| Composite honeycomb sandwich structures are year by year more and more used in various industries,bringing with them huge innovations in the future.In the past few decades they reached their highest value in aircraft manufacturing,shipbuilding and automotive because of their high specific stiffness and specific strength.On the basis of this,small changes in some mechanical properties and stability due to the different ratio of the thickness of the honeycomb core and covering it from two sides of the composite layers to achieve weight reduction of the structure deserves increased attention.Going deeper into research,due to the complexity level of this structure,it is difficult to predict most of the failure modes of composite multi-layer structures directly under difficult conditions,the study of impact resistance and mechanical properties of multi-layer structures,as well as the analysis of the destruction mode,have acquired quite significant importance.In this article’s chapter one we shall discuss the study of low-velocity impact damage to the composite Nomex honeycomb sandwich panels.Using a nonlinear explicit dynamic analysis procedure in the commercial software package ABAQUS to simulate an impact of rigid ball on the finite element models.This program allows to get an effective analysis,a fairly accurate assessment,as well as the mutual influence of the parameters of this structure and their further understanding,which affects the provision of a complex response.The second chapter deals with the derivation of elastic parameters of the honeycomb base layer,namely the use of the model of a thick-walled double-walled inner layer called the theory of sandwich panels and the Gibson cells theory of material.The next chapter is a description of the construction of a basic example of an honeycomb model in the ABAQUS software,their interconnections,the application of load,the fixing of the basic models,the selection of the step time and gives an example describing a simple impact on a sheet metal.The fourth Chapter provides a comparative analysis between the complex structure of the honeycomb panel with a core height of 6mm and a simple equivalent model.Displays graphs of the dependence of force from the displacement,get the value of the Mesis damage criteria.In the fifth chapter will be presented the results of calculations for different values of impact damage on the hexagonal center of the honeycomb core sandwich panel with 6mm height with the three values of the kinetic energy equal: 10 J,15J and 20 J.The main idea is to track the dependence of the panel deformation increment on the impact load force applied to it.Make the graphs of impact loading and the graphs of the contact force on the displacement,study the Mises criteria and Hashin criteria for upper layer of composite honeycomb sandwich panels.The next step was to study the dependence of the low-speed impact load from the parametric change of the height of the composite core.In analysis were used all the same values as in the first paragraph,with only two different parameters of the panel height of 8mm and 10 mm.Compare the obtained values with the other values of kinetic energy,analyzed getting results and finite element model,made the conclusions about the dependence of panel rigidity on the height of the honeycomb core,that its value increases with height increasing,depth of the deformed surface,and the amount of energy absorbed by the panel.Last part was determining the above values of kinetic energy and height on a composite panel and graphs,but this time only for impact damage,which is made on the hexagonal core connection of this composite structure,using the same three values of kinetic energy and three parametric change of the height of the plate.Made a comparative analysis of two finite element models,the construction of comparative graphs,and obtaining summary results,where stiffness of the last finite element model is bigger than the stiffness of the hexagonal center of the honeycomb core sandwich structure. |
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