Dynamic quasi-isentropic compression techniques: applications to aluminum and tungsten
A novel impact technique involving the use of a ''pillow'' to obtain quasi-isentropic loading in materials is reported. A pillow is fabricated using powder metallurgical and sedimentation techniques, such that a smooth variation in shock impedance across its thickness results. This variation in shock impedance as a function of thickness gives rise to a finite rate of loading at the impact interface when the pillow is used as an impactor. The pillow can be used with smooth bore guns to introduce nearly isentropic loading states in a target material. The usefulness and the success of this technique have been demonstrated by using it in an equation-of-state study of 6061-T6 aluminum to 9 GPa and of tungsten to 78 GPa. In each instance, it is observed that the quasi-isentrope lies above the Hugoniot, contrary to initial expectations. The results indicate that the dynamic yield strength of the material is dependent on the loading rate with the strength of the material being higher for the relatively slower rates of isentropic loading than for shock loading. The techniques reported herein, when used in conjunction with the two-stage light-gas gun, will potentially allow the determination of loading isentropes to Megabar stresses.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA). Thermomechanical and Physical Div.
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5341054
- Report Number(s):
- SAND-86-1888; ON: DE86016027
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dynamic quasi-isentropic compression of tungsten
Shear strength of tungsten under shock- and quasi-isentropic loading to 250 GPa