Study On The Characteristics Of Elastic Wave Propagation In Honeycomb Paperboard

Porous materials exist widely in the nature. Because of their uniqueproperties and potential applications, porous materials become to be thescientific research hot spot in recent years. As one kind of the porous material,honeycomb paperboards have many advantages, just like being a high pressurestood, good resilience, noise insulation and so on. They can be used as packagingmaterials and they are paid close attention now. With the environmentalprotection requirements, honeycomb paperboards are needed more and more.In recent years, the propagating characteristics of elastic wave in materialhave been paid more and more attention. Compared with the research ofcardboard in statics, those of dynamics are few. In statics researchers onlyconsider the load and deformation before and after the load without consideringthe process of the deformation. In elastodynamic, the process of time isconsidered, when the object is subjected to local disturbance, the points whichare away from the disturbance distant part do not respond immediately. Thevibration of each point will change along with time. Then the displacement, thestress and the speed are not only about a function of spatial coordinates, but alsoabout a function of time.During the transport of the product, especially the process of shock andvibration, packages with cushioning material are in dynamic environmentalconditions. The material element will vibrate over time. Studying thecharacteristics of elastic wave propagation in honeycomb paperboard and thekinetic parameters with time variation is significant. In this thesis, elastic wavetheory is applied in the honeycomb paperboard. The hexagonal honeycombstructure is selected to be researched. The researchers study the characteristics ofelastic wave propagation in both the single cellular structure and the honeycombpaperboard. This study can provide some theoretical guidance for the dynamics study of the honeycomb structure.Firstly, the author describes the concept of elastic wave, and thensummarizes the history and current status of the elastic wave theory.Secondly, the author simplifies the honeycomb paperboard to be ahomogeneous linear elastic mezzanine plate, and solves out the equivalent elasticmodulus of the hexagonal honeycomb structure in the second part, and alsostudies the relationship between the modulus of the honeycomb unit size. It willpave the way for later research.In the third part of the thesis, the author establishes the functions of thestress, strain and also the function of stress and strain relations based on the basicassumptions of the elastodynamics. The wave equations are established to soluteout the parameters of the transverse wave and longitudinal wave.In the fourth part of the thesis, the author establishes the fluctuationsgoverning equations and the harmonic equation, and analyzes the propagationcharacteristics of elastic waves in a single cellular structure. The Elastic wavetheory is applied to the sound insulation of honeycomb paperboard. Theresearchers control the sound insulation function by changing the material of thehoneycomb structure, radius, and cellular thickness of honeycomb cellularstructure. The results obtain for the elastic wave propagation in these materialsprovide useful insights. Due to the complexity of the cellular structure, studyingthe propagation of waves in such a complex structure has certain difficulties. Inthe fifth part, the honeycomb paperboard is simplified to a linear elasticmezzanine plate to study the characteristics of elastic wave propagation in suchstructure, and solve the displacement field, stress field and velocity.Finally, the author does the finite element analysis simulation of thepropagation of elastic stress in the honeycomb paperboard by ABAQUS. Can beobtained by simulation analysis the following conclusions:1) During the propagation of elastic stress in the cellular material model, thefrequency and the cycle of the elastic stress does not change. The waveform ofthe stress wave does not change, and the shape is the same as the original inputwaveform. The elastic waves propagate with constant velocity in the samemedium.2) During the propagation of elastic stress in the cellular material model, the stress amplitude and the displacement amplitude of the elastic wave are reducedwith the extension of the distance and the increase of the time.3) Elastic stress propagates in cellular materials with parasitic oscillationphenomenon.