Wire rope fatigue and size effect- Discussion

Wire rope fatigue and size effect- Discussion

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The size effect of running wire ropes is composed of the effect of rope diameter d and of bending length I. ln Ciuffi & Roccati (1995) the size effect was mainly discussed in respect to the rope diameter d. Forthis influence in (Feyrer 1974) the equation is given with N for the number of bending cycles. The regression, analysis for the exponent n which gave a value - 0.32 was made in 1980 on the basis of nearly 700 bending tests, most of them made by Hugo Müller. The diagram from Müller shown in Ciuffi & Roccati (1995) is an example of his results. It is the only diagram on this subject published from Müller (1966) and it is that with the strongest influence of the rope diameter (without correction for the different strength). Recently Karol Virsik (1995) a student of our Institute made a new regression for the effect of diameter with 1376 test results with wire ropes over a wide diameter range. As an exponent he got n = - 0.314. Which is, considering the scatter, practically the same result of n = - 0,32 that Shitkow & Pospechow (1957) obtained. It would, nevertheless, be interesting to get an exponent n from a new investigation in OIPEEC-co-operation.

Author: K. Feyrer