Surrogate Expressions for Dynamic Load Factor

Abstract

AbstractIn this paper the elastic dynamic load factor in structural dynamic is revisited. The existing literature in which the response exists only for isosceles triangular pulse and shock load pulse is criticized.A new pulse shape parameter is introduced by which both isosceles triangle impulse and shock load impulse and other unsymmetrical pulses can be expressed. This enables the elastic Dynamic Load Factor (DLF) to be computed versus the pulse shape parameter.Thereafter a surrogate model is found by which the load factor can be computed via pulse duration, natural period and pulse parameter. The conservative values of the load factor extracted from the surrogate model and can be used for structural dynamic aspect of the design.In numerical examples the Single Degree Of Freedom (SDOF )model subjected to blast loading is investigated. It is shown that numerical scheme for elastic dynamic load factor in this paper is very accurate. The accuracy is demonstrated in case when isosceles triangular pulse blast load is applied. Moreover, by introducing the pulse shape index parameter, any unsymmetrical pulse can be expressed and their response can be determined.Two types of surrogate functions are introduced to substitute the elastic DLF data. It is concluded that nonlinear low order surrogate functions are not accurate enough to predict elastic DLF. However, higher order surrogate polynomials are very accurate and can be used in computational design of protective structures.KeywordsDynamic load factorNonlinear ODEProtective structures