Research On Dynamic Properties Of Brittle Material Based On The Split Hopkinson Pressure Bar Experiment Technology

People found in the study of science and technology, practical application, militaryindustry, civil production and a series of field, the impact load, or explosion conditions,mechanical response normally are very different from the static response. Research on themechanical response under the condition of explosive or impact load, show a guidance for theengineering design and industrial productionThis paper selects fine-grained granitic rocks as experimental materials, to explore theeffect of strain rate on the dynamic properties of materials, through the theoretical modelcalculation and experimental observation and draw the corresponding conclusion. In thetheoretical study of a new method is proposed, this method combines the " dynamic fracturecriterion " and " the theory of damage mechanics ". Verification part adopts experimental withclassic split Hopkinson pressure bar (SHPB) and related test. Dynamic SHPB experimentswith pulse shaping technique, the specimen under uniform stress and constant strain ratedeformation, in order to verify the validity of the modified technique, we have the technologywas tested and simulation.In order to explore the influence of microstructure of materials under different loadinglead to possible failure of dynamic fracture, We collect and analyze the sample fragmentsproduced by each experiment, by the impact of granitic rocks, broken into the size is not thesame crystal shards, Indicated through the research and analysis of these fragments: the effectof strain rate on fragment related to the microstructure of rock; At the same time, this paperalso studied the length of specimen effect on the dynamic failure intensity and the effect ofstrain rate on the size of the fragment, and through the theoretical model were used toestimate the numerical fragment size, experimental results and the theoretical simulation isthe same. The study also shows that, the transverse inertia caused by dynamic loading, reducethe influence of friction resistance caused by the test piece with two SHPB rod contact ofcylindrical specimens of dynamic response, through the observation of experiments, theconclusion and the related theory model matches.Resistance strain gage plays a basic role in this paper, it was used to collect related strainsignal, signal conversion part using the Wheatstone bridge circuit, the circuit will changestrain signal into the electrical signal which can be measured easily; and design a set ofamplifier, filter circuit, and to identify and eliminate the negative influence of noisemeasurement process by using the FFT algorithm, the signal effect reaches the requiredstandard experiment. Using advanced RIGOL-DS4000oscilloscope to do correspondingsignal acquisition, storage, computation and analysis. Experiments prove that the testingsystem: stable performance, strong anti-interference ability, can achieve the performancerequirements of strain measurement. The research results and conclusions on the dynamic properties of brittle material of thisthesis has some reference and practical value for selection of brittle materials,Researchfindings lay the theoretical and experimental foundation for the next step of research brittlematerials’sCrack growth law of dynamic fracture.