SOME REMARKS ON THE ACOUSTIC FATIGUE OF ALUMINUM SKIN-STRINGER STRUCTURES WITH EITHER INTEGRALLY MILLED OR RIVETTED EDGE REINFORCEMENTS

Edge reinforcements improve the endurance as is known. But published d ata on stress reduction are not always quite conservative. Random vibr ation calculation gave more precise predictions of stress reduction wh ich were well confirmed by measurements on seven different test coupon s. Separated doublers were found to be much more effective than reinfo rcements by chemically milling though the S-N curves for doublers show a somewhat steeper decrease. The improvement mainly results from a mu ch larger structural damping. In comparison with other publications, t he measured S-N curves were found to be in general more optimistic. On ly above 10(9) load cycles the steeper decrease of the curves for doub ler show more pessimistic results. (C) Elsevier, Paris.