Study on the Transient Response of a Stepped Column Subjected to an Impact Load

摘要

Dynamic buckling of structures has been studied in the fields of naval architecture and aerospace and civil engineering. Transient or impulsive loads that may exceed the critical static Euler limit also can be an important design consideration in these fields. In the case of warships and submarines, the design of structures to resist shock loads from hostile weapons or missile launching is important for the protection of the crew and the vessel. Because of that, many people have researched dynamic buckling of structures. There are many studies of a continuous beam or cylinder under axial shock load, but it is not easy to find studies on stiffness variation, an important factor in the preliminary design stage of ships, aircraft, and missiles. Generally, the body section stiffness of these structures differs because of access doors, stiffeners, and other skin cutouts. Therefore, the costs of trial and error can be reduced if the structure design process considers the stiffness distribution of a system in the preliminary design stages. This study investigates the effect of stiffness variation on a stepped, simply supported beam under an axial impact load and a stepped, cantilever beam under a vertical impact load. The study also investigates the effects of a vertical impact load on a cylindrical shell, and of frequency variation of an impact load on the response of structures. Finite element modeling and numerical analysis were performed using the MSC/PATRAN and MSC/NASTRAN programs. (4 tables, 42 figures, 11 refs.).