In this report, we firstly point out that all kinds of composite failures can be analyzed through micromechanics only. One apparent reason is as such: given the composite subjected to any arbitrary load, one cannot tell when the interface debonding between the fiber and matrix will occur if he does not know the internal stresses in the fiber and matrix. The latter is obtainable only by micromechanics. And this problem has been resolved, and is presented in this report. 

Secondly, we demonstrate that the internal stresses in the fiber and matrix obtained by a micromechanics theory are homogenized quantities, which must be converted into “true” values before a failure assessment can be efficiently made. The true stresses of the matrix are very much different from its homogenized counterparts. It is the true stresses of the matrix that open the door to solving all kinds of composite failure problems. 

 Lastly, we show that the failure and strength of a laminated composite subjected to various types of loads can be efficiently assessed only using the original fiber and matrix properties, plus a transverse tensile strength of a unidirectional composite if an earlier interface crack is involved. Several examples are included.