Analysis of the rocket sled boot and rails impact response characteristics

Abstract During rocket sled testing, the collision impact between the rocket sled boot and rails is the primary cause of high overload on the sled and slide rail. To analyze the response characteristics of the slide rail under impact loads, a finite element model of the slide rail was initially established using three-dimensional Euler-Bernoulli beam elements. Based on the actual support conditions of the fasteners in the slide rail, the corresponding nodes were subjected to a degree of freedom constraints and equivalent stiffness constraints. By comparing the measured natural frequency of the slide rail with the modal frequency of the finite element model, the equivalent constraint stiffness at the slide rail fastener was determined. Subsequently, transient analysis was conducted on the slide rail at various impact positions under impact loads. The results indicated that the closer the impact position was to the fastener, the smaller the acceleration response of the slide rail. By analyzing the RMS value of acceleration response, it was found that the average attenuation rate of vibration was 28.3 % when a fastener was spaced 1m apart in the slide rail. When the two sliding boots of the rocket sled make contact with and impact the track sequentially, and the interval frequency is close to the first-order modal frequency of the slide rail, the acceleration response of the slide rail reaches its maximum.