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Academic literature on the topic 'Polyethylene Stresses'

Author: Grafiati

Published: 6 September 2023

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Journal articles on the topic "Polyethylene Stresses"

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Huang, Chang-Hung, Yung-Chang Lu, Lin-I. Hsu, Jiann-Jong Liau, Ting-Kuo Chang, and Chun-Hsiung Huang. "Effect of material selection on tibial post stresses in posterior-stabilized knee prosthesis." Bone & Joint Research 9, no. 11 (November 1, 2020): 768–77. http://dx.doi.org/10.1302/2046-3758.911.bjr-2020-0019.r2.

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Aims The material and design of knee components can have a considerable effect on the contact characteristics of the tibial post. This study aimed to analyze the stress distribution on the tibial post when using different grades of polyethylene for the tibial inserts. In addition, the contact properties of fixed-bearing and mobile-bearing inserts were evaluated. Methods Three different grades of polyethylene were compared in this study; conventional ultra high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (HXLPE), and vitamin E-stabilized polyethylene (VEPE). In addition, tibial baseplates with a fixed-bearing and a mobile-bearing insert were evaluated to understand differences in the contact properties. The inserts were implanted in neutral alignment and with a 10° internal malrotation. The contact stress, von Mises stress, and equivalent plastic strain (PEEQ) on the tibial posts were extracted for comparison. Results The stress and strain on the tibial post for the three polyethylenes greatly increased when the insert was placed in malrotation, showing a 38% to 56% increase in von Mises stress and a 335% to 434% increase in PEEQ. The VEPE insert had the lowest PEEQ among the three materials. The mobile-bearing design exhibited a lower increase in stress and strain around the tibial posts than the fixed-bearing design. Conclusion Using VEPE for the tibial component potentially eliminates the risk of material permanent deformation. The mobile-bearing insert can help to avoid a dramatic increase in plastic strain around the tibial post in cases of malrotation. The mobility allows the pressure to be distributed on the tibial post and demonstrated lower stresses with all three polyethylenes simulated. Cite this article: Bone Joint Res 2020;9(11):768–777.

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Fisher, H. P., R. K. Eby, and R. C. Cammarata. "Surface stresses in paraffin and polyethylene." Polymer 35, no. 9 (January 1994): 1923–30. http://dx.doi.org/10.1016/0032-3861(94)90982-2.

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Swieszkowski, W., P. Bednarz, and P. J. Prendergast. "Contact stresses in the glenoid component in total shoulder arthroplasty." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 217, no. 1 (January 1, 2003): 49–57. http://dx.doi.org/10.1243/095441103762597737.

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Several studies of retrieved glenoid components from total shoulder arthroplasty show an erosion of the rim, surface irregularities, component fracture and wear resulting from polyethylene deformation in vivo. Particles resulting from polyethylene wear might be one of the reasons for the very high rate of glenoid component loosening found clinically. Because wear can be the result of high contact stresses, the aim of this study is to find out whether or not contact stresses are high enough to cause wear of the glenoid component and what influence the component type and geometry have on polyethylene contact stresses for different humerus abduction angles. Elasticity theory is used in a parametric study of contact stresses in several glenoid component designs. A finite element method is used to confirm the accuracy of the analytical solution. The analysis shows that the peak stress generated in glenoid components under conditions of normal living can be as high as 25 MPa; since this exceeds the polyethylene yield strength, wear and also cold flow of the components can be expected. It is predicted that more conforming components have lower contact stresses, which might result in lower wear rate and less cold flow. It is also found that a metal-backed component promotes higher contact stresses than an all-polyethylene component with the same total thickness, therefore it can be expected that metal-backed components have inferior wear properties.

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Masayuki, Nishida, Hanabusa Takao, and Yasukazu Ikeuchi. "X-Ray Stress Measurement of Fiber Reinforced Plastics Composite Material." Key Engineering Materials 353-358 (September 2007): 2423–26. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2423.

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X-ray stress measurement with sin2ψ method is one of useful tools to detect residual stresses in manufactured products. In this study, the residual stresses in the tungsten fiber reinforced polyethylene composite were examined by X-ray stress measurement technique. The transmission diffraction method was employed in residual stress measurement of polyethylene matrix. The X-ray elastic constant of high density polyethylene (HDPE) which formed matrix of the composite was estimated before residual stress measurement. The results of sin2ψ diagram with transmission method show good linearity under the several tensile loading. After that the residual stresses in the composite were investigated for HDPE matrix phase. From the measurement results, the tensile residual stresses existed in fiber longitudinal direction and compressive ones in transverse direction for HDPE matrix.

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Serebrennikov, Anatoly, Daniil Serebrennikov, and Zufar Hakimov. "Polyethylene Pipeline Bending Stresses at an Installation." American Journal of Engineering and Applied Sciences 9, no. 2 (February 1, 2016): 350–55. http://dx.doi.org/10.3844/ajeassp.2016.350.355.

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Bilgin, Ömer. "Modeling Viscoelastic Behavior of Polyethylene Pipe Stresses." Journal of Materials in Civil Engineering 26, no. 4 (April 2014): 676–83. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0000863.

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Kandemir, Göksu, Simon Smith, and Thomas J. Joyce. "The influence of contact stress on the wear of cross-linked polyethylene." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 232, no. 10 (August 23, 2018): 1008–16. http://dx.doi.org/10.1177/0954411918796047.

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Generation of wear debris and wear particle-induced osteolysis are the main limitations of metal-on-polyethylene artificial joints. Cross-linked polyethylene has been recently used, particularly in hip replacements, as an alternative material to conventional ultrahigh molecular weight polyethylene due to its superior wear resistance. This study focused on the wear behaviour of cross-linked polyethylene under different contact stresses in order to make interpretations of its long-term in-vivo performance. A 50-station SuperCTPOD (pin-on-disc) machine was used to investigate the influence of contact stress on the wear of cross-linked polyethylene pins which were articulated against cobalt chromium discs. It was found that the wear rate of cross-linked polyethylene was lower at higher contact stresses.

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Triwardono, Joko, Agung Shamsuddin Saragih, Fuad Abrar, Muhammad Satrio Utomo, Ika Kartika, Yudan Whulanza, and Sugeng Supriadi. "Finite Element Analysis Contact Stresses on Tibiofemoral Joint and Post Polyethylene Components Used to Evaluated Predesign Knee Implant." Journal of Biomimetics, Biomaterials and Biomedical Engineering 55 (March 28, 2022): 46–55. http://dx.doi.org/10.4028/p-uv1qax.

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At the time of prayer, most Muslims kneel with fully extended limbs (between 150° and 165°). Meanwhile, incidents such as hyperflexion in total knee arthroplasty (TKA) implant outside their designated configuration can lead wear or fracture of the polyethylene component. In this study, polyethylene component of posterior-stabilized right knee joint implant have been developed to facilitate higher range of motion (ROM). Finite element analysis (FEA) was used to analyze contact stresses on the polyethylene component. FEA was used to simulate weight-bearing condition at 0°, 30°, 60°, 90°, 120°, and 150° of knee flexion. Modified polyethylene component results in better performance in terms of contact stresses, especially at 120° of knee flexion. Current result shows contact stresses above 120 MPa were measured at the posterior post polyethylene, when 4000 N force was applied. Minimum contact stress on the medial condyles was 630 KPa at 120° of knee flexion, while on the lateral condyles, the minimum contact stress was 250 KPa at 150° of knee flexion. With this finding, the current polyethylene component design is expected to accommodate deep knee flexion movement in daily activities and can reduce potential of wear or fracture of the polyethylene component during deep knee flexion.

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Miller, M. C., P. Smolinski, S. Conti, and K. Galik. "Stresses in Polyethylene Liners in a Semiconstrained Ankle Prosthesis." Journal of Biomechanical Engineering 126, no. 5 (October 1, 2004): 636–40. http://dx.doi.org/10.1115/1.1798011.

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A finite element model of a semiconstrained ankle implant with the tibia and fibula was constructed so that the stresses in the polyethylene liner could be computed. Two different widths of talar components were studied and proximal boundary conditions were computed from an inverse process providing a load of five times body weight appropriately distributed across the osseous structures. von Mises stresses indicated small regions of localized yielding and contact stresses that were similar to those in acetabular cup liners. A wider talar component with 36% more surface area reduced contact stress and von Mises stresses at the center of the polyethylene component by 17%.

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D???Lima, Darryl D., Peter C. Chen, and Clifford W. Colwell. "Polyethylene Contact Stresses, Articular Congruity, and Knee Alignment." Clinical Orthopaedics and Related Research 392 (November 2001): 232–38. http://dx.doi.org/10.1097/00003086-200111000-00029.

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Dissertations / Theses on the topic "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.

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Zhang, 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.

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Choollun, 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.

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Previous studies of high-density polyethylene pipes have been based on the premise that residual stresses have no effects and have almost no role to play in the failure and performance of theses pipes. It is thought that previous studies have underestimated the effects of the residual stresses in pipes at the design stage particularly when assessing pipe-soil interaction and ground loading effects. This project tried to assess the effect of residual stresses in soil-pipe interaction of HDPE (PEIOO) pipes, and opened two main areas of research: (a) to investigate the actual residual stress profile in the pipes as a result of the manufacturing process; and, (b) to take these residual stress profiles, which have been previously ignored, in consideration to assess the performance of the pipe and the surrounding soil. A review of the existing techniques available for the determination of residual stresses was carried out and a literature review was done on how these techniques were used by various authors. On the whole, most of these techniques involved destructive tests that are believed, here, to alter the residual stress profile and magnitude in the pipe wall. The current study has tried to develop an innovative stress-optical technique for the determination of residual stresses with minimal alteration to the residual stress profile and its magnitude. After determining the residual stress profile and magnitudes by the new method, the interaction of the residual stress with internal pressure effects and ground loading effects on pipes is studied. The studies included the numerical modelling of the pipe when the residual stress in the pipe wall incorporated and the pipe subjected to internal pressure loading as well as external loadings from the weight of the surrounding soil. A number of earlier researchers have investigated the soil structure interaction parameters which affect the structural behaviour of buried flexible pipes. However, to date none of the studies have incorporated residual stresses in pipe-soil interaction modelling and the current study has raised awareness of the consequent absence in current design procedure [BS EN 1295-3; 1998].

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Danikas, 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.

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Lees, 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.

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Daming, 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.

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Farid, 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.

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Willoughby, 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.

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Bali, 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.

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Magister Scientiae - MSc (Biotechnology)
Water 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.

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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.

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O presente trabalho foi desenvolvido para avaliar o potencial de utilização de um reator anaeróbico fabricado em PEAD Polietileno de Alta Densidade, produzido pelo processo de rotomoldagem em substituição aos reatores convencionais construídos em concreto e alvenaria, trabalhando em regime de batelada e enterrados no solo. Os estados de tensões e deformações foram avaliados utilizando o programa de Elementos Finitos ABAQUS versão 6.5 e a malha dos nós utilizando o programa MSC PATRAN 2005 formando 7329 nós e 2004 elementos, em uma malha otimizada para as regiões de maior curvatura (pontos concentradores de tensão). O carregamento é formado com uma pressão interna do biogás de 5 kPa acrescido da carga hidrostática de biomassa de 6000 kgf em uma fundação elástica calculada pela razão tensão/recalque a partir do Módulo de Elasticidade equivalente do solo (Esolo). Comparando o estado de tensões avaliado durante o carregamento foi possível constatar que a maior tensão obtida no elemento mais crítico para a utilização mais provável do reator atingiu o valor de 7,46 MPa (não supera 40% do menor valor de resistência à tração e ao cisalhamento do PEAD de 20 MPa) e a maior razão de deformação dR/R foi de 1.0%. O caso mais crítico avaliado foi quando o reator está enterrado, totalmente vazio, em solo com Esolo = 1,55 MPa e o material com EPEAD = 1550 MPa e com uma sobrecarga superficial no terreno de 20kN/m2 gerando uma tensão de 17,80 MPa no elemento 1955 (atingindo 89% do menor valor de resistência à tração e ao cisalhamento do PEAD igual a 20 MPa). Os resultados obtidos comprovam que o reator produzido em PEAD substitui com vantagens os modelos fabricados em concreto ou alvenaria, suportando a pressão interna do biogás e a carga de biomassa.
The 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.

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Books on the topic "Polyethylene Stresses"

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Victor, Elias, United States. Federal Highway Administration. Offices of Research and Development., and Turner-Fairbank Highway Research Center, eds. Stress cracking potential of HDPE geogrids. McLean, Va: U.S. Dept. of Transportion, Federal Highway Administration, Research and Development, 1998.

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Viscoelastic properties of wood-fiber reinforced polyethylene: Stress relaxation, creep and threaded joints. Ottawa: National Library of Canada, 2000.

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Lees, John Simon. Vibrational spectroscopy of stressed and unstressed polyethlene and isotactic polypropylene: Raman and F.T.I.R. spectroscopic studies of uniaxially drawn films of stressed polyethylene.... Bradford, 1987.

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Book chapters on the topic "Polyethylene Stresses"

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Velho, A. M., A. C. Diogo, and G. Marin. "Time Evolution of Normal Stresses in Strong Shear Flows of Polyethylene Melts." In Progress and Trends in Rheology V, 413–14. Heidelberg: Steinkopff, 1998. http://dx.doi.org/10.1007/978-3-642-51062-5_199.

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Sweeney, J., and I. M. Ward. "Modelling Stress Relaxation and Creep in Oriented Polyethylene." In Anisotropy and Localization of Plastic Deformation, 520–23. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3644-0_121.

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Kip, Bert J., Marcel C. P. van Eijk, and Robert J. Meier. "Molecular Strain in High Modulus Polyethylene Fibers During Stress Relaxation Studied by Raman Microscopy." In Integration of Fundamental Polymer Science and Technology—5, 183–87. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3890-1_22.

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Zhang, Ling, Yuanxiang Zhou, and Zhaowei Wang. "Electrical Property of Polypropylene Toughened by β Nucleating Agent." In Polypropylene Materials [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107118.

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High-performance polymer insulating material is a crucial knob for developing HVDC power cables. However, the production process of traditional cross-linked polyethylene, especially degassing, is complicated. The space charge accumulation could render severe electric field distortion under high temperatures and electrical stresses, detrimental to the insulation reliability. As a potential alternative, polypropylene (PP) has excellent properties and is environmentally friendly. However, crucial challenges for the PP application include brittleness deficiency at low temperatures and space charge problems caused by toughened PP composites. In recent years, the β nucleating agent (β-NA) has emerged as an effective additive to improve mechanical and electrical properties due to the introduction of the β-crystal form. Herein, PP/β-NA with different contents and self-assembled β-NA were subsequently prepared, respectively. The melting and crystallization behaviors, crystalline structure, and electrical properties were systematically investigated, and the influence on the space charge characteristics of PP/β-NA composites was explored. We aim to summarize the β-crystal form regulation strategies for advanced PP materials and how they perform, point out the critical characteristic parameters to improve the target performance, and offer suggestions for the rational design for future HVDC cable engineering.

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Lustiger, Arnold. "Understanding Environmental Stress Cracking in Polyethylene." In Medical Plastics, 65–71. Elsevier, 1998. http://dx.doi.org/10.1016/b978-188420760-0.50010-7.

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"Stress Crack Testing Of Polyethylene Geomembranes." In Geomembranes - Identification and Performance Testing, 251–63. CRC Press, 1990. http://dx.doi.org/10.1201/9781482267501-19.

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Rao, Vyshnavi V., Sonashree R., and Rashmi R. Halbavi. "Review on Plastic Waste Disposal and Role of Microorganisms in Bioremediation of Plastics." In Advances in Environmental Engineering and Green Technologies, 236–47. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4921-6.ch011.

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Plastics are the most commonly used polymers for conventional applications. Plastic wastes accumulating the environment are presenting an ever-increasing ecological threat. Low density polyethylene is major cause of long-term environmental pollution. An eco-friendly approach to resolve this ever-growing persistent menace is bioremediation. The diverse metabolic capability of microbes can be effectively exploited for breakdown of plastic wastes. Another approach is to synthesise biodegradable or organic plastics which is soluble in the natural environment. There are several advantages associated with these biodegradable plastics or plastic degrading microbes. They can be composted with organic wastes and returned to enrich the soil. Their use will not only reduce stress and loss of habitat of wild animals caused by dumping of conventional plastics but will also lessen the labor expenses for the removal of plastic wastes in the environment because they degrade naturally. This review describes bioremediation/biodegradation process, production, types of and advantages of bioplastics.

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Rao, Vyshnavi V., Sonashree R., and Rashmi R. Halbavi. "Review on Plastic Waste Disposal and Role of Microorganisms in Bioremediation of Plastics." In Research Anthology on Emerging Techniques in Environmental Remediation, 481–92. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3714-8.ch025.

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Plastics are the most commonly used polymers for conventional applications. Plastic wastes accumulating the environment are presenting an ever-increasing ecological threat. Low density polyethylene is major cause of long-term environmental pollution. An eco-friendly approach to resolve this ever-growing persistent menace is bioremediation. The diverse metabolic capability of microbes can be effectively exploited for breakdown of plastic wastes. Another approach is to synthesise biodegradable or organic plastics which is soluble in the natural environment. There are several advantages associated with these biodegradable plastics or plastic degrading microbes. They can be composted with organic wastes and returned to enrich the soil. Their use will not only reduce stress and loss of habitat of wild animals caused by dumping of conventional plastics but will also lessen the labor expenses for the removal of plastic wastes in the environment because they degrade naturally. This review describes bioremediation/biodegradation process, production, types of and advantages of bioplastics.

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Conference papers on the topic "Polyethylene Stresses"

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Suggs, Jeremy F., George R. Hanson, and Guoan Li. "In-Vivo Tibiofemoral Contact Stress in the Knee After TKA." In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176664.

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Polyethylene wear is a leading cause of failure in total knee arthroplasty (TKA). Knowing the stresses experienced by the polyethylene would be pivotal information for efforts to improve polyethylene longevity. Previous investigations into the stress and wear of the polyethylene have required estimates of in-vivo conditions [1]. This work investigates the feasibility of using actual in-vivo kinematics obtained using dual fluoroscopy as boundary conditions for finite element analysis of the polyethylene.

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Chu, Taiming, Jing Chen, and Michael Pappas. "Finite Element Analysis of Contact Stresses in Metal-Plastic Total Knee Replacement." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0115.

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Abstract Clinical observation indicates that the polyethylene wear in replacement knee with metal to plastic articulation is a significant problem. The case studies (Knezevich et al., 1993) reinforce the concept that the design of the knee components is critical to minimize polyethylene wear and thus reduce the chances of subsequent failure. Many factors affect wear. They are, for example, contact surface configuration, material, surface finishing, loads, motion, temperature, lubrication, contaminants and previous use conditions. Among them, the essential factor is the contact surface configuration (Pappas, 1986). From the design viewpoint, avoiding high wear rates in a metal polyethylene articulation prosthesis is equal to avoiding a high contact stress in excess of the fatigue strength of the polyethylene. The aim of this study is to investigate the contact stress distribution on the tibial (bearing) component at different walking positions using the finite element method. Results can help to predict the wear potential of the tibial component.

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Hachour, Kamel, Meziane Aberkane, and Rabah Ferhoum. "Experimental Investigation of High Density Polyethylene Yield Surface Under Biaxial Loading." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82674.

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A series of biaxial experiments are performed to investigate the yield envelope of high-density polyethylene (HDPE). An Arcan apparatus is achieved in order to load a newly-designed flat specimen “butterfly specimen” to various combinations of tensile/compressive and shear loading. It subjected a central section of the specimen to a uniform state of plane stress. The stresses have local maxima at the central section, thus ensuring that yielding occurs there. The yield stresses are determined from the load-displacement curves and plotted in two-dimensional principal stress. The experimental results are compared with a predicted yield envelope based upon a pressure modified von Mises criterion, which accounts for the difference in tensile and compressive yield stress; additionally the hydrostatic pressure on yielding is also considered. Good agreement is found.

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Kurtz, Steven M., Charles W. Jewett, John E. Moalli, and Avram A. Edidin. "An Elastic-Plastic Material Model for the True Stress-Strain Behavior of Ultra-High Molecular Weight Polyethylene in Tension and Compression." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0353.

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Abstract Prediction of stresses and strains for orthopaedic total joint replacement components depends upon accurate knowledge of the true stress-strain behavior for ultra-high molecular weight polyethylene (hereafter polyethylene), which has been investigated in uniaxial tension but not yet in uniaxial compression. Previous research has suggested that the maximum strains in tibial components are less than 0.12 [1]. An exponential model has been shown to accurately describe the tensile true stress-strain behavior of polyethylene up to 0.12 true strain [2], but no distinction has yet made between the linear elastic and nonlinear plastic regions of the true stress-strain curve.

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Houchaime, W., A. Petrella, T. Dietz, J. Halloran, and P. Rullkoetter. "Development of a Rate-Dependent Material Model for UHMWPE Joint Replacement Components." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/bed-23050.

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Abstract Polyethylene wear has been implicated in osteolysis and can lead eventually to implant loosening. Abrasive/adhesive wear and delamination or pitting damage in ultra-high molecular weight polyethylene (UHMWPE) joint replacement components has been in part attributed to high joint contact stresses. The propensity of total joint replacement systems for these types of wear is often assessed by evaluating the joint contact stresses and contact areas and these often serve as a basis for differentiation of systems. The rate-dependency of polyethylene can have a significant effect on these contact characteristics of joint replacement components. Previously, researchers have used experimental and analytical methods to determine joint contact characteristics. Most of the analytical studies, however, have not included the important time-dependent behavior of UHWMPE.

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Marohl, Michael P. H., Glenn R. Frazee, and Thomas M. Musto. "Relative Influence of Soil Stiffness and Elbow Geometry on Buried Piping Thermal Stresses." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65591.

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The design of buried piping systems requires special considerations. Historically, buried piping was evaluated for thermal expansion and contraction using simple hand calculations considering the piping to be fully-constrained by the surrounding soil. With the development of analytical software, more advanced analysis of buried piping is possible considering detailed piping routing and the stiffness of the surrounding soil and of the piping itself (in cases of more flexible piping materials). Typically, the areas of highest thermal stress occur at changes in direction (i.e. elbows, etc.) due to the applied moments, and the relative stress magnitude is influenced by the stiffness of the surrounding soil. Due to the relatively high coefficient of thermal expansion of polyethylene, stresses in buried piping due to thermal expansion and contraction are of particular note for high density polyethylene (HDPE) piping. This paper examines the relative influence of the analytical representations of a variety of HDPE piping elbow geometries (e.g. mitered elbows, molded elbows, etc.) and corresponding soil restraint. The study demonstrates that total longitudinal stress calculated in a finite element analysis may be reduced using minor to moderate efforts of refinement.

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Baldini, Todd H., Timothy M. Wright, Jaime A. Estupiñán, and Donald L. Bartel. "An Apparatus for Studying Wear Damage in UHMWPE: Description and Initial Test Results." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0167.

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Abstract Wear of ultra high molecular weight polyethylene (UHMWPE) in total joint arthroplasties causes release of particulate debris that contributes to long term complications such as osteolysis and implant loosening (Wright and Goodman, 1996). Despite the magnitude of this clinical problem, little is known about wear mechanisms in UHMWPE implant components and the factors that control them. Total knee replacement designs, for example, require non-conforming metallic on UHMWPE joint surfaces to assure appropriate kinematics and function. Finite element analysis (FEA) has shown that contact between such surfaces leads to high surface and subsurface stresses (Bartel, et al., 1986). Dynamic FEA has also that shown that femoral rollback on the tibia results in considerable residual stresses in the polyethylene (Estupiñán, et al., 1996). In an effort to complement our analytical studies of stresses associated with wear damage, we have developed a wear apparatus. Our objective is to independently control factors including geometry of the joint surfaces, contact load, the presence (sliding) or absence (rolling) of surface velocity, and the polyethylene material properties, so as to experimentally examine their effects on the creation of damage similar to that observed on retrieved joint implants.

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Romero, Francisco, Farid Amirouche, Mark Gonzalez, and Todd Render. "Induced Stresses and Shell/Liner Micromotions in THA Components During Dislocation: A Finite Element Study." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32614.

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During total hip replacement (THR) many supporting structures for the retention of the femoral head within the acetabulum are removed. Previous studies have determined that this lack of supporting structures leads to separation of the femoral head within the UHMWPE liner. During the relocation phase the femoral head impacts with the liner creating high stress conditions that may contribute to premature polyethylene wear and instabilities.

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9

Kurtz, Steven M., Jorge A. Ochoa, and Christopher V. White. "Liner/Shell Load Transfer Mechanisms in a Modular Acetabular Component for Total Hip Replacement." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0349.

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Abstract Modular acetabular components have seen widespread clinical use since the 1980’s (Collier et al., 1992). However, nonconformity between the polyethylene liner and the metal shell may exist in modular acetabular components by design, due to limitations on polyethylene liner manufacturing tolerances, or from the incorporation of locking mechanisms to attach the liner to the shell. Previous research has demonstrated that the stresses at the articulating surface are sensitive to nonconformity between the liner and the metal shell (Kurtz et al., 1994). Deleterious rim loading may also occur in a rimmed polyethylene liner with radial interference between the liner and the metal shell (Kurtz et al., 1993).

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10

Haeri, Navid, and Brian A. Cornah. "Repercussion of Autofrettage on the Fatigue Crack Growth in the Vicinity of Catalyst Entry Opening for Polyethylene Autoclave Reactor." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45402.

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Background. The authors conducted a study to analyse the impact of autofrettage practice on the fatigue crack growth in the vicinity of the catalyst entry nozzle in a MK.15 ICI LDPE autoclave reactor. Methods. The authors created 3-D finite element models of the quadrant of the opening. Elastic-plastic analysis was carried out to evaluate the residual stresses from the autofrettage which were then used as an input to the fracture mechanics analysis. Linear Elastic Fracture Mechanics (LEFM) methodology was then deployed associating a Radial Direction, Quarter-Circular Corner Crack pattern as per API 579/ASME VIII Div.3 for the purpose of calculating the crack tip stress intensity. A number of hypothetical pressure cycles were considered in order to calculate the crack growth rate as per ASME Div.3 (Paris’ Law) both with and without residual stresses from autofrettage analysis. Results. The study results showed the change in the crack behaviour as a result of adding the autofrettage residual stresses onto the model and discussed the implications of such a practice on the design life for autoclave reactors.

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Reports on the topic "Polyethylene Stresses"

1

Rogers, C. E. Stress Cracking of Polyethylene in Organic Liquids. Fort Belvoir, VA: Defense Technical Information Center, February 1986. http://dx.doi.org/10.21236/ada165733.

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Watson, Mark, Martyn Wilmott, and Brian Erno. GRI-96-0452_2 Stress Corrosion Cracking Under Field Simulated Conditions II. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), November 1997. http://dx.doi.org/10.55274/r0011974.

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The pH of solutions found under disbonded polyethylene tape coatings in the field is generally in the range of 6.5 to 7.5. Electrochemically determining corrosion rates for pipeline steels exposed to neutral pH solutions in this pH range indicate that corrosion rates are too low to account for the observed crack growth rates from field excavation programs. This suggests that for the SCC process to be based on a simple dissolution mechanism then the pH at the crack tip would have to be lower than the bulk solution pH. A computer model was developed to determine solution chemistry changes within an SCC crack under anaerobic conditions as a function of time The numerical simulation model showed that the pH at a crack tip is lower by at least one pH unit than the trapped electrolyte outside the crack. A second thermodynamic model was used to show that under appropriate conditions dilute groundwater can be converted to a concentrated carl ornately bicarbonate solution. High temperatures were not required to concentrate on this solution. The concentration of this electrolyte under coal tar or asphalt coatings can occur by a cyclical process in which groundwater levels fluctuate and in tum influence the ability of cathodic protection to reach the steel surface. The high pH is generated by effective cathodic protection and the carbonate concentration is developed by absorption of CO2 from soil gases.

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Bruce and Li. L51666 Surface Preparation and Coatings on the Susceptibility of Line Pipe to Stress-Corrosion Cracking. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), February 1992. http://dx.doi.org/10.55274/r0010315.

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Within the last decade, a number of gas pipeline companies throughout the world have identified the presence of Stress-Corrosion Cracking (SCC) on their pipelines. While the cause of the SCC resulted from a multitude of factors, there appeared to be a commonality relating to pipeline coatings. Although SCC has occurred under polyethylene/PVC tapes and enamel coatings, not a single incident has been recorded where SCC has occurred on a fusion-bonded-epoxy coated line. The three major factors that were thought to account for the difference in the SCC performance of the various coatings were; (1) resistance of a coating to disbonding, (2) the ability to pass current through the coating and thereby protect the disbonded regions and (3) the surface preparation of the line pipe prior to coating application. These factors were addressed in this three-year program for PRCI. This report examines the relationship between coatings and surface preparation and the likelihood of subsequent stress corrosion cracking. Standard Cathodic disbondment tests, measurements of potential gradients beneath disbonded coating, electrochemical measurements of current passages through coatings and actual SCC tests are described and results reported.

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