Studies On The Notch Sensitivity Of Impact Toughness Of Tungsten Alloy With The Rare Earth Element

Due to a series of excellent properties of high density,tungsten alloy has been widely used in military,industrial sector and the civilian industry departments. For the reasons of their structural characteristics and processing,there will be a notch which results in “The notch effect”. “The notch effect” has an influence on the process of elastic deformation,plastic deformation and fracture.In this paper two groups of tungsten alloy specimens were chose. One group of tungsten alloy specimens has no notch,and the other group have notch of standard V type. The impact tests of two groups of specimens were performed in impact testing machine respectively. After Mathematical statistics of the data on the test machine, values of impact toughness of two groups were obtained by calculating. The Impact processes were simulated by using finite element analysis software ANSYS/ls-dyna, and the feasibility and correctness of the simulation method was verified after comparing experiment results with simulation results. Corresponding variations of physical quantity of tungsten alloy specimen during the impact processes were viewed and analyzed with the software. A total of 11 samples with different height of notches were designed,and their impact processes were simulated by employing finite element software. Based on analysis of toughness values in the simulation results, the relationship between tungsten alloy impact toughness and notch size,namely tungsten alloy notch sensitivity of impact toughness were obtained. The specific conclusions of this paper are as follows:(1) Tungsten alloy samples without notch have larger impact toughness compared with the standard V type notch tungsten alloy specimens. The toughness of tungsten alloy specimen with no notch is 164 J/cm2,and the impact toughness of the standard V type notch tungsten alloy specimen is 117 J/cm2. The difference between them is 47 J/cm2.(2) The simulation value of impact toughness of samples without notch is 158J/cm2,which has a difference of 4% from the value of experiment;However the simulation value of impact toughness of the standard V type notch tungsten alloy specimen is 108J/cm2,which has a difference of 7% from the experiment value. Since the difference between the experiment value and simulation value is small,the accuracy and feasibility of the simulation method using finite element software ANSYS/ls-dyna can be confirmed.(3) with the ANSYS/ls-dyna post processing,stress,strain and strain rate of the two groups of tungsten alloy at the breaking time were observed.it were found that:Compared with the tungsten alloy samples without notch, the standard V type specimens experienced shorter time before destruction; Meanwhile the standard V type specimens had a greater strain rate and smaller area of stress concentration at the notch. The comprehensive effects of the two aspects determine the smaller impact toughness of specimen with notch.(4) A total of 11 samples with different height of notches were designed. Through the simulation results which were obtained by using the software ANSYS/ls-dyna,it was found that with the change of the height of notch impact toughness of tungsten alloy changed obviously with the change of the height of notch,namely impact toughness of the tungsten alloy has a high notch sensitivity,its values of ci? vary slightly between 0.21~0.3.