New insights on fractional thermoelasticity from anomalous heat conduction
Anomalous heat transport of low-dimensional nanomaterial,e.g.,divergent effective thermal conductivity,has been observed from both atomistic simulations and experimental studies.It is greatly urgent to establish the phenomenological anomalous thermo-elastic model,and study the thermoelastic coupling due to strong heat transfer.The aim of this work is to revisit fractional wave-type thermoelastic models from the anomalous heat conductive viewpoint.Firstly,it has been suggested that anomalous heat conduction is due to the second sound,hence wave-type heat conduction is considered:the analogy between wave-type heat conduction and viscoelastic model is given,and thus the connection between Cattaneo-Vemotte and Green-Naghdi heat conductive models is clarified.Secondly,it has been recognized that the divergent thermal conductivity of one-dimensional systems satisfies the fractional order power law,therefore fractional derivative should be incorporated:Fractional order thermoelastic models based on Cattaneo-Vemotte and Green-Naghdi theories are summarized and compared,theoretically.Numerical investigations are conducted by using Laplace transform method,and the plot of thermoelastic responses vs.fractional order parameter shows:for all fractional order range[0,1],fractional Cattaneo-Vemotte(FCV)Ⅰ model and fractional Green-Naghdi(FGN)Ⅰ-Ⅲ models can predict anomalous thermoelastic responses,i.e.,higher temperature and compressive stress than classical thermoelasticity.Fur-thermore,the history of temperature or stress indicates:FGN Ⅱ model can predict anomalous responses for all time range.Further systematical studies are expected for Green-Naghdi model and its fractional versions to shed light on anomalous heat conduction and thermoelastic coupling,and to facilitate the applications of nanomaterials due to such anomalous behaviors.