Vlad
I think it might be an improved sectional modulus as well as improved glue joint
Just a thought .
See ya,
Chuck
email: chucks2000_at_roadrunner.com
From: Indoor_Construction_at_yahoogroups.com [mailto:Indoor_Construction_at_yahoogroups.com]
Sent: Friday, January 22, 2016 5:27 PM
To: Indoor_Construction_at_yahoogroups.com
Subject: [Indoor_Construction] Boroned spars
Dear all
I have done some testing on spars with boron
2 variations boron glued on top of premcut spars vs cutting a groove and adhering spars. The groove was made with specialty tool 0.004 deep and boron treated with glue and re activated with 80 percent acetone 20 percent glue. The other variation gluing boron to precut spars boron applied directly to spar without pre treatment. The wood was same youngs modulus for testing. The testing results on average of 5 samples made the breaking load was 37 percent higher on the pre cut spars with boron applied on top. Also the stifness and resistance to bending the ones with boron applied onntop wer to be flexing 49 percent less before reaching the yeild point of failiure.Interesting is when they failed it was due to wood buckling. Th inlaid boron on other type with the groove showed that the failiure was caused by unadeuate adhesion meaning boron glue giving way. This can be explained that there is no good layer below the boron and the groove creates a stress layer in he composite spar. Just my observations.
Vladimir Linardic
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Received on Fri Jan 22 2016 - 15:26:02 CET