Flexing Fatigue of Glass-Fiber Filter Cloth

A flexing endurance test, using a modification of ASTM D643-43 for paper, is suit able for the evaluation of glass-fiber filter cloth. The test can be applied to new cloths and cloths after exposure to heat, this being the major cause of deterioration of the cloth properties in practice. Superior flexing endurance, when new, is not necessarily main tained after heat exposure. The life distribution is log-normal for the texturized-yarn weft direction and bi-modal log-normal for the continuous-filament-yarn warp direction. For the warp, a two-stage mechanism leading to failure is evident from the observed specimen elongations; for the weft, only one stage was observed. The log of life is inversely proportional to the flexing angle, which is explained by considering the flexing angle (proportional to the length of specimen being flexed) as an equivalent of specimen length in axial-stress cycle fatigue.