The magnetic pulse method is a method for creating controlled pressure pulses of microsecond duration. Although the method has been known since the 80s, it is usually used for revealing patterns of fracture processes of nonconductive materials. This method was practically not applied to shape memory alloys, with the exception of some works devoted to the three-point bending tests. We adapted the method for high-strain rate uniaxial tension of TiNi alloy specimens. The paper demonstrates the scheme of magnetic pulse method for uniaxial tension. Analytical assessments of the magnitude of the magnetic pressure created by magnetic-pulse drivers under the action of a current pulse, strain in the working part of the sample and the strain rate are carried out. For an analytical solution, the resistance of the material to external forces is proposed to be considered as a piecewise linear approximation to the stress-strain diagram. Analytical solution demonstrates qualitative and quantitative agreement with experiment, even for samples of TiNi alloy with a unique stress-strain diagram. It is a difficult task to estimate the strain rate at short loading pulses of 6 – 7 μs. However, in the first approximation, the results show that at the considered loading scheme, the strain rate reaches 6700 s−1 on average and in local areas it is estimated at 10 000 –12 000 s−1. Thus, having the parameters of the material and the parameters of the current pulse, it is possible to estimate the strain of the material with good accuracy and obtain an initial estimate of the strain rate.
Предметные области Scopus
- Материаловедение (все)