THEORETICAL ANALYSIS AND EXPERIMENTAL
VERIFICATION ON TERNARY-WAVES METHOD
TO COMPILE ACCELERATED SPECTRA*
Xiong Junjiang Wu Zhe Gao Zhentong
Aircraft Design Bureau, Beijing University of Aeronautics and
Astronautics,
Beijing 100083, China |
Abstract:
The equivalent damage calculation formulae of fatigue crack
formation and growth are established. In order to compile the
fatigue crack formation and growth accelerated load spectra, the
main wave shapes and load sequence of the actual load spectrum
are kept constant, and the carrier waves are cut off. And
secondary waves are put together into new secondary waves to
shorten the test time according to the equivalent damage
calculation formulae respectively. Then by the fatigue
cumulative damage calculation of the fatigue crack formation and
growth accelerated load spectra, the one corresponding to the
bigger damage is determined as the fatigue accelerated test load
spectrum. Therefore in the test process, the fatigue accelerated
test spectrum may be applied till fatigue failure, the
engineering fatigue crack length of full-scale structure need
not be inspected, and the fatigue crack formation accelerated
load spectrum need not be transferred into the fatigue crack
growth accelerated load spectrum. Finally, it is verified by
tests of two kinds of specimens that the damages of the
specimens caused by the accelerated load spectra are near to
those by the actual load spectra; namely, the tested life of
actual load spectra is similar to that of accelerated load
spectra. But the test time of accelerated load spectra is
shortened by about three-quarters that of actual load spectra.
From these tests, it is also found that the fatigue accelerated
test spectrum has an advantage over FALSTAFF spectra.
Key words:
Ternary-waves Actual load-time history Accelerated load
spectra Equivalent damage calculation Main wave Secondary
wave Carrier wave
* This project is supported by National Natural Science and Aeronautic
Science Foundation of China (No. 50005003, No. 01A51011).Received
February 10, 2001; received in revised form July 26, 2001; accepted December 12, 2001
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