Дисертації з теми "Polyethylene Stresses"
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Olasz, Lorant. "Residual Stresses and Strains in Cross-linked Polyethylene Power Cable Insulation." Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4020.
Повний текст джерелаZhang, Jingyu Hsuan Grace. "Experimental study of stress cracking in high density polyethylene pipes /." Philadelphia, Pa. : Drexel University, 2006. http://dspace.library.drexel.edu/handle/1860/747.
Повний текст джерелаChoollun, Virendra Kumar. "Residual stresses in high density polyethylene pipes with particular reference to its effects on soil-pipe interaction." Thesis, University of East London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.532873.
Повний текст джерелаDanikas, Michalis G. "A study of the behaviour of a uniaxially orientated polyethylene tape/oil insulating system subjected to electrical and thermal stresses." Thesis, Queen Mary, University of London, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297024.
Повний текст джерелаLees, J. S. "Vibrational spectroscopy of stressed and unstressed polyethylene and isotactic polypropylene." Thesis, University of Bradford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379832.
Повний текст джерелаDaming, Duan. "Fracture toughness and term fracture behaviour of polyethylenes." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243909.
Повний текст джерелаFarid, Syed Imran. "Viscoelastic properties of wood-fiber-reinforced polyethylene, stress relaxation, creep and threaded joints." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ58722.pdf.
Повний текст джерелаWilloughby, Carl Edward Peter. "Investigation of the effects of internal stress in polyethylene fibre-epoxy resin composites." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311237.
Повний текст джерелаBali, Sinazo. "Polyethylene glycol (PEG) induced water stress alters the physiological and molecular responses of chia plants." The University of the Western Cape, 2017. http://hdl.handle.net/11394/5787.
Повний текст джерелаWater deficit is known to be one of the most detrimental environmental factors to affect crop production and growth in South Africa. This factor has become more apparent with increasing cases of drought in the country.
Bicalho, Julio Roberto Santos. "Modelagem computacional de um reator anaeróbico fabricado em polietileno de alta densidade rotomoldado." Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=415.
Повний текст джерелаThe present work was developed to evaluate the potential of uses of an anaerobic reactor manufactured in HDPE High Density Polyethylene produced by the rotomolding process in substitution to the conventional reactors built in stonemasonry, working in a batch regime and buried in the soil. The state of tensions and the deformations were assessed using the program of Finite Elements ABAQUS version 6.5 and the mesh of the knots using the program MSC PATRAN 2005 forming 7329 knots and 2004 elements, in an optimized mesh for the areas of larger curvature (tension concentrator points). The loading is formed with an internal pressure of the biogas of 5kPa added of biomass hydrostatic load of 6000 kg in an elastic foundation calculated by the ratio pressure/settling starting from the Module of equivalent Elasticity of the soil (Esolo). Comparing the state of tensions assessed during the loading was possible to verify that the largest tension obtained in the most critical element goes the most probable utilization of the reactor, reached the value of 7, 46 MPa (it doesn't surpass 40% of the smallest resistance value to the traction and to the shearing strain of HDPE of 20 MPa) and the largest ratio of dR/R deformation was of 1.0%. The most critical assessed case was when the reactor is buried in soil with Esolo = 1,55 MPa and material with EPEAD = 1550 MPa, totally empty and with a superficial overload in the land of 20kN/m2 generating a tension of 17,80 MPa in the element 1955 (reaching 89% of the smallest resistance value to the traction and the shearing strain of a 20 MPa HDPE). The obtained results confirmed that the reactor produced in HDPE substitutes with advantages the models manufactured in stonemasonry, supporting the internal biogas pressure and the biomass load.
Suharjo, Usman Kris Joko. "Use of Polyethylene Glycol (PEG) 8000 for Rapid Screening of Potato (Solanum tuberosum L) Genotypes for Water Stress Tolerance." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/SuharjoUKJ2004.pdf.
Повний текст джерелаYoshikawa, Katsuyuki. "STUDIES ON NONLINEAR VISCOELASTIC BEHAVIOR OF HIGHLY ENTANGLED POLYMER SYSTEMS." Kyoto University, 2020. http://hdl.handle.net/2433/252988.
Повний текст джерелаKanuga, Karnav D. "A FUNDAMENTAL STUDY ON THE NON-LINEAR MECHANO-OPTICAL BEHAVIOR OF POLYETHYLENE NAPHTHALATE, ITS BLENDS WITH POLYETHERIMIDE AND ITS NANOCOMPOSITES." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1138038431.
Повний текст джерелаOatway, Wayne Brian. "Time resolved study of the deformation of polyethylene at high strain rates using X-ray diffraction and stress-strain techniques." Thesis, Keele University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263196.
Повний текст джерелаAyyer, Ravishankar. "Failure Processes in Polymers: Environmental Stress Crack Growth and Adhesion of Elastomeric Copolymers to Polypropylene." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1243608270.
Повний текст джерелаTitle from PDF (viewed on 19 August 2009) Department of Macromolecular Science and Engineering Includes abstract Includes bibliographical references Available online via the OhioLINK ETD Center
Ghazavizadeh, Akbar. "Modeling and simulation of the micromechanical behavior of semi-crystalline polyethylene including the effect of interphase layer." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD048/document.
Повний текст джерелаElastic characterization of the interphase layer in polyethylene is implemented by applying the relationships of two micromechanical approaches, “Extended Composite Inclusion Model” and “Double-Inclusion Method”, to the Monte Carlo molecular simulation data for the interlamellar domain. The results of the two approaches match perfectly. The interphase stiffness lacks the common feature of positive definiteness, which indicates its mechanical instability. Comparison with experimental results endorses the proposed methodology. For the hyperelastic characterization of the interlamellar domain and the interphase layer, the proposed hybrid algorithm consists in applying the constitutive equations of an isotropic, compressible, hyperelastic continuum to the molecular dynamics simulation results of a polyethylene stack. Evolution of the interphase boundaries are introduced as auxiliary variables and the notion of minimizing a set of nonnegative objective functions is employed for parameter identification. The identified hyperelastic parameters for the interlamellar domain arein good agreement with the ones that have been estimated experimentally. Finally, the large, viscoplastic deformation of an aggregate of polyethylene is reexamined. The Gent model adopted for the back stress of the noncrystalline phase, correcting the projection tensor for the modified Taylor approach, and the idea of multilevel optimization are among the contributions made
Lavoie, Fernando Luiz. "Estudo do fenômeno de fissuramento sob tensão (stress cracking) em geomembranas de polietileno (PE) virgens e degradadas." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-18082006-133723/.
Повний текст джерелаThis work presents results of stress cracking tests (SC) accomplished in virgin and degraded polyethylene (PE) geomembranes at laboratory. Geomembranes were degraded by exposition to ultraviolet radiation, by thermal aging in oven with circulation of air, and by chemical compatibility with sodium hydroxide and with leachate of alcohol production. The results of these tests demonstrate that the degradation processes of the geomembranes were submitted can be considered catalysts of the phenomenon of SC, because they happened resistance reductions to stress crack resistance of the order from 50 to 60%, with exception for the sample in chemical compatibility with leachate of alcohol production, that had an increase of 17% in the stress crack resistance
Dominguez, John Alexis. "INFLUÊNCIA DA INCORPORAÇÃO DE UM PLASTIFICANTE E UM POLIETILENO DE ALTO PESO MOLECULAR NAS PROPRIEDADES DE UMA RESINA EXPERIMENTAL E DIMINUIÇÃO DO ESTRESSE DE CONTRAÇÃO." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2015. http://tede2.uepg.br/jspui/handle/prefix/1722.
Повний текст джерелаThe objectives of this study were: 1) to evaluate the degree of conversion, shrinkage stress, flexural and compressive strength of an experimental resin with a lactic polyacid and castor oil; 2) to evaluate the cytotoxicity of an experimental resin with a lactic polyacid, and castor oil; 3) evaluate, degree of conversion, shrinkage stress, flexural and compressive strength an experimental resin with addition of a high molecular weight polyethylene; 4) to assess the cytotoxicity of an experimental resin with addition of a high molecular weight polyethylene. Initially, it was synthesized a poly (lactic acid) (PLA) via a polycondensation process. After 24 hours, the castor oil (OR) was incorporated by an esterification process with N, N-Dicyclonecylcarbodimide and 99% 4-Dimethylamino-Pyridine in 40 mL of tetrahydrofuran. After this, the blend was characterized by X-ray diffraction (XRPD), Raman spectroscopy, scanning electron microscopy (SEM) and shrinkage stress, where was proven the incorporation of PLA + OR in the experimental composite resin. In the third chapter, PLA + OR were manipulated in two concentrations (1.5% and 3%) in an experimental composite: (2,2 bis [4- (2-hydroxy-3-metacrilatoxypropoxy) phenol] (BisGMA) Triethylene glycol dimethacrylate (TEGDMA), camphorquinone (CQ), N, N-dimethylaminoethyl methacrylate (DEMA-EMA), butylated hydroxytoluene (BHT), silanated barium borosilicate glass, and the tests of degree of conversion, compressive and flexural strength and shrinkage stress were made. The cytotoxicity assay was done; a suspension of 3 x 103 cells/mL of culture medium was prepared. For this, the cells were detached from the bottom of the bottle by the addition of trypsin with EDTA, after incubation in 5% CO2 with 3 mL Eagle's medium supplemented culture. After 24 h incubation period, the culture medium was removed and 200 uL of a solution of culture medium and methylltetrazolium salt (MTT). Subsequently, the analysis of mitochondrial activity was performed in a spectrophotometer (Biotek EL 800, Biotek, Winooski, VT, USA) with a 10 wavelength of 570 nm. The data from each test were analyzed by one-way ANOVA. No significant differences were found (p <0.005) in compressive and degree of conversion tests, and significant differences in shrinkage stress where obtained, up to 69% decrease. and flexion, statistically significant . In the fourth chapter, it was incorporated a high molecular weight polyethylene and polypropiylene, in the experimental resin proposed in chapter two, at two concentrations (1.5% and 3%), and tested by degree of conversion, compressive and flexural strength and shrinkage stress. The data from each test were analyzed by one way ANOVA, finding no significant difference (p> 0.005) in degree of conversion, compressive and flexural strength, and the contraction stress showed a significant reduction of up to 40%. Conclusion: PLA + castor oil and the high molecular weight polyethylene decreases the shrinkage stress and properties like flexural and compressive strength and degree of conversion were not influenced.
Os objetivos deste estudo foram: 1) avaliar o grau de conversão, tensão de contração, resistência à flexão e compressão de uma resina experimental com um poliácido lático e óleo de rícino; 2) avaliar a citotoxicidade de uma resina experimental com um poliácido lático e óleo de rícino; 3) avaliar o grau de conversão, tensão de contração, resistência à flexão e compressão de uma resina experimental com adição de um polietileno de alto peso molecular e 4) avaliar a citotoxicidade de uma resina experimental com adição de um polietileno de alto peso molecular. Previamente realizou-se a síntese de um Poli-ácido lático (PLA) por meio de um processo de policondensação. Após 24 horas, foi incorporado o óleo de rícino (OR) por meio de um processo de esterificação junto a N,N-Diciclonecilcarbodimida e 4-Dimetilamino-Piridina a 99% em 40 mL de tetrahidrofeurano. Em seguida, o conjunto foi caracterizado por difração de espectroscopia Raman, microscopia eletrônica de varredura (MEV) e estresse de contração, onde foi comprovada a incorporação do PLA+OR numa resina composta experimental. No terceiro capítulo foi feita a incorporação do PLA+OR em duas concentrações (1,5% e 3%) numa resina composta experimental: (2,2 bis[4-(2-hidroxi-3-metacrilatoxipropoxi)fenol](BisGMA), Trietilglicoldimetacrilato (TEGDMA), canforoquinona (CQ), N,N– dimetilaminoetil metacrilato (DMAEMA), hidroxitolueno butilado (BHT), vidro de borossilicato de bário silanizado e foram realizados os testes de flexão, compressão, grau de conversão e estresse de contração. Foi feito o teste de citotoxicidade, uma suspensão de 3 x 103 células/mL de meio de cultura foi preparada. Para isso, as células foram descoladas do fundo da garrafa por meio da adição de tripsina com EDTA, após incubação em estufa com 5% de CO2 e 3 mL de meio de cultura Eagle suplementado. Após o período de incubação de 24 h, o meio de cultura foi removido e 200 μL de uma solução de meio de cultura e sal metiltetrazólio (MTT).Posteriormente, a análise da atividade mitocondrial foi realizada em espectrofotômetro (Biotek EL 800, Biotek, Winooski, VT, EUA) com comprimento de onda de 570 nm. Os dados obtidos de cada teste foram analisados com ANOVA um fator. Não encontrou-se diferença significativa (p> 0.005) nos testes de compressão e grau de conversão; já para o teste de estresse de contração, houve diminuição estatisticamente significativa de até 69% e no teste de resistência à flexão . No quarto capítulo foi feita a incorporação de um polipropileno (PP) e o polietileno de ultra-alto peso molecular (UTEC) a uma resina experimental com os mesmos materiais manipulados no capítulo dois, em duas concentrações (1,5% e 3%), e realizados os testes de compressão, flexão, grau de conversão e estresse de contração. Os dados de cada teste foram analisados com ANOVA um fator. Não houve diferença significativa (p> 0.005) nos testes de compressão, flexão e grau de conversão; já para o teste de estresse de contração houve diminuição estatisticamente significativa de até 40%. Conclusão: OPLA+óleo de rícino e o polietileno de ultra alto peso molecular em 1,5%, diminuíram o estresse de contração e propriedades como resistência à flexão, compressão e grau de conversão não foram influenciadas.
Poduška, Jan. "Popis residuálních napětí v polymerních trubkách." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231705.
Повний текст джерелаGok, Abdulkerim. "Degradation Pathway Models of Poly(ethylene-terephthalate) Under Accelerated Weathering Exposures." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1449244610.
Повний текст джерелаSrinivas, Gunti Ranga. "Applications of Advanced CAE Methodologies to Orthopaedic Implant and Vehicle Occupant cum Pedestrian Safety Countermeasure Design." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4270.
Повний текст джерелаChen, Jung-Horng, and 陳榮宏. "Environmental Stress Cracking of Short-chain Branch Polyethylene." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/46171110204075286938.
Повний текст джерелаAlvarado, Contreras Jose Andres. "Micromechanical Modelling of Polyethylene." Thesis, 2007. http://hdl.handle.net/10012/3427.
Повний текст джерелаSardashti, Amirpouyan. "Methodologies for Obtaining Reliable Indicators for the Environmental Stress Cracking Resistance of Polyethylene." Thesis, 2014. http://hdl.handle.net/10012/8255.
Повний текст джерелаCheng, Joy J. "Mechanical and Chemical Properties of High Density Polyethylene: Effects of Microstructure on Creep Characteristics." Thesis, 2008. http://hdl.handle.net/10012/4121.
Повний текст джерелаChih-Sheng, Wu, and 吳智勝. "Finite Element Stress Analysis of Polyethylene inserts in Acetabular Components for Total Hip Arthroplasty." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/89620798640700603871.
Повний текст джерела中原大學
醫學工程研究所
86
Total hip replacement (THR) surgery has been performed for over thirty years for patients with severe hip joint problems. Although THR surgery has provided satisfactory outcomes, there are still failures, such as stem loosening, osteolysis, and bone resorption, which occur occasionally. It has raised great attention by orthopaedic surgeons and biomedical engineers on how to improve implant designs and surgical techniques in order to avoid THR failures. It is widely believed that osteolysis is mainly caused by the wear debris of the ultra high molecular weight polyethelyne (UHMWPE) insert in the acetabular cup. Therefore, how to reduce the contact stress in the UHMWPE insert so as to reduce wear debris has become an important issue. In this research, the stress distributions on the UHMWPE insert of the acetabular cup at different inclination angles and anteversion angles were investigated. Different variations for the inclination and anteversion angles were investigated with twenty five different finite element models. Finite element analyses were performed by using a commercial finite element package - MARC K6.2. The linear and volumetric wear rates of the UHMWPE insert for two different sizes of femoral heads were also evaluated. Results showed that as the inclination angle and anteversion angle increased, the peak stress on the UHMWPE insert increased substantially and vice versa. This result can provide a guideline for surgeons when selecting implantation angles for the acetabular cup. In the wear rate prediction, for a femoral head with 26 mm diameter, the linear wear rate was 0.34 mm per year while the volumetric wear rate was 154.1 mm3 per year. For a femoral head with 32 mm diameter, the linear wear rate was 0.29 mm per year while the volumetric wear rate was 210.0 mm3 per year. These results all fall within the range observed from earlier clinical follow-up studies. Further parametric studies on the design of acetabular components can be performed based on this wear prediction model.
Khosravipour, Ida. "Contact stress analysis of surface guided knee implant using finite element modeling." 2015. http://hdl.handle.net/1993/30782.
Повний текст джерелаOctober 2015
Martyn, Michael T., R. Joseph, W. J. McGregor, K. E. Tanner, and Philip D. Coates. "Effect of polymer matrix on the rheology of hydroxapatite filled polyethylene composites." 2002. http://hdl.handle.net/10454/2944.
Повний текст джерелаThe effect of matrix polymer and filler content on the rheological behavior of hydroxyapatite-filled injection molding grade high-density polyethylene (HDPE) has been studied. Studies of the flow curves revealed that the matrix and the composite exhibit three distinct regions in the flow curve, namely, a pseudoplastic region at low to moderate shear rates, a plateau and a second pseudoplastic region at high shear rates. The shear stress corresponding to the plateau (Tc) is dependent on both the filler concentration and the melt temperature. Addition of HA in the HDPE matrix increases the value of Tc and decreases compressibility of the melt. An increase in temperature also raises the value of Tc. From the nature of flow curves it is concluded that the matrix polymer largely decides the rheology of the composite.
Palacio, Luis A. "Small Angle Scattering Of Large Protein Units Under Osmotic Stress." Thesis, 2020. http://hdl.handle.net/1805/22679.
Повний текст джерелаLarge protein molecules are abundant in biological cells but are very difficult to study in physiological conditions due to molecular disorder. For large proteins, most structural information is obtained in crystalline states which can be achieved in certain conditions at very low temperature. X-ray and neutron crystallography methods can then be used for determination of crystalline structures at atomic level. However, in solution at room or physiological temperatures such highly resolved descriptions cannot be obtained except in very few cases. Scattering methods that can be used to study this type of structures at room temperature include small-angle x-ray and neutron scattering. These methods are used here to study two distinct proteins that are both classified as glycoproteins, which are a large class of proteins with diverse biological functions. In this study, two specific plasma glycoproteins were used: Fibrinogen (340 kDa) and Alpha 1-Antitrypsin or A1AT (52 kDa). These proteins have been chosen based on the fact that they have a propensity to form very large molecular aggregates due to their tendency to polymerize. One goal of this project is to show that for such complex structures, a combination of scattering methods that include SAXS, SANS, and DLS can address important structural and interaction questions despite the fact that atomic resolution cannot be obtained as in crystallography. A1AT protein has been shown to have protective roles of lung cells against emphysema, while fibrinogen is a major factor in the blood clotting process. A systematic approach to study these proteins interactions with lipid membranes and other proteins, using contrast-matching small-angle neutron scattering (SANS), small angle x-ray scattering (SAXS) and dynamic light scattering (DLS), is presented here. A series of structural reference points for each protein in solution were determined by performing measurements under osmotic stress controlled by the addition of polyethylene glycol-1,500 MW (PEG 1500) in the samples. Osmotic pressure changes the free energy of the molecular mixture and has consequences on the structure and the interaction of molecular aggregates. In particular, the measured radius of gyration (Rg) for A1AT shows a sharp structural transition when the concentration of PEG 1500 is between 33 wt% and 36 wt%. Similarly, a significant structural change was observed for fibrinogen when the concentration of PEG 1500 was above 40 wt%. This analysis is applied to a study of A1AT interacting with lipid membranes and to a study of fibrinogen polymerization in the presence of the enzyme thrombin, which catalyzes the formation of blood clots. The experimental approach presented here and the applications to specific questions show that an appropriate combination of scattering methods can produce useful information on the behavior and the interactions of large protein systems in physiological conditions despite the lower resolution compared to crystallography.
Cholewa, Johnathan. "Ground displacements and pipe response during pulled-in-place pipe installation." Thesis, 2009. http://hdl.handle.net/1974/1734.
Повний текст джерелаThesis (Ph.D, Civil Engineering) -- Queen's University, 2009-04-01 18:19:24.434
MacPherson, Meoghan Elizabeth. "Photo-Curing Through Single Apertures: The Phenomenon and Its Influence On Polymerization." Thesis, 2013. http://hdl.handle.net/1805/3900.
Повний текст джерелаReduction of the polymerization shrinkage stress inherent of dimethacrylate-based resin composites has been a work in progress since the phenomenon was first described by Dr. Rafael L. Bowen in 1967. Contemporary efforts to modify the composites or the curing protocols for polymerization have proven a challenging task with controversial results. Influenced by existing mathematical models relating exposure, curing time and depth of cure of resin composites, a novel method for the reduction of polymerization shrinkage stress is proposed. By polymerizing through a single aperture mask, a dental light curing unit is transformed from a planar light source to a point light source, and a fully cured, three-dimensional “bullet” shaped curing front is predicted for the cured resin below. So long as the edges of the bullet do not touch the cavity walls or floor, the shrinkage stress of the bullet is not transferred. Follow-up with an unmasked curing unit then fully polymerizes the restoration. By reducing the volume of uncured composite in contact with the cavity walls and floor, shrinkage stress of the restoration is also reduced. The objective of the present study was to demonstrate this curing phenomenon with a model resin composite using masks with aperture diameters of 0.5, 0.4, and 0.25 mm and curing times of 10, 20, 30, and 40 seconds. The resulting curing front was evaluated quantitatively and qualitatively. From this, mathematical models of the curing front were derived. Selected combinations of aperture mask and curing time were then investigated to evaluate the influence of this phenomenon on the degree of conversion, Knoop hardness, and polymerization shrinkage stress of the same model resin composite. Group differences were analyzed using a one-way ANOVA at 5% significance.