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Bearings and Seals
Published in Peter Lynwander, Gear Drive Systems, 2019
Material Factor D The predominant material for rolling element bearings is AISI 52100. AISI is the American Iron and Steel Institute designation for steels of various specific chemistry. The basic bearing dynamic capacities which are presented in catalogs are based on air-melted 52100 steel through-hardened to Rc 58 minimum. The mathematical model to define bearing load capacity evolved in 1949 and since then the bearing steels have been improved such that they are more homogeneous with fewer impurities. A materials factor D of 2 is suggested for currently available steels. Case-hardened materials, used in tapered roller bearings and other applications, have also improved over the years, but insufficient data are available to recommend a materials factor.
Seismic Performance of Internal Partition Walls with Slotted and Bracketed Head-Tracks
Published in Journal of Earthquake Engineering, 2023
Jitendra Bhatta, Rajesh P. Dhakal, Timothy J. Sullivan, Jordan Bartlett, Glen Pring
The bracket is attached to the top slotted head-track using a bolt and to the slab using concrete anchors, as shown in Fig. 6. The horizontal gap between the head track and the top-slab is generally equal to the diameter of the 180° bends at the ends. During an earthquake, under the imposed out-of-plane lateral displacement “,” the bracket deflects while the partition wall tries to remain stationary, as shown in Fig. 6. As a result, a horizontal force “H” develops in the bracket, the magnitude of which depends on the bracket’s initial stiffness “Kib” (i.e. ). Any vertical forces induced due to the brackets deformation will be insignificant compared to the horizontal forces. In this research, the initial stiffness “Kib” is obtained directly from component level tests of the brackets. The head-track slot must have enough strength to transfer the out-of-plane force developed in the bracket “H,” through the steel frame to the anchors at the bottom track. Otherwise, the slot is likely to get damaged before the bracket’s displacement capacity is reached. According to the American Iron and Steel Institute (AISI S100–2007 2007), the bearing strength of cold-formed steel bolted connections without considering the hole deformation is given by:
Multiscale Thermal-Hydraulic Analysis of the ATHENA Core Simulator
Published in Nuclear Technology, 2023
P. Cioli Puviani, I. Di Piazza, R. Marinari, R. Zanino, M. Tarantino
CIRCE is a pool-type facility working with lead-bismuth eutectic (LBE) as primary coolant and pressurized water as secondary. The experimental tests on the Integral Circulation Experiments (ICE) test section addressed phenomena related to natural and gas-enhanced circulation and characterized heat transfer in HLM fuel bundles. The CIRCE FPS consists of 37 electrical pins placed in a wrapped hexagonal lattice with a pitch-to-diameter (P/D) ratio of 1.8 (Table I). Each pin has an outer diameter of 8.2 mm, a linear power of 25 kW/m, and a wall heat flux of 1 MW/m2 (to be considered as maximum values). The active length is 1000 mm, while the flow area through the bundle is 6027 mm2. The bundle is equipped with three spacer and several N-type thermocouples having diameters of 0.5 mm, with an insulated hot junction and an accuracy of ±0.5°C.[15] The thermocouples are fixed to the walls through the American Iron and Steel Institute (AISI) metal sheet pointed in the pin itself.
MEPhIST-0 Tokamak for Education and Research
Published in Fusion Science and Technology, 2023
S. Krat, A. Prishvitsyn, A. Alieva, N. Efimov, E. Vinitskiy, D. Ulasevich, A. Izarova, F. Podolyako, A. Belov, A. Meshcheryakov, J. Ongena, N. Kharchev, A. Chernenko, R. Khayrutdinov, V. Lukash, D. Sinelnikov, D. Bulgadaryan, I. Sorokin, K. Gubskiy, A. Kaziev, D. Kolodko, V. Tumarkin, A. Isakova, A. Grunin, L. Begrambekov, R. Voskoboinikov, A. Melnikov
The main idea of the vacuum vessel’s design was to decrease toroidal conductivity, that is, conductivity in the toroidal direction, without introducing technologically complex and expensive solutions, such as bellows or ceramic sections. The vacuum vessel can be roughly partitioned into three main parts: the inner cylinder, the domes, and the outer cylinder. The inner cylinder is made from 1-mm-thick American Iron and Steel Institute (AISI) 316 stainless steel. The thickness is a compromise between mechanical toughness and loop conductivity, which leads to the conductivity of the inner cylinder in the toroidal direction. Numerical modeling demonstrated that even a 0.5-mm-thick inner cylinder could withstand atmospheric pressure,12 and a 1-mm thickness was taken as an extra precaution. The upper and lower domes were obtained by rolling a 2.5-mm-thick AISI 321 stainless steel sheet over a form that guaranteed a zero-torque shape of the dome in regard to atmospheric pressure–generated forces. The 2.5-mm thickness was chosen as minimal, which still allowed successful production of the domes. The actual thickness of the domes varies from ~1.3 mm at the outer diameter to ~2.5 mm at the inner diameter. The outer belt is 3 mm thick; this thickness was chosen to make it possible to anchor both the vacuum vessel and various heavy diagnostics to the outer belt without deforming it. The resulting loop conductivity of the chamber is estimated to be 0.8 mOhm based on numerical calculations in COMSOL Multiphysics.