Abstract
Some experiments concerning the generation of a negative stress pulse have been performed for the purpose of investigating the response of material under negative shock stress. The electromagnetic induction method was used for the generation of a negative stress pulse. Strip plates made of photoelastic material (DAP) were prepared as the specimen. The stress pulse was observed by the dynamic photoelasticity method and confirmed to be negative by using a semiconductor strain gauge. The stress pulse was generated with a good reproducibility and its stress amplitude and pulse width were easily controllable.
Moreover, a negative stress pulse was generated in the strip plate with a natural crack, and the growth phenomenon of the crack was observed while the pulse was passing the crack. The crack grew slowly till the peak of pulse reached the crack position and after that the crack grew rapidly. The growth speed of the crack was about 250m/sec. No growth phenomenon was observed for a positive stress pulse.
