Semester

Fall

Date of Graduation

2004

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Julio F. Davalos.

Abstract

In recent years, the demands in civil infrastructure have provided opportunities for development and implementation of Honeycomb Fiber-Reinforced Polymer (HFRP) sandwich panels, both in rehabilitation projects and new constructions.;This dissertation is the first study on strength evaluation of HFRP sandwich panels with sinusoidal core geometry. Core materials for sandwich structures are primarily subjected to out-of-plane compression and shear. Therefore, three major contributions are included in this dissertation: out-of-plane compression, out-of-plane shear, and study on facesheet laminates. Two analytical models, corresponding to pure compression and elastic buckling failure, respectively, are provided for panels subject to out-of-plane compression. The facesheet and core are attached by contact molding and are, therefore, not rigidly connected. Thus, the buckling problem can be described as the instability of an FRP core panel with two rotationally restrained loaded edges. An elastic restraint coefficient is introduced to quantify the bonding layer effect between the facesheet and core, and a simple and relatively accurate test method is proposed to obtain the restraint coefficient experimentally. By solving a transcendental equation, the critical compression buckling stresses are obtained, and a simplified expression to predict buckling strength is formulated in terms of the elastic restraint coefficient.;Most of past studies in the area of out-of-plane shear are focused on stiffness only. As a step further, analytical models, including shear crushing, shear buckling, and delamination considering skin effect are provided. Two factors are addressed that contribute to the skin effect: shear and bending warping. A closed-form solution, based on proper description of displacement field at the interface, is derived considering shear warping. Four-point bending tests were carried out according to ASTM standards to study shear strength and shear stiffness of the core materials. Two types of beam samples were manufactured by orienting the sinusoidal wave: (1) along the length ("longitudinal"), and (2) along the width ("transverse"). Design equations are provided to predict the failure load due to different failure modes and good correlations are obtained.;Strength properties of the facesheet are studied in detail to develop an optimized facesheet configuration. A progressive failure model is developed using FE method to predict the behavior of laminated composite plates up to failure, where the failure criteria are introduced through prescribed user defined subroutines. The accuracy of the model is verified through correlations between FE results and existing experimental data. The test results are also used to validate the progress failure model developed in this study. Through this combined experimental and analytical study, the strength properties of facesheet are obtained, which permits the optimization of facesheet design. (Abstract shortened by UMI.).

Download

Share

COinS