Nonlinear Cumulative Damage Model Research Articles

A Cumulative Damage Model for Fatigue Life of Composite Laminates

The objective of the research is to make an attempt at relating the fatigue failure of a composite laminate to the fundamental damage and fatigue behavior of its laminae. Damage accumulation and property degradation of each lamina in the laminate are studied. Internal load redistribution among all the laminae is evaluated from the model of stiffness reduction. A nonlinear cumulative damage model is developed to determine the failure of the critical lamina which controls the final fracture of the laminate. The pre dictions of fatigue life agree with experimental data of cross-ply laminates made of graphite/epoxy.

Monitoring progression of Mode II delamination during fatigue loading through acoustic emission in laminated glass fiber composite: Polymer Composites, Vol. 9, No. 5, pp. 345–351 (Oct. 1988)

Acoustic emission (AE) was used to monitor damage development in a glass fiber/epoxy composite during monotonic and cyclic Mode II loadings of DCB specimens. AE parameters such as event count rates and accumulative event counts together with the distribution of events by time and location in the DCB specimen were used as proper indicators of the damage growth at various stages during testing. AE proved to be a powerful technique to predict in real time the interlaminar failure stress (delamination in Mode II) in both the static and the dynamic tests. An S-N curve constructed entirely on the AE signatures recorded during fatigue testing exhibits three distinct stages enabling delineation of period of damage initiation, the period of damage growth, and finally the occurrence of delamination. A generalized expression based on the nonlinear cumulative damage model was developed to correlate AE activity with the damage development in the composite during cyclic loading. The fatigue data to date agree well with this method of prediction of the fatigue life.

Monitoring progression of mode II delamination during fatigue loading through acoustic emission in laminated glass fiber composite

AbstractAcoustic emission (AE) was used to monitor damage development in a glass fiber/epoxy composite during monotonic and cyclic Mode II loadings of DCB specimens. AE parameters such as event count rates and accumulative event counts together with the distribution of events by time and location in the DCB specimen were used as proper indicators of the damage growth at various stages during testing. AE proved to be a powerful technique to predict in real time the interlaminar failure stress (delamination in Mode II) in both the static and the dynamic tests. An S‐N curve constructed entirely on the AE signatures recorded during fatigue testing exhibits three distinct stages enabling delineation of period of damage initiation, the period of damage growth, and finally the occurrence of delamination. A generalized expression based on the nonlinear cumulative damage model was developed to correlate AE activity with the damage development in the composite during cyclic loading. The fatigue data to date agree well with this method of prediction of the fatigue life.