Stiffness Of Car Body Research Articles

Ride analysis of railway vehicle considering rigidity and flexibility of the carbody

ABSTRACT In this paper, a twenty-one degrees of freedom mathematical model of a railway vehicle is formulated, considering its main components (i.e. carbody, bolster, bogie frame, and wheel axle) as rigid for the rigid body analysis of ride behavior of the vehicle. The ride comfort of the vehicle is analyzed and optimized using ISO 2631 criteria. Further, vertical flexibility of the carbody is accounted for with few modifications in the model, and the effect of vertical stiffness on ride behavior is analyzed and compared with a rigid carbody analysis using the Spering ride index. The carbody bending frequencies are investigated using the covariance method, and it is found that the reduction in stiffness of carbody beyond a specific frequency introduces significant carbody acceleration and declines the vehicle ride. The increased carbody bending frequencies can achieve higher vehicle speed and adequate isolation from track excitations.

Fatigue failure analysis of express freight sliding side covered wagon based on the rigid-flexibility model

PurposeThe car body stiffness of express freight sliding side covered wagon decreased for the sliding and the resonance vibration based on the flexible car body has affected the dynamics performances. Dynamic loading will cause fatigue cracks and eventually lead to fatigue failure of the car body. This paper aims to investigate the influence of car body flexibility on the evaluation of the failure.Design/methodology/approachIn this paper, the railway vehicles random analysis procedure (RVRAP) is employed to study the fatigue failure of the rigid-flexibility model. Following the analysis process, the rigid-flexibility model is established and four contrastive schemes for simulation analysis are designed. To verify the results, an experimental test using the real car body structure on the vibration test plant is carried out; the RMS of dynamic stress is obtained and compared with the simulation results.FindingsThe results show that the flexibility of the car body has a crucial influence on the fatigue life.Originality/valueThe reliability is verified regarding the use of RVRAP at an appropriate stage on the antifatigue design of the vehicle.

Experimental and analytic determining of the characteristics of deformation and side stiffness of a motor car body based on results of side-impact crash tests

Front-to-side collisions of motor vehicles very often occur on Polish roads. Every fourth road accident may be defined as a collision of this kind between moving vehicles. The analysis of accident effects, including the accident reconstruction process, is usually based on results of measurements of post-accident vehicle deformation and on information about vehicle body stiffness. Unfortunately, the information about the characteristic curves that would represent the deformation of a car body side is hardly available.The objective of this study is to present a method of determining the characteristics of deformation and side stiffness of a motor car body based on crash test results. This objective was pursued with using results of NHTSA crash tests and of crash tests carried out at PIMOT. The analysis covered herein has been based on crash tests representing front-to-side collisions of motor cars, motorcycle impact against a car side, and frontal impact of a car against a barrier. Based on a combined analysis of the course of such experiments, mathematical models have been built that describe the dynamics of the deformation process in the vehicle contact zone. The model calculation results obtained with using results of measurements carried out during the crash tests have been worked out with using the linear regression method.Based on the experimental and analytic methods, curves were plotted that represented the impact force as a function of the deformation of individual car bodies and then the characteristics of car body side deformation were determined. The range of this deformation and the hazard arising from the side impact to vehicle occupants were also shown. A special aspect of this hazard has also been unveiled by the calculation results, according to which the side stiffness of a car body decreases with growing deformation depth. In the initial deformation phase, this stiffness is even by 35 % higher in comparison with that observed when the vehicle body side is deformed by more than 20 cm.

Research on Dynamic Performance of Container Flat Car Body Based on the Car Body Stiffness

Research on Dynamic Performance of Container Flat Car Body Based on the Car Body Stiffness

Effect of train carbody’s parameters on vertical bending stiffness performance

Finite element analysis(FEA) and modal test are main methods to give the first-order vertical bending vibration frequency of train carbody at present, but they are inefficiency and waste plenty of time. Based on Timoshenko beam theory, the bending deformation, moment of inertia and shear deformation are considered. Carbody is divided into some parts with the same length, and it’s stiffness is calculated with series principle, it’s cross section area, moment of inertia and shear shape coefficient is equivalent by segment length, and the fimal corrected first-order vertical bending vibration frequency analytical formula is deduced. There are 6 simple carbodies and 1 real carbody as examples to test the formula, all analysis frequencies are very close to their FEA frequencies, and especially for the real carbody, the error between analysis and experiment frequency is 0.75%. Based on the analytic formula, sensitivity analysis of the real carbody’s design parameters is done, and some main parameters are found. The series principle of carbody stiffness is introduced into Timoshenko beam theory to deduce a formula, which can estimate the first-order vertical bending vibration frequency of carbody quickly without traditional FEA method and provide a reference to design engineers.

Analysis and Study of the Transmission Path Based on the Body and NVH

In the field of automotive engineering, noise and vibration in the car comes mainly from the engine and the road passed through the body, suspension, mount and exhaust system path to the car or reverberation. So this article , a model of white body transfer path analysis and research, improves the rigidity of white body, to reduce noise, vibration, and weight is reduced, and find out the resonance phenomena because of insufficient stiffness of car body, combining body CAE modal analysis results provide the theoretical basis for the optimization of structural damping.

Substitution of corrugated sheets in a railway vehicle's body structure by a multiple-requirement based selection process

To simplify construction, reduce weight and improve mechanical properties, a sandwich panel substitution process is performed on corrugated sheets in the floor and roof of a rail vehicle car body. A requirement based selection is used to design the sandwich panels with the corrugated sheet mechanical characteristics as boundaries. Car body stiffness is evaluated by modal analysis. The derived panels reduce the mass of the car body by 600–700 kg. Results show the varying importance of the longitudinal, transverse and shear properties of the floor and roof panels, as well as how efficient the corrugated sheets actually are.

2303 空気ばねによる鉄道車体の上下振動低減に関する研究(OS3-2 ビーグル制御,OS3 交通・物流システムの制御,オーガナイズド・セッション(OS))

Railway vehicles have been reduced the car body weight for energy-saving, noise-reducing and speed-up. However, it triggered the increase in a vertical vibration because stiffness of car body was reduced. Human being feel especially distasteful by frequency of the vibration, ride quality became worse. Therefore, Railway vehicles have actuator to control vertical vibration. And vertical vibration was reduced. But it cost more money and increase weight of car body to set up actuator on railway vehicles. So object of this study is to control vertical vibration by air spring which is secondary suspension of railway vehicles. And it is investigated with the vibration experiment to reduce elasticity vibration by controlling air spring.

Combinational Methods of Vehicle Frontal Crashworthiness Optimization Based on Conceptual Model

Through full factor analysis of the stiffness of the components which have potential influence on vehicle front impacts, through sensitivity analysis of vehicle front impacts using Linear Regression Method, the stiffness significantly affected the impacts are chosen as the optimization variables. The vehicle intrusion and the deceleration waveform of B pillar are weighted as the optimization objective. The Latin Hypercube Sampling Method is used to do sampling; a response surface of the calculation results is established using Kriging Method; the optimization is done using Method of Feasible Direction, finally the most optimal car body stiffness is determined, and which can provide the basis for frontal crash safety design of the electric vehicle.

Analysis on the Vertical Coupled Vibration between Bogies and Metro Car Body

With a vertical metro vehicle model including the flexibility of car body, the influences of car body stiffness and the coupled vibration between the metro vehicle flexible car body and bogie bounce mode are researched. Results show that the higher the car body stiffness is, the lower the influences of car body flexibility would be on the ride quality and it is the geometric filtering phenomenon rather than the bogie natural frequency of bounce mode that causes the car body resonant vibration. An example study shows that when the first bending frequency of the fully equipped metro vehicle coincides with that of bogie bounce mode, there will not have the resonant vibration of the flexible car body.

Influences of car body vertical flexibility on ride quality of passenger railway vehicles

To study the influences of carbody vertical stiffness on vehicle ride quality, a vertical model of railway passenger vehicles, which includes the carbody flexible effects and all vertical rigid modes, is built. With the model and the covariance method, the requirements for the carbody bending frequency are researched. The results show that when the stiffness of a carbody decreases to certain frequencies there are significant vibrations in the carbody, although structural damping provided by a fully equipped carbody will help attenuate the vibration to some extent. A simple way to avoid resonant vibration is to increase the bending frequencies of a carbody: the higher the vehicle running speed, the higher carbody stiffness could be required. However, there are practical limitations to such an increase and the method used in this study can readily obtain the lowest bending frequency required by vehicle ride quality. Finally, the geometric filtering phenomenon and its influences on the carbody resonant flexural vibration are analysed. Results show that it is this phenomenon rather than the natural vibrations of bogie bounce that most strongly influences the resonant flexural vibration of a railway carbody.