Numerical Analysis Of Explosive Blast Shock Wave Spread And Dynamic Instability Of Spherical Shell

As science and technology develop,explosions are used more and more widely in national defense industry and economy. In recent years, dynamic responses of building structural and industrial products under blast loading have got more attention. Structural dynamic response is also one of important sides of solid mechanics. Counter-intuitive dynamic response is a special dynamic response, that is, structural final deformation is opposite to the direction of loading when under short-term impulsive loading.Since 1980s, P.S. Symonds and other scientists found the counter-intuitive response of beam when they studied dynamic response of beam supported by both hinged ends. More and more scientists pay close attention to the research. The structural counter-intuitive may occur under implusive loading (blast loading), projectiles (bullets shock) or explosive loading (pulse loading). And this has been confirmed in numerical simulation and experiments. But in related studies researchers rarely consider the influence of the shape of explosive on shock wave and pay little attention to the counter-intuitive response of spherical shells under explosive loading.In this paper, the structural counter-intuitive behaviour and simulations of blast shock in recent years are reviewed. Physical and chemical phenomena in the process of explosion are described. Then some theories of the finite element method and the ALE algorithm are introduced. At the same time, the following work is done with numerical simulation method:1,Comparing the peak blast overpressure of several empirical formula, It is considered that when the distance is larger than distance Z, the results of numerical simulation are more in line with empirical formula.The blast wave propagation is researched with numerical simulation after the detonation of explosives with different shapes in the air. The detonation propagation characteristics and two vertical peak overpressures are compared among several forms of explosives. After detonation explosives have larger impulse on larger surface in normal direction and spread faster.2,The dynamic response of forms of explosives with the same quality to spherical shell are studied. The peak overpressure and impulse are reached. To the same quality explosive, rectangular explosives produce the largest impulse and overpressure, but ball explosives produce the smallest impulse and overpressure, this document presents the experiment results are consistent. 3,ALE arithmetic are used for numerical simulation on dynamic response of spherical shell after detation of explosives. And the blasting distance area of spherical shell, which is under explosive load and produces counter-intuitive phenomenon, is obtained. Results of numerical simulation show that the height and thickness of spherical shell have greater influence on counter-intuitive phenomenon. Meanwhile, the diagram of proliferation of detonation products is gained, and the distribution of air overpressure is researched. Then, comparisions are done among pressure-time curves of some points near spherical shell. There are two peaks in front region of spherical shell. It is reached that spherical shell has reflection on shock wave.Finally, the phenomenon of counter-intuitive is explained individually from the perspectives of dynamic coupling, plastic deformation, energy transformation, etc. The mechanism interpreting the reasons for the phenomenon of shell counter-intuitive is also presented.