springs and dampers which are passive modules that should be controlled accurately. This paper proposes optimal control of robot moving at passive docking mechanism in battery system for reducing docking time, rebounding force and stable docking using Pontryagin’s minimum principle. Also this paper verifies proposed optimal control using dynamic analysis program, Recurdyn and Matlab Simulink.

How Multibody Dynamics Simulation Technology is Used

An efficient method to dock and exchange batteries for a mobile robot was verified using RecurDyn. RecurDyn was able to evaluate the dynamics of the system with a specific control method without experimentally testing each case.

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In Machinery, Machinery with Belts/Chains/Cables, Research

Analysis and Research of Automotive Trapezoid Synchronous Belt’s Fatigue Life

Analysis and Research of Automotive Trapezoid Synchronous Belt’s Fatigue Life

Li Zhanguo, Jiang Ming, Li Jiaxing, International Conference on Computer, Mechatronics, Control and Electronic Engineering (CMCE), Chungchun, August 2010, Volume 2, pp 193-195.

Abstract

The dynamic simulation model of synchronous belt meshing transmission is established in dynamics software “RecurDyn” applying the theory of MFBD (Multi-Flexible Body Dynamics), which analyzed the contact force on the working surfaces and stress distribution during the meshing transmission. The Finite Element Analysis Method was used to make the synchronous belt model meshed in Femap and investigated the belt’s teeth stress distribution after the model was imported into RecurDyn. A new design of synchronous belt’s and pulley’s tooth profiles for improving the transmission capacity of the automotive synchronous belt was proposed, in order to discover better materials to increase the fatigue life of the belt by optimization of the geometry of tooth profiles.

How Multibody Dynamics Simulation Technology is Used

RecurDyn was used to simulate a timing belt as a flexible body. The stress distribution of the belt is obtained during typical operating conditions. New designs and materials for the belt could be easily tested in RecurDyn to find the optimal design more quickly.

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In Machinery, Machinery with Belts/Chains/Cables, Research

Simulation methods for conveyor belt based on virtual prototyping

Simulation methods for conveyor belt based on virtual prototyping

Kun Hu, Yong-cun Guo, Peng-yu Wang, International Conference on Mechanic Automation and Control Engineering (MACE), Wuhan, June 2010, pp 2332-2334.

Abstract

Belt simulation is the key point of virtual prototyping (VP) technology for belt conveyor. ADAMS can carry on the simple conveyor belt simulation. For its low precision and heavy work, ADAMS is not suitable for belt conveyer VP modeling and simulation. A new simulation method based on RecurDyn is introduced in this paper. The conveyor belt is divided into finite discrete micro belt segments. With the connecting force, the adjacent belt segments are connected to simulate the continuous belt. The results show the correctness of this method and the feasibility of belt conveyor VP, and there are also some limitations in this method. Further, the simulation method of conveyor belt has important guiding significance for simulation of flexible cable, such as the steel rope.

How Multibody Dynamics Simulation Technology is Used

The RecurDyn Belt toolkit provides convenient entities for quickly modeling belt systems. This includes automatic and intelligent modeling, discretization, and assembly of a belt combined with fast calculating speed and convenient sensors. The author finds the belt capabilities in RecurDyn to be superior to that of ADAMS. The virtual prototype of this heavy-duty belt conveyor developed in RecurDyn could be used for future design problems instead of an expensive physical prototype.

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In Machinery, Machinery with Belts/Chains/Cables, Research

Mock-up of a support structure of the ITER vacuum vessel

Mock-up of a support structure of the ITER vacuum vessel

H.J. Ahn, J.W. Sa, Y.K. Kim, Y.S. Hong, J.H. Choi, T.H. Kwon, J.S. Lee, K.H. Park, T.S. Kim, W.I. Ha, I.S. Choi, B.C. Kim, K.H. Hong, C.H. Choi, Fusion Engineering and Design, June 2009, Volume 84, Issues 2-6, pp 375-379.

Abstract

The ITER vacuum vessel support systems located in the lower level sustain loads in radial and vertical direction. The support system consists of various sub-components like a linkage system, a pot type bearing, a vertical rope, a toroidal constraint, and dampers. In order to examine performance of the mechanism of the system, a mock-up of the linkage system which is comparatively complicated has been manufactured. Various fabrication methods were studied through the mock-up fabrication, and also several tests have been done using the mock-up. Those include assembly study, stroke test, static load test and fatigue test. In the full stroke test, the functional mechanism of the support structure has been demonstrated. In the structural test, the strength of the all components is evaluated by measuring reaction and strain of each component. In order to investigate the effect of tolerances and the damage due to the tests, the performance tests were conducted before and after the static and fatigue tests. The backlash for each stage is found from measured displacement hysteresis. As results of those tests, the performance of the ITER vacuum vessel support structure as well as its structural integrity has been evaluated in this study.

How Multibody Dynamics Simulation Technology is Used

RecurDyn was used to test the design of a vacuum vessel support system. The reaction forces at rotational joints, displacements, and rotation angles were obtained from the model. This information could be used to make intelligent design decisions regarding the geometry and materials used in the system.

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