TENACITY(C), FRACTURE-MECHANICS, AND UNKNOWN COATER WEB BREAKS

A webbbreak model, based on fracture mechanics, was used to investigat e unknown coater web breaks. Runnability was defined as L(b), the leng th between breaks. The model included the size distribution of defects (holes and light spots), web strength, and web tension. Defects were most detrimental to L(b). Tenacity and tensile strength are used inter changeably due to their high correlation on these specific grades (No. 3 and No. 4 medium, blade-coated) from a single paper machine. Tenaci ty is a simple, precise, valid fracture toughness test that is easy to use. Strength correlated strongly with web breaks. A 10% increase in tensile related to a 26% increase in L(b).