An elastohydrodynamic analysis of a rotary lip seal is performed numerically, incorporating both the fluid mechanics of the lubricating film and the elastic deformation of the lip, by solving the Reynolds equation with flow factors. Asperities on the lip surface dominate the behavior of the flow field in the lubricating film and the elastic deformation of the lip. Since previous analyses treated those asperities deterministically, they required very large computation times. The present approach is much less computationally intensive because the asperities are treated statistically. Since cavitation and asperity orientation play important roles, these are taken into account in the computation of the flow factors. An asperity distortion analysis is introduced to obtain a more realistic model of the complex variations in the asperity distribution on the surface of the seal. Results of the analysis show how the operating parameters of the seal and the characteristics of the asperities affect such seal characteristics as the thickness of the lubricating film, reverse pumping rate, power dissipation and load carrying capacity.

Seven empirical equations were developed for the prediction of seal strength for medical device trays. A new methodology was developed and used for identifying burst and peel locations and comparing burst pressure and peel force. Multiple linear regression was used to fit 76 models, selecting the best models based on the Akaike Information Criterion (AIC) and adjusted R2 (R2 adj) value of each model. The selected models have R2 adj and prediction R2 (R2 pred) values of .83 to .94. Factors investigated for the peel force response were sealing pressure (3 levels), dwell time (3 levels), sealing temperature (3 levels), and adhesive. Additional factors investigated for the burst pressure response were restraining plate gap, and tray volume, height, length-to-width ratio and area. Polyethylene terephthalate-glycol (PETG) trays with Tyvek 1073B lids and two popular water-based adhesives were used. Trays were selected to yield three levels of area and three levels of length-to-width ratio, defining nine package configurations. Packages for burst testing were sealed under a fractional factorial design with 27 treatments. Packages for peel testing were sealed under a 17-point face-centered central composite design. Packages were tested using peel testing following the ASTM F88-07 standard and restrained burst testing with three gap distances following the ASTM F2054-00 standard. All possible subsets of the factors were evaluated, with the best models selected based on AIC value. Equations were developed to predict peak and average peel force based on sealing process parameters (R2 pred =.94 and .92), burst pressure based on tray and sealing parameters and gap (R2 pred =.94), and four peel force responses based on burst pressure and gap (R2 pred =.83 to .86). Models were validated through cross-validation, using the prediction error sum of squares (PRESS) statistic. The R2 pred was calculated to estimate the predictive ability of each model.

Rod seals are one of the most critical components of hydraulic systems. However, the fundamental physics of seal behavior is still poorly understood and the seal designers have virtually no analytical tools with which to predict the behavior of potential seal designs. In pursuit of a comprehensive physics based seal analysis/ design tool, in this work, a multi-scale multi-physics (MSMP) seal model is developed. The model solves the transient problem involving macro-scale viscoelastic deformation mechanics, macro-scale contact, micro-scale two phase fluid mechanics in the sealing zone, micro-scale asperity contact mechanics and micro-scale deformation mechanics of the sealing edge in a strongly coupled manner. The model takes into account surface roughness, mixed lubrication, cavitation and two phase flow, transient squeeze film effects and the dynamic operation as well as the effect of macro/micro/nano scale viscoelasticity. A hybrid finite element-finite volume-statistical computational framework is developed to solve the highly coupled multi-physics interactions of the MSMP model simultaneously. Surface characterization experiments are performed to extract the parameters like RMS roughness, asperity density, autocorrelation length and asperity radius needed by MSMP. To remove the high frequency noise without removing the high frequency real surface features, a wavelet transform based adaptive surface extraction method is implemented. Dynamic mechanical analysis (DMA) is performed to extract the macro-scale viscoelastic parameters of the seal. Through atomic force microscopy (AFM) experiments, the local micro/nano scale elastic moduli were found to be varying within two orders of magnitude higher than the bulk of the polymer. Significant differences in local stiffness, adhesion and the relaxation time scales of individual surface asperities were also observed. With the MSMP model, dynamic seal performance was analyzed. The results confirmed the mixed lubrication and the effect of surface roughness. Thicker fluid films during instroke and cavitation during the outstroke were found to be important for non-leakage. Seal behavior was a function of the complex dual dependence on the time varying sealed pressure and hydrodynamic effects. Viscoelasticity is seen to critically affect the leakage and friction characteristics. It produces thicker fluid films and produces a significant increase in Poiseuille component of flow during instroke. Ignoring viscoelasticity leads to under-prediction of the time required to reach the zero leakage state. Several high pressure - high frequency sealing applications were analyzed. In such applications, a new phenomenon of "secondary contact" was observed. Viscoelastic creep was seen to critically affect the contact pressure and hence the friction characteristics. In high frequency applications, viscoelasticity induced significant differences in Poiseuille flow and friction force from cycle to cycle. Cycle frequency was seen to play an important role in governing visco-elastohydrodynamics and the leakage of such seals. The seals need to be designed by considering the relationship between relaxation time scales of the polymer and the cycle frequencies. Study also revealed the presence of characteristics like "critical temperature" and "critical frequency". Using the multi-physics modeling capability of MSMP framework, several novel seal designs using smart materials like piezo-ceramic embedded polymers are proposed and analyzed. The MSMP computational framework developed here has a great potential to be used as a stand-alone seal design and analysis software in academic and industrial research.

No description available.

This thesis presents an exploratory approach using detailed zooarchaeological analysis to evaluate the nature of ringed seal ( Phoca hispida) remains from three seasonally different Thule sites in the Hazard Inlet area of Somerset Island, Nunavut. Most Thule research focuses on winter occupation and presents Thule as a whaling society. Little attention has been given on the nature of sealing during Thule occupation and research on seasonal differences of seal remains from Thule sites remains scarce. This thesis is thus one of the first to focus on ringed seal remains from seasonally different Thule sites through an analysis of over 30,000 bone specimens. The goal of this thesis is to determine if the seal assemblages are a product of differential butchering and transport, taphonomic processes, or if external factors are also playing a role in shaping the faunal record. The analysis considers variability within each site as well as between the sites. Overall, a moderate to strong correlation was found between bone density and the seal bone elements identified while a negative correlation existed with the elements and FUI (food utility indices). This led to the conclusion that taphonomy was the leading agent shaping the seal remains at Hazard Inlet. However, enough variation existed within each site to consider the role of outside factors, such as the presence of dogs, food preferences, food storage and season of occupation in shaping the seal remains at Hazard Inlet.

Dental annuli analyses were performed on 170 ringed seal (Phoca hispida) canines recovered from five Thule semisubterranean houses located at site PaJs-13 at Hazard Inlet, Somerset Island in the central Canadian Arctic. Season of death results indicate greater seal hunting during the spring. Age at death results were used to produce mortality profiles which, when compared with idealized patterns, revealed a prime-dominated pattern indicating the presence of some selective factor in the subsistence strategy. Based on ethnographical studies of traditional seal hunting techniques, conscious selection was eliminated as a factor. Biological studies of ringed seal demonstrate that during the spring, older, sexually mature seals, occupy breeding areas in stable fast ice formations located close to the coast in complex coastal areas. Younger immature seals, on the other hand, occupy areas of unstable pack ice formations either further from the shore in complex coastal areas, or along simple coastlines. The archaeological mortality patterns do not clearly resemble either complex or simple coast modern populations, although a trend toward simple coasts was observed. This observation is consistent with the site location, which allows greater access to pack ice formations. The appearance of selective biological factors affecting random human subsistence strategies indicates that caution must be utilized when interpreting mortality patterns.

This thesis performed on master level covers an assignment given by the cab division at Volvo Construction Equipment (Eskilstuna, Sweden). The thesis has been carried out by Josefin Hult during the period 2014-01-23 to 2014-05-30 at Mälardalen University. Volvo Construction Equipment manufactures products including wheel loaders, backhoe loaders and articulated haulers. The assignment involves developing the standard door for larger wheel loaders. The current door has a welded frame surrounding the glass that is considered outdated and not cost effective. Volvo Construction Equipment wishes that the door was made in glass in a greater extent. The aim of the assignment has been to generate concepts regarding a glass door that fulfills given requirements. Three research questions have been stated and answered during the process. The product development process has consisted of three phases: information gathering, concept development process and development of detailed concept. For example, field studies and benchmarking have been performed to gather information about competitors’ products and the manufacturing and assembling of the current door. Concepts for handrails, sealant and overall door design have been generated in an iterative process. All components of the door have been developed into a detailed concept during the last phase of the process. The process has resulted in a frameless glass door. The concept suggestion consists of; a tempered sheet of glass, a clip list (sealant) that covers the edges of the glass, two different handrails, inner and outer handles, a gas spring, components to attach handrails against the glass, a cover and a lock mechanism. The major conclusion that is drawn is that it is fully possible to develop a door made in glass in a greater extent than the current door. Many competitors have machines where the door is made in glass in a large extent. This makes it believable that the glass door also will be perceived as timely and more modern and clear. Recommendations have been developed if there is interest in further development. The recommendations include, among others, development of handrail and test of prototype to ensure that all requirements are fulfilled. Figures are produced by the author if not stated otherwise.

Diss. Stockholm : Karol. inst.

Thesis (M.S.)--Texas State University--San Marcos, 2009. / Vita. Includes bibliographical references (leaves 52-54). Also available on microfilm.

Thesis (Ph. D.)--Australian National University, 2001. / Title from PDF title page (viewed May 8, 2005). Consists of reprints of thirteen published papers, some co-authored with others, plus an introductory chapter, two unpublished manuscripts, and a conclusion. Includes bibliographical references.