Conference of the International Journal of Arts and Sciences 1(18): 72 - 88 (2009) CD-ROM. ISSN: 1943-6114 © InternationalJournal.org Stress Strain Characteristics of Glass Fiber Reinforced Plastic as Wind Turbine Blade Materials Alper UYSAL, Yildiz Technical University, Turkey Aysegul AKDOGAN EKER, Yildiz Technical University, Turkey Bulent EKER, Namik Kemal University, Turkey Abstract: Wind energy, which is limitless and clean source, takes first place in alternative energy sources because of its developments last several years. Beside research and development studies of wind turbines produced to transform wind energy to electrical energy increase every day, design and materials of wind turbine blades lead researches carried out intensively at wind turbine constructions. A study about using composite materials with plastic matrix is chosen because the aim of wind turbine blade studies is producing lighter constructions. In this study, stress-strain characteristics of random short glass fiber mat reinforced polyester or vinylester matrix composite materials produced by using hand lay up molding method are analyzed. Consequently stress-strain characteristics of composites materials which are manufactured by using different layers of glass fiber mat reinforcement are compared. 1. Introduction In our world energy requirement increases approximate 4-5% every year. But fossil fuel reserves, which compensate this requirement, increase much more. The most optimistic predictions show that oil reserves will run out at the latest 2030 – 2050 and will not compensate requirements. Also same situation is expected for coal and natural gas. Therefore humankind must tend to renewable energy resources before fossil fuel reserves come to an end. Due to research and development studies, renewable energy resources will be same level with other conventional systems as cost and also efficiency. Wind energy, which is one of renewable energy resources, is kind of clean, harmonious to environment and economic energy. Using wind power neither consumes fossil fuel nor makes dirty atmosphere. As it is known, in wind turbine constructions wide range of materials are used. Suitable materials must be chosen for each unit to obtain high efficiency