Stress Analysis And Strength Assessment Of Wedged-ring Connection Structure

Wedged-ring connection has some advantages, such as making structure surface smooth, making structure compact, reducing additional mass and disassembling conveniently. Thus, Wedged-ring connection is widely used in shell connection of torpedo and rocket. Wedged-ring connection structure is multi-body combined structure with components contacting and frictionating each other, which is composed of two shells and a pair of wedged rings.The criteria of strength assessment and analytic solution of stress play important roles in the design of wedged-ring connection structure. Thus, using theoretical analysis, finite element method and experimental approach, this paper studies the strength and stiffness variability of the structure due to local yielding, then analyzes the limit tensile load of the structure, discusses the criteria of strength assessment and failure mode of the structure, and researches the analytic solution of stress of wedged-ring connection structure.The main results include:(a) Wedged-ring connection structure under tensile loading is analyzed by elastic-plastic finite element method. The results show that the yielding process starts from local line yielding to inner surface yielding of ring slot, and finally to outer surface yielding of ring slot. Initial local yielding does not influence the strength and stiffness of wedged-ring connection structure.(b) Based on double elastic-slope method and tangent-intersection method, the limit tensile loads of wedged-ring connection structure are obtained from the load-displacement and load-strain curves of characteristic points.(c) Membrane stress, bending stress and non-linear stress of weak cross section are calculated by using Kroenke method under tensile loading, then the strength of wedged-ring connection structure under the tensile loading is evaluated based on stress-classification assessment method.(d) Based on one-point stress assessment, limit load design method and stress-classification assessment method, different allowable tensile loads of wedged-ring connection structure are calculated. The maximum value of allowable tensile load is obtained by limit load design method, and the minimum value of that is obtained by one-point stress assessment method.(e) The mechanics model of wedged-ring connection structure under tensile loading is established in this paper. It is assumed the connected shell is composed of two elastic rings, a short and a long cylindrical shell. Then, a set of equations for solving exact inner force ofcross section are deduced using force method. When the ring slot is long, the simplified solution of inner force is discussed in this paper. Then, the analytic solution of stress is verified by numerical result. Finally, through analytic solution, the variation of outer shell stress with geometric sizes is quantitatively analyzed, and the application condition of simplified solution is also discussed.