WEBINAR: Ductile to Brittle Transitions in Plastics
October 18, 2018 at 11:00AM EST
Webinar via Zoom
The objective of a failure investigation is to identify the mechanism and cause of the failure. The characterization of the failure mode such as, fatigue, overload, environmental stress cracking, etc… is often straightforward through fractographic methods. However, the determination of the cause of the failure is in many cases less apparent. Plastic materials are utilized in many applications because of their unique property set, including their ductile response to applied stress. This ductility is associated with the viscoelastic nature of polymers and is attributed to their unique molecular structure. In spite of that inherent ductility, most plastic components fail through one of the many brittle fracture modes. Experience has shown that less than 5% of failures are associated with ductile overload. The remainder represent brittle fractures of normally ductile materials. Thus, within evaluations of plastic component failures, the focus of the investigation frequently turns to identifying the nature of the ductile to brittle transition. This relatively brittle response to stress is evident through the examination and characterization of the fracture surface morphology.
There are numerous factors that influence a ductile-to-brittle transition within plastic materials, such as:
- Stress Concentration
- Chemical Contact
- Molecular Weight
- Filler Content
- Poor Fusion
- Strain Rate
- Time Under Load
- Plasticizer Content
Jeffrey A. Jansen is Senior Managing Engineer and a Partner at The Madison Group, an independent plastics engineering and consulting firm. Jeff specializes in failure analysis, material identification and selection, as well as compatibility, aging, and lifetime prediction studies for thermoplastic materials. He has been solving polymer-related problems for 26 years. In that time, he has performed over 3,820 investigations, both for industrial clients and as a part of litigation. Jeff is a regular presenter on the SPE webinar series, covering a wide range of topics related to plastics failure, material performance, testing, and polymer technology. Jeff is a graduate of Carroll College and the Milwaukee School of Engineering.