I have presented expert testimony in a materials-related automotive case and assisted in the discovery phase of an injury-related case that involved the failure of trailing edge spar of a helicopter blade which was fabricated from unidirectional aramid composite The photo at left is of a failed PBO test vessel looks a little like that failure - there is usually little left for analysis. Key in the latter case was the knowledge of the shear properties and allowables of unidirectional aramid composites and the discovery of a stress direction not anticipated by the designers.
Typically, failed aramid composites look similar to the failed burst bottle at the left, particularly if they have been designed correctly. (The bottle at left is, in reality, made of a fiber similar to aramid, called PBO and was designed, built and tested to destruction by Lincoln Composites of Lincoln, NE)
The analysis of many composite failures can be difficult because of the lack of "pointers." In metals there are more indications which can help pinpoint type of the fractujrte or the origin, such as beach marks in a fatigue failurewhich are many times visible to an experienced investigator. The problem is further complicated with aramid and some other composites, which fail in a very high energy way, with little left to analyze
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