Investigation Of Mechanical Parameters For Rate-Sensitive Material And Its Applications

In the present thesis a new version of over-stress function of viscoplastic constutitive equation is proposed. The impact experiment of the certain steel is examined by means of SHPB method under the room temperature and the elevated temperature situations.The quasi-static and dynamic elasto-viscoplastic solutions of the thick-walled cylindrical shell are analyzed in detail. The radius of the interface of elastio and viscoplastic regions with respeot to time is derived.The effects of the inertia and the elastic deformation on viscoplastic solutions are discussed respectively. The thermo-viscoplastic solutions are presented in the stable temperature field.Another experiment considering the influence of strain-rate on mechanical parameters of low-carbon steel is made in INSTRON test machine under loading , unloading and cyclic loading conditions. The stress yield criterion including strain-rate variable is proposed. Analytical solutions of a tube subjected to the internal pressure are derived by using the proposed criterion during the loading , unloading and reversed loading process.The effect of strain-rate on the mechanioal autofrettage tube is discussed.