الفهرس 
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Abstract
A study of dynamic behavior of notched woven roving glass reinforced polyester (GRP) subjected to sinusoidal and impact tension loads is presented. In this study, tests were conducted on two fiber orientations [0°,90°] and [45°,¬45°] flat specimens. These specimens were fatigue tested under different values of mean and alternating stresses and under different impact stresses The stages of damage mechanism were studied in the two fiber orientations [0°,90°] and [45°,-45°] under sinusoidal and impact loads. It is shown that under sinusoidal loads; the damaged area is proportional to the value of alternating stress and to the’ number of cycles to failure. The failure in specimens with [0°,90°] fiber orientation is perpendicular to the load axis direction, this type of failure is named fiber mode failure. In specimens having [45°,-45°] fiber orientation the failure is parallel to the fiber direction and is named the matrix mode. Under impact loads the damaged areas at the two sides of the specimen are not symmetric, the side of the fixed grip has a bigger area, this is due to the difference in the wave velocity in the fiber and the matrix The results of tests conducted under sinusoidal loads exhibit a linear relationship, like modified Goodman line, when plotted on σmσa curves The specimens tested under. sinusoidal load exhibit fatigue lives larger than specimens under impact load for the same maximum load. A new proposed theory of failure is introduced based on the use of equivalent static stress, as given by modified Goodman line, to be coupled with the corresponding static strength to define the failure of the composite. A stress concentration factor is introduced to the terms of equivalent stress having the amplitude stress. This is due to the presence of a notch as well as the effect of the woven fiber.