Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 131-134).

M.Ing. (Mechanical Engineering) / This dissertation evaluates the suitability of the finite element method as a tool for the design and analysis of elastomeric materials in general and flexible shaft couplings in particular. The theoretical background covers numerous aspects that are essential to the comprehension of the functioning of elastomeric materials and the difficulties inherent to the numerical modelling of such materials. These aspects include the properties of rubber, the functioning and selection of flexible couplings and some details regarding linear -, non-linear - 'and dynamic finite element analysis. The problems investigated for the purposes of this study may be divided into three categories: • The capabilities of the finite element method to compare different variations of a flexible coupling design parametrically is investigated. • Uni-axial tensile - and compressive material tests are numerically simulated to assess the ability of the finite element method to predict the response of materials subjected to large-scale nonlinear deformation. The numerical results are also verified by means of physical material tests. • Based on the modelling methods that were optimized in the first two categories, a numerical model of a flexible coupling in start up mode is developed. The accuracy of predictions is evaluated by comparison with physically measured results.

This thesis investigates the prospects of measuring anomalous triple gauge boson couplings in the ATLAS detector at the Large Hadron Collider (LHC). The most general(V ZZ, V = Z, g) vertex is parametrised by four couplings, fV = Z,gi=4,5 , all of which are zero in the Standard Model. Non-zero couplings would manifest themselves as an excess of events in ZZ diboson channels, and, if observed, would be a direct probe of new physics beyond the Standard Model. A set of criteria are outlined to select events recorded by ATLAS in two such channels, ZZ to llll(l = e, mu) and ZZ to llnunu. With 1 fb-1 of integrated luminosity at a centre of mass energy of sqrt(s) = 7 TeV, ATLAS can expect to observe 10+/-1 events in the ZZ to llllchannel, with 0.5+0.9-0.2 background events. In the ZZ to llnunu channel, 6.2+/-0.7 signal events are expected, with a background of 1.9+2.0-0.2 events. The expected sensitivity of ATLAS to non-zero anomalous couplings is calculated by performing extended, unbinned maximum-likelihood fits to the Z boson transverse momentum spectrum. For 1 fb-1 of integrated luminosity at sqrt(s) = 7 TeV, ATLAS has the potential to place constraints on the coupling parameters of |fZi | < 0.06 and |fig | < 0.07 at the 95% confidence level. These limits assume a form factor with a cutoff of Lambda_FF = 1.2 TeV. As a prelude to ZZ observation, criteria are defined to select Z to ll(l = e, mu) events in the first 315 nb-1 of ATLAS pp collision data at sqrt(s) = 7 TeV. In total 57 events are observed in the electron channel, with 109 in the muon channel, leading to cross-section measurements of sigma (Z to ee) = 0.70+/-0.09 (stat)+/-0.10 (syst)+/-0.08 (lumi) pband sigma(Z to mumu) = 0.90+/-0.09 (stat) +/-0.07 (syst) +/-0.10 (lumi) pb, both of which are consistent with the Standard Model predictions. In addition, this thesis presents a summary of developments made to the Data Acquisition (DAQ) system of the ATLAS Semiconductor Tracker (SCT). These include the construction of a test system, involving a scaled-down version of the entire SCT readout chain. The test system was subsequently used to develop a number of new DAQ features, including a hardware-based event simulator and monitoring framework.

Misalignment in turbomachinery has been commonly known to produce twotimes- running-speed (2N) response. This project aimed to investigate the source of the 2N vibration response seen in misaligned vibrating machinery by simulating misalignment through a coupling. Three flexible disc-pack couplings (4-bolt, 6-bolt, and 8-bolt coupling) were modeled, and parallel and angular misalignments were simulated using a finite element program. The stiffness terms obtained from the coupling simulations had 1N, 2N, and 3N harmonic components. The 4-bolt coupling had large 1N reaction components under angular and parallel misalignment. The 6-bolt coupling model only had a 1N reaction component under angular misalignment, and both cases of parallel misalignment showed a strong 2N reaction component, larger than both the 1N and 3N components. The 8-bolt coupling model under angular misalignment produced large 1N reaction components. Under parallel misalignment, it produced 1N, 2N, and 3N components that were similar in magnitude. All the couplings behaved linearly in the range studied. A simple model predicted that the 2N frequency seen in the response is caused by the harmonic (1N) term in the stiffness. The amplitude of the 2N component in the response depends on the amplitude of the 1N term in the stiffness compared to the average value of the stiffness and the frequency ratio. The rotordynamic response of a parallel and angular misaligned system was completed in XLTRC2. When the frequency ratio was 0.5, the system response with the 4-bolt and 6-bolt coupling had a synchronous 1N component that was much larger than the 2N component. The response did not have a 2N component when the 8-bolt coupling was used but the response did have a 1.6N component that was considerably larger than the 1N component. When the frequency ratio was 2, the system response with the 4-bolt and 6-bolt coupling had a synchronous 1N component and a relatively small ½ frequency component. The response with the 8-bolt coupling had a 0.4N component that was larger than the 1N component. A 5-tilting pad journal bearing was also tested to better understand its behavior under misalignment because some experts attribute the 2N response to the nonlinear forces produced by bearings with high unit loads. The response of the 5-tilting pad bearing did not produce any 2N components while the bearing was subjected to unit loads of up to 34.5 bars.

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