Marshall University Music Department Presents William R. Davidson, Piano

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Shrink-Fit Stress Systems in Built Crankshafts

Among applications of the well-known practice of shrink-fitting, the assembly of large marine crankshafts from relatively small forgings is perhaps the most outstanding example, having regard to the stringent operating conditions in which the component must function satisfactorily. Variations in shrink-fitting practice and failures attributable to slipping of the grip have directed attention to the lack of information on crankshaft assemblies and instigated an investigation, the results of which are presented in this thesis. A major part of the investigation comprises a survey of published literature relevant to the subject. It has been found that little is yet known about stress or grip conditions at the shrink-fit, and that the rules for sizes and proportions have evidently no theoretical foundation. The scope of the survey has therefore been extended to include work on all types of interference fits, from v/hich it is evident that, while a useful amount of empirical data on factors affecting grip strength exists, treatment of interface pressure and stress has been limited to the application of elastic thick cylinder theory. With a view to analysing stress conditions in assemblies overstrained by fit allowances which cause permanent enlargement of the hollow element, a part of the survey is devoted to examining work on thick cylinders subjected to internal fluid pressure. A number of features of shrink-fitting, such as prevention of free axial shrinkage, overstrain of the hollow element, and the influence of temperature on the elastic constants of the material, have been analysed as part of the theoretical work of the present investigation. On the basis of certain reasonable assumptions, a solution for the stress in a representative crank web shape has been obtained, using Relaxation Methods of analysis. Stress concentration and radial stiffness values, which correlate the complex shape to the rotationally-symmetrical, follow readily from the solution. The experimental investigations comprise tests on rings-and-plugs, on model crank webs, and on large crank webs removed from a vessel which had been scrapped. The results indicate that prevention of free axial shrinkage does, in fact, occur to a marked degree. Furthermore, the presence of axial grip has been detected in large crank webs which had suffered extensive cold-working due to pulsating bending actions during service. Model experiments have demonstrated the influence of surface finish on the grip strength to be quite unimportant. Friction values in the large crankshaft, on the mating surfaces of which tool-marks were clearly visible, were comparable with those in model webs with near-perfect honed surfaces. Interface pressure and stress values predicted from theoretical considerations were in sound agreement with values measured by electrical strain gauges and inferred from deformations. A list of design formulae and data, and recommendations for improvements to shrink-fitting practice, based on the results of the investigation, are presented

Independent Orbiter Assessment (IOA): Analysis of the hydraulics/water spray boiler subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results for the Orbiter Hydraulics/Water Spray Boiler Subsystem. The hydraulic system provides hydraulic power to gimbal the main engines, actuate the main engine propellant control valves, move the aerodynamic flight control surfaces, lower the landing gear, apply wheel brakes, steer the nosewheel, and dampen the external tank (ET) separation. Each hydraulic system has an associated water spray boiler which is used to cool the hydraulic fluid and APU lubricating oil. The IOA analysis process utilized available HYD/WSB hardware drawings, schematics and documents for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 430 failure modes analyzed, 166 were determined to be PCIs

An Overview of Disease and Parasitism in Southeastern Bobwhite Quail

(Invited Paper) Salient information on diseases and parasites of bobwhite quail (Colinus virginianus) in the southeastern United States is summarized. Major diagnostic findings on 146 bobwhites submitted to our regional wildlife disease laboratory from 1972 through 1981 included traumatic injuries, various toxicoses, and avian pox. Traumatic injuries were diagnosed frequently throughout the 10-year period, whereas toxicologic problems occurred sporadically. Avian pox emerged in outbreak proportions in the region in 1978 and thereafter has been prevalent in localized areas, Prompted by severe aflatoxin contamination in southeastern corn crops in 1977, studies on aflatoxicosis in bobwhites indicated that risks to wild bobwhite populations were minimal, Serologic, pathologic, and virus isolation studies disclosed infections of quail bronchitis virus and TR-59 adenovirus in bobwhites in northcentral Florida, Extensive studies have revealed only infrequent minor lesions associated with ectoparasites and endoparasites, and it was concluded that parasitism is not an important mortality factor in wild bobwhites, Two diseases encountered in pen-raised bobwhites, avian pox and histomoniasis (blackhead disease), clearly have potential to produce problems in wild bobwhites and wild turkey

Avian Pox Infections in Southeastern Bobwhites: historical and Recent Information

Historic and recent information on the occurrence of avian pox, an infectious viral disease, in southeastern bobwhite quail (Colinus virginianus) is summarized. An apparent long-term(\u3e 50 year) low-level (\u3c 2 percent) rate of infection occurred prior to an outbreak with a 12-fold increase in prevalence in 1978-1979. Post-outbreak monitoring during the two succeeding years disclosed that the regional prevalence of infection declined to near the pre-outbreak rate. The significance of avian pox as a regional and local mortality factor is discussed

Survival of Northern Bobwhite Infected with Avian Pox

Avian pox is an enzootic disease among northern bobwhite (Colinus virginianus) in the southeastern United States, but occasionally it occurs as local or regional epizootics. Little information exists concerning survival of wild bobwhite infected with this disease. During the winters of 1985 and 1986, we compared survival of radio-tagged bobwhite with and without pox lesions. Pox lesions were considered wet or dry depending on field evaluations. The incidence of pox was greater in 1985 (x1=\u27 16.536, df= 1, P\u3c 0.005) than in 1986. Bobwhite with wet pox lesions weighed less than those with dry pox (t = 2.550, P = 0.014) or no pox (t = 2.393, P = 0.018). In 1985 6-week survivorship of bobwhite showing signs of wet pox was different compared to those with dry pox (Z = 1. 7 498, P = 0.0402) and no pox (Z = 2.9992, P = 0.0014). Survivorship of birds with dry pox and no pox was not different (Z = 0.6460, P = 0.2611. Bobwhite with wet pox in 1985 had 45.6 and 53.3% overall lower 6-week survival rates than birds with dry and no pox, respectively. No difference in survivorship existed between bobwhite with dry pox and those with no pox in 1986 (Z = 1.1727, P= 0.1210). No difference in predatory agents responsible for mortalities between birds with or without pox occurred (X2 = 0.8851, df= 2, P\u3e 0.05). All mortality of infected birds appeared to be caused by predation and not the disease itself. Implications of these data for inter- and intraspecific disease transmission are discussed