Originally Posted by Stumble
I always find it interesting that people raise concerns about the fatigue life of aluminium, but no one ever raises the issue with fiberglass. Given that fiberglass has the same fatigue problems as aluminium it seems more of a theoretical problem than an actual one, so long as the boat is properly designed in the first place.
There is a good reason people who know are concerned with fatigue life of aluminum.. because it is aluminums most critical issue. And it fatigue failures are thousands of well documented real-life fatigue cracks that show up in a multitude of aluminum products.
There is a simple solution.. subject your product to fatigue tests. That is what the airline manufacturers and auto manufacturers do.
On the other hand, the fatigue life of something like steel is so well defined that you can build a product, and predict its life with software on a computer.
The way I see fiberglass is that there is not such widespread fatigue failure in fiberglass based on experiences of people. Rather fiberglass failure seems most often due to core failure or impact damage. The study below suggests that fiberglass fatigue might be predicted using steel type predictions.
Although I am sure some structural test engineers would cringe at the test setup these guys used.. its an interesting read.