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Machinery

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

A Cable-Passive Damper System for Sway and Skew Motion Control of a Crane Spreader

A Cable-Passive Damper System for Sway and Skew Motion Control of a Crane Spreader

La Duc Viet, Youngjin Park, Shock and Vibration, 2015, Volume 2015, Article ID 507549, 11 pages.

Abstract

While the crane control problem is often approached by applying a certain active control command to some parts of the crane, this paper proposes a cable-passive damper system to reduce the vibration of a four-cable suspended crane spreader. The residual sway and skew motions of a crane spreader always produce the angle deflections between the crane cables and the crane spreader. The idea in this paper is to convert those deflections into energy dissipated by the viscous dampers, which connect the cables and the spreader. The proposed damper system is effective in reducing spreader sway and skew motions. Moreover, the optimal damping coefficient can be found analytically by minimizing the time integral of system energy. The numerical simulations show that the proposed passive system can assist the input shaping control of the trolley motion in reducing both sway and skew responses.

How Multibody Dynamics Simulation Technology is Used

RecurDyn simulations of a crane spreader show significant vibration, sway, and skew. A passive damper is added to the system and the RecurDyn model shows that the damper is effective in reducing these unwanted motions.

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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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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 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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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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In Machinery, Machinery General, Research

Necessary conditions of stability moving parts of rotor centrifuge

Necessary conditions of stability moving parts of rotor centrifuge

Jens Strackeljan, Andriy Babenko, Iaroslav Lavrenko, Journal of Mechanical Engineering, 2014, Number 72.

Abstract

Considered design features modern centrifuges. Revealed that their rotors have moving parts that rotate around a horizontal axis. The dynamics of said moving elements. Using Lagrange equation of the second kind derived differential equations of motion. The simulation visualization of motion using the software package RecurDyn. The research results obtained with the package RecurDyn and analytically showed that their movement can not be sustained, in the positions that are optimal in terms of process. The resulting differential equations can not be prointehrovani elementary functions, so direct traffic analysis difficult. Due to the foregoing stability conditions investigated linear movement approach. Necessary conditions for stability of motion required of the design.

How Multibody Dynamics Simulation Technology is Used

A dynamic model of a modern centrifuge with moving parts that rotate around a horizontal axis. The goal of this design was to have a high centrifugal force while maintaining motion stability. RecurDyn simulations showed that the motion was unstable in positions that were optimal for the technological process. The results showed that the design needs to be adjusted to provide additional stability.

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In Machinery, Machinery General, Research

A Numerical Method of Large-Scale Concrete Displacing Boom Dynamics and Experimental Validation

A Numerical Method of Large-Scale Concrete Displacing Boom Dynamics and Experimental Validation

Wu Ren, Yun-xin Wu, Zhao-wei Zhang, Wen-ze Shi, Advances in Mechanical Engineering, January 2014, Volume 6 943847.

Abstract

Concrete displacing boom is large-scale motion manipulator. During the long distance pouring the postures needs to frequently change. This makes the real-time dynamic analysis and health monitoring difficult. Virtual spring-damper method is adopted to establish the equivalent hydraulic actuator model. Besides boom cylinder joint clearance is taken into account. Then transfer matrix method is used to build the multibody concrete placing boom model by dividing the system into two substructures. Next typical working conditions displacements and accelerations during the pouring process are studied. The results of the numerical method are correct and feasible compared with RecurDyn software and the experimental ones. So it provides reference to the real-time monitoring and structure design for such light weight large scale motion manipulators.

How Multibody Dynamics Simulation Technology is Used

A numerical method for concrete-displacing boom dynamics is developed and found to be in good agreement with RecurDyn and experimental results. RecurDyn simulations offer validity to the numerical and experimental methods while providing additional information that may not be available with instrumentation.

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

Cable installation simulation by using a multibody dynamic model

Cable installation simulation by using a multibody dynamic model

Cai Jin Yang, Di Feng Hong, Ge Xue Ren, Zhi Hua Zhao, Multibody System Dynamics, December 2013, Volume 30, Issue 4, pp 433-447.

Abstract

A major concern when installing the cables into the underground conduit is minimizing the tensile forces exerted on the cables as they are pulled. This knowledge makes it possible to avoid over conservative design practices and to achieve substantial saving during construction. A general computing algorithm of predicting the tensile force of the cable pulled through the underground conduit with an arbitrary configuration is presented in this paper, which is based on multibody system dynamic formulation. The presented multibody dynamic model for this problem consists of the cable, the underground conduit, and the interaction between the cable and the conduit. In this paper, the cable is modeled by the finite cable element based on an absolute nodal coordinate formulation. The interaction between the cable and the underground conduit is described by the Hertz contact theory. Numerical examples are presented to illustrate the effectiveness and efficiency of the proposed method for estimating the cable tension.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to validate a computing algorithm for pulling a cable through an underground conduit. The cable is modeled as a flexible body and the stress profile and deformation are tracked over time. This model validates the simplified model and gives stress information in a dynamic environment that otherwise would be difficult to attain using physical testing.

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In Machinery, Machinery General, Research

Quantitative diagnosis of a spall-like fault of a rolling element bearing by empirical mode decomposition and the approximate entropy method

Quantitative diagnosis of a spall-like fault of a rolling element bearing by empirical mode decomposition and the approximate entropy method

ShuanFeng Zhao, Lin Liang, GuangHua Xu, Jing Wang, WenMing Zhang, Mechanical Systems and Signal Processing, October 2013, Volume 40, Issue 1, pp 154-177.

Abstract

Spalling or pitting is the main manifestation of fault development in a bearing during the earlier stages. Previous studies indicated that the vibration signal of a bearing with a spall-like defect may be composed of two parts; the first part originates from the entry of the rolling element into the spall-like area, and the second part refers to the exit from the fault region. The quantitative diagnosis of a spall-like fault of the rolling element bearing can be realized if the entry–exit event times can be accurately calculated. However, the vibration signal of a faulty bearing is usually non-stationary and non-linear with strong background noise interference. Meanwhile, the signal energy from the early spall region is too low to accurately register the features of the entry–exit event in the time domain. In this work, the approximate entropy (ApEn) method and empirical mode decomposition (EMD) are applied to clearly separate the entry–exit events, and thus the size of the spall-like fault is estimated.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to simulate the dynamic effects of rolling element bearings with spall-like faults. A variety of spall widths and bearing speeds were tested without the cost and time associated with physical prototypes.

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