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Research

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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In Manufacturing, Multibody Dynamics, Research

Concept for a self-correcting sheet metal bending operation

Concept for a self-correcting sheet metal bending operation

U. Damerow, D. Tabakajew, M. Borzykh, W. Schaermann, W. Homberg, A. Trachtler, Procedia Technology, 2014, Volume 15, pp 439-446.

Abstract

Geometrical deviations can appear in the production of plug contacts used in electrical connection technology and in fittings for the furniture industry. The reasons for this can be a variation in the properties of the semi-finished product, or wear phenomena on the forming machine itself or on the bending tools. When geometrical deviations appear, the process parameters normally have to be adjusted manually. Finding the most appropriate process parameters is currently done manually and is thus very time consuming. In order to reduce the scrap rate and the setup time for production scenarios, a concept for self-correcting bending operations is being developed using the V-model of the VDI guideline 2206. In this case, the V-model will make it possible to set up a self-correcting control strategy consisting of a closed-loop control approach, measurement devices and actuators. Having implemented these components in the forming machines, it will be possible to recognize geometrical deviations automatically and to take corrective action during production, aiming at a reduction of the scrap rate and setup-time.

How Multibody Dynamics Simulation Technology is Used

RecurDyn was used to simulate sheet metal bending operations. A RecurDyn model has a major advantage over traditional FEA models when it comes to designing a control strategy for bending operations. RecurDyn simulations can determine what corrective actions need to be taken when geometrical deviations appear.

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In Research, Tracked Vehicles General, Tracked Vehicles Robots

Design, simulation and manufacturing of a tracked robot for nuclear accidents

Design, simulation and manufacturing of a tracked robot for nuclear accidents

Jie Ma, Jun Luo, Huayan Pu, Yan Peng, Shaorong Xie, Jason Gu, Robotics and Biomimetics (ROBIO) IEEE International Conference, Nyeon, December 2014, pp 1828-1833.

In Biomechanics, Multibody Dynamics, Research

Surface Modification and Software Design of Customized Knee Joint

Surface Modification and Software Design of Customized Knee Joint

Chin YU Wang, Chien Fen Huang, Yi-Lin Liou, Life Science Journal, December 2014, Volume 11, Number 12, Article 137.

Abstract

This paper used the medical image of a patient’s knee joint as basis to assemble a complete human knee through geometric software. Because this model can’t precisely align the position, local contact will occur which would cause stress concentration. It should undergo the tension adjustment of the ligaments to adjust the relative positions of the cartilage of the femoral condyle, the meniscus and the femoral cartilage to the minimal relative position of the contact stress to comply with the lowest energy or stress allowed by the law of nature for our body needs. First, this study used the spring simulation in the ligament tension and used the software, RecurDyn, to find the relative position of the minimum contact stress of the knee system. Second, the customized man-made knee was imported in the biomechanical software called LifeMod to build muscles and the ligaments system to simulate the ligament tensions of the artificial knee under a variety of sports. Aside from being the basis for the spring coefficient setting of the human knee, the tension can also select the specific posture of the knee in the model and then convert it into a file of ANSYS stress analysis software to complete a more accurate stress analysis. Finally, we can retest the human and artificial knee joints under different postures in the above steps to know the changes in the patterns between contact stress and contact area to obtain customized artificial knee prosthesis closest to the patient’s original human knee joints. The concept is the same if the original denture tooth shape is kept, we can be able to organize the most stable and compatible peripherals, prolong the life of the prosthesis and reduce its possibility of loosening.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to perform dynamic simulation of an artificial knee. The geometry of the artificial knee is imported into RecurDyn from a CAD program. Accurate data from physical testing can be limited and difficult to obtain. RecurDyn provides an easy way to test if design parameters are within an acceptable performance range.

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