This work uses the finite element technique to model the elastoplastic deformation of a hemisphere contacting a rigid flat for various material properties typical of aluminium, bronze, copper, titanium and malleable cast iron. Additionally, this work conducted parametric finite element method (FEM) tests on a generic material in which the elastic modulus and Poisson's ratio are varied independently while the yield strength is held constant. A larger spectrum of material properties are covered in this work than in most previous studies. The results from this work are compared with two previously formulated elastoplastic models simulating the deformation of a hemisphere in contact with a rigid flat. Both of the previously formulated models use carbon steel mechanical properties to arrive at empirical formulations implied to pertain to various materials. While both models considered several carbon steels with various yield strengths, they did not test materials with various Poisson's ratios or elastic moduli. The previously generated elastoplastic models give fairly good predictions when compared with the FEM results for various material properties from the current work, except that one model produces more accurate predictions overall, especially at large deformations where other models neglect important trends due to decreases in hardness with increasing deformation.
Mechanical face seal rotor dynamics is investigated through both simulation and real-time monitoring of a non-contacting¯exibly mounted rotor (FMR) mechanical face seal in a seal test rig. Dynamic simulation is performed to investigate the seal rotor angular response to the stator misalignment, the stator angle, the initial rotor misalignment and clearance. Rotor angular response orbit is introduced and is able to characterize the rotor dynamic response. A real-time monitoring system is constructed in the test rig to monitor the instantaneous dynamic behaviour of the seal rotor, including its angular response, precession angle and angular response orbit. Experimental results agree qualitatively well with those of the dynamic simulation. Potential applications of the monitoring system for detecting seal face contact and for seal control are stated.
Detection and diagnosis of failure in non-contacting mechanical face seals may prevent catastrophes in some critical applications. Seal failure due to face contact may occur because of large relative misalignment between the seal rotor and stator faces. The objective of this work is to study the sensitivity of the relative misalignment to changes in the design and operational parameters of a non-contacting¯exibly mounted rotor (FMR) mechanical face seal. These sensitivities can be eciently exploited to prevent possible contact through proper selection of the seal parameters and working point in both the design and the control stages. Among the design parameters, the seal coning angle is by and large independent of other design requirements and should be properly selected to avoid contact. The operational variables greatly in¯uencing the relative misalignment are the clearance, the bearing¯uid pressure and the shaft speed. Where active control is considered, the relative misalignment sensitivity to changes in the control parameters should determine the working point. The sensitivity analysis is demonstrated using the data of an existing seal test rig.
The current research experimentally quantifies and maps the behaviour of various thrust washer configurations under various conditions. The bearings are tested at controlled loads and speeds for a governed period of time (up to 14 h) or until failure. The experimental results show that at some loads and speeds the bearing operates with a near full hydrodynamic film and under more harsh conditions it operates in the boundary lubrication regime. The experimental results indicate that coatings enhance performance by decreasing friction and thus decreasing the heat generated. By decreasing the generated heat, the physical mechanisms of thermoelastic instability and thermoviscous distress are less likely to occur. Using bronze will decrease the friction between the bearings, although it may also decrease the life of the bearing. However, using more than one round washer appears to not significantly benefit washer-bearing performance.
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