All Posts By

Nelson Woo

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 RecurDyn in Education, Research

Design and Implementation of a Capstone Course to Satisfy the Industry Needs of Virtual Product Development and ABET Engineering Criteria

Design and Implementation of a Capstone Course to Satisfy the Industry Needs of Virtual Product Development and ABET Engineering Criteria

Mohamed A. Omar, Education Research International, Volume 2014, Article ID 578148, 18 pages.

  •  Abstract

    Over the past two decades, computer aided engineering (CAE) processes and procedures became an integral part of the product development cycle. Virtual product development (VPD) refers to procedures that integrate the CAE tools in a unified approach that spans all the product development phases. Current industrial trends utilize VPD tools and procedures to reduce the product development time without jeopardizing the product quality. These trends led to an increasing demand for engineers with computer skills, multidisciplinary engineering knowledge, and acquaintance with VPD tools. ABET program outcomes emphasize providing courses with an accumulated background of curricular components to solve realistic open-ended engineering problems. Capstone design project (CDP) course has been regarded as important learning activity that could be designed to provide senior engineering student an opportunity to solve such problems. A major objective of the CDP course is to simulate industrial setting and allow students to experience real-life engineering practice. This paper presents an implementation of the VPD procedures in a mechanical engineering CDP course. This integration simulates the industrial environment through multidisciplinary teams working together in subsystems to produce one product using standard commercial VPD tools. This course implementation is demonstrated using a case study of teams working to design and build a solar car.

    How Multibody Dynamics Simulation Technology is Used

    RecurDyn can be used as part of an undergraduate capstone design project to provide a meaningful learning experience for students. Using engineering tools like RecurDyn can prepare students more fully for future work opportunities.

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In Biomechanics, Multibody Dynamics, Research

Influence of Bundle Diameter and Attachment Point on Kinematic Behavior in Double Bundle Anterior Cruciate Ligament Reconstruction Using Computational Model

Influence of Bundle Diameter and Attachment Point on Kinematic Behavior in Double Bundle Anterior Cruciate Ligament Reconstruction Using Computational Model

Oh Soo Kwon, Tserenchimed Purevsuren, Kyungsoo Kim, Won Man Park, Tae-Kyu Kwon, Yoon Hyuk Kim, Computational and Mathematical Methods in Medicine, January 2014, Volume 2014, Article ID 948292, 8 pages.

  • Abstract

    A protocol to choose the graft diameter attachment point of each bundle has not yet been determined since they are usually dependent on a surgeon’s preference. Therefore, the influence of bundle diameters and attachment points on the kinematics of the knee joint needs to be quantitatively analyzed. A three-dimensional knee model was reconstructed with computed tomography images of a 26-year-old man. Based on the model, models of double bundle anterior cruciate ligament (ACL) reconstruction were developed. The anterior tibial translations for the anterior drawer test and the internal tibial rotation for the pivot shift test were investigated according to variation of bundle diameters and attachment points. For the model in this study, the knee kinematics after the double bundle ACL reconstruction were dependent on the attachment point and not much influenced by the bundle diameter although larger sized anterior-medial bundles provided increased stability in the knee joint. Therefore, in the clinical setting, the bundle attachment point needs to be considered prior to the bundle diameter, and the current selection method of graft diameters for both bundles appears justified.

    How Multibody Dynamics Simulation Technology is Used

    RecurDyn provides nonlinear force entities to model tissues such as ligaments, as well as contact modeling capabilities needed to simulate the movement of ligaments around bone and cartilage boundaries.

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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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