The effect of aminations in graphite/PEEK composite plates on modal dynamic characteristics

Abstract A computationally efficient ‘plate type’ finite element model is developed to accurately predict the effect of delaminations on the modal dynamic characteristics of a laminated composite plate. The model is based on use of eight-noded shear deformable plate elements. To represent the delaminated region, stacks of elements are tied together only along their boundaries using a penalty parameter approach. Three AS4/PEEK composite plates, including intentionally formed delaminations, were fabricated. After inspection using infrared thermography verified the presence and location of the delaminations, vibration testing was performed with the plates simply supported on all four edges. The limited vibration test data was in reasonable agreement with the computational results. The results showed that the natural frequencies of the delaminated plates were lower than those of the non-delaminated plate. The differences were most apparent in the higher frequencies.