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End notched flexure (ENF) tests were performed to investigate the effects of temperature and fiber orientation on Mode II interlaminar fracture behavior, G[sub IIC] (G[sub II] at the crack initiation), of carbon fiber-reinforced epoxy composites, T800H/#3631. The values of G[sub IIC] for three kinds of laminates, [0[sub 12]//0[sub 12]], [22.5/-22.5/0[sub 8]/-22.5/22.5//-22.5/22.5/0[sub 8]/22.5/-22.5] and [45/-45/0[sub 8]/-45/45//-45/45/0[sub 8]/45/-45], with a pre-cracked interface, that is // in each laminate, were obtained at three temperatures, i.e. -100°C, 25°C and 150°C. It is shown that G[sub IIC] is obviously affected by the temperature and fiber orientation. The scanning electron microscope (SEM) observation was also carried out to investigate the fracture surface. SEM analysis suggested that the decreased Mode II interlaminar fracture toughness for all kinds of specimens at high temperature could be attributed to temperature-induced matrix property change or fiber-matrix interfacial weakening. [ABSTRACT FROM AUTHOR]

This paper presents modal-based structural damage detection. Specifically, we focus on localized flexibility properties that can be deduced from the experimentally determined global flexibility matrix. We describe the damage detection theory that can be viewed a generalized flexibility formulation in three different generalized coordinates, viz., localized or substructural displacement-basis, elemental deformation-basis and element strain-basis. The three localized flexibilities are applied to a CFRP plate having internal damage. The results show that the elemental strain-basis flexibility is the most accurate in detecting the damage of the CFRP laminates. [ABSTRACT FROM AUTHOR]