Date of Graduation
Based on a generalized laminate plate theory, the formulation of a one-dimensional Beam finite element with Layer-wise Constant Shear (BLCS) is presented. The linear layer-wise representation of in-plane displacements permit accurate computation of normal stresses and transverse shear stresses on each layer for laminated beams with dissimilar ply stiffnesses. For the accurate computation of interlaminar shear stresses, the layer-wise constant shear stresses obtained from constitutive relations are transformed into parabolic shear stress distributions in a post-processing operation. The accuracy of the BLCS is demonstrated by solving various experimental and numerical examples reported in the literature. The BLCS formulation is extended to the analysis of plane frames with rectangular laminated sections and flexible joints. A progressive failure model for laminated composite beams is incorporated in BLCS, by implementing a material-degradation approach and existing failure criteria. Maximum Stress and Tsai-Wu failure criteria are used to predict failure at the Gauss points. A load- and displacement-controlled schemes are used to trace load-displacement paths. The predictions of the model correlate well with experimental results of graphite-epoxy beams and glued-laminated timber (glulam) beams reinforced with glass fiber-reinforced plastics (GFRP). Full-scale tests of glulam-GFRP beams are conducted, and the experimental responses and analytical predictions are discussed and correlated. The model can accurately predict the linear and failure behavior of the test-beams. An analytical model to predict delamination buckling is developed for laminated beams reinforced on the compression face with thin strips, and the model is verified with experimental results for top- and-bottom reinforced glulam-GFRP beams.
Kim, Youngchan, "A layer-wise theory for linear and failure analysis of laminated composite beams." (1995). Graduate Theses, Dissertations, and Problem Reports. 9184.