Joint Materials/Solid Mechanics Seminar Series

Joint Materials/Solid Mechanics Seminar Series

“Simulations of projectile impact on ceramic”

Prof. R. M. McMeeking
Department of Mechanical Engineering and Materials Department
University of California, Santa Barbara

Abstract:
We have developed a new constitutive law for ceramic based on the growth of wing cracks under compression, in which it is recognized that these cracks can be closed under pressure. Thus a damaged material under severe compression regains its undamaged strength. In such states of triaxiality, with some degree of deviatoric stress, plastic flow due to dislocation motion or twinning can occur independently of brittle damage. This phenomenon is allowed for in our model, which involves viscoplasticity as well as a brittle damage accumulation. In tension, the material readily cracks and is weak. In compression, the growth of brittle damage causes comminution of the ceramic, and in such circumstances a Mohr-Coulomb inelastic behavior develops to represent the granular flow of the rubblized material. The model is valid at low strain rates, and can be used to model static indentation of ceramic by a hard sphere, used for calibration purposes. Data for the dynamic impact of metal spheres on the ceramic are also used to calibrate the model. The constitutive law is then used to simulate the deep penetration of tungsten rods into SiC (the Lundberg experiment) and the impact of steel cylinders on trilayers of steel/ceramic/steel.

Monday, February 15, 2010 4:00-5:00 pm B&H Room 190

Note: There will be a dinner for Prof. McMeeking after the seminar.
Please contact Ms. Pat Capece at x1501 if you wish to attend.