Page 41 - 4749

a) b)

Figure 2.11

The diagram of compression of brittle material (fig.2.11, b) is
similar to the diagram its tensile. It allows you to set the limit of
С
compressive strength  (corresponding breaking load) and the
st
relative residual deformation  . It should be noted that for brittle
С
materials compressive strength limit is much larger than the
st
t
tensile strength limit  .
st

2.8 Allowable stress. Strength calculation

Strength calculations should ensure the absence of residual
deformations in structures (for plastic materials) or signs of
destruction (for brittle materials). From mechanical tests the
stresses are known, when in a plastic material the plastic
deformation  appears, and in a brittle material – fracture  .
t st
These stresses are called limit.
Since, on the actual design unfavorable factors can influence
that are ignored or cannot be taken into account in the calculation,
41