Design and Stress Analysis of Extraterrestrial ... - The Black Vault

When r a ÷ 1 radial stresses approach zero while circular stresses
approach maximum.
In examining thermal stresses (see Fig. 3.57) we can make the
following conclusions.
- Thermal stresses are due to nonuniform heating of the disk.
With uniform heating there will be .no thermal stresses.
- Thermal stresses substantially distort the pattern of stresses
obtained only from the rotation of the disk, particularly the pattern
of stresses aq. On tne periphery of the disk with the examined
character of temperature variation negative (compressive) stresses
appear.
We should note that the strength of the disk will be different
depending upon whether it is heated or not, even if in the heated
disk there is no temperature gradient. If the degree of heating
determines the strength of the disk material, nonuniform heating
determines its
thermal stresses.
Analyzing disk with allowance for plastic
flow
An attempt to obtain higher criteria for a turbine and reduce
its weight has lead to an increase in the angular velocit!.es of
rotors and stresses in the disk up to their operation in the elasticplastic
region.
In individual sections of the disk stresses reach
the yield point aT. Meanwhile, Lther less loaded sections are
loaded with additional forces. All this leads to a redistribution
of stresses in the disk and is particularly apparent at high temperatures,
since with an increase in
continuously.
temperature the yield point drops
We should mention one more effect connected with plastic flow.
As a consequence of the plastic flow of material under elevated
temperatures, a continuous decrease in thermal stresses (stress
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