The Effects of Manufactured Defects on the Axial Damping Characteristics of Composite Specimens

University of Utah

The effects of manufactured defects on the damping of laminated composite materials with constrained viscoelastic layers are investigated using finite element analysis and testing. lnterlaminar stresses, which are the primary contributors to constrained layer damping, are described. The modal strain energy method is used to measure the extent to which the finite element models are damped. Decisions for the selection of certain finite elements are presented and discussed. The results of the finite element analysis using the software IDEAS are presented. The half-power bandwidth method is used in testing the composite specimens. The test set up is explained and illustrated and test results for the experimentally determined loss factor are presented. Correlation between the finite element and testing results are presented. The presence of manufactured defects was found to substantially increase the damping capacity of the finite element models. Frequency response tests of composite specimens indicate that damping increases in composites with manufactured defects, however, stiffness is reduced.