Aircraft are often designed with numbers determined by testing in a lab, rather than by repeatedly building prototypes. These lab tests conform to testing specifications so that the numbers can be compared between manufacturers, suppliers, and lab technicians. One such specification is ASTM specification E238 – 84(08), and it is used to determine important properties of a bearing pin joint like hinges, bolt holes, and rivet joints. The properties determined from this fastener-through-plate method are bearing strength, bearing yield strength, and bearing stiffness. Adhering to the methods outlined in ASTM E238, a study was performed, looking at the effects that plate material, fastener used, fastener lubrication, and plate hole preparation method (whether drilled and reamed or just drilled) have on the three bearing joint properties. The plate materials used were Al 7050 – T7451, Ti – 6Al – 4V (mill annealed), and PH13 – 8Mo – H1000. The fasteners were Ti – 6Al – 4V screws, coated A286 screws, and high speed steel (HSS) pins used as a control. Lubrication was tested using a corrosion inhibitor, PR – 1776M B – 2 from PRC – DeSoto, on the fastener or leaving the fastener uncoated. The HSS pins were always tested in the uncoated condition. 54 runs were performed, as outlined by a D-optimal design of experiment. It was discovered from the statistical analysis of the results via ANOVA that both the plate material used and the pin material, whether a screw or a pin, had a significant effect on the bearing strength, bearing yield strength, and bearing stiffness. The interaction between the two factors was also significant on all responses but the bearing stiffness. PH13 – 8Mo – H1000 plates seemed to perform best on average, followed by Ti – 6Al – 4V plates, then Al 7050 – T7451 plates. PH13 – 8Mo – H1000 and Ti – 6Al – 4V plates had similar bearing strength and bearing yield strength averages with the HSS control pins being used, which had the highest mean values for a given plate and fastener. The Ti – 6Al – 4V and A286 screws behaved and performed statistically similar in most cases, except when hole preparation method was take into account. The Ti – 6Al – 4V screws performed better when the hole was drilled and reamed, while the coated A286 screws performed better when the hole was drilled only. All screws had lower resulting bearing properties than the HSS control pins. It was also found that ASTM specification E238 – 84(08) is a precise test method, since the method could be performed repeatably and reliably with no missing data points. Therefore, this ASTM testing method is reasonable for determining bearing properties, which can then be used to design aircraft.

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The aim of this thesis is to calculate the stiffness and damping coefficients for radial hydrodynamic bearings. Cylindrical and lemon hydrodynamic bearings are considered. The solution to this problem mainly depends on the hydrodynamic pressure in the bearing. The numerical solution of the Reynolds equation is used to calculate the pressure. The effect of variable viscosity and density of the lubricant due to temperature changes is considered. The static equilibrium position of the journal centre is also solved. The stiffness and damping coefficients are determined using small amplitude journal motions about the equilibrium position. Three methods for determining these coefficients are presented. The outcome of this thesis is an algorithm for the calculation of stiffness and damping coefficients for cylindrical and lemon bearings. Results for lemon bearings are presented and comparison with the commercial software DynRot BR is made. The benefit of this thesis is the creation of an algorithm for the calculation of journal centre equilibrium position, a new way of incorporating the temperature changes in the viscosity and the density of the lubricant, and the modification of a method for calculating stiffness and damping coefficients based on experimental analogy.