Tantalum Constitutive Relation

The constitutive relations of materials, especially dynamic plastic constitutive relations, were one of the emphases in mechanical and material fields. The mechanical properties of tantalum and tantalum-based alloys attracted interest of many researchers due to their widely utilization. And the constitutive relation of tantalum attracted interests of many researchers. There was a review of past researches of both domestic and abroad firstly. Two kind of currently used constitutive models, namely empirical Johnson-Cook model and physically based Zerilli-Armstrong model, were analyzed and compared. The descriptions to temperature effect, strain rate effect and strain harding behavior of every model were discussed. In the second section, the behavior of tantalum over a wide range of strain rates(1 O~? o~ Is) and temperatures (-1 OO550 0C) was studied. The experiments under quasi-static compression were performed using a MTS material test system, while dynamic compression tests were conducted using the Split Hopkinson Pressure Bar technique. The temperature effect was added too. The influence of the electromagnetic interference on stress wave was investigated. A method named mallest coil area?was adopted to resolve the problem of electromagnetic interference. In addition, the influence of the temperature gradient in the pressure bar on the transmission of the stress wave was investigated for SJ-IPB high temperature test. The stress-strain curves under different temperatures and strain rates were measured. The test results were analyzed and compared with results of other researchers. The different responses between tantalum plate and tantalum bar were analyzed. A simple discuss of plastic deformation mechanism for tantalum was given too. The Johnson-Cook and Zerilli-Armstrong constitutive models were obtained by fitting with experimental data. The fitting results did not have a good agreement with the experimental data. Then a rectified Johnson-Cook model was presented. It gave a very good agreement between calculated and experiment results. And this rectified Johnson-Cook constitutive model widened its original utilization.