SHPB Tests For Cement Mortar Materials And Their Parameter Sensitivity And Uncertainty Analysis

Concrete is one of the most important structural building materials.As the concrete structure is often subjected to dynamic impact loads in the process of use,the dynamic mechanical properties of concrete materials have been a hot topic for many scholars.SHPB experiment equipment is widely used to obtain the dynamic mechanical properties of various materials.In the SHPB experiment of concrete materials,many parameters are uncertain,and these uncertainty parameters will apparently affect the experimental results.In this paper,SHPB experiment of plain concrete is carried out firstly and the validity of the experiment is verified by the analysis of experimental data.Secondly,a numerical model is established,the validity of the numerical model is verified by comparing the numerical simulation results with the experimental results.Then,the sensitivity and uncertainty analysis of the interfacial friction effect parameters in SHPB experiment are conducted based on the numerical model.Finally,the sensitivity and uncertainty analysis of the whole experimental parameters in cement mortar SHPB experiment are analyzed based on the numerical model.The main research work of this paper is as follows:(1)The SHPB experiment of two kinds of cement mortar materials with two strengths was completed at three strain rates,and the validity of the experiment was verified by experimental data analysis.Firstly,the main compositions and basic principles of SHPB experiment device are introduced.Secondly,the preparation process of two kinds of cement mortar materials is described.Then,the SHPB experiment of two kinds of cement mortar materials under the three strain rate are completed,the validity of the experiment is verified by the study of waveform analysis for the recorded three waves.The experiment obtained the stress-strain curve and strain rate.Finally,the effects of material strength and strain rate on dynamic mechanical properties are analyzed,including the dynamic compressive strength,the dynamic energy absorption characteristics,the failure mode analysis and the crack propagation under high speed camera.(2)The numerical model of SHPB experiment for cement mortar is established,and the validity of the model is verified by comparison with the experiment results.Firstly,the SHPB experiment numerical model corresponding to the experiment is established.Secondly,the parameter meaning and value of the Drucker-Prager material model are introduced.Finally,the numerical simulation is solved and analyzed,the one dimension of stress wave propagation is verified by analyze of the propagation process of stress wave in the pressure bar.The consistency of loading process is verified by comparing the three waveforms obtained by numerical simulation and experimental data.The stress-strain curves obtained by numerical simulation and experimental data are compared at six different conditions,and thus the validity of the numerical model is verified.(3)Sensitivity analysis and uncertainty analysis are carried out on the friction effect parameters of the cement mortar SHPB experiment.Firstly,the interfacial friction effect is analyzed by stress wave propagation theory and the interfacial friction effect is summarized into three parameters.Secondly,according to the operation process of the experiment and the measurement result of the specimen,the interfacial friction effect parameters are expressed in interval values.Then the parameter sensitivity analyses at six different conditions are preformed according to the full factorial experiment design and range analysis method.The interaction effect between parameters is discussed and the parameter sensitivity rank is obtained.Finally,the uncertainty analysis of interfacial friction parameters is performed by using non-probabilistic interval analysis algorithm.By comparing the results of the uncertainty analysis and the results of the experiment,the validity of this method is verified.(4)Sensitivity analysis and uncertainty analysis are carried out on the whole experimental parameters of cement mortar SHPB experiment.Firstly,experiment operation process is analyzed to find the uncertain parameters that affect the repeated experiment.Secondly,the interval of each parameter is quantified according to the experimental operation process and measurement results.Then,the sensitivity analysis of whole experimental parameters is conducted according to the full factor experiment design and the range analysis,the sensitivity ranking of the whole experimental parameters is obtained.Finally,the top three sensitivity parameters are chosen for uncertainty analysis.By comparing the uncertainty analysis with the experimental results,the validity of this method is verified.