Academic literature on the topic 'Stress block parameters'
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Journal articles on the topic "Stress block parameters"
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Singh, Brijesh, Vikas Patel, P. N. Ojha, and V. V. Arora. "Analysis of stress block parameters for high strength concrete." Journal of Asian Concrete Federation 6, no. 1 (June 30, 2020): 1–9. http://dx.doi.org/10.18702/acf.2020.6.6.1.
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Singh, Brijesh, Vikas Patel, P. N. Ojha, and V. V. Arora. "Analysis of stress block parameters for high strength concrete." Journal of Asian Concrete Federation 6, no. 1 (June 30, 2020): 1–9. http://dx.doi.org/10.18702/acf.2020.6.6.1.1.
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Bae, Baek-il, Hyun-Ki Choi, and Chang-Sik Choi. "Stress Block Parameters for Steel Fiber Reinforced Reactive Powder Concrete." Advanced Science Letters 13, no. 1 (June 30, 2012): 115–19. http://dx.doi.org/10.1166/asl.2012.3832.
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Oztekin, Ertekin, Selim Pul, and Metin Husem. "Determination of rectangular stress block parameters for high performance concrete." Engineering Structures 25, no. 3 (February 2003): 371–76. http://dx.doi.org/10.1016/s0141-0296(02)00172-4.
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Braga, Franco, Rosario Gigliotti, Michelangelo Laterza, and Michele D'Amato. "An Analytical Formulation of Stress-Block Parameters for Confined Concrete!" Open Construction and Building Technology Journal 2, no. 1 (September 26, 2008): 156–65. http://dx.doi.org/10.2174/1874836800802010156.
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Akbar, Fachreza, Ari Wibowo, and Wisnumurti Wisnumurti. "Preloaded Reinforced Concrete Beam Stress Block Parameters : A Preliminary Approach." Rekayasa Sipil 12, no. 1 (February 20, 2018): 1–9. http://dx.doi.org/10.21776/ub.rekayasasipil.2018.012.01.1.
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Assi, Nizar, Husain Al-Gahtani, and Mohammed A. Al-Osta. "Numerical Investigation of Stress Block for High Strength Concrete Columns." Civil Engineering Journal 6, no. 5 (May 1, 2020): 974–96. http://dx.doi.org/10.28991/cej-2020-03091522.
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This paper is intended to investigate the stress block for high strength concrete (HSC) using the finite element model (FEM) and analytical approach. New stress block parameters were proposed for HSC including the stress intensity factor (α1) and the depth factor (β1) based on basic equilibrium equations. A (3D) finite element modeling was developed for the columns made of HSC using the comprehensive code ABAQUS. The proposed stress parameters were validated against the experimental data found in the literature and FEM. Thereafter, the proposed stress block for HSC was used to generate interaction diagrams of rectangular and circular columns subjected to compression and uniaxial bending. The effects of the stress block parameters of HSC on the interaction diagrams were demonstrated. The results showed that a good agreement is obtained between the failure loads using the finite element model and the analytical approach using the proposed parameters, as well as the achievement of a close agreement with experimental observation. It is concluded that the use of proposed parameters resulted in a more conservative estimation of the failure load of columns. The effect of the stress depth factor is considered to be minor compared with the effect of the intensity factor.
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Yeon, Kyu-Seok, Jai-Chul Yi, and Yoon-Sang Choi. "Stress-Strain Relation and Stress Block Parameters on Flexural Compressive Strength of Polymer Concrete." Journal of The Korean Society of Agricultural Engineers 50, no. 5 (September 30, 2008): 29–37. http://dx.doi.org/10.5389/ksae.2008.50.5.029.
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Zhang, Xiu Fang, and Shi Lang Xu. "Rectangular Stress-Block Parameters for Bending Design of Reinforced UHTCC Beam." Advanced Materials Research 243-249 (May 2011): 32–40. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.32.
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The full replacement of plain concrete with ultra-high toughness cementitious composite (UHTCC) in structural members can obtain the enhanced structural performance over traditional concrete structures because of its prominent advantages such as the markedly ductile deformation capacity after post-cracking and excellent damage tolerance ability. In the current article, aimed at setting up the theoretical formula for the practical use in the bending design of reinforced beam made of UHTCC, the equivalent parameters introduced in rectangular stress block approach are analytically determined. Two existing models in compression for UHTCC, i.e., bilinear model and parabolic line then horizontal line (nonlinear model) are adopted in the derivation of the equivalent parameters. By comparing moment-curvature curve obtained from the experiment with the calculated one, the nonlinear model is verified to be rational and could predict bending capacity with sufficient accuracy. Further comparison between moment-curvature curves calculated according to two compression models shows that the nonlinear model can give a bending response prediction with almost the same accuracy as the bilinear model. Finally, it is suggested that, in the case that nonlinear compression model is adopted for the compressive behavior in UHTCC, the equivalent parameters α=0.8 and β=1.0 could be used to estimate ultimate load bearing capacity of reinforced UHTCC beam.
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Karthik, Madhu M., and John B. Mander. "Stress-Block Parameters for Unconfined and Confined Concrete Based on a Unified Stress-Strain Model." Journal of Structural Engineering 137, no. 2 (February 2011): 270–73. http://dx.doi.org/10.1061/(asce)st.1943-541x.0000294.
Full textDissertations / Theses on the topic "Stress block parameters"
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Van, Schalkwyk Francois. "The influence of specimen size on the compression stress block parameters of reinforced concrete." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/62799.
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The stress-strain distribution in flexural compression has been at the forefront of investigation ever since the 20th century. The original formulation of the flexural stress-strain distribution and the subsequent development of the stress block parameters, were based on specimens with a 127 x 203 mm (4 x 8 in.) cross section. The design of reinforced concrete flexural and flexural compression members at the Ultimate Limit State is based on the equilibrium of forces and moments obtained by using these stress block parameters. The calculation procedure entails the determination of the neutral axis depth, which varies depending on the magnitude of the applied action and the section dimensions. If the load action is small, the internal bending moment can be equilibrated with a reduced neutral axis depth, however, current design models do not consider the influence of a reduction in neutral axis depth (specimen size) on the stress block parameters, possibly resulting in an underestimation of the flexural compression capacity. This study aimed to evaluate the influence of specimen size and compressive strength on the stress block parameters of concrete by testing twenty-seven plain concrete specimens in flexural compression. Nine specimens were tested for each specimen size (50 mm, 100 mm, and 200 mm), three for each of the cylinder target strengths of 40 MPa, 65 MPa, and 80 MPa. The stress block parameters, obtained from the stress-strain curves, were compared to the data obtained by previous researchers, and the influence of specimen size on the stress block parameters evaluated for the different concrete strengths. Along with the size effect in flexural compression, the size effect for cubes and cylinders were also evaluated, and the associated cylinder strength used to eliminate the size effect of the stress block parameters. A comparison of the error between the predicted Moment-Axial force (M-N) interaction diagram, obtained by using the BS 8110-1 (1997), SANS 0100-1 (2000), ACI-318 (2014), and EN 1992-1-1 (2004) codes, and the actual M-N interaction diagram, obtained from the experimental points, were made, and conclusions regarding their applicability for the design of concrete containing South African materials drawn. Lastly, the flexural stress-strain behaviour was modelled, and a comparison made between the calculated and actual stress block parameters.Dissertation (MEng)--University of Pretoria, 2017.
Civil Engineering
MEng
Unrestricted
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Tabassum, Javeria, and javeriaajaz@yahoo co in. "Analysis of current methods of flexural design for high strength concrete beams." RMIT University. Civil, Environmental & Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080725.143153.
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Considerable amount of research was carried out into the properties and structural performance of high strength concrete for more than few decades. Whilst this research has produced relevant and useful results, there are several properties of high strength concrete like compressive and tensile strengths, stiffness, durability etc. that need to be evaluated and investigated to determine an accurate representation for the determination of different structural properties of beams made of high strength concrete. For this purpose, an investigation into the behaviour of beams made of higher concrete strengths has been carried out and conclusions drawn for the design of high strength concrete beams in flexure. Experimental data from previous research was considered for the study to establish some understanding of flexural behavior of HSC beams. A number of spreadsheets in Excel were developed using available data and various graphs were plotted to determine the accuracy of the code provisions for calculating the ultimate moment capacity of beams. A study on flexural ductility of beams has been carried out using a computer program FRMPHI which generates moment-curvature curves for the beams. Ductility has been studied using ductility factors. The influence of ductility on the value of the depth of neutral axis has been analysed and discussed. A chapter on the short-term deflection of simply supported high strength concrete beams under instantaneous deflections is presented. This chapter includes analysis of the available formula to calculate deflection to determine if these can be adopted for high strength concrete. Extensive ongoing research on the shear strength of beams by several researchers since many years has lead to the generation of a large body of knowledge. Although each author has analysed the data comparing them with existing relationships, the whole body of information has not been analysed to establish a statistical significance. In this study, regression analysis on experimental data collected from published research is carried a relationship between the different parameters affecting the shear strength of beams. The level of significance of the association between parameters influencing shear strength is also discussed.
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Taliotis, Anastasios S. "Evolving Geometries in General Relativity." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274838401.
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Murugesan, Reddiar Madhu Karthik. "Stress-Strain Model of Unconfined and Confined Concrete and Stress-block Parameters." Thesis, 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7545.
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Stress-strain relations for unconfined and confined concrete are proposed to overcome some shortcomings of existing commonly used models. Specifically, existing models are neither easy to invert nor integrate to obtain equivalent rectangular stress-block parameters for hand analysis and design purposes. The stress?strain relations proposed are validated for a whole range of concrete strengths and confining stresses. Then, closed form expressions are derived for the equivalent rectangular stress-block parameters. The efficacy of the results is demonstrated for hand analysis applied for deriving the moment-curvature performance of a confined concrete column. Results are compared with those obtained from a computational fiber-element using the proposed stress-strain model and another widely used model; good agreement between the two is observed. The model is then utilized in the development of a new structural system that utilizes the positive attributes of timber and concrete to form a parallel. Timber has the advantage of being a light weight construction material, easy to handle, is environmentally friendly. However, large creep deflections and significant issues with sound transmission (the footfall problem) generally limit timber use to small spans and low rise buildings. Concrete topping on timber sub-floors mitigate some of these issues, but even with well engineered wood systems, the spans are relatively short. In this study, a new structural system called structural boxed-concrete, which utilizes the positive attributes of both timber and reinforced concrete to form a parallel system (different from timber-concrete composite system) is explored. A stress-block approach is developed to calculate strength and deformation. An analytical stress-block based moment-curvature analysis is performed on the timber-boxed concrete structural elements. Results show that the structural timber-boxed concrete members may have better strength and ductility capacities when compared to an equivalent ordinary reinforced concrete member.
Books on the topic "Stress block parameters"
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Rigo, Fausto, Covadonga Fernández-Golfín, and Bruno Pinamonti. Dilated cardiomyopathy. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198726012.003.0043.
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Dilated cardiomyopathy (DCM) is characterized by a globally dilated and dysfunctioning left ventricle (LV). Therefore, echocardiographic diagnostic criteria for DCM are a LV end-diastolic diameter greater than 117% predicted value corrected for age and body surface area and a LV ejection fraction less than 45% (and/or fractional shortening less than 25%). Usually, the LV is also characterized by a normal or mildly increased wall thickness with eccentric hypertrophy and increased mass, a spherical geometry (the so-called LV remodelling), a dyssynchronous contraction (typically with left bundle branch block), and diastolic dysfunction with elevated LV filling pressure. Other typical echocardiographic features of DCM include functional mitral and tricuspid regurgitation, right ventricular dysfunction, atrial dilatation, and secondary pulmonary hypertension. Several echocardiographic parameters, measured both at baseline and at follow-up, are valuable for prognostic stratification of DCM patients. Furthermore, re-evaluation of echocardiographic parameters during the disease course under optimal medical therapy is valuable for tailoring medical treatment and confirming indications for invasive treatments at follow-up. The stress echo can play a pivotal role in the different phases of DCM helping us in stratifying the prognosis of these patients. Finally, familial screening is an important tool for early diagnosis of DCM in asymptomatic patients.
Book chapters on the topic "Stress block parameters"
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Rathish Kumar, Pancharathi, M. L. V. Prasad, and K. L. Radhika. "Stress Block Parameters of Confined Fibrous Recycled Self Compacting Concrete." In Emerging Trends of Advanced Composite Materials in Structural Applications, 179–200. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1688-4_8.
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Han, Chang Dae. "Continuum Theories for the Viscoelasticity of Flexible Homogeneous Polymeric Liquids." In Rheology and Processing of Polymeric Materials: Volume 1: Polymer Rheology. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195187823.003.0008.
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There are two primary reasons for seeking a precise mathematical description of the constitutive equations for viscoelastic fluids, which relate the state of stress to the state of deformation or deformation history. The first reason is that the constitutive equations are needed to predict the rheological behavior of viscoelastic fluids for a given flow field. The second reason is that constitutive equations are needed to solve the equations of motion (momentum balance equations), energy balance equations, and/or mass balance equations in order to describe the velocity, stress, temperature, and/or concentration profiles in a given flow field that is often encountered in polymer processing operations. There are two approaches to developing constitutive equations for viscoelastic fluids: one is a continuum (phenomenological) approach and the other is a molecular approach. Depending upon the chemical structure of a polymer (e.g., flexible homopolymer, rigid rodlike polymer, microphase-separated block copolymer, segmented multicomponent polymers, highly filled polymer, miscible polymer blend, immiscible polymer blend), one may take a different approach to the formulation of the constitutive equation. In this chapter we present some representative constitutive equations for flexible, homogeneous viscoelastic liquids that have been formulated on the basis of the phenomenological approach. In the next chapter we present the molecular approach to the formulation of constitutive equations for flexible, homogeneous viscoelastic fluids. In the formulation of the constitutive equations using a phenomenological approach, emphasis is placed on the relationship between the components of stress and the components of the rate of deformation (or strain) or deformation (or strain) history, such that the responses of a fluid to a specified flow field or stress can adequately be described. The parameters appearing in a constitutive equation are supposed to represent the characteristics of the fluid under consideration. More often than not, the parameters appearing in a phenomenological constitutive equation are determined by curve fitting to experimental results. Thus phenomenological constitutive equations shed little light on the effect of the molecular parameters of the fluid under investigation to the rheological responses of the fluid.
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Omrane, Amira, Taoufik Khalfallah, and Lamia Bouzgarrou. "Ergonomic Evaluation of Thermal Stress in a Tunisian Steel Industry." In Occupational Wellbeing. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98697.
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This work aims to assess thermal stress based on the various measurable thermal stress parameters (wet bulb temperature, air speed, radiation temperature, black globe temperature…). A cross-sectional study was carried in a steel company. The evaluation of thermal stress was made by physical parameters measurment (air temperature, relative humidity, air velocity, globe temperature, clothing insulation, metabolism of work) and analyzed according to the International Standard Organization (ISO) 7933 “Analytical determination and interpretation of heat stress using calculation of the predicted heat strain”. Eighty male workers were mean ageed of 37.9 ± 9.25 years. The climatic conditions category was three (meaning a Long-term stress) in 68.18% of the workers and four (Short-term stress meaning the occurrence of health problems within 30 to 120 minutes of exposure) in 30.3% of workers. The long and short-term thermal stress identified in this study spearhead a prevention strategy (automation of manufacturing processes, improvement of the organization of tasks, and the strengthening of medical surveillance of workers).
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Merckel, Y., M. Brieu, J. Diani, and D. Berghezan. "Effect of material and mechanical parameters on the stress-softening of carbon-black filled rubbers submitted to cyclic loadings." In Constitutive Models for Rubber VII, 253–58. CRC Press, 2011. http://dx.doi.org/10.1201/b11687-47.
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"Black Bass Diversity: Multidisciplinary Science for Conservation." In Black Bass Diversity: Multidisciplinary Science for Conservation, edited by Dennis R. DeVries and Russell A. Wright. American Fisheries Society, 2015. http://dx.doi.org/10.47886/9781934874400.ch25.
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<em>Abstract.</em>—Largemouth Bass <em>Micropterus salmoides</em> is typically thought of as a freshwater species, but populations occur in oligohaline portions of estuaries throughout the U.S. Atlantic and Gulf of Mexico coasts, often with popular fisheries. These coastal populations must deal with the physiological stresses associated with salinity variation and may be isolated from inland freshwater populations, increasing the potential for differentiation. To understand factors important to the ecology and management of these coastal populations, we quantified individual- and population-level parameters for Largemouth Bass across a natural salinity gradient in the Mobile-Tensaw River delta in southwestern Alabama during 2002–2009 (including population demographics, feeding ecology, movement, recruitment, and bioenergetics processes). Combining traditional mark–recapture and telemetry techniques with otolith microchemical analyses, we demonstrated that Largemouth Bass of all ages moved very little, even in response to increasing salinity (up to 15‰) in downstream areas. Large individuals were rare in our sampling across both fresh and brackish habitats (only 7 out of 9,530 individuals were >2.27 kg), and fish body condition increased downstream with increasing marine influence. Growth responses for fish across the estuary were more complex, varying with both fish age and salinity. Faster growth was observed in the brackish, downstream areas for fish ≤age 2, while growth of older fish was faster in freshwater upstream sites. Using bioenergetics modeling, we demonstrated that a complex combination of spatial variation in water temperature, prey energetic content, and metabolic cost of salinity was responsible for age-specific spatial variation in growth. Preliminary genetic analysis suggests that these coastal Largemouth Bass may differ genetically from inland fish. Coastal Largemouth Bass populations face a number of potential conservation concerns, and their management will require different approaches compared to their inland counterparts, including different goals and expectations, likely even requiring consideration as unique stocks.
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Leitner, Walter. "Fluorous Phases and Compressed Carbon Dioxide as Alternative Solvents for Chemical Synthesis: A Comparison." In Green Chemistry Using Liquid and Supercritical Carbon Dioxide. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195154832.003.0009.
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The principal goal of basic research in chemical synthesis is the development of efficient tools for functional group transformations and for the assembly of building blocks during the construction of molecules with increasing complexity. Traditionally, new approaches in this area have focused on the quest for new reaction pathways, reagents, or catalysts. Comparably less effort has been devoted to utilize the reaction medium as a strategic parameter, although the use of solvents is often crucial in synthetically useful transformations. The first choice for a solvent during the development of a synthetic procedure is usually an organic liquid, which is selected on the basis of its protic or aprotic nature, its polarity, and the temperature range in which the reaction is expected to proceed. Once the desired transformation is achieved, yield and selectivity are further optimized in the given medium by variation of temperature, concentration, and related process parameters. At the end of the reaction, the solvent must be removed quantitatively from the product using conventional workup techniques like aqueous extraction, distillation, or chromatography. If the synthetic procedure becomes part of a large-scale application, the solvent can sometimes be recycled, but at least parts of it will ultimately end up in the waste stream of the process. Increasing efforts to develop chemical processes with minimized ecological impact and to reduce the emission of potentially hazardous or toxic organic chemicals have stimulated a rapidly growing interest to provide alternatives to this classical approach of synthesis in solution. At the same time, researchers have started to realize that the design and utilization of multifunctional reaction media can add a new dimension to the development of synthetic chemistry. In particular, efficient protocols for phase separations and recovery of reagents and catalysts are urgently required to provide innovative flow schemes for environmentally benign processes or for high-throughput screening procedures. Fluorous liquid phases and supercritical carbon dioxide (sc CO2) have received particular attention among the various reaction media that are discussed as alternatives to classical organic solvents. The aim of this chapter is to compare these two media directly and to critically evaluate their potential for synthetic organic chemistry.
Conference papers on the topic "Stress block parameters"
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Bhende, Gaurav P., Pallavi B. Kulkarni, and Priyanka M. Kale. "Analyzing Effects of Soil Parameters on Buried Pipe Behavior and Deciding Governing Parameter Using Statistical Approach." In ASME 2015 India International Oil and Gas Pipeline Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/iogpc2015-7908.
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One of the most common and practical difficulties a pipeline engineer faces at the initial stage of the project is the lack of Soil survey data. Hence, various soil parameters like soil type, density, friction angle, cohesive pressure, depth of cover, pipe coating etc. are needed to be assumed. The critical designs like anchor block requirement, pipe route changes, support loads which involve a huge cost are required to be ‘Issued for Construction’ based on assumed data. This paper briefly illustrates and compares the results obtained from the two most common buried pipe stress analysis methods viz. ‘American Lifeline Alliance - Appendix B’ (1) and ‘Stress Analysis Methods for Underground Pipelines’ (2) and shows their effects graphically on the various Stress Analysis results like pipe movement, end force, active length (virtual anchor length) and bending stress generated in the buried pipeline. Further, this paper comes up with an unique application of ANOVA, a Statistical method, to find out the most significant soil parameter affecting the said results. The paper explains this method with a solved example. These results are useful for a pipeline engineer to determine the governing soil parameter in the design and thus provide a useful tool to make optimum assumptions in absence of soil data so as to minimize the changes in future design and helps saving the cost of the project due to rework.
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Ju, Jae-Woo, Sang-Moon Lee, and Kwang-Yong Kim. "Numerical Study on an Outlet Plenum of the PBMR." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-18008.
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Parametric study on an outlet plenum of a PBMR type gas cooled nuclear reactor has been carried out using three-dimensional Reynolds-Averaged Navier-Stokes equations. Shear stress transport turbulence model is used for analysis of turbulence. Two geometric parameters are selected, namely, displacement on the horizontal line and angle of rotation about the center of gravity of the roof support block. Pressure drop and uniformity of flow distribution in the outlet plenum have been considered as the performance parameters of an outlet plenum of the PBMR. The results show that the performance parameters are affected considerably by the location of the roof support block.
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Leggatt, N. A., R. J. Dennis, and P. R. Hurrell. "Residual Stress Analysis of Tube Attachment Weld in Pressure Vessel Forging: Baseline FE Analysis and Sensitivity Studies." In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71326.
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Full two and three-dimensional single or multi-pass weld simulations are now feasible and practical given the development of improved analysis tools (e.g. ABAQUS), and significantly greater computer power. This paper describes a finite element analysis undertaken to predict the as-welded residual stress field following the welding of a tube attachment weld inside a thick pressure vessel (PV) forging. The coupled thermal-mechanical analysis was performed using the finite element (FE) code ABAQUS, A heat source modelling tool was employed to calculate welding fluxes, which were read into ABAQUS via a user subroutine. The ‘block’ dumped approach was utilised in the 2D thermal analysis such that complete weld rings are deposited instantaneously. Heat inputs were based on the actual weld parameters and bead sizes. The predicted fusion depths matched well with those found in sectioned weld test pieces. 2D FE sensitivity studies were performed examining the effect of variations in a number of parameters (bead sequence, hardening law, inter-pass temperature and annealing temperature). The hardening law was changed from isotropic to kinematic to investigate the effect of material behaviour. Large weld residual tensile stresses were calculated with significant compressive stresses in the adjacent vessel wall. Stress results were generally insensitive in the tube and forging, indicating that the vessel constraint dominates over local welding conditions. Weld hoop stresses were overestimated partly due to the ‘tourniquet’ effect of depositing rings of weld metal and the isotropic hardening law assumed.
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Wang, B., and L. X. Kong. "Development of Bone Graft Using Wire Mesh Solids." In ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58157.
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Bone graft is often used to restore instability of lumber spines following a surgical removal due to tumour growth or other diseases. The application of a newly developed, low cost wire mesh is examined as a potential candidate for graft. Mechanical properties of the mesh block were tested and finite element analyses were conducted to calculate stress distribution in the vertebra, with a number of parameters examined, including cross-sectional size, position, and stiffness of a graft. It is found that the intra-vertebra stress is most influenced by the graft position, followed by the cross-sectional size of the graft, while the stiffness of the graft material has the least effect.
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Nucera, Claudio, and Francesco Lanza di Scalea. "Nonlinearity in Ultrasonic Guided Waves Propagation in Solids Under Constrained Thermal Expansion." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63755.
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Finite strain theory has been employed in the past to mathematically describe nonlinear wave propagation phenomena such as acoustoelasticity (wave speed dependency on quasi-static stress), wave interaction, wave distortion, and higher-harmonic generation. The present work expands the topic of nonlinear wave propagation to the case of a constrained solid subjected to thermal loads. In this framework, the anharmonicity of interatomic potentials, and the absorption of the potential energy corresponding to the (prevented) thermal expansion, are identified as sources of nonlinear effects. Such “residual” energy is, at least, cubic as a function of strain, hence leading to a nonlinear wave equation and higher-harmonic generation. Closed-form solutions are given for the longitudinal wave speed and the second-harmonic nonlinear parameter as a function of interatomic potential parameters and temperature increase. According to the proposed model, the prevented thermal expansion of the solid leads to thermal stresses that, in turn, produce a decrease in longitudinal wave speed and a corresponding increase in nonlinear parameter with increasing temperature. Experimental measurements of the ultrasonic nonlinear parameter on a steel block under constrained thermal expansion confirm this trend. Emphasis is placed on the potential of a nonlinear ultrasonic measurement to quantify thermal stresses from prevented thermal expansion. This knowledge can be extremely useful to prevent thermal buckling of various structures, such as continuous-welded rails in hot weather.
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Teimoori, Khashayar, Ferri Hassani, Agus Pulung Sasmito, and Ali Ghoreishi Madiseh. "Numerical Investigations of the Single-Mode Microwave Treatment Effects on Rock Breakage." In Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9646.
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In this study, a rock model which consists of a conceptual block (host rock and ore sample) is numerically modeled by using the finite element method. The rock model is subjected to several single-mode microwave treatments with different power levels, distances from the antenna, and exposure times in order to calculate and compare the corresponding effects including temperature distribution and mechanical stress/damage profiles. The main objective of the present study is to analyze the distribution of temperature and mechanical stress at the boundary of two different attached rocks when exposed to microwaves. This enables comparing the intensity of the distribution with respect to the applied microwave input operating parameters and, consequently, understanding rock preconditioning. The results of the present study verify that an increase in temperature by microwave treatment facilitates the rock weakening process. Also, a more efficient selection of the distance from the antenna and the power level can maximize the overall impact of the microwave treatment on rock preconditioning which ultimately helps with the rock breakage mechanism.
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Persent, Emmanuel, Daniel Averbuch, and Jean Guesnon. "An Improved Methodology for the Design of Marine Drilling Riser Couplings." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20965.
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The current trend in offshore drilling is a significant increase in water depth in the specification of drilling risers, associated with high density muds. This situation presents a real challenge for the design of the drilling riser which depends to a large extent on these parameters, as well as other related to operational and environmental conditions. In particular, improved design methodologies are required to better assess the margins of riser couplings regarding their static performance and fatigue life. As recommended by API Spec 16R, the stress linearization and classification in one of the key steps to design a riser connector. The designers are encountering some difficulties in the application of this methodology to 3D finite element results. IFP has then proposed a simple approach that applies to non-axisymmetric geometries of connectors. It consists in calculating the membrane and bending stresses in a given plane by averaging over a suitable portion of a cross-section the results of the linearization in the stress classification lines (SCLs) located in the selected plane. A short presentation of a breech-block type riser connector, on which the methodology has been applied, is given at the beginning of this paper. The API specification 16R requirements regarding the design criteria are then discussed. A simple approach to extend the stress linearization and classification methods to three-dimensional FEA is proposed. The proposed methodology is applied to the design of the Clip connector. At last, the R&D work aiming at improving the fatigue analysis of riser connectors is introduced at the end of the paper.
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James, Sagil, and Shripal Bhavsar. "Finite Element Analysis and Simulation of Ultrasonic Powder Consolidation Process." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6356.
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Ultrasonic welding is a solid-state joining process which uses ultrasonic vibration to join materials at relatively low temperatures. Ultrasonic powder consolidation is a derivative of the ultrasonic additive process which consolidates powder material into a dense solid block without melting. During ultrasonic powder consolidation process, metal powder under a compressive load is subjected to transverse ultrasonic vibrations resulting in a fully-dense consolidated product. While ultrasonic powder consolidation is employed in a wide variety of applications, the effect of critical process parameters on the bonding process of powder particles during consolidation is not clearly understood. This study uses a coupled thermo-mechanical finite element analysis technique to investigate the effect of critical process parameters including vibrational amplitude and base temperature on the stress, strain, and particle temperature distribution during the ultrasonic powder consolidation process. The study finds that during this process, the ultrasonically vibrating tool imparts cyclic vibratory shear stress on the particles. The simulation also revealed that the particle temperature just reaches the recrystallization point. Higher vibration amplitude imparted higher frictional heat on the particles, thereby aiding the consolidation process. The simulation study also showed indications of thermal softening and restricted grain boundary sliding during the ultrasonic powder consolidation process. The outcomes of this study can be used to further the industrial applications of ultrasonic powder consolidation process as well as other ultrasonic welding based processes.
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Khanoki, Sajad Arabnejad, and Damiano Pasini. "Multiscale Design and Multiobjective Optimization of Orthopaedic Cellular Hip Implants." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-47487.
Full textAbstract:
A multiscale design and multiobjective optimization procedure is developed to design a new type of graded cellular hip implant. We assume that the prosthesis design domain is occupied by a unit cell representing the building block of the implant. An optimization strategy seeks the best geometric parameters of the unit cell to minimize bone resorption and interface failure, two conflicting objective functions. Using the asymptotic homogenization method, the microstructure of the implant is replaced by a homogeneous medium with an effective constitutive tensor. This tensor is used to construct the stiffness matrix for the finite element modeling (FEM) solver that calculates the value of each objective function at each iteration. As an example, a 2D finite element model of a left implanted femur is developed. The relative density of the lattice material is the variable of the multiobjective optimization, which is solved through the non-dominated sorting genetic algorithm II (NSGA-II). The set of optimum relative density distributions is determined to minimize concurrently interface stress distribution and bone loss mass. The results show that the amount of bone resorption and the maximum value of interface stress can be reduced by over 70% and 50%, respectively, when compared to current fully dense titanium stem.
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Xiong, Fu-Rui, and Bin Lan. "Cooperative Design and Optimization of Reactor Coolant System Piping Supports Under Static and Dynamical Load Conditions." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84026.
Full textAbstract:
The main pipes of reactor coolant systems (RCS) are usually long flexible structures that are connected to multiple key equipment and components of the nuclear system (e.g., reactor pressure vessel, steam generator, main pump, etc.). Mechanical analysis of pipe responses at key elbows and weld seams under static and dynamical load conditions is an essential step to ensure safety and reliability of the whole RCS. Common practice to keep the structural integrity of RCS piping under dynamical load (seismic or shock load) is to impose supporting devices at various locations so that the stiffness at weak spots can be improved. Nevertheless, the introduction of supporting devices, especially the mechanical stops, may cause significant increase of thermal stress due to the block of thermal expansion path of the piping. Hence, cooperative design and optimization of RCS piping supports by jointly considering the piping responses under static and dynamical load cases becomes quite a necessity. In this paper, such an optimal design task is formulated as a multi-objective optimization problem (MOP) with the stress level at key elbows and weld seams of the main pipes as objectives; and various parameters of each supporting device as design variables. The key feature of such MOP is that the number of design variables is unknown in prior. A single support sampling strategy is first proposed to observe the influence of one supporting device. Clustering algorithms are then applied to discover patterns from the single support sampling pool. A 3-snubber-3-stop main pipe support layout is determined via unsupervised clustering algorithms. We perform the surrogatemodel based parameter optimization once the optimization framework is fixed. Simulation results of the optimal piping support design show good satisfactions of stress level according to ASME boiler and pressure vessel code (BPVC) under both static and dynamical load cases. The data-driven design and optimization procedures presented in this paper suit the optimal design with conflicting objectives and unclear number of design variables.