Abstract
The purpose of this paper is to clarify the strength criteria and the mode of failure of orthogonally reinforced fiber composites under tension with emphasis on the effect of a circular hole on the tensile strength of these materials.
It is well known that for the unidirectionally aligned fiber composites, the strength and the mode of failure are related quantitatively with the fiber orientation, and many investigations have been carried out on this problem. For the orthogonally reinforced fiber composites, these properties have also been determined and the results have been found to be in good agreement with the authors' calculation.
It has been found that the Strength reduction. factor η=(σ-σi)/σ, Where σ and σi are the tensile strengths of specimens without and with a central hole, respectively, becomes minimum for the specimen having glass fabrics of a certain number of plies. An analysis has been presented here, which can explain the experimental results well.
The effects of strain rate on the tensile strength and strength reduction factor of the glass fiber reinforced plastics have been studied also. Both the tensile strength and the strength reduction factor changed linearly with the logarithmic value of the strain rate.
