Dynamic Strength And Energy Dissipation Of Rock-like Porous Solid

Porous solids,such as foam concrete,is increasingly used in the construction industry due to its low density and high durability.As a relatively new building material,the foam concrete volatilizes a major role in many areas,such as the sound insulation and heat insulation.Because of its excellent energy consumption characteristics of them,it was also gradually introduced into the other fields,like vibration reduction and explosion protection.However,its mechanical behavior under dynamic loading is still unknow.Therefore,the dynamic mechanical responses of the rock-like pore solid is taken as the research target in this work.The main contributions are listed as follows:(1)Firstly,the tensile strength and energy dissipation of a single pore model was numerically investigated.The deformation resistance and energy dissipation law of a rock ring model were studied by using the 4D-LSM.Firstly,the ability of 4D-LSM to solve the rock ring model is verified for the first time through comparing with the existing physical experiments.On this basis,some factors like porosity and thickness to diameter ratio on the dynamic tensile strength of the single porous model were studied.It’s found that the relationship of the tensile strength and deformation resistance of the model is nonlinear.Taking the advantages of 4D-LSM on solving large deformation problem,we found that the ring model would exhibit a different failure mode comparing with the traditional small deformation physics experiment and numerical calculation if we consider the large deformation.This result reveals that if the matrix has a high toughness,the corresponding porous solid would present a different form of failure compared with these normal toughness porous solids.Moreover,the deformation resistance,the energy resistance and the failure of a porous structure are studiedby constructing a porous array combination.It was found that the failure mode of the composite structure is different from that of the single pore model,but the deformation resistance and energy dissipation law of the single pore rock ring model are still applicable.(2)Secondly,the dynamic compressive and tensile strength of the rock-like porous solid was further explored using the 4D-LSM.By introducing a coupled macroscopic strength criteria and nonlinear mesoscopic constitutive model,the 4D-LSM can effectively reproduce the high compressive-tensile strength ratio of brittle materials.Its effectiveness is verified by comparing a series of numerical experiments with the theoretical precition of the classical tension-cut model.Based on this,the effects of pore morphology and porosity on the compressive strength and tensile strength of the porous solid are studied.Our results show that the porosity has a linear relationship with the tensile strength,whereas,a nonlinear correlation was observed beweeen the compressive strength.The compression-tension strength ratio will decrease with increasing of the porosity.Moreover,the loading rate effect of the porous solid was also explored.It was found that the porosity would introduce dynamic effect for both the the compressive strength,tension strength and the compressive-tensile strength ratio.Neverthless,this dynamiceffects would decrease slightly with the increase of porosity.(3)Finally,the failure mechanism and strength characteristics of the rock-like porous solid under ultra-high loading rates were numerically investigated.First,a plate impact test on marble was used as the experimental data for constitutive model and parameter calibration of the DLSM.By developing a mesoscopic trilinear dynamic compression failure constitutive model for the DLSM,the dynamic behavior of the marble under ultra-high loading rate is characterized.Through a detailed comparsion between the numerical and the experimental results,it is found that the failure mechanism of the rock under impact compression should be the failure of the rock grain bonds under hydrostatic rather than the meso-shear or tensile failure in conventional experiments under quasi-static loading condition.Following this,the numerical plate impact test on samples with different pore morphology and porosity were carried out to investigate the relationship between the porosity,the impact velocity,the pore morphology and its impact strength.