Study On Impacting Characteristics Of Self-similar Hierarchical Honeycomb Materials And Structures

Impacting phenomena is widespread in human production and life.The impacting harm is closely related to our life and property security.Therefore,the design of efficient safety protection structure is very critical to resist the damage caused by impacting.Lightweight materials have been widely used in the protection structures design of automotive and other engineering equipment.Honeycomb as a typical lightweight material,has attracted the attention of researchers because of its unique mechanical properties.One kind of novel self-similar hierarchical honeycomb structure based on triangular bionic design was proposed in this paper.To reveal the impacting mechanical response of the self-similar hierarchical honeycomb under multiple conditions,the experimental model,numerical model and theoretical analysis model were established.The mian research contents can be concluded as follows:(1)In-plane impacting characteristics of self-similar hierarchical honeycombs were studied by experimental and numerical methods.First,compared the mechanical response of self-similar hierarchical honeycombs with regular triangular honeycombs.Honeycombs with hierarchical configuration present more stable plastic deformation,collapse deformation and higher stress level than regular triangular honeycombs under in-plane loading.It is shown that the self-similar hierarchical structure can better improve the impact mechanical behavior under in-plane impacting.Furthermore,analyzed the mechanical response rules of self-similar hierarchical honeycombs with different hierarchy designing factors and relative densitys,found that the geometric parameters have a great influence on its mechanical properties.Finally,abided by main deformation characteristics and energy balance principle of self-similar hierarchical honeycombs,the theoretical plateau stress model was derived and verified,which provides a theoretical reference for predicting the in-plane loading mechanical response of self-similar hierarchical honeycomb structures.(2)Out-of-plane impacting characteristics of self-similar hierarchical honeycomb were studied.First,based on the super folding theory,established the theoretical mechanics model of hierarchical honeycomb under out-of-plane loading,and the reliability of numerical analysis was validated by theoretical mechanics model.Meanwhile,compared the crashworthiness between self-similar hierarchical honeycomb structures,odinary single-cell triangular honeycombs and double-cell honeycombs.It has been identified that honeycomb with hierarchical configuration can significantly improve the folding collapse and load level under out-of-plane compression.Besed on the characteristics of load force and deformation shapes of elf-similar hierarchical honeycomb,explored the mian manchanical response with different hierarchy design factors,relative densitys and specimen dimensions.It provides effective guidance and theoretical support for the impacting resistance design of novel self-similar hierarchical honeycomb.