Fracture failure analysis and strength criterion for PTFE-coated woven fabrics

Abstract

This paper presents the research on fracture failure analysis and failure criterion for PTFE-coated woven fabrics. First, groups of on-axial and off-axial tensile tests are carried out, and the corresponding failure mechanisms are analyzed. Then, the samples with initial defects are tested and the fracture toughness is discussed. Finally, several current strength criteria are compared to predict the failure strength of PTFE-coated woven fabrics and a new strength criterion is proposed. Results show the material failure strength depends on the stress ratio and off-axial angle of sample. The ratio of principal stress decides the material strength, and the angle between the principal stress and yarn orientation decides the failure mode. The predictions of current strength criteria agree well with most of the experiment data, except for the samples of small off-axial angles. The disagreements could be attributed to the unbalanced woven structure due primarily to the crimp interchange in the weaving and coating processes. The new strength criterion can make a good prediction of the failure strength of PTFE-coated woven fabrics.