Volume 22, Issue 5 (September 1994)
Fatigue Testing of High-density Polyethylene and Polycarbonate with Crack Length Measurement Using Image Processing Techniques
A new automated method of measuring fatigue cracks in polymers is discussed. The new method is based on a video signal of the crack which is analyzed with “image processing” techniques. With this technique the crack length is measured every 20 s during a fatigue test. The accuracy of one single measurement is about 0.05 mm, but this can be increased by averaging a large number of measurements. The applied automated data collection and subsequent data processing is discussed in relation to the recommendations given in ASTM E 647, Test Method for Measurement of Fatigue Crack Growth Rates.
The use of the new technique is illustrated on the basis of fatigue tests performed on transparent polycarbonate (PC) and nontransparent polyethylene (PE). The fatigue behavior of PE and PC is briefly discussed.