Experimental and Numerical Investigation on the Damage Mechanism of Inter-Stage Bolted Flange Connecting Structure

A series of damage tests and numerical simulation were carried out on inter-stage bolted flange connecting structure of missiles (rocket) under the action of horizontal abnormal overload, and the following results were obtained: (1) damage mechanism of connecting structure under abnormal external load; (2) an effective numerical modeling approach for its damage simulation. To be specific, the four specimens assembled with M5 bolts, shear pins, buffer blocks and column sections were simplified according to the structural characteristics of actual missiles, and then repeated tests were conducted twice under quasi-static and impact conditions, respectively. An innovative bolt response signal acquisition sensor was modified and manufactured based on the idea of indirect measurement. In addition, the damage mechanism of the inter-stage connecting structure is systematically studied for the first time. The M5 bolted flanged structure exhibits the stage damage characteristics of the sequential failure mode under transverse loads, however, in the quasi-static case, a more pronounced gradient effect is additionally captured. The test results show that the combined force of prying effect and impact-shear effect of flange is observed in a single screw under impact load, and the bolt assembly, respectively, presents shear-bending coupling mode and stretch-bending coupling mode under impact conditions and quasi-static conditions. Furthermore, the numerical simulation of the failure process is provided at a component level. Finally, the damage performance and mechanism of a M6 bolted flange connecting structure are studied by numerical analysis, which shows that the finite element method can effectively solve the problem of study on parameter sensitivity.