Decomposition of strain energy density in fiber reinforced composites

✍ Scribed by P.S. Theocaris

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 673 KB
• Volume: 33
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(89)90084-2

✦ Synopsis

The elliptic paraboloid failure surface (EPFS) has been shown to constitute an ideal criterion for yielding and failure of fiber reinforced materials, whose predictions coincide with extensive experimental evidence in various fiber laminates. Using this failure surface and limiting ourselves to transtropic materials describing all fiber reinforced composites we have shown that the total elastic strain-energy density can be divided into two independent parts, derived from orthogonal states of stress in such a manner that each component of stress in either part of the energy does not contribute to the energy belonging in the other part. Then, it was shown that while the orthogonal part of energy parallel to the hydrostatic axis of principal stress space is constant and independent of the orientation of the total stress vector, the terms parallel to the deviatoric plane are variable depending on the angle subtended by the stress vector and the principal diagonal plane containing the strong ptincipal axis. Furthermore, whereas all terms of strain-energy density are created from couples of stresses and strains derived from each one of their ~m~nents, only the term parallel to the deviator& plane and normal to the principal diagonal plane is derived from collinear corresponding components. This term for transtropic materials expresses a strain energy density due exclusively to shear along the isotropic transverse plane of the material.