A numerical analysis is conducted to investigate the elastohydrodynamic effect of deterministic microasperities on the shaft of a lip seal. Various geometries of microasperities (triangular, square, hexagonal, and circular) are put into a 100×100μm2 unit cell and are investigated using Reynolds equation. For each shape, the area fraction of the microasperity is varied between 0.2 and 0.8, and the asperity height is varied between 0.3μm and 5μm. The calculation for load capacity and friction coefficient indicates that there are values for asperity height, where the load capacity and friction coefficient are optimized. These optimum heights were reached at 1–3μm. Although the lip seal surface is considered to be smooth, reverse pumping can still be obtained using an oriented triangular design. The Couette flow rate for this asperity showed lubricant is reverted back toward the seal side 2.6 times more than using a conventional lip seal. The addition of microasperities to the shaft surface shows significant improvement in lubrication characteristics for the lip seal in the form of a simultaneous reduction in friction coefficient and increase in the reverse pumping rate.

No abstract

A plate of PZT5h was prepared with a single electrode on one face connected to a power amplifier. The opposite face was left as bare ceramic material which was then exposed to an electron beam. Sixteen strain gages were attached atop the electrode to measure the strain response and as a function of electrode potential (backpressure voltage). A range of sinusoidal voltage inputs were applied to the electrode and the strain response and current draw through the PZT were recorded.Electrode potentials between -15 and 100 V yield very predictable strain response and extremely small currents (approcimately 10 -7 -10 -6 amperes) which appear to be independent of the electrode potential. Below -15 V the current through the PZT suddenly increases to 10 µa. At -15 volts level the strain response is still predictable but, as the electrode voltage decreases the strain signal begins to display significant drift. The root cause of this phenomenon is examined with the aid of the deBroglie-Einstein postulate and the Schrödinger wave equation.

The electric field induced strain in piezoelectric materials subjected to an electron flux is examined in this paper. An analysis using quantum mechanics indicates that stable and controllable strains with very low current draw should be achievable over a range of positive and negative control potentials. The model also predicts an instability in the internal electric field at larger negative potentials. The model was evaluated by observing the strain output of PZT5h plates subjected to an electron flux on one face and voltage inputs from a single electrode on the opposite face. The strain response and current flow were measured as a function of electrode potential and electron energy. All of the significant predictions of the model were verified by the experimental results. Further experiments were performed to examine the time response of the strain induced in the plate. It was found that the location and potential of the electron collector dramatically influences the dynamic response of the system.

No abstract