DYNAMIC STRESS-STRAIN TESTING OF RIBBONS OF FILM

摘要

This disclosure refers to an improved method and apparatus for dynamically, non-destructively testing ribbons of film to determine the stress-strain characteristics of the film under conditions substantially identical to the conditions to be imposed on the same film during subsequent processing. Specifically, a moving ribbon of film is first subjected to constant tension and is thereafter looped through a pair of constant surface speed nips, the surface speeds of which are selected to cause the film to elongate a pre-determined constant amount as it passes from one to the other. Total tension parallel to the machine direction of moving the film is continuously sensed in the looped film path intermediate the nips. Provision is made for continuously recording the total tension and for winding the tested film, under constant tension, into a roll of film.