So judging from the pictures and suggestions the layers are 2mm to 3mm. and the core can be thick as designed (in the pictures for example It looks like it varies 5mm to 30mm) and even tapered to a point at the edges.
Ply thickness varies but averages about 1.5 mm.the tub in the pic is joined by the tounge an groove method so a loose tool has been placed in the botton tub mould an laminated over.At the core stage full thickness core is laid upto the joggle then thinner core over the joggle(If for example your chassis skins were 2mm you would have a 2mm joggle,If your main core thickness was 18mm in the area of the joggle you eould have 14mm,the 4mm differance due to the 2mm joggle on the outer surface an the matching 2mm joggle you need to create on the inner surface
the top half of the tub has a plug that is placed instead of core in the joggle area an removed after cooking,this gives you your female part of the tounge an groove
The tub dosent taper to a point on the edge,thats where the parts are designed so you join the inner an outer laminates together around openings to aid strengh
thick core in the bulkheads,but on the return flanges you bring the skins together an just have all carbon as its a bonding face and is stronger
thats a joggle but on the tub join where it starts at A it goes straight in 2mm an does the same on the opposite side of panel and at B thats edge of part/end of the tub
Last edited by polarboy on 19 Dec 2010, 02:20, edited 1 time in total.
I'm not a composites expert, but I don't ever recall seeing many instances of core (honeycomb or foam) joggled like that. Composite structures are designed to carry loads through the outer skin's fibers in tension, with the core simply serving to transmit shear between the inner and outer skins. Since the outer/inner skin fibers really only transmit loads in tension, they don't like changes in direction such as those created by core "joggles".
Where thicker, cored panel structures must transition to a section with all fiber and no core, such as a bonded or fastened interface, the core must be gradually tapered off in thickness. Otherwise, any abrupt change in direction of the laminate's fibers will create stress concentrations. The same is true for the edges of thick composite laminate panels, they are usually gradually thinned out by "ply drop-off".
"Q: How do you make a small fortune in racing?
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I have not heard about joggle joints but tongue and groove joints.these simply create an area where plies overlap the structure to be bonded to both halves joining faces do not expose the core material but consist of pure cf plies and the surface was finished of with peeloff fabric creating the perfect bonding surface.
riff_raff wrote:I'm not a composites expert, but I don't ever recall seeing many instances of core (honeycomb or foam) joggled like that. Composite structures are designed to carry loads through the outer skin's fibers in tension, with the core simply serving to transmit shear between the inner and outer skins. Since the outer/inner skin fibers really only transmit loads in tension, they don't like changes in direction such as those created by core "joggles".
Where thicker, cored panel structures must transition to a section with all fiber and no core, such as a bonded or fastened interface, the core must be gradually tapered off in thickness. Otherwise, any abrupt change in direction of the laminate's fibers will create stress concentrations. The same is true for the edges of thick composite laminate panels, they are usually gradually thinned out by "ply drop-off".
it is usually done with just plies I cant remember core ever being used on any of the ones I worked on. They are then grit blasted acetone wiped bonded and peel stops installed sometimes a wetlay is done over the top creating more of a tongue and grove as marcush was talking about. If you look at the tub on the first page you can see the bottom joggle where the top will slide on.
[quote="riff_raff"]I'm not a composites expert, but I don't ever recall seeing many instances of core (honeycomb or foam) joggled like that. Composite structures are designed to carry loads through the outer skin's fibers in tension, with the core simply serving to transmit shear between the inner and outer skins. Since the outer/inner skin fibers really only transmit loads in tension, they don't like changes in direction such as those created by core "joggles".
When you have your chassis mould the 1st thing you will make in it is the "tooling joggle" this is a laminate that is laid up then cooked an once trimmed is placed in the mould an creates the joggle seen in the tub bottom seen in the 1st pic in this post.If your skins in the joggle area are 2mm thick you would make your tooling joggle slightly bigger to allow for a glue gap
When you lay up a chassis the 1st ply is cosmetic (usually a 200 gram at +_ 45 with the weave stripe matching across the chassis all tight corners then get a uni directional bootlace of solid carbon to "loose" the tight corners
where you have something like the tooling joggle you will stagger several plies to "loose" the joggle.Normally you will have 5mm staggers on your plies all going from the tooling staggering out so your sharp 2mm joggle becomes a gentle slope over an area of 30/40mm so there is no step in your structural plies
When you fit the core you sand it down to allow for the slight slope up to the joggle.On top of the area of the joggle you will have a thinner core than the main area,core to core joins are done with redux 212 expanding glue film
When you come to do the inner plies you will do some plies with a 5mm stagger to loose the sharp step in the diffrent thickness cores to allow your inner plies to have a smooth run
here's a pretty literal view.
i'm not sure if it's all that safe an assumption that the legend refers to thickness in mm, but it's not wholly unreasonable that it has been done in that way.
the four immutable forces:
static balance
dynamic balance
static imbalance
dynamic imbalance
Gives you a genral idea but with a F1 chassis you will have the squeeze tests,the side impact bar mountings,larger fuel tank and a full roll hoop that will change things quite a bit
