EFFECTS OF STRUCTURAL CONSTRAINT AND IMPACT ENERGY ON FRACTURE BEHAVIOR OF A FLEXIBLE COMPOSITE TUBING

摘要

By using scanning electron microscopic analysis, we fractographically examine failure modes of flexible, braiding-reinforced composite tubes under impact energy pulses. The tubes are subjected to different extents of structural constraint imposed by other catheter components. The effects of impact energy pulses and structural constraints on failure modes are qualitatively evaluated. It is practically shown that under certain extents of structural constraint, minimal impact energy input can introduce catastrophic, brittle fracture mode dominant over either fatigue fracture mode or ductile failure behavior. In an attempt to identify the root causes for the formation of observed brittle fracture phenomena, various material characterizations, including differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) are conducted on the thermoplastic elastomer material of the tubes to attest material integrity after fabrication.