ISO B Properties

Discussion in 'Class Societies' started by willfox, Nov 3, 2013.

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willfoxJunior Member

Hi there,

Wondering about ISO B properties. So if you do the small amount of testing required to validate the fiber weigh fractions used, must you use the fiber weights outlined in the rule with the given equations or can you use the fiber weights that were found when testing? I know that if you don't do any testing, you must use the given fiber weights and 0.8 times the calculated property values. In my mind, it would make sense that if you validate the fiber weights (ensure you meet at least these fiber weights through testing), then you still use the given fiber weight, you simply use 1 x times the calculated value rather than 0.8 times.

Does anyone have experience with this?

Thanks

Will

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AlikSenior Member

ISO12215-5 Method B is when You evaluate fiber content by burn out test. So it is all about validation of fiber content and using this fiber content for evaluation of structural properties.

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willfoxJunior Member

So say if it was chop strand matt and in ISO C for a complex panel you must use a fiber weight of .25 and the derived properties from the property equations. If I then did the burn off test and found that I achieved .33, I can then use this fiber weight in the equations and use these derived properties. SO not only do I get the benefit of using 1 x the derived properties (rater than 0.8 x for ISO C), I can also use higher properties derived form the better fiber weight fraction using the property equations.

Thanks

Will

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TANSLSenior Member

In my opinión, to use method B, we need to handle real data of what is being done at the shipyard. It could be the opposite of what is presented, ie to calculate the scantlings to method B and, once built the panel and analyzed their fiber content, check that the properties do not reach the expected values ​​for method B and, therefore have to reject the panel.
What do you think about it?

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AlikSenior Member

We usually recommend the builders to produce the panels once we start something new. From that, we check weight and know all the specs, first of all calculated weight to actual weight that is much related to fiber content and consumption of resin into core. But mostly this is done for lamination team so they know how to go ahead to keep the build within design parameters.

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TANSLSenior Member

Alik, I agree and I think that is the correct procedure. Then it is the responsibility of the head of the work to verify that the actual work is done as the test was performed.

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willfoxJunior Member

I am still unsure of what the correct procedure is. Once the fiber weight of the panel has been found, this fiber weight is then used in the equations, not the defaults which are used for ISO C.

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TANSLSenior Member

Weigh the sample. w1
Burn the sample
What remains is cleaned and weighed. w2
The relationship Fi = w1/w2 gives the weight percentage of the fiber.
With that percentage, Fi, enter C.4 tables to determine the physical properties of the material.

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