Studies Of Failure For Bolt Flange Connection Structure Under Transient Impact Load

Bolt-flange connection structure is widely used as separate connection structure of rocket and missiles etc.The connection structure is liable to failure under a large transient impact loads,which would result in rocket,missile launch failure,causing significant economic losses.The safety of the structure is very important.In this paper,for the possible transient failure of separate connection structure of rocket and missiles,the impact failure rule of bolt-flange connection structure is studied,to provide basis for structural design.The main research is as follows:1.The experimental scheme of the bolt-flange connection structure impact failure is designed,and experimental research is carried out.Based on the finite element analysis software ABAQUS,and the predecessors of bolt connection structure modeling ideas,three-dimensional finite element dynamic failure model,which include bolt pre-tightening force and can reflect the contact,slip,and separation of each contact surface,is set up.the numerical simulation results are in good agreement with the experimental data,which verifies the accuracy of the finite element analysis model.2.Based on the finite element analysis model,by changing the load condition,the failure characteristic of the connection structure under the transient loads of tensile,shear and bend is studied,and the characteristic that the actual bolt load is "partial load" is obtained;the change rule of the connection structure carrying capacity for the interactions under the load by tensile,shear and bending Composition is studied,and the "bending coupling self-locking characteristic" is obtained;According to the first order natural frequency of the structure,the failure process of the structure under different pulse width and peak load is studied,the dominant factor,the peak load,of structure failure is obtained.3.Based on the finite element analysis model,by changing the structural parameters,The influence of the structural strength,stiffness and failure process by changes,which from the pre-tightening force of the bolts,distribution of the bolts,the thickness of the flange,the stiffener of the flange and the clearance of the bolts and shear pin,is Studied.The rule,the influence of structure stiffness by the pre-tightening force is very small,and the influence of the bearing capacity of the structure by distribution(non-uniform or uniform)of the bolts is very small,and flange stiffeners can improve the rigidity and the shock resistance of structure greatly,and the changes of gap between the bolt and shear pin will affect local stress of the connection structure,is obtained.