Summary

The goal of a failure analysis is to discern the mechanism and cause of the component failure - essentially to identify how and why the part broke. Fractography plays critical role in this, particularly in identifying the failure mode. Cracking occurs as a result of the exertion of stresses, both external and internal, on a component. Cracking is simply a stress relief mechanism in which the material is attempting to reach a lower energy state. Plastics fail through a disentanglement mechanism in which polymer chains slide past each other.

The features on the fracture surface are created based upon a number of parameters:

• Type of material and formulation constituents;
• Type of applied forces (tensile, compression, shear);
• Magnitude of forces;
• Frequency of forces (continuous, intermittent, rapidly applied);
• Environmental effects (temperature, presence of chemical).

Much of the information regarding the failure mechanism can be gleaned by interpreting the features found on the fracture surface. The examination and interpretation of the fracture surface is known as fractography. This presentation will explore some common plastics failure mechanisms and the associated telltale features.

About Speaker

Jeffrey A. Jansen
Engineering Manager
The Madison Group

Jeffrey A. Jansen is the Engineering Manager and a Partner at The Madison Group, an independent plastics engineering and consulting firm. Jeff is a proven plastic professional with more than 30 years of experience solving problems and addressing opportunities related to polymeric materials. He specializes in failure analysis, material identification and selection, as well as compatibility, aging, and lifetime prediction studies for thermoplastic materials. Jeff has performed over 5,000 investigations, both for industrial clients and as a part of litigation. He 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.