An analytical–numerical method to analyze single degree of freedom models under airblast loading

In this paper, an analytical–numerical method to predict the response of a linear spring–mass system without damper, excited by a family of pulse loads, is proposed. The external loading is described by a four parameter expression, involving the peak overpressure, the loading duration and two parameters which characterize the pulse shape (λλ and γγ). A parametric analysis for ranges of pulse shape parameters suitable to describe a wavefront pressure profile produced by an airblast from high explosives is developed. The influence of the pulse shape on the dynamic load factor representation of structural response and on pressure–impulse isodamage curves is graphically shown. An expression of the transient response spectrum generated by a typical exponentially decaying load (λ=1,γ=2.8) is proposed, and a discussion about the formulation of a general expression for the transient response spectrum is introduced. Various features of the spectrum and pressure–impulse diagrams are analyzed, and all the problems concerning the building of graphics are discussed. Finally, a review of existing simplified isodamage curves is reported and an existing method to eliminate pulse shape effects, the effective pressure–impulse diagram, is discussed.