Semielliptical Cracks along Holes in Plates and Lugs.

摘要

This report summarizes a basic research effort directed at characterizing the growth of semielliptical surface cracks embedded along the bore of a hole in a large plate or an attachment lug. Fatigue cracks are grown in transparent polymer test specimens which allow in situ observation of the crack plane. Crack growth was recorded by time lapse photography. Subsequent measurement of the crack photographs gave crack size and shape changes as a function of elapsed cycles. A multidegree of freedom fracture mechanics model was developed to predict the growth of embedded surface and corner cracks located at open holes in plates loaded in remote tension. Crack growth predictions gave excellent agreement for the embedded surface crack plate results obtained under the current effort and also gave good results for corner cracked hole tests conducted under an earlier program.