Fatigue Failure in Test Bars (IMAGE) University of Pittsburgh Caption The supporting structures failed for these four fatigue test bars. The stress buildup in the longer length of the bars created an excessive curling force on the outer edges of the support structures, resulting in fracture. Credit Albert To/Swanson School of Engineering Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.