Page 304 - Mechanics Analysis Composite Materials
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Chapter 6. Failure criteria and strength ojlaminates 289
This equation being rewritten as
((T~'}~((T"}= 1 (6.30)
[R4']
specifies the strength criterion for the same material but referred to coordinates
(l', 2'). The strength matrix has the following form:
[R"] = [TIT[Ro][T]=
where
(6.31)
The explicit form of Eq. (6.30) is
(6.32)
However, since criterion in Eq. (6.25) is a tensor relationship, it can be written in
coordinates (1', 2') if we change (TI, 02, 212for 0j5,$;, 81)for a45, and To for fjj.
The result is as follows:
(6.33)
Because Eqs. (6.32) and (6.33) are the two equivalent forms of one and the same
criterion, we arrive at the following equations:
The second of these equations can be easily reduced to the first one. So, there is only
one condition showing that the combination of strength characteristics
