Thursday, 29 November 2007

structural bending tests...

as Fibre-C has been developed as a cladding material, not a structural material, we have had to have some tests done. In particular, because the tests that have been done by Rieder in the past, have only tested it's structural capacity perpendicular to the layout of the fibres, while we will be loading the forces in the axis of the fibres.

So today we began the structural bending tests at the labs in Aachen, Germany. According to AKT the tests have been going well...we have no bending failure and no problems with buckling or shear failure. AKT will provide some numbers on capacity of the profiles and further analysis.

In the meantime, here's a video from the testing labs posted for us on'll see a big crack begin to appear eventually, but no structural failure!!

Wednesday, 28 November 2007

plywood mock-up v1.0

The first plywood mock-up test is complete, with a lot of help from Yusuke and some of the Phase One students at the AADRL. Many thanks to Brian Houghton, Abhishek Bij, and Rajat Sodhi for their assistance.

Below you will see some photos documenting the process. The fabrication of the profiles was done on the 3-axis CNC machine at the AA's Hooke Park facilities designed by Frei Otto in the 1970's. The assembly was done at the DRL's John St. studios.

While it wasn't successful in standing, it was definitely successful in teaching. This is what we learned:
  • 1. Cutting. The translation of line types from rhino to the CAM cutting programme caused the shape of the profiles and notches to change in places. This must be carefully reviewed and solved before any final cutting.
  • 2. The internal corners of the notches must be controlled – if the corners are rounded with a 5mm radius it will reduce the fit of the profiles and any silicone gasket. It a rounded corner is chosen here to reduce stress build up in the working joint then the gasket must be modified to deal with the curvature
  • 3. Assembly. The cross profiles on the floor deck should be moved to the outside of the primary profiles. This will give the structure contact with the ground over the full width of the edge and more importantly it will provide a stable jig to fit to insert and align all of the tilted primary profiles. The cross profiles on the ground should be constructed as a mat that is fully bolted of fixed together to help provide full dimensional control of the assembly.
  • 4. The assembly sequence should involve erecting a number of primary rings in the centre and either side of the shell and then infilling with the remaining profiles. This will help maintain overall dimensional control and ensure everything fits.
  • 5. The tilting of the rear primary profiles in the opposite direction to the front will provide a more efficient structural solution and provide balance to allow easier assembly.
  • 6. The joints at the splices on the side walls and floor should be much deeper – approximately 60-80mm
  • 7. The numbering of pieces and referencing of specific joint correspondence needs to be further developed. At least one joint at the end of each profile needs to be marked to match a corresponding joint in the other direction.
  • 8. Another plywood mock-up of the same area should be made before Christmas after the above changes are incorporated into the design. This should be made of high quality beech ply and assembled in Hooke park.
  • 9. Wear gloves next time to avoid splinters!