# Certification and failure criteria

**URL:** <https://forums.nlr.gov/t/certification-and-failure-criteria/55>\
**Category:** Materials\
**Created:** [November 9, 2005, 11:30am UTC](https://forums.nlr.gov/t/certification-and-failure-criteria/55 "2005-11-09T11:30:13Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Corrado.Pinzana](https://avatars.discourse-cdn.com/v4/letter/c/a9a28c/32.png) [@Corrado.Pinzana](https://forums.nlr.gov/u/Corrado.Pinzana)\
**Post date:** [November 9, 2005, 11:30am UTC](https://forums.nlr.gov/t/certification-and-failure-criteria/55/1 "2005-11-09T11:30:13Z")

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Hi

from a German Lloyd report about the certification of blades, I read that the failure criteria used up to know by aerospace community are not so reliable as one could think. The Puck failure criteria is mentioned as the most suitable for wind turbine.  
What is the thought of NREL about this topic ?

bye

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**Author:** ![Marshall.Buhl](https://avatars.discourse-cdn.com/v4/letter/m/f14d63/32.png) [@Marshall.Buhl](https://forums.nlr.gov/u/Marshall.Buhl)\
**Post date:** [November 11, 2005, 12:08am UTC](https://forums.nlr.gov/t/certification-and-failure-criteria/55/2 "2005-11-11T00:08:33Z")

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Corrado,

We don’t have a lot of expertise in materials here at NREL. I’ve never even heard of the Puck failure criteria. However, Sandia National Labs, our sister lab, has very extensive experience in that field. Hopefully, one of them will see this post and respond. I believe they are aware of this forum.

Marshall

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**Author:** ![dayhoc.nauan](https://avatars.discourse-cdn.com/v4/letter/d/fbc32d/32.png) [@dayhoc.nauan](https://forums.nlr.gov/u/dayhoc.nauan)\
**Post date:** [April 25, 2017, 3:52am UTC](https://forums.nlr.gov/t/certification-and-failure-criteria/55/3 "2017-04-25T03:52:15Z")

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thanks you for share