| With the increasing speed of trains, studying the dynamic characteristics at high speed crash behavior of the train has important significance to estimate possible collision accident and then minimize the casualties in the train crash accident.It urgently need to evaluate and test the train collision passive safety performance from the perspective of theoretical method and experimental device.In this paper, based on the purpose of improve railway locomotive vehicle passive safety, it has developed a drive systems used to the train collision test.Focus on solving the dynamic load equipment ejection technology of test system in full size conditions, the study mainly involves airbag stretch catapult theory, air bag inflated stretch propel dynamics, airbag configuration and mixed catapult, numerical simulation of multi-dimensional airbag catapult, application of airbag catapult system in the train crash tests, airbag catapult experiment, etc.1.On the basis of the general train collision experimental methods and experimental device, the method that utilizing the release energy of compressed gas inflation in the air-bag and the elongation of air bag to solve the propelling energy problem of train collision experiment was proposed.Utilizing the elongation characteristic of air bag moving boundary to change boundary conditions of traditional cylinder compressed air energy release, thus the traditional rigid boundary constraint was expanded to dynamic stretchable boundary constraints.The uniform pressure control model, fluid-structure model and contacting impact model of flexible boundary constraints were studied.Combining the theory of air bag ejection drive, give out the constant mass model, constant pressure model, constant flow model and controlled equations of ejection process.These can lay the foundation for the air bag inflated stretch propel apply to train collision test bench.2.The structural characteristics of the airbag and its relationship with drive capability and the organization form of multidimensional of air bag ejection drive and study the influence of air bag series and parallel structure on airbag performance and guide the way were studied.Obtain that when the mass of the moving object is constant, a certain speed can be reached through configuring different number of series air bags, or make different air bags in parallel connection or series and parallel combinations.Based on air bag inflated stretch propel, the hybrid ejection acceleration method and system was put forward and give out the energy equations of first-order gasbag catapult and the second-order air bag, outer cylinder hybrid catapult.The results show:compared to the energy obtained from first-order gasbag catapult, the energy obtained from the second-order mixed ejection is more than 1.5 times.The catapult characteristics of the system have a great correlation with the volume expansion factor.And the greater the volume expansion factor is, the greater the propel ability of second-order mixed ejection.3.The characteristics of a moving object in the air bag catapult accelerated process and airbag ejection phase characteristic acceleration and expand numerical model were studied.Single inflatable balloon compression model catapult and the air bag three-dimensional catapult of simulation model were built.The GF150/298-3 rubber air bag catapult characteristics was analyzed.Through specific simulation example analysis, it obtained some characteristic parameter (such as speed, acceleration, energy, displacement and force, etc.) in the process of air bag inflated, stretch and propel.The results show:through changing the rigid wall constraint and blastability characteristics of the general cylinder when the compressed air releasing energy and utilize the variable boundary of air bag to adapt to the constraints wall self- stretch effect, it makes the high pressure gas push to do work in a large distances in the case of the constraint and without blasting.Movable objects contacts with the end portion of airbag in the acceleration process, thrust of airbag ends will fluctuate.And the fluctuate has otherness in the different phase of air bag inflated, stretch and propel, which can be decreased by increasing contact area between the air bag ends and the movable object or changing the geometry characteristic of the annular folded airbag, thus improve the system stability.The amount of energy that the movable objects obtained is associated with many factors, and the key factors are the operating distance, airbag inflation pressure, contact area.The more the number of folds annular folded airbag is designed to catapult the stronger it has the ability and energy.4.For high-speed, heavy-duty equipment ejection technical requirements, the basic principles of the train the ejection collision test bench, the system components and its scale model were studied.The results show:because energy is an important indicator of airbag catapult test bench which based on the airbag ejection, so the size of scaling model of train the ejection collision test bench has nothing to do with prototype size of train.According to the textile fabric burst performance test methods in GB/T 7742.1 2005, utilize MTS experimental system to do pneumatic test for fabrics used in air bag.Obtained that the failure pressure of air bag fabrics is 3MPa and airbag fabric work pressure can reach 2Mpa, so this kind of material can be applied to catapult experiment.A locking and safety releasing mechanism device for the movable vehicle was analyzed, and it solved the actual vehicle spacing and ejection stability control problem by using a new blocking valve with quick ejection system.Through analyzing the stability of the gasbag ejection system, it obtained: Along with the increase in air bag series, one dimension propel system is formed by the annular folded airbags, the swing of the air bag ends is also increased.Swing of the balloon can be controlled by the aspect ratio.It ensures the stability of the airbag ejection direction by using hanging guide and support-oriented approach.Methods can be used to improve the synchronization of multidimensional balloon catapult.5.It has studied the airbag collision experiment station test systems, pressure sensors, speed sensors, acceleration sensors, solenoid controller, high-speed photographic apparatus, the trigger controller were combined into a multiplex signal control system, it can achieve signal acquisition and control.By multiple regression analysising and experiment studying, the approximate function relation between test index speed and influencing factors was obtained.Gasbag ejection system by using GF150/298-3 and GF580/384-3 rubber capsule as air bag, which propel catapult ability has been carried on the forecast analysis.According to EN 15227 standard crash test requirements, in the case of 2MPa initial pressures, the 60? 70T heavy locomotive can be accelerated to 36km/h by using four standard airbags ?1000×2000 promote the formation of an array of parallel.In summary, the gasbag ejection acceleration method is suitable for high speed, overloaded locomotive vehicle passive safety performance test experiment platform.It can effectively promote the localization of locomotive vehicle passive safety testing equipment and promote the crash test technique upgrade.Methods of this paper, the results can promote the in-depth study of the passive safety of high-speed trains.It has a strong theoretical and practical significance for promoting the development of China's construction of rail transit and improve the safe operation of the train. |
PDF Full Text Request