Theoretical Analysis of ATJS Graphite Disks Fractured by Spinning
Technical rept. 1975-1976
CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIED SCIENCE
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Refractory materials are frequently used in reentry vehicle nosetips to combat the severe heating conditions encountered. The thermal stresses thereby induced introduce a risk of fracture. To calculate the survival probability, it is necessary to be able to determine the stresses and strains induced by the combined thermal and aerodynamic loads, to find the probability of fracture in each volume element, and from the latter to estimate the survival probability of the entire nosetip. Among the things needed to accomplish this task are sufficiently accurate constitutive laws for the materials employed, and a knowledge of the fracture statistics of the material as affected by specimen size and the generally biaxial or triaxial stress state involved. In a recent experimental study to shed light these matters, ATJS graphite disks and bars were tested to destruction by spinning. The primary objective of the present paper is to show how the uniaxial stress-strain data and uniaxial fracture statistics can be generalized with the aid of theory to stress analyze the rotating disks and also account for the observed failure statistics. It is shown that agreement between theory and experiment is good for both types of problems.
- Ceramics, Refractories and Glass
- Guided Missiles