Tension fatigue of glass/epoxy and graphite/epoxy tapered laminatesSymmetric tapered laminates with internally dropped plies were tested with two different layups and two materials, S2/SP250 glass/epoxy and IM6/18271 graphite/epoxy. The specimens were loaded in cyclic tension until they delaminated unstably. Each combination of material and layup had a unique failure mode. Calculated values of strain energy release rate, G, from a finite element analysis model of delamination along the taper, and for delamination from a matrix ply crack, were used with mode I fatigue characterization data from tests of the tested materials to calculate expected delamination onset loads. Calculated values were compared to the experimental results. The comparison showed that when the calculated G was chosen according to the observed delamination failures, the agreement between the calculated and measured delamination onset loads was reasonable for each combination of layup and material.
Document ID
19910032634
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Murri, Gretchen B. (NASA Langley Research Center Hampton, VA, United States)
O'Brien, T. Kevin (NASA Langley Research Center; U.S. Army, Aerostructures Directorate, Hampton VA, United States)
Salpekar, Satish A. (Analytical Services and Materials, Inc. Hampton, VA, United States)