This paper examines the effects of interaction and coalescence of multiple surface cracks in water environment on fatigue behavior in brittle materials such as glass ceramics. For glass ceramic specimens with the three collinear cracks which introduced the different crack center distances by Vickers indentation, the cyclic fatigue tests in water environment were carried out with four point bending load. It was found that the time to failure for glass ceramics in water environment significantly decreased with the decrease in the crack center distance of multiple surface cracks, and was shorter than that in air. Moreover, from the crack growth parameter for a single crack, the predictions of the time to failure for multiple surface cracks were conducted by taking the interaction and coalescence into consideration. The predictions using the proposed crack growth model agree well with the experimental results.
