Mechanical characterization of the tie rods for the ATLAS B0 model coil

The ATLAS Barrel Toroid (BT) consists of 8 superconducting coils of 25 m length and 5 m width. Each coil is equipped with eight titanium alloy tie rods acting as support for the magnetic forces, the intensity of which will be up to 180 t for the most loaded one. The B0 model coil is about 1/3 length scale of the BT, equipped with three tie rods. In order to simulate the behavior of the coil supports, a test facility has been built to test individual tie rods at cryogenic temperature. The initial aim was to verify the amount of stick and slip, the possibility of it occurring during the excitation and the flexion of the support at the anchoring point on the magnet. This was achieved by inducing in the support the same movements foreseen during the cool-down and the excitation of the magnet and loading with the same forces. Following the evolution of the project it was decided to test the tie rod simply in traction at 250 tons, without displacements. In this paper the test facility is described and the data of the tests of the B0 tie rods are reported.