Cam takviyeli plastik malzemelerde takviye açısının kırılma davranışına etkisi

Abstract

ABSTRACT Ph.D. Thesis THE EFFECT OF REINFORCEMENT ANGLES ON THE FRACTURE BEHAVIOUR OF GLASS REINFORCED PLASTICS Ibrahim GÜLDÜ Selçuk University Graduate School of Natural and Applied Sciences Department of Mechanical Engineering Supervisor: Prof.Dr. Remzi ÇETİN 1995, Page: 145 Jury: Prof.Dr. A. Ünal ERDEM Prof.Dr.RafetARIKAN Prof.Dr. Remzi ÇETİN Glass reinforced plastics plates, which contain sharp change in cross section and are loaded to tension, are used extensively in many engineering areas. The stress, concentration on the composite plates differ from isotropic cases in relation to fiber directions and loading conditions thus, the reinforcement type and orientations effect both the crack growth behaviour and fracture toughness values, considerably. In the first stage of this investigation, stress concentration factors were calculated by finite element method for various reinforcement angles and fillet radii at glass cloth-polyester, kevlar-epoxy and graphite-epoxy composite plates. Also the stress concentration factors were obtained by strain-gauge methods for glass cloth- polyester composites experimentally. Then the result obtained in the experimental work were compared with those obtained in the theoretical calculations. In the second stage were carried out on compact tension specimen which prepared in accordance with ASTM E-399. The effect of reinforcement angle to the fracture behaviour and to the fracture toughness, were, experimentally, determined. Toughness values were determined by using the compliance calibration methods and Srawley methods respectively, then all the results were compared. KEY WORDS: Glass Reinforced Polyesters, Woven Roving, Glass Cloth, Fracture Toughness, Stress Concentration.