Fiber Composites Failure Criteria

  A new failure criterion has been formulated for fiber composite materials.  It is the anisotropic counterpart of a recently derived isotropic criterion.  The targeted applications are for carbon fiber, polymeric matrix (or equivalent) types of materials.   The complete treatment can be accessed at the new website:                                                                 http://www.failurecriteria.com

No special assumptions are used in the derivation, the only condition taken is that of a large degree of anisotropy for both stiffness and strength of the transversely isotropic, aligned fiber lamina.

     The failure characterization naturally and necessarily decomposes into two distinct modes of failure, one for the fiber controlled mode and one for the  matrix controlled mode.  The fiber controlled criterion becomes that of the maximum stress form.  This form has always been considered to be highly useful for composites, but also totally empirical.  The present derivation shows that this result is not empirical, rather it is a rigorous consequence of the common condition of high anisotropy.  The matrix controlled criterion is not quite as simple, but it is still completely calibrated  by standard strength testing results.

     This anisotropic failure criterion is specifically coordinated with and complementary to the isotropic material failure criterion already given in the  above website.  The relationship to previous and historical failure criteria also is covered.  Finally, it may be noted that the technical specification of the failure limits for composite materials is now more important than ever before.   The advent of the Boeing 787 and current Airbus designs warrant this, as well as many other energy efficient  applications in naval, aviation, automotive and civil infrastructure systems.