markwindsurf

Basic original design. First image shows design, 2nd shows forces, 3rd shows deformation

Right here you go front end 3/4 impact direct onto corner of vehicle, impact evenly distributed on the corner. Slightly vague analysis as have just built the cage and assumed rigid fixings to the chassis ( chassis does not move in the impact at all ), vehicle impact is 7 mph with a 2000 Kg car, impact is based on 65000 N against a tree which will only permit a 0.05 M deformation ( hard wood worst case ). However that is all reasonibly immaterial as we are looking at a comparison analysis between the designs. All deformation is subject to a 20 times magnification to make the bend visible, real numbers are shown on the displacement vector graph on the right hand side of the images. Have also included the force diagrams so you can see how the load is distributed through the frame. I have not included a roof cross brace, but would say the brace only functions in support of the system down the length of the tube, if impact is from the other front corner the brace will actually slightly weaken the frame as it will promote locally maximised stresses encouraging the frame to deform, so would put a cross form going front to back diagonally from both front corners. I will post the images up seperately following as otherwise it will be hard to differentiate the different results.

Absolutely brilliant the looking for road kill section had me in tears have not laughed that hard in ages, best reflection was my girlfriend who hates the show spent the entire show giggling continuously. It was without doubt the best show they have done to date.

Lewis, the model is not quite finished will aim to get it completed today if we are quiet in the office. In the mean time here are some pics of the Tomcat set up, which as I said we use for winch challenge events and gets bounced off trees and rocks fairly regularly.

Lewis will model up the frames over the weekend if I get a chance, will take rough dimensions off the Tomcat, unless you want me to specifically use your measurements, should be able to give you an idea of how it looks by next week, my email is mark980@btinternet.com if you have anything dimensions wise you particulary wanted to use. The chassis rails will be a little vague as laziness and ease of measuring them will probably prevent me getting them too close, but will treat them as rigid beams which don't bend in the impact probably anyway. Will is dead right on the impact front, all the front end will only be as good as the weld, and would not like to see the welds to the a post breaking loose and coming into the cab...

For my 2pence worth as an automotive structural designer, there are two options, a, do you wnat the tree bars to be absolutely solid and assume they are just tree bars, or b, are you looking for some deformation inan impact to prevent the full pulse from being passed onto yourself. Due to the nature I would assume 'a' is the direction you're aiming for in which case I would go with the first of your two sketches but would make use of some tubular front shock mounts which would attach to the two upper bars and down to the chassis, with the shock mounts suspended bellow the cross brace between the two top bars. If you wanted to go the whole hog and get a little indepth I could model the options in CATIA and run them through the analysis program to let you know which performs better. ( the more technical version of Simon's straws ) I would be tempted to look at the Raid Rally cars for their bracing ideas, Tomcat ( obviously my personal favorite ) and Wildcat pictures are all over the net, but if you can't find any I can get a wing on the Tomcat and take a picture. It is more simple than my suggestion and still incredibly robust, just the fibreglass which lets it down.

Give David Foers a call on 01273 794864 or email him on david.foers@ricardo.com, he is David's son and is now running the IBEX program at the southcoast for Ricardo, he will I am sure be able to give you all the info you want and is always on the look out for sales.

The internal rear light cover is an ideal location and was where mine were prior to becoming a truck cab, I ran a + from the battery along the chassis rail on the passenger side, there are loads of protrusions to cable tie to, allowingyou to keep it out of harms way and then just earthed through chassis. I managed to get two demo covers from where I work, not sure where they came from but the rubber covers are rather hard to get off.

At 100 mm that would make for a nice rear step as well. I was kind of hoping that I could stash it out of sight and therefore out of prying hands, am more than happy to remove it every now and then, could even seal a little perspex into the rear floor to ensure it spools straight. I assume in the installation you've done you put in a winch bucket and welded that back into the X member for reinforcement?

These all look fantastic for the 90's has anyone seen a tidy install for a crew cab 110 with the fuel tank still in the rear? I would rather not use a bulkhead or pick up mount so was thinking of going slightly further forward underfloor, but this would put the winch a long way forward or possibly a similar location to the ibex and positioning it under the rear seats. I theory I guess it would be possible to mount it under the rear seats bellow the floor and run the plamsa over the rear tank? What are anyones thoughts?