We can’t always press a proper test specimen. In order to test rubber sheet material with AYO-IV, one can use a layered approach. Get a 3/4″ hole punch. As seen left, punch out enough round plugs so that total thickness is close to 1/2 inches. The idea is to put enough round plugs on top of each other to reach approximately 1/2 inches in height. During AYO-IV setup, enter the actual height. In this case the area is the same as a standard specimen, 3/4 inches. Thus the area is the same as the standard specimen. Please note that this approach is not approved by ASTM D945; however, it is useful for comparing different sheet materials.
System Calibration Procedure
Yerzley Oscillograph is an efficient means of obtaining the mechanical properties of rubber and similar materials. The calculations for dynamic properties rely on the “moment of inertia – I” of “the beam”. The component of the oscillograph, called “the beam” does not have a simple geometry; so it is not easy to determine it’s “I” value purely from geometry. Furthermore, there are many components attached to this beam that affect the actual moment of inertia. The ASTM Standard D945-06 on page 9, in paragraph 13.10 mentions that 0.100 slug-ft.sq is an approximate value that has historical acceptance.
It is possible to determine the moment of inertia of the beam together with all it’s attached components experimentally. The method is based on the paper by Dr. F.L.Yerzley, published in the proceedings of the ASTM in volume 39, 1939.