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Fatigue performance of external fixator pins
Author(s) -
Kasman Roberta A.,
Chao Edmund Y. S.
Publication year - 1984
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.1100020410
Subject(s) - materials science , external fixator , fatigue limit , composite material , bending , reduction (mathematics) , stress concentration , cyclic stress , fracture (geology) , structural engineering , tapping , orthodontics , engineering , fracture mechanics , mathematics , medicine , mechanical engineering , geometry
Abstract The fatigue performance of several types of commonly used external fixator pins was examined. The pins were tested under a cyclic bending mode. A strength reduction factor (SRF) was defined to quantify the effect of stress concentration caused by the pin threads as compared with the smooth portion of the pin. The half pins tested had much higher SRF values than the corresponding full pins because of the smaller root diameter of the threaded regions. The use of finer threads and a cold rolling process appeared to increase the pin fatigue strength. In some pins, the depth markers on the smooth portion and the self‐tapping fluted region were sites of significant stress concentration. When certain half pins are severely loaded under clinical conditions, they may fracture because of fatigue.