Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"Maxwell Model"”.
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Modified Maxwell Model for hysteresis compensation of piezoelectric stack actuators
… actuators and proposes an Input-Range Dependent Maxwell Model for more accurate hysteresis compensation. Experimental studies show that the assumptions of the classical Maxwell model do not fully hold: the actuator behaves differently in the initiation stage compared to the later cycles, and the …
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Modeling Droplet Impingement Dynamics on Micropillar-Arrayed Viscoelastic Substrates Through Microgeometry-Free and Multiscale Methods
… has been thoroughly investigated by two distinct modeling methods, i.e., microgeometry-free and multiscale modeling methods. The viscoelasticity of the micropillar-arrayed substrate is characterized by a five-parameter generalized Maxwell model via the Laplace-Carson transform. In the …
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On the Rheology of Soft Cellular Materials, An Experimental Investigation of the Microstructure and Rheology of a Novel Tissue-Mimic Material
… and with the sample temperature. A fractional Maxwell model is used to model the creep response, revealing a correlation between the model’s parameters that persists across a wide range of sample preparation and measurement parameters. The final contribution addresses the question of how the …
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Viscous Dampers for Optimal Reduction in Seismic Response
To model dissipation of energy in vibrating civil structures, existence of viscous damping is commonly assumed primarily for mathematical convenience. In such a classical damper, the damping force is assumed to depend only on the velocity of deformation. Fluid viscous dampers that provide this type …
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Some dynamic mechanical properties of apple fruits and their use in the solution of an impacting contact problem of spherical fruit
… to be frequency dependent. Due to scatter, Maxwell model approximations were the best mechanical model representations that could be developed directly. These, however, appeared to be sufficiently good approximations for the data. A statistical curve fitting procedure resulted in expressions …
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Measuring The Nanomechanics Of Nanoconfined Water Layers
… were analyzed with the help of two viscoelastic models, the Kelvin model and the Maxwell model. The stiffness and damping coefficient oscillate with period 2.7 ± 0.8 Å below 1 nm thickness of the water film. The retardation time and the relaxation time were measured as a function of both the …
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Deformation, yield, relaxation and recovery in partially processed leather
… interpreted using rheological and structural models. It was found that for wet leather the relationship between applied strain and long term set is nonlinear. Moreover, below a critical strain no set is imparted. At this critical strain there is a change from a bending to a tensile mode of …
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Transient analyses of viscoelastic materials with applications to numerical models
… of eschewing common schemes like the General Maxwell Model. In the second part, some alternative models to commercial finite element approaches are explored. A simple model of damping in viscoelastic layers is presented to illuminate the role of viscoelasticity in acoustic absorption. A new …
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An Investigation of the Rheology of Reactive and Nonreactive Highly Filled Polymer Systems
… storage and loss moduli. Three reactive model systems that stiffen due to polymerization, crosslinking, or flocculation and a nonreactive model system consisting of spherical glass bead particles and a polydimethylsiloxane polymer phases were studied in addition to two calcium aluminate …
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Polymer-Metal–Organic Framework (MOF) Mixed-Matrix Membranes for Gas Separation Applications
… reliably form defect-free MMMs so that transport models can be applied to estimate pure-MOF property sets, thereby enabling the development of robust structure–property relationships. To address these interfacial challenges, this thesis describes a developed method to surface functionalize MOFs …
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On the stability of plane viscoelastic shear flows in the limit of infinite Weissenberg and Reynolds numbers
… analysis. We focus on the upper convected Maxwell model in the limit of infinite Weissenberg and Reynolds numbers. Specifically, we study the effects of elasticity on the instability of a few classes of simple parallel flows, specifically plane Poiseuille and Couette flows, the …
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Micro- and macro-rheological studies of the structure and association dynamics of biopolymer gels
… maintenance of oral health. Quantification and modeling of the mechanical properties of these materials can provide insight into their microstructures, which is particularly important when structural changes are associated with impaired biological function. In this thesis, we use a combination …
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Creep and damage models for the service behaviour of structural members
… studied from the material and the structural modelling point of view. Moreover, two materials have been handled: pultruded composites and concrete. A new finite element model for thin-walled beams has been introduced. As a main assumption, cross-sections rigid are considered rigid in their …
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Investigations into the mechanics of connective tissue
… mechanical properties of connective tissue. A model system of hydrogels was used to investigate how volume change through water flow is coupled to relaxation. This was done using digital image correlation (DIC) and a custom built setup. It was found, in hydrogels, that water loss is directly …
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Influences of Higher Order Modeling Techniques on the Analysis of Layered Viscoelastic Damping Treatments
… layer beams is done with mathematical models proposed by Kerwin and extended by DiTaranto, Mead and Markus, and others. The mathematics proposed by these early researchers was tailored to fit the damping treatments in use at that time: thin foil damping tapes applied to panels for noise …
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Theories of slow dynamics: from glassy colloidal suspensions to entangled macromolecular liquids
… non-Gaussian activated ``hopping'' events by modeling motion on a dynamic free energy surface. By coarse graining over the initial separation between the tagged particles many aspects of ``dynamic heterogeneity,'' a set of phenomena accompanying the glass transition, can be understood. …
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Modeling Moisture-Induced Damage in Asphalt Concrete
… In this study, Finite Element Method (FEM) modeling technique is used to identify initiation and progression of adhesive and cohesive damage. In addition, the effects of moisture in the mastic materials (i.e. mixture of fines passing no. 200 sieve and asphalt binder) are determined by …
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A viscoelastic hydrodynamic approach to the density fluctuations in classical liquids
… to the relaxation tensor by viscoelastic models, the collective modes responsible for the density and current fluctuations could be derived accordingly at small wavenumbers. Based on the examinations of two fundamental viscoelastic models, namely, the Kelvin-Voigt model and the Maxwell …
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Mathematics, Methods, and Models for Data-Driven Rheology
… fluids. In this thesis, we explore methods and models that combine domain knowledge curated over the nearly century-long history of rheology with modern advancements in data science and machine learning, whose aim is to maximize the utility of the available rheological data and rheometric tools. …
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Fabrication and Characterization of Polyimide-based Mixed Matrix Membranes for Gas Separations
… Permeability results of larger gases followed a Maxwell Model. A third system was prepared using a poly(imide siloxane) (6FDA-6FpDA-PDMS) and untreated zeolite L. The primary focus of this investigation was to determine if the addition of the flexible segment would promote direct contact with the …
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