关键词: 本构方程, 压缩和拉伸, 失效应变, 应变率, 温度相关性, 流动应力

Abstract:

The compression and tension tests of three aluminium alloys, 2024-T351,7050-T7451 and LY12-CZ, are carried out at the temperature from 77 K to 573 K, the compression strain rate is from 10^-3/s to 6 000/s and the tension strain rate is from 10^-3/s to 3 000/s. The stress-strain relationship and the failure strain of three aluminium alloys are obtained separately. The comparative research on the mechanical properties of these three materials shows that the flow stress is not sensitive to the strain rate at room temperature; but the sensitivity of strain rate increases and the flow stress decreases with the temperature rising. The coupling effect between strain rate and strain is not visible. The higher strain rate under dynamic load brings the temperature rising of the sample which reduces the flow stress of the sample. The failure strain decreases with increasing strain rate and the 7050-T7451 has the minimum failure strain among three aluminium alloys at the same strain rate. Finally, all the parameters of the model based on Johnson-Cook model are determined by curvefitting. The prediction results based on the corresponding model agree fairly with the experimental data.

Key words: constitutive , model,  , compression , and , tension,  , failure , strain,  , strain , rate,  , temperature , dependency,  , flow , stress