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Research

In Machinery, Machinery General, Research

Design of planar static balancer with associated linkage

Design of planar static balancer with associated linkage

Sang-Hyung Kim, Chang-Hyun Cho, Mechanism and Machine Theory, November 2014, Volume 81, pp 79-93.

Abstract

This paper presents a design method for a static balancer with associated linkage. Various mechanisms can be obtained with modifications to the associated linkage. Gravity compensators for various mechanisms can be achieved similarly from a gravity compensator for the associated linkage. The space mapping method is adopted to design a gravity compensator for the associated linkage. Conversion rules are derived by investigating the variances of a mechanism from the associated linkage and are applied to the design equation for the associated linkage generated by the space mapping method. Rows and columns of the design equation are deleted by conversion rules, leading to deletion rules. A new gravity compensator for the mechanism derived from the associated linkage is obtained by applying the deletion rules to the design equation (i.e., gravity compensator) for the associated linkage. The four-bar mechanism is adopted as the associated linkage, and various gravity compensators for planar mechanisms are derived from the gravity compensator of the four-bar linkage. Simulations are conducted, and the results show that complete gravity compensation is possible for various planar mechanisms.This paper is mainly about quadruped robot gait planning with stair environment constraints, where the environment constraints are mainly embodied in the form of robot gait planning constraints and robot stair traversing feasibility, etc., and the problem of quadruped robot gait planning can be solved theoretically with Stair-Aimed-SSG (Static Stable Gait). The feasibility of this scheme is proved by Matlab and RecurDyn simulation. This paper is mainly about quadruped robot gait planning with stair environment constraints, where the environment constraints are mainly embodied in the form of robot gait planning constraints and robot stair traversing feasibility, etc., and the problem of quadruped robot gait planning can be solved theoretically with Stair-Aimed-SSG (Static Stable Gait). The feasibility of this scheme is proved by Matlab and RecurDyn simulation.

How Multibody Dynamics Simulation Technology is Used

RecurDyn was used for dynamic simulations of gravity compensators. Several designs could be tested quickly to fine tune the design without having to build many physical prototypes.

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In Machinery, Machinery General, Research

Changing law of launching pitching angular velocity of rotating missile

Changing law of launching pitching angular velocity of rotating missile

Guang Liu, Bin Xu, Xiaojuan Jiao, Tiesheng Zhen, Chinese Journal of Aeronautics, October 2014, Volume 27, Issue 5, pp 1171-1179.

Abstract

In order to provide accurate launching pitching angular velocity (LPAV) for the exterior trajectory optimization design, multi-flexible body dynamics (MFBD) technology is presented to study the changing law of LPAV of the rotating missile based on spiral guideway. An MFBD virtual prototype model of the rotating missile launching system is built using multi-body dynamics modeling technology based on the built flexible body models of key components and the special force model. The built model is verified with the frequency spectrum analysis. With the flexible body contact theory and nonlinear theory of MFBD technology, the research is conducted on the influence of a series of factors on LPAV, such as launching angle change, clearance between launching canister and missile, thrust change, thrust eccentricity and mass eccentricity, etc. Through this research, some useful values of the key design parameters which are difficult to be measured in physical tests are obtained. Finally, a simplified mathematical model of the changing law of LPAV is presented through fitting virtual test results using the linear regression method and verified by physical flight tests. The research results have important significance for the exterior trajectory optimization design.In this paper we describe the necessity and significance of coal preparation plant inspection robot, propose the robot design requirements and design the system framework of hardware and software. Then we use RecurDyn software to simulate and analysis the stability and fitness of the inspection robot in coal preparation plant complex environment based on virtual prototype technique.

How Multibody Dynamics Simulation Technology is Used

A multi-flexible body dynamics (MFBD) virtual prototype of a missile launching system is simulated using the RecurDyn FFlex module. A meshed model of the missile and the launching canister were imported into RecurDyn to perform dynamic analysis. The stress profile of the missile and launching canister were obtained where instrumentation for physical testing would be difficult.

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In Railway, Research

Power loss analysis of tracked travelling unit of high-speed tracked vehicle

Power loss analysis of tracked travelling unit of high-speed tracked vehicle

Zhifu Wang, Liu Bin, Yihui Zhao, IEEE Conference and Expo Transportation Electrification Asia-Pacific (ITEC Asia-Pacific), Beijing, August 2014, pp 1-4.

In Manufacturing, Multibody Dynamics, Research

Compensation of geometrical deviations via model based-observers

Compensation of geometrical deviations via model based-observers

B.Denkena, L.Overmeyer, K.M.Litwinski, R.Pesters, 2014, The International Journal of Advanced Manufacturing Technology, July 2014, Volume 73, Issue 5, pp 989-998.

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

Dynamic Analysis and Simulation of a Roller Chain Drive System on RecurDyn

Dynamic Analysis and Simulation of a Roller Chain Drive System on RecurDyn

Juntian Zhao, Shunzeng Wang, Shengyang Hu, Yu Liu, Journal of Applied Science and Engineering Innovation, June 2014, Volume 1, Number 1, pp 71-76.

Abstract

This paper is on the dynamic analysis and simulation of the roller chain drive systems, which are widely used in various high-speed, heavy-load and power transmission application. Presently, most studies were only focused on the analysis of the chain tight span, not the whole system. In this paper, a mathematical model is developed to calculate the dynamic response of the whole roller chain drive working with RecurDyn software. It presents the generalized recursion theory of the chain links in the model, with the initial condition and various tension. In this simulation model, the dynamics of any roller chain drive with two sprockets and two spans can be analyzed by the procedure. Finally, it provides velocity curves, displacement diagrams, accelerating curves and dynamic tension curves. This study provides an effective way for the dynamic analysis of all the chain drive system.

How Multibody Dynamics Simulation Technology is Used

The chain module in RecurDyn provides an easy way to model a roller train drive system. Built in tools make the dynamic analysis of a chain subsystem much easier to accomplish. Velocity, acceleration, and dynamic tension curves can provide effective means to design a chain drive system.

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Related Case Studies
In Machinery, Machinery General, Research

Modeling and dynamics analysis of helical spring under compression using a curved beam element with consideration on contact between its coils

Modeling and dynamics analysis of helical spring under compression using a curved beam element with consideration on contact between its coils

C.J. Yang, W.H. Zhang, G.X. Ren, X.Y. Lin, Meccanica, April 2014, Volume 49, Issue 4, pp 907-917.

Abstract

Helical springs are indispensable elements in mechanical engineering. This paper investigates helical springs subjected to axial loads under different dynamic conditions. The mechanical system, composed of a helical spring and two blocks, is considered and analyzed. Multibody system dynamics theory is applied to model the system, where the spring is modeled by Euler–Bernoulli curved beam elements based on an absolute nodal coordinate formulation. Compared with previous studies, contact between the coils of spring is considered here. A three-dimensional beam-to-beam contact model is presented to describe the interaction between the spring coils. Numerical analysis provides details such as spring stiffness, static and dynamic stress for helical spring under compression. All these results are available in design of helical springs.

How Multibody Dynamics Simulation Technology is Used

RecurDyn simulations were used to validate a simplified contact model between coils of a spring. The spring was modeled using beam elements and important information for the design of helical springs such as spring stiffness, static and dynamic stress are compared with RecurDyn simulations. The result is that the simplified method is proven to be effective.

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