Flexible joint has the most critical role in Thrust Vector Control (TVC) solid fuel rockets. In this paper, a new analytic method for calculation of stiffness of spherical Elastomer-Metal joint by the theory of linear elasticity and Velasof Kantorowicz analytic method is developed. Velasof Kantorowicz analytic method is based on cross displacement which is driven from bending equation. Then flexible joint is simulated by ABAQUS code under bending load when thrust vector angle is critical (i.e. 15 degrees). Seven different configurations of metal and rubber layers are considered. In each configuration, required bending is determined when thrust vector is 15 degrees and maximum stress is calculated. Based on these results best selection of elastomer material and stiffness is proposed. Finally, the results of analytical and those of simulation are compared which show good agreement. This comparison shows that the derived formula predicts stresses precisely. تفاصيل المقالة

Impact loading of free-free beam is of high interest to researchers as well as industry application. In this article a free-free beam subjected to concentrated impact loading is considered. Beam material is considered to be a rigid perfect plastic. Different combinations of loads, energy absorption and load location are considered. The result of the analysis show that when the load is less than critical load, the beam acts as a rigid body and when the load is greater than critical load three different mechanisms prevail. The result of the experiment is compared with analytical as well as simulation process using ABAQUS. The results of the compression are in good agreement with experimental investigation. تفاصيل المقالة

Successful development, evaluation, and qualification of propulsion systems such as turbojet and turbofan engines and rocket motors require the measurement of the performance and reliability of these systems. Thrust stands or testers are instruments for solid and liquid motors test. In this paper, a method for calculating of solid motors random vibrations effects on a thrust stand structure is developed. At first some Power Spectral Density (PSD) of three kinds of solid motors has been calculated by MATLAB codes. Then a typical thrust stand which has been designed based on special dynamics principles, has been modeled in Solidworks and transferred to ANSYS. In ANSYS, the structure has been analyzed modal and spectral. Then each motor's PSD has been applied on structure separately and maximum stress has been determined by ANSYS codes. Fallowed by structure fatigue life has been estimated by a formula derived from compound of Miner's cumulative fatigue damage ratio equation and Gaussian distribution curve. Results showed amount of PSD at first frequencies has more effect on structure fatigue life and just based on maximum motor thrust can not come to a definite conclusion about the vibrations effects. تفاصيل المقالة