Fatigue of Adhesive Joints - 3. Statistical Mathematical Evaluation.

The durability of adhesive joints under conditions of vibratory stress is a factor subject to wide fluctuations, a characteristic common also to other material categories. This phenomenon is interpreted as the result of the interaction between two different effects. Variations in quality of a group of similar adhesive joints included under ″specific adherend″ are relatively minute, independent of the limiting value of stress cycle endured and the length of overlap. It is only in relationship to these quality parameters that statistical evaluations can be useful and practical. As the result of a second ″steering effect″ , caused by the pattern of the ″characteristics″ , the primary variations are transformed into wide fluctuations of the life expectancy.