tag:blogger.com,1999:blog-4848544913740911582.post9110618601729543712..comments2020-12-02T08:47:28.353-08:00Comments on The 'Dart-Boards' Project: Flex modelling - whats the point?MattMahttp://www.blogger.com/profile/04256614801832932462noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-4848544913740911582.post-53627220629110050372011-09-04T13:50:01.449-07:002011-09-04T13:50:01.449-07:00much obliged!
It is all much more clear now :).much obliged!<br /><br />It is all much more clear now :).MirsadChttps://www.blogger.com/profile/07470227301646971357noreply@blogger.comtag:blogger.com,1999:blog-4848544913740911582.post-78453861540349566032011-09-03T19:29:06.455-07:002011-09-03T19:29:06.455-07:00Hi MirsadC. Thanks for the really good question - ...Hi MirsadC. Thanks for the really good question - and I'm very happy to hear someone is reading it!!!!<br /><br />Its a case of both are right but it depends on which part of the core you are thinking about. Flexural rigidity is the product of elastic mod. and 'I', the secod moment of inertia. 'I' relates the shape of the cross-section only and E relates only to the properties of the material that its made up from. I for a rectangle is width*height^3/12. So if you are talking about the core material withouth any laminate on the outside (no fibreglass etc) then the flex. rig. is proportional to the height cubed. <br /><br />If you talking about just the 'shell' of reinforcement on the outside of the core then for this thin 'shell' of laminate has an 'I' whose largest term is core thickness squares times the thickness of the laminate 'shell'. This is because you can find the I of a complex shape by simply adding or subtracting the I of its components. I for a shell is then <br /><br />w*(c+t)^3/12 - (w-2t)*c^3/12; where c is core thickness and t is laminate thickness<br /><br />when you expand this out the c^3 terms cancel and you get c^2wt as the largest terms.<br /><br />The 'E' for pvc foam compared to the E for fibreglass is so small it is effectively zero for flex calculations so the core felx. rig is due just to laminate shell. Woodcores have an E can't be ignored and so the flex rig of a wood core is the sum of the flex rig for the core (proportional to c^3) and the reinforcement (c^2t).MattMahttps://www.blogger.com/profile/04256614801832932462noreply@blogger.comtag:blogger.com,1999:blog-4848544913740911582.post-11526063249536754442011-09-03T04:20:07.843-07:002011-09-03T04:20:07.843-07:00Hi Matt,
A quick question. Was reading your blog ...Hi Matt,<br /><br />A quick question. Was reading your blog and observed that in april blog u indicated that the flexual rigidity is proportional to the core thickness cubed (^3) (1mm core thickness change was equal to 28% flex change on 10mm core), however here you are indicating that the relation is squared(^2). Could you elaborate, did i miss something...?MirsadChttps://www.blogger.com/profile/07470227301646971357noreply@blogger.com