The Research For Coupled Dynamics Of High Speed Rocket Sled-Track Systems

The coupled dynamics of high speed rocket sled-track system is researched in detail, which is one type of large ground equipments between indoor and outdoor test. The irregularity of high precision test track and its influences on rocket sled are studied firstly. Then the general models are established for rocket sled-track coupled nonlinear dynamics, which are derived from dynamics theories. The computation software RSTdyn (Rocket Sled-Track dynamics) for rocket sled-track coupled dynamics is developed on object oriented technique. The getparms methods, system coupled dynamics models and computation codes are validated. Finally the coupled dynamics are applied to one monorail rocket sled-track system. The main works are as follows:(1) According as the method of track random irregularity analysis, the USA HHSTT track testing random irregularity Power Spectrum Density (PSD) curves are processed using C++ to gain the high precision track PSD functions and parameters by Particle Swarm Optimization method. The influences of track short range irregularities to sled are theoretically analyzed by velocity method and motion method; the PSD dimension method is put forward for long range rail irregularities affecting sled; the results of three methods are compared. These researches show that: the high precision track irregularities have clearer high frequent character, smaller irregularity amplitude, more concentrative high frequent powers and better regularity; with rocket sled velocity increasing, the long and short range irregularity magnitudes are smaller, the wave lengths are longer, the track precisions are higher, which are needed by track; rocket sled design should avoid the disturber of track high frequent short wave.(2) On the basis of rocket sled moving on track process, the dynamics coordinates are established for rocket sled-track system by relative coordinate method and transformed by direction cosine matrix. The mechanical analyses are carried out for rocket sled, rail and rail sleep by vector mechanics Newton-Euler method. The general models of rocket sled coupled track dynamics are derived by dynamics theories, which consider the nonlinear factors such as aerodynamics, ground winds, rocket thrusts, collision contact forces, impact braking forces and gaps of sled shoes to rail. The mathematical equations of dynamics are gained by the types of vector, matrix and scalar, which support the computation of the rocket sled-track system dynamical responses.(3) Based on the rocket sled-track coupled dynamics model, the dynamics computation codes are developed by object oriented Visual C++6.0, which solves the equations using self-adaption step algorithm of Runge-Kutta-Fehlber. The rocket motor thrusts model, track irregularity samples reconstruction method of Blackman-Tukey (B-T), sled aerodynamics coefficient obtaining method of computation fluid dynamics (CFD), getparms method of finite element analysis (FEA) for sled shoes impacting to rail, system coupled dynamics model and RSTdyn codes are validated by analysis and test results of existing rocket sled-track system. These researches show that:the dynamics model, getparms methods and codes have well reliability and credibility, which can be used in new rocket sled-track system analysis and design.(4) The dynamical responses of a certain monorail rocket sled-track system are gained by rocket sled-track coupled dynamics models and RSTdyn codes. The relative radius vector, velocity, acceleration of rocket sled centroid and inertia moments are formulated by rocket motor charge geometric burning law. The parameters of monorail rocket sled-track system are obtained by CAD, FEA, CFD and B-T methods. Then the dynamics results of sled and track are achieved such as accelerations, velocities, displacements and contact forces, which are compared with other methods'results. The parameters of shoe-rail gaps, track irregularities and ground winds are analyzed with the influences to system responses. Finally the dynamical characters of sled-track are analyzed with those results and relative dynamics laws are obtained. These researches show that:when sled runs under lower velocity, sled's vibration presents low frequency and weakens as its velocity increases; but when sled runs under higher velocity, its vibration presents high frequency and enhances with sled velocity arguments; the rail and sleep of track vibrate high frequently and enhance with its velocity grows; the dynamical contact forces are smaller than the quasi-static contact forces because of track's damping and sled designed by quasi-static method has higher safety factors, so the sled can be optimized to reduce weight hereunder; sled design should avoid the dynamical high frequent vibration, which is similar with the conclusion of track PSD dimension method; the gaps of shoe-rail and track irregularities affect the dynamical responses seriously, which should be chosen as proper values that match the sled-track during system design; ground winds have little influences to system and can be ignored.The methods and results can meet the demand of rocket sled-track design and analysis. These researches enhance the cognition to the ground equipment sof rocket sled-track system. The achievements are applied to the engineering prototype developments.