. A body is deformed under the action of forces. Strain components _αβ at a point are measured experimentally. Excluding a common factor, the components are given by the strain array   7 2 0 2 6 −2...

.
A body is deformed under the action of forces. Strain components
_αβ
at a point are

measured experimentally. Excluding a common factor, the components are given by the

strain array





7 2 0

2 6 −2

0 −2 5





(a)
Determine the principal values
_1 ≥
_2 ≥
_3 of the strain tensor. Hence, determine

the principal strain directions associated with
_2.

(b)
The stress components
σαβ
of part (a) are given by the array (excluding a common

factor)





21 6 0

6 18 −6

0 −6 15





Determine the principal stresses
σ1 ≥
σ2 ≥
σ3. Determine the principal stress direction

0)      associated with
σ2.