Papers by Keyword: Multibody System

Abstract: The aim of this paper is to develop computer simulation model of railway vehicle using multibody system (MBS) package. ADAMS/Rail was used in modeling and simulating complex realistic railway vehicle system to study their dynamics response to curve and straight track inputs. The Malaya Railway Limited or Keretapi Tanah Melayu Berhad (KTMB) railway vehicle is used as reference model to develop computer simulation model in ADAMS/rail. Curve track input was based on KTMB rail network with maximum curve radius of 1000 m. Straight track input with random vertical irregularity was applied to the 1000 m track to evaluate the vehicle behavior response to track vertical roughness. The results show the roll angle, lateral and vertical acceleration of the carbody was increases with the increases of vehicle speed.

Abstract: In this work, the re-design of the camfollower mechanism of an industrial cutting file machine is presented. The actual mechanical system includes a forceclosure cam mechanism, which requires an external force to keep the contact between the cam and the follower provided by a spring. This system is substituted by a new cam mechanism of the type of formclosure, which does not require external force. The formclosure camfollower mechanism, also called positive-return cam mechanism, guarantees that the cam surface is always in contact with the follower surface, and is characterized by having constantbreadth. Classical Mechanic Theory performs the study of the kinematic and dynamic characteristics of the cam mechanism analyzed throughout this work. Furthermore, a commercial package software was used to create a virtual model and analyze the motion characteristics of the new cam mechanism.

Abstract: The hybrid simulation method based on Multibody Simulation (MBS) and finite element method (FEM) were proposed here and applied to study the relation between carbody structure vibration behaviors and structure fatigue strength characteristic. The detailed steps include: Firstly, rigid-flexible couple vehicle multibody system dynamic model was created and performed to obtain the load time histories corresponded to the typical load cases. Secondly, the carbody structure stresses was calculated through Finite Element (FE) quasi-static stress method. Finally, with the material fatigue property and some uncertainty factors, carbody fatigue damage distribution and life was calculated and evaluated. And the conclusions can be understood that the mechanism between the full vehicle dynamic property and structure damage distribution. The results are also shown that the hybrid simulation technology could be applied into the carbody structure fatigue design.

Abstract: According to engineering requirements, structure of multibody systems would change and lead to obvious modifications in dynamics model obtained by traditional methods. In this paper, an existing method for rigid body systems with changing structures is extended to systems with flexible appendages, which is more common in engineering. Application of the new generalized approach to a typical 4-body system is actualized. Numerical simulation is carried out and results are the same as theoretical analysis, which indicate the availability and applicability of the new approach.

Abstract: As a main handling device the portal crane is widely used in port, railroad, etc.The crane handling procedure is mainly carried out through its combined-boom system luffing or swing .In general, in order to reduce drive power and improve the operational performance, the luffing trajectory should meet the design requirement. At the same time, structure stress should be secured in the whole process of handling the cargo. Recently, to deal with more heaver and further cargo, the portal crane is becoming more large-scale. So that the large-scale components such as jib elastic deformation effect on large displacement motion cannot be ignored longer. In addition to the structure high speed motion in the process of handling also make the structure dynamic behaviors spending more obvious specially in the condition of luffing combined with swing. However, the problem for this dynamic behavior brings about to physical design sometimes has no method to solve according to the conventional analysis algorithm and dynamics method. To reduce the deviation caused by the common analysis, design and analysis method based on the multibody is put forward in this thesis. According to the method, the result on the luffing trajectory and stress-time history are analyzed easily. So that it ensure the efficiency and increase the accuracy of the initial design according to the conventional design and analysis method.

Abstract: The theoretical and computational aspects of interval methodology based on Chebyshev polynomials for modeling multibody dynamic systems in the presence of parametric uncertainties are proposed, where the uncertain parameters are modeled by uncertain-but-bounded interval variables which only need the bounds of uncertain parameters, not necessarily knowing the probabilistic distribution. The Chebyshev inclusion function which employs the truncated Chevbyshev series expansion to approximate the original function is proposed. Based on Chebyshev inclusion function, the algorithm for solving the nonlinear equations with interval parameters is proposed. Combining the HHT-I3 method, this algorithm is used to calculate the multibody systems dynamic response which is governed by differential algebraic equations (DAEs). A numerical example that is a slider-crank with uncertain parameters is presented, which shows that the novel methodology can control the overestimation effectively and is computationally faster than the scanning method.

Abstract: In this paper, the concept and application of virtual prototype technology are simply introduced, and analyses the veracity program in course of complex multi-body system simulation. The rigid-flexible couple virtual prototype model of complex multi-body system including collision is built, and the veracity of virtual prototype simulation is evaluated combining limited test data. Updating some typical system parameters by sensitivity method and perturbation method, it makes the simulation results have better consistency with test results, and improves the simulation precision of virtual prototype model.

Abstract: The aim of this work is to implement a new nondestructive testing (NDT) method based on the metal magnetic memory (MMM) effect into comprehensive diagnostic approach for power-line connectors, which is of great practical importance. Essence of this method lies in detection of stress concentration zones (SCZs) in material of the considered element during its operation (before micro-cracks and fracture occurs). If to compare with the traditional NDT methods, which indicate SCZs after the failure (post factum), this method provides major progress in the field of NDT. In this paper an approach of connection of numerical structural simulation (static and dynamic) with MMM-based testing method is also proposed. SCZs in power-line mechanical connector were evaluated and dynamic analysis of a complete power line, which included the analyzed connector, was carried out by means of MSC.ADAMS. Uniqueness of this analysis consist in integration of FEM analysis, MSC.ADAMS multibody system analysis (for testing of working conditions in advance - during virtual prototyping) and verification using MMM method. This hybrid approach enables to accomplish diagnostic analysis of selected construction elements and provides the possibility to take into consideration actual working conditions (e.g. vibrations) of the element. Proposed diagnostics method can substantially increase operational safety of electrical connectors and lines.

Abstract: Up to now a coherence between pain and technical systems has almost not been researched. Whereas some aspects of the nociceptive pain which serves human beings as a warning system and is also described as useful, can be transferred necessarily to technical systems. The idea of pain detection is an additional product of the Mesoscopic Particle Method [2-4]. Thereby the transformation of kinetic energy into heat energy caused by impact- and friction processes in the boundary layer of contact areas is described correctly with respect to thermodynamics. Between the properties of pain and heat there obviously exist analogies. Pain increases when certain external effects get higher and decreases smoothly, when the effect is taken off [5]. Generally pain is a vector of different phenomena. By means of the developed sensor concept the application of energy is detected including implicit frequency selective information about the jerk. It will experimentally and numerically be shown how e. g. a “hard-soft-detection” of surfaces can be evaluated by the developed sensor concept.