Research On Several Problems Of Air-blast Protection

In recent years,except the damaging effects of contiguous explosion on protective structures,the effects of air-blast shock waves have to be evaluated in more and more situations,especially when the standoff distance is relatively close or the charge quantity is relatively large.The former studies mainly focused on the dynamic response behaviors and deformations of protective structures.It has not been investigated whether transmitted shock wave overpressure will occur at the back of the protective structure,which may cause blast injuries of the people inside.Explosion containment vessels have been widely used as important equipments in explosive experiments or explosive workings.It is of great importance to research the dynamics responses and protection of explosion vessels.The question here can be considered as another form of air-blast protection.The compressive stress-strain curve of metal foams has a long even region.So they have excellent energy absorption property and are widely used as the core of sandwich structures on protection of explosion and impact.In this thesis,some issues of air-blast protection mentioned above were investigated.And the utility of aluminum foams in protective structures is examined.First the characteristics and mechanical properties of mental foams were discussed.Quasi-static and dynamic compressive tests were carried out on seven different aluminum foam materials.Their compressive stress-strain curves are typically three-region curves,including elastic region,collapse region and densification region.And they show signally strain rate sensitivity.The experiments of transmitted shock wave in an airtight chamber due to air-blast outside were designed and carried out.It is proved that transmitted shock wave overpressure can occur here and may cause blast injuries.When aluminum foam sandwich structure panels were used,the peak overpressure was markedly attenuated.The numerical methods and process procedures on air-blast and fluid-structure simulations were discussed.And FEA simulations of the overpressure experiments above were carried out.The simulation results have good agreements with the experiments.In addition,the process method here can be used to solve other similar problems on fluid-structure-fluid interaction.The numerical simulation methods on dynamics response behaviors of explosion vessels were discussed.For a spherical explosion vessel and an assembled vessel, their dynamics responses were simulated by FEA.Moreover their vibration characteristics,the frequency spectrum characteristics of responses and the factor of strain growth were studied.The protection of explosion vessels was preliminarily simulated and discussed.The aim of protection should be reduce metal fatigue caused by alternating stresses.And the protection should be considered on two aspects:blast isolation and vibration absorption.