Dynamic Response Of The Hemispherical Shell Structure Subject To Impact Loading

With the development of economic, more and more people pay attention tosafety and protection. The hemispherical shell structures can absorb moreimpact energy with less mass because of their special geometrical configuration.In this paper, empty hemispherical shell, liquid-filled hemispherical shell andspherical array structure are analyzed by the way of experiment and numericalsimulation. The main work is as follows:The deformation modes and impact force time history curves of emptyhemispherical shell and liquid-filled hemispherical shell subjected to impactloading have been found by experiment. The dynamic responses of them withdifferent ratio of radius to thickness (R/t) are compared through analysis ofvertex displacement and peak force. The dynamic response of emptyhemispherical shells with different (R/t) and impulse of hammer are comparedthrough analysis of vertex displacement, peak force and energy absorption. The crashworthiness of two kinds of liquid-filled hemispherical shell are analyzed.The crashworthiness of three kinds of hemispherical shell are compared throughcompression force efficiency and specific energy absorption. Dynamicresponses of spherical array structure with uniform(UNI), increased(INC) anddecreased(DEC) hemispherical wall thicknesses along direction of impact areinvestigated through numerical simulation with different velocities(10m/s、50m/s、100m/s and150m/s). The deformation modes and the nominalstress–strain curves of three kinds of spherical array structure at the impact endand the distal end under different impact velocities are obtained. Comparingdensification strain energy and energy absorption it deduces the best foams forenergy absorbing for different velocities. The main conclusion is as follows:(1) The deformation of empty hemispherical shell under impact can bedivided into three stages: local flattening, axially symmetric inward depressionand polygon deformation. With increasing R/t, the vertex displacementdecreases and the peak force decrease. Horizontal expansion of uncompressedregion can be observed obviously. The dynamic response time of hemisphericalshell varies with impulse of hammer. In the low energy impact, if hammer is thesame, the dynamic response time of hemispherical shell is basically the same.(2) The deformation of empty hemispherical shell under impact can bedivided into four stages: local flattening; axially symmetric inward depression;inward dimpling ironed; deformation recovery. By comparing three kinds ofstructure, double liquid-filled hemispherical shell is the best protection structure.(3) From the perspective of densification strain energy, DEC is applicablefor v=150m/s and UNI is applicable for three other kinds of velocity; From theperspective of ideal energy absorption efficiency, DEC is applicable forv=150m/s,100m/s and UNI is applicable for two other kinds of velocity.