| In this paper,a new type Ⅰ-Ⅴ sandwich panel protection structure is proposed for the protection of civil building wall and plate component under the combined loading of close-range blast wave and fragments.Using the nonlinear finite element analysis software LA-DYNA,the protection performance of Ⅰ-Ⅴ sandwich panel uunder the combined loading of close-range blast wave and fragments is studied,and the results are as follows:(1)The explosive-air-fragment-Ⅰ-Ⅴ sandwich panel finite element model was established,with the selection of material model,contact algorithm and coupling algorithm.The results of numerical simulation are compared with experimental results and theoretical results,which shows that using the finite element model,material model and fluid-structure coupling method are reasonable and effective in this paper.(2)Under the combined loading of close-range blast wave and fragments,the shock wave reaches the Ⅰ-Ⅴ sandwich panel before the fragmengts.The shockwave mainly causes the overall deflection of the sandwich panel,while the fragments mainly have the penetrating effect on the structure.The former has the greater damage effect than the latter.The response of the effect of the sandwich panel under the combined effect of shock wave and fragments is cumulative amplification,which is obviously greater than the linear superposition of the damage effect of the two actions.(3)Under the condition of the same loading and the constant steel quantity,the protection performances of the six different sandwich panel are compared,in which the protection effect of Ⅰ-Ⅴ type sandwich panel is optimal.The thickness of the upper and lower panel and the configuration of the sandwich layer have a great influence on the protection performance of the Ⅰ-Ⅴ sandwich panel.The Ⅰ-Ⅴ sandwich plate has the basically same protection performance under five typical penetration locations,with no weak location for protection performance,and the overall protective performance is better.As the size of the fragments increases,the maximum vertical peak displacement of the bottom panel of the Ⅰ-Ⅴ sandwich panel increases slowly to the highest point and then drops rapidly.(4)From the three aspects of the quality loss,the energy absorption,and the peak vertical displacement of the Ⅰ-Ⅴ sandwich panel,it can be seen that with the increase of scale distance caused by the increase of the distance between the center of theexplosion and the observation point,the overall damage degree of the Ⅰ-Ⅴsandwich panel reduces continuously,and the reducing rate is increasing.With the decrease of scale distance caused by the increase of the mass of explosion,the overall damage degree of the Ⅰ-Ⅴsandwich panel reduces continuously,and the increasing rate is increasing firstly,then decreasing.With the constant scale distance caused by the increase of the distance between the center of the explosion and the observation point and the corresponding increase of the mass of the explosion,the overall damage degree of the Ⅰ-Ⅴsandwich panel increases continuously,and the increasing rate is increasing firstly,then decreasing.(5)From the three aspects of the quality loss,the energy absorption,and the peak vertical displacement of the Ⅰ-Ⅴ sandwich panel,it can be seen that the damafe of the Ⅰ-Ⅴ sandwich panel caused by different positions of explosive initiation is different.Although the mass of the explosion does not change,the the actual effective mass of the explosion change.The increase of the number of detonation points on the axis of the explosion can not significantly increase the damage degree of the Ⅰ-Ⅴ sandwich panel.(6)There is only a small amount of detached concreteconcrete and no reinforced exposed on the front surface,without concrete fall off and no reinforced exposed on the back surface,lesser plastic deformation area,and the whole is not formed through destruction with the protection of Ⅰ-Ⅴ sandwich panel.The damage degree of the reinforced concrete slab with Ⅰ-Ⅴ sandwich panel is far less than the unprotected einforced concrete slab.The actual protective effect of the Ⅰ-Ⅴ sandwich panel proposed in this paper is very good,which can provide an important reference for engineering design. |
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