Fatigue analysis of the main frame of over head transportation vehicles using flexible multibody dynamics

The industrial over head transportation vehicle is a guided railway vehicle that is attached overhead and transports cargo, hoisting it up and down from the factory ceiling. The vehicle is widely used in many industries, such as automobile and liquid crystal display (LCD), because it can carry freight very safely and quickly to destinations. This kind of freight transportation usually operates for several months to a few years, carrying large amounts of products. Accidently, the vehicle often fails during operation because of a part’s plastic deformation from large loads. Furthermore, periodic dynamic loads cause fatigue accumulation, which leads to OHT failure. This failure is directly connected to significant economic loss during mass production processes. Therefore, the prediction of fatigue life for the important parts becomes an important task. In this study, the fatigue life of an OHT main frame was calculated and predicted by using a flexible multibody dynamic model. The development of a flexible multibody dynamic model and the procedure of fatigue life prediction were presented. To predict the fatigue lives of parts of interest, the prediction procedure required three kinds of data: Dynamic stress time history from a dynamic analysis, material properties of the parts, and stress-life curves of the parts. Using a finite element model and a multibody model, a flexible multibody model was developed. To ensure the reliability of the model, displacement and strain measurement tests were conducted. After verification of the reliability, the fatigue life of the main frame was predicted.     

Analysis of vehicle rollover using multibody dynamics

This study reports on the analysis of vehicle deformation due to rollover using multi-body dynamics which enables estimating motions of rigid bodies subjected to external forces. For the vehicle rollover analysis using the ADAMS, we have developed a FEA-based numerical vehicle model consisting of a rigid lower body and a deformable upper body. Here, comprehensive analysis of the static and dynamic roof strength resistance of a vehicle using our prediction model is described. We obtain the displacement of A-pillar top-end of a vehicle for each of the static and dynamic tests according to the FMVSS 216 protocol and the Controlled rollover impact system (CRIS) condition, respectively. The displacement of A-pillar top-end represents the roof intrusion causing injuries for passengers in the front seats, thereby evaluating the Strength to weight ratio (SWR) of a vehicle.

     

Chute design of mackerel automatic grader using multibody dynamics

An automatic mackerel grader is a machine that automatically sorts mackerel according to size. The chute spreads the mackerel to allow the latter to enter each roller evenly. Sorting is simulated to confirm that the multibody dynamics model of the automatic grader correctly sorts the mackerel. This process is completed according to the shape of the chute to confirm the effect on performance. A new shape of the chute and the application are proposed and evaluated by a comparison with conventional chute shapes. RecurDyn, a multi-body dynamics program, is used for the sorting simulation. The contact parameters are defined by Hertzian contact theory using the material information of mackerel and C/S steel. A rigid-body mackerel model is used to express the behavior of mackerel. Sorting is simulated for each shape. The sorting accuracy and error of the new shape are compared with those of two existing shapes. The new shape shows a 0.29 mm sorting error and better sorting accuracy than the existing shapes.     

Investigation of in-train stability and safety assessment for railway vehicles during braking

In-train stability of railway vehicles has becoming a major concern for railway vehicles, which refers to the jackknifing behavior of couplers under large in-train forces. For the train to train rescue scenario, braking induced impacts from couplers can adversely affect the dynamic performance of the coupled train. It is indicated from field tests that in-train forces if combined with large rotational angles of couplers can produce vertical components, which will further lead to the interference of adjacent carbodies and structural damages. In this paper, the dynamic model of the train and coupler system is developed. The model verifications are conducted by comparing the calculated responses with the tested results. The safety indices are formulated on the basis of which the running safety of the coupled train is evaluated. The propelling test in the laboratory is conducted to reproduce the coupler jackknifing behavior. The quasi-static analysis and anti-jackknifing mechanism under compressing in-train forces are analysed. Parametric studies are then conducted to propose some limitations for the application of train to train rescue. It is indicated from numerical and testing results that the decrease of the braking deceleration or a limitation of the free rotational angle of couplers is beneficial to lower the amplitude of braking induced impacts.     

Fatigue life analysis of wheels on guideway vehicle using multibody dynamics

A guideway vehicle is used in automobile, semiconductor and LCD manufacturing industries to transport products efficiently. Since the operating speed of the guideway vehicle should be increased for maximum productivity, the weight of the vehicle has to be reduced, and this weight reduction may cause a failure of a part in the system. Therefore, the estimation of the fatigue life of the parts becomes an important problem. In this study, the fatigue life of the wheels in the guideway vehicle is estimated using an S-N curve. To obtain the fatigue life of a part, the S-N curve, the dynamic stress time history applied to the part, and the material property of the part are required. The S-N curve of the driving wheel is obtained from the fatigue experiment on wheels. To obtain the material properties of the driving wheel, which is composed of aluminum with urethane coating, the result of a compression hardware test and static analysis of the wheel’s FE model are used. The dynamic stress time history influencing the driving wheel can be obtained from linear superposition of the dynamic load time history and the static stress. The dynamic load time history is estimated by multibody dynamic analysis, and the static stress is obtained by finite element analysis.     

Recent developments in multibody dynamics

Multibody system dynamics is based on classical mechanics and its engineering applications originating from mechanisms, gyioscopes, satellites and robots to biomechanics Multibody system dynamics is characterized by algorithms or formalisms, respectively, ready for computer implementation As a result simulation and animation are most convenient Recent developments in multibody dynamics are identified as elastic or flexible systems, respectively, contact and impact problems, and actively controlled systems Based on the history and recent activities in multibody dynamics, recursive algorithms are introduced and methods for dynamical analysis are presented Linear and nonlinear engineering systems are analyzed by matrix methods, nonlinear dynamics approaches and simulation techniques Applications are shown from low frequency vehicles dynamics including comfort and safety requirements to high frequency structural vibrations generating noise and sound, and from controlled limit cycLes of mechanisms to penodic nonlinear oscillations of biped walkers The fields of application are steadily increasing, in particular as multibody dynamics is considered as the basis of mechatronics     

Vehicle dynamics analysis of a heavy-duty commercial vehicle by using multibody simulation methods

In this paper, the computer-aided vehicle dynamics analysis of a 6?×?2 heavy-duty commercial vehicle is examined. For the analysis, Mechanical Simulation Corporation's TruckSim multibody dynamics simulation and SuspensionSim multibody statics simulation softwares are used. The aim of this study is to design and model the front suspension and tandem rear axle suspensions, compose the full-vehicle model representing the real-life vehicle, and examine the dynamic behavior of this model. The models related to the front and rear suspensions are prepared and solved in SuspensionSim and the solutions are imported thereafter to TruckSim. The full-vehicle model excluding the suspension system is formed by using TruckSim. The simulation scenarios, runs of which are made to observe the effects of different parameters concerning the dynamic behavior of the full-vehicle model, are also prepared in TruckSim environment.     

Integrated modeling and simulation of vehicle and human multi-body dynamics for comfort assessment in railway vehicles

An integrated vehicle-biodynamic model is developed in this article by using multi-domain energy domain bond graph model simulation and multi-body simulation software ADAMS VI-Rail. These models are specifically used to evaluate passenger ride comfort in a railway vehicle where vertical and lateral excitations at the wheels arise out of the track irregularities. In the bond graph model, the carbody of the railway vehicle is treated as an Euler-Bernoulli beam and its first five modes are included in the model. Thereafter, a detailed model of the railway vehicle is created in ADAMS VI-Rail. The International Organization for Standardization (ISO) 2631 specification is used to determine the passenger comfort for different travel durations and track irregularities.     

A relative contact formulation for multibody system dynamics

Dynamic analysis of many mechanical systems is often involved with contacts among bodies. This paper presents a relative contact formulation for multibody dynamics in the context of the compliance contact model. Many conventional collision detection algorithms are based on the absolute coordinate system. This paper proposes to use the relative coordinate system in detecting a contact. A contact reference frame is defined on the defense body of a contact pair. Since all geometric variables necessary to detect a contact are measured relative to the contact reference frame attached to the defense body, the variables for a defense body are constant, which significantly reduces computation time. Therefore, the contact frame plays a key role in developing an efficient contact search algorithm. Contour of a defense body is approximated by many piecewise straight lines, while contour of a hitting body is represented by hitting nodes along its boundary. Bounding boxes containing each body of a contact pair are defined at a pre-search stage to eliminate the exhaustive contact inspection process when two bodies are in a distance. Domain of the bounding box for a defense body is divided into many sectors each of which has a list of line segments lying inside or on the sector boundary. Post-search for a contact is processed in the sequence of broad and narrow phases. In the broad phase, the bounding boxes of a contact pair are inspected for a contact. If two boxes are in a contact, each node on the hitting boundary is inspected to find out to which sector the node belongs. Since each domain sector of the defense body has a list of line segments, each node on the hitting boundary is tested for a contact only with the line segments in the list. In the narrow phase, actual contact calculation is carried out to find the contact penetration used in calculating the contact force. Since the searching algorithm is coupled with the stepping algorithm of the numerical integration, a strategy for deciding an integration stepsize is proposed. One numerical example is presented to demonstrate the validity of the proposed method.     

铁路车辆轮对检测技术综述

车轮对作为铁路车辆重要的走行部件,对于铁路的安全运输起着关键性的作用.因此准确的检测车轮的磨耗状况是非常重要的.本文从静态和动态检测两方面介绍铁路车辆轮对检测技术状况,简述了相关检测装置的原理及其优缺点.     

Subsystem synthesis methods with independent coordinates for real-time multibody dynamics

For real time dynamic simulation, two different subsystem synthesis methods with independent generalized coordinates have been developed and compared In each formulation, the subsystem equations of motion are generated in terms of independent generalized coordinates The first formulation is based on the relative Cartesian coordinates with respect to moving subsystem base body The second foimulation is based on the relative joint coordinates using recursive formulation Computational efficiency of the formulations has been compared theoretically by the arithmetic operational counts In order to verify real-time capability of the formulations, bump run simulations of a quarter car model with SLA suspension subsystem have been carried out to measure the actual CPU time     

The thermo-mechanical behavior of brake discs for high-speed railway vehicles

Journal of Mechanical Science and Technology - The structure of a brake disc is coupled to the axle and rotates together with the wheel. A brake disc is a friction-type device that presses the pad...     

Influence of hexapod robot foot shape on sinking considering multibody dynamics

Journal of Mechanical Science and Technology - Hexapod robots have attracted attention for their excellent terrain adaptabilities. When a robot walks on soft soil, dynamic subsidence and slippage...     

Turning dynamics and equilibrium of two-wheeled vehicles

The equations of motion of two-wheeled vehicles, e g bicycles or motorcycles, are developed by using Lagrange’s equations for quasi-coord mates The pure rolling constiatnts between the ground and the two wheels aie considered in the dynamical equations of the system For each wheel, two nonholonomic and two holonomic constraints are introduced in a set of differential-algebraic equations (DAE) The constraint Jacobian matrix is obtained by collecting all the constraint equations and converting them into the velocity form Equilibrium, an algorithm for searching for equilibrium points of two-wheeled vehicles and the associated problems are discussed Formulae foi calculating the radii of curvatures of ground-wheel contact paths and the reference point are also given     

多体动力学的三轮摩托车动态特性研究

为了获得三轮摩托车人-车系统在振动载荷下的各项动态特性指标,基于多体动力学理论,对整个系统的固有频率、模态振型、加速特性和制动特性进行研究,得到系统在各状态下的性能指标,并对研究结果进行评价,为整车开发和优化设计提供了参考指标。     

Integrated control strategies for railway vehicles with independently-driven wheel motors

This paper studies the development of integrated control strategies for railway vehicles with independently-driven wheel motors. First, a non-linear vehicle dynamic model and motor drive strategy are presented, which are followed by an investigation of the integrated control of stabilization, steering, and traction for the vehicle. Meanwhile a reformulated Kalman filter is developed and applied to estimate the required feedback by the control system. Finally, the effectiveness and practicality of the proposed integrated controller are examined and assessed by real-time simulation based on host-target computer technology provided by Matlab/Simulink. __________ Translated from Control and Decision, 2007, 22(8): 864–868 [译自:控制与决策]     

Integrated control strategies for railway vehicles with independently-driven wheel motors

This paper studies the development of integrated control strategies for railway vehicles with independently-driven wheel motors. First, a non-linear vehicle dynamic model and motor drive strategy are presented, which are followed by an investigation of the integrated control of stabilization, steering, and traction for the vehicle. Meanwhile a reformulated Kalman filter is developed and applied to estimate the required feedback by the control system. Finally, the effectiveness and practicality of the proposed integrated controller are examined and assessed by real-time simulation based on host-target computer technology provided by Matlab/Simulink.     

基于ADAMS的铁道车辆脱轨后动态行为分析

采用ADAMS仿真软件建立了脱轨前的车辆系统动力学轮轨接触模型和脱轨后的多刚体接触碰撞模型来研究制动盘对铁道车辆脱轨后运行行为的影响。为了真实地模拟车辆脱轨后的运行行为和接触力,接触模型包含车轮-轨道板和制动盘-钢轨两对接触,设置了合理的接触参数并使用了真实的三维几何外形和非线性接触算法。仿真结果表明,制动盘在车辆脱轨后与钢轨发生了连续的接触碰撞,可以抑制脱轨车辆进一步脱离线路。     

柔性多体系统动力学理论应用于轧制工业的综述

结合轧制工业的发展现状及柔性多体系统动力学的理论成果,从轧机设备的设计、改造、过程控制、系统特性、接触-碰撞问题的建模、轧制过程中多领域集成化、多体动力学软件的发展等几个方面阐述了将柔性多体系统动力学理论应用于轧制工业的可行性和必要性.     

自动化立体库在铁路机车车辆检修中的应用

自动化立体库在现代工业得到了广泛应用。随着中国铁路的快速发展,自动化立体库逐步应用于铁路机车车辆检修环节中。本文汇总了铁路机车车辆检修过程中立体库的需求种类和应用的环节及对象,重点说明了特定物品存放的立体库,如转向架库、轮对库、轴承库等。