Abstract: An apparatus and method uses vacuum restraint, or other pressure differenl, to hold the ends of a sheet specimen to two opposing surfaces, thereby creating a fold in the specimen. As the opposing surfaces cycle along a parallel axis in opposite directions, the fold repeatedly rolls through a specific region of the specimen. The spacing between the opposing surfaces can be adjusted to increase or to decrease the radius of the fold. The velocity of the fold and the number cycles also can be controlled precisely. After repeated movement of the fold, the adhesion of surface treatments, coatings or printing on the specimen substrate begins to break down. Additionally, the integrity of the substrate itself may begin to deteriorate, if it is susceptible to deterioration and to varying degrees depending upon the susceptibility. The extent to which the specimen coating is degraded and substrate integrity reduced is a function of spacing, fold velocity and number of cycles.

Abstract: Method and apparatus for nondestructively estimating density of contiguous segments along the length of a straight, elongated specimen which is uniform in cross-section and heterogeneous in density throughout its length comprising maintaining the specimen in a horizontal position by supporting it at two points near opposite ends of the specimen; measuring the downward force exerted by the specimen at one of the points while periodically moving the other support along the length of the specimen. The measurements are applied to a static equilibrium equation together with external dimensions to determine segment densities.