  The Multiparticle Models of Multilayered Materials (models M4) are developed
to analyze easily the 3D stress fields which produce delamination or transverse
crackings in laminates. The M4 models are built from 3D approximate stress
fields in z per layer and the Hellinger-Reissner's formulation. Here-in we
express two of these models: the M4_5n model of which the kinematics, with 5n
fields (n: number of layers), is the one of n Reissner's plates and, the
M4_(2n+1)M model of membrane with 2n+1 fields. The latter gives simple analytic
solutions and a concentrated edge force per unit length that could be a natural
support for the criteria of delamination. We illustrate this concept by the
analytic resolution of (0 deg, 90 deg)s in traction and give some results for
more complex stackings.
