IMPACT FRACTURE TESTING OF POLY(OXY METHYLENE)

摘要

To characterize the dynamic fracture behaviour of poly(oxy methylene), instrumented impact tests were performed with a servohydraulic test system using single edge notched bending (SENB) specimens. The primary objective of this study was to develop and implement a test methodology and a data recording and reduction scheme for various impact rates (0.01 to 7.9 m/s). As far as the instrumentation is concerned, load-time signals were measured and recorded using an instrumented tup equipped with a piezo load cell and strain gages, respectively. Furthermore, the time-to-fracture was detected with different strain gage types applied to the specimen side surfaces in the immediate vicinity of the crack tip. The data reduction to determine dynamic fracture toughness values was carried out according to different procedures taking account of the specific impact rates. Due to the viscoelastic nature of plastics, the strain rate dependence of the elastic modulus required for the calculation of dynamic fracture toughness values was determined experimentally.