Failure Analysis of Glass-Filled Plastic Poppet Valve
Circumferential fracture observed in hollow stem. Secondary parallel cracking noted suggesting fatigue failure.
SEM Examination of fracture surface showed smeared plastic and occasional fatigue striations.
Failure was related to improper component assembly. Internal spring was found to be abrading against inner wall of stem. Flexure and eventual fatigue cracking of hollow plastic stem of fuel valve occurred.