Possible fabrication techniques and welding specifications for the external cylinder of the CMS coil

The Compact Muon Solenoid (CMS) is one of the experiments, which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN. The design field of the CMS magnet is 4 T, the magnetic length is 12.5 m and the free aperture is 6 m in diameter. This is achieved with a 4 layer and 5 module superconducting Al- stabilized coil energized at a nominal current of 20 kA at 4.5 K. In the CMS coil the structural function is ensured, unlike in other existing Al-stabilized thin solenoids, both by the Al-alloy reinforced conductor and the external cylinder. The calculated stress level in the cylinder at operating conditions is particularly severe. In this paper the different possible fabrication techniques are assessed and compared and a possible welding specification for this component is given. (9 refs)

Mechanical behavior of the ATLAS B0 model coil

The ATLAS B0 model coil has been developed and constructed to verify the design parameters and the manufacture techniques of the Barrel Toroid coils (BT) that are under construction for the ATLAS Detector. Essential for successful operation is the mechanical behavior of the superconducting coil and its support structure. In the ATLAS magnet test facility, a magnetic mirror is used to reproduce in the model coil the electromagnetic forces of the BT coils when assembled in the final Barrel Toroid magnet system. The model coil is extensively equipped with mechanical instrumentation to monitor stresses and force levels as well as contraction during a cooling down and excitation up to nominal current. The installed set up of strain gauges, position sensors and capacitive force transducers is presented. Moreover the first mechanical results in terms of expected main stress, strain and deformation values are presented based on detailed mechanical analysis of the design. (7 refs)

Design and test of the titanium alloy tie rods for the CMS coil suspension system

The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is 12.5 m and the free bore is 6 m. Thirty titanium alloy tie rods are used to support the 225 tonne weight of the cold mass inside its vacuum vessel and react against the forces generated by potential magnetic misalignment. This paper describes the suspension system and its mechanical analysis in different loading cases corresponding to operating conditions of the magnet. Two grades of titanium alloy are foreseen (Ti 6 Al 4 V ELI and Ti 5 Al 2.5 Sn ELI). Based on mechanical tests at room temperature and at 4.2 K, the safety criteria are analyzed for both materials. Before final installation, all tie rods will be tested at 110% of the maximum load with one end at room temperature and the other one at cryogenic temperature. The test system and the test results of the prototype tie rods are also presented. (4 refs)

Thermomechanical analysis of thermal shock fracture in the brittle/ ductile transition zone - Part II: Numerical calculations and interpretation of the test results

The integrity of PWR pressure vessels is assured by keeping the crack tip stress intensity factor below the toughness of the material under monotonic isothermal loading. To study the effects of sudden cooling associated with a thermal gradient, a specially modified compact specimen has been developed. This has been used to carry out tests in the transition zone with different loading-temperature sequences liable to call the conventional criteria into question. The test is described in detail in Part I of this article [Chapuliot S, et al. Thermomechanical analysis of thermal shock fracture in the brittle/ ductile transition zone. Part I: Description of the tests. Engng Fract Mech, 72, 2005, 661-73]. The second part describes numerical investigations to estimate the local mechanical fields at the crack tip and the overall parameters of the fracture mechanics. Finite element thermomechanical calculations are used to interpret the results of these new thermal shock tests using the master curve concept [ASTM E 1921-1997. Standard test method for determination of reference temperature To for ferritic steels in the transition range, 1997] and the Beremin statistical model [Beremin FM. A local criterion for cleavage fracture of a nuclear pressure vessel steel. Metall Trans A, 14A, November 1983, 2287-777]. © 2005 Elsevier Ltd. All rights reserved

Study of cleavage initiation under thermal shock by tests on cracked rings and thermomechanical calculations

This article describes a new type of test that easily creates a thermal shock combined with mechanical loading by using standard laboratory equipments. The method consists of rapidly heating a ring initially at -175 °C by circulating hot water through judiciously placed holes. It allows to obtain, at minimal cost, data on crack initiation under thermal shock in the transition zone of steel 16MND5 used for pressure vessels, these data being necessary for work on fracture criteria. Details of two tests are given, one with preloading in which cleavage fracture was observed and one without preloading in which cleavage initiation did not occur. The thermomechanical calculations necessary for the interpretation of both tests are also given. Finally, the global approach to fracture is used involving comparison of the loading paths J(T) with the master curves [ASTM E1921-97, 1997. Standard test method for determination of reference temperature to for ferritic steels in the transition range, ASTM standards], as well as the local approach proposed by Beremin [Beremin, F.M., 1983. A local criterion for cleavage fracture of a nuclear pressure vessel steel. Metall. Trans. A 14A, 2777-2287] for estimating the probability of fracture of such rings. It is shown that, in both approaches, the calculated probabilities are consistent with the experimental observations. © 2005 Elsevier B.V. All rights reserved

Modeling Fatigue Spectrum of Aircraft Structure Under Gust Loads

International audienceno abstrac