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Artículos de revistas sobre el tema "Residual stress field":
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Hashikura, Yasuaki, Masahiro Otaka, Kazuo Ogawa y Kotoji Ando. "Crack Growth Behavior and Redistribution of Residual Stress Caused by Crack Propagation from Residual Tensile Stress Field through Residual Compressive Stress Field". Proceedings of the 1992 Annual Meeting of JSME/MMD 2004 (2004): 99–100. http://dx.doi.org/10.1299/jsmezairiki.2004.0_99.
Lai, Man On y Zhimin He. "Residual stress field of ballised holes". Journal of Mechanical Science and Technology 26, n.º 5 (mayo de 2012): 1555–65. http://dx.doi.org/10.1007/s12206-012-0326-6.
Kim, Ho Kyeom, Martyn J. Pavier y Anton Shterenlikht. "Plasticity and Stress Heterogeneity Influence on Mechanical Stress Relaxation Residual Stress Measurements". Advanced Materials Research 996 (agosto de 2014): 249–55. http://dx.doi.org/10.4028/www.scientific.net/amr.996.249.
Two common problems of mechanical strain relaxation(MSR) residual stress measurement methods are investigated in this work:(1) assumption of stress uniformity and (2) the effect of plasticity at relaxation. A new MSR technique, designed specifically for highly non-uniformin-plane residual stress fields, is applied in this work to measure the residual stress field resulted from pure bending of an Al7075 alloy.The method involves introducing a straight cut across the whole part in a single increment, and collecting full field displacement fields from the side surface. Application of a 2D high resolution digital image correlation (DIC) method proved successful in this work.The reconstructed residual stress agrees well with that predicted by FE modelling. It is shown that the direction of the propagation of the slit has a major influence on plastic flow during relaxation.The major conclusion from this work is that it is possible to substantially reduce, or completely eliminate, plastic flow on relaxation by careful planning of the slit orientation and the cutting schedule.
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Kim, Dong Won y Dongil Kwon. "Mapping of Residual Stress Field Based on Residual-Stress-Free State by ESPI Analysis". International Journal of Modern Physics B 17, n.º 08n09 (10 de abril de 2003): 1534–39. http://dx.doi.org/10.1142/s0217979203019289.
We study the residual stress mapping of indented Cu by ESPI (electronic speckle pattern interferometry). Based on the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI), we modeled the relaxed stress in annealing, the thermal strdin/stress and the residual stress field in case of both single and film/substrate systems by using the thermo-elastic theory and the relationship between relaxed stresses and displacements. Thus we mapped the surface residual stress fields on the indented bulk Cu and the 0.5⊔ Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -800 MPa to 700 MPa and -600 MPa to 600 MPa respectively around the indented point.
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Roskosz, Maciej, Andrzej Rusin y Michał Bieniek. "Analysis of relationships between residual magnetic field and residual stress". Meccanica 48, n.º 1 (30 de agosto de 2012): 45–55. http://dx.doi.org/10.1007/s11012-012-9582-x.
Wang, Liang, Ya Zhi Li y Hong Su. "On the Stress Intensity Factor of Cracks in Residual Stress Field". Key Engineering Materials 353-358 (septiembre de 2007): 1078–81. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.1078.
The use of weight function technique in fatigue crack growth subjected to external cyclic loading and residual stress field has been questioned by several researchers in that the technique is unable to account for the residual stress redistribution during the crack growth. In this paper a center cracked tension specimen containing residual stresses was analyzed by finite element method. The crack growth was simulated by releasing the nodes ahead of crack tip in stepwise and the stress intensity factors induced by residual stresses at different crack lengths were estimated. The results from the numerical analysis are identical to the weight function solution, which demonstrates that the weight function technique can be used for the fatigue crack growth analysis in residual stress field, unless the residual stress distribution is disturbed by the plastic yield.
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Wilson, John W., Gui Yun Tian y Simon Barrans. "Residual magnetic field sensing for stress measurement". Sensors and Actuators A: Physical 135, n.º 2 (abril de 2007): 381–87. http://dx.doi.org/10.1016/j.sna.2006.08.010.
Mukai, Yoshihiko, Arata Nishimura y Eung-Joon Kim. "Redistribution of residual stress caused by crack propagation initially through residual tensile stress field." QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 4, n.º 1 (1986): 154–59. http://dx.doi.org/10.2207/qjjws.4.154.
Mukai, Yoshihiko, Arata Nishimura y Eung-Joon Kim. "Redistribution of residual stress caused by crack propagation initially through residual compressive stress field." QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 4, n.º 3 (1986): 634–39. http://dx.doi.org/10.2207/qjjws.4.634.
Kikuchi, Masanori, Yoshitaka Wada, Yuto Shimizu y Yu Long Li. "Stress Corrosion Cracking Analysis under Thermal Residual Stress Field Using S-FEM". Key Engineering Materials 462-463 (enero de 2011): 431–36. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.431.
Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. In order to confirm the validity of this analysis, numerical results are compared with previously-reported analytical and experimental results. Then, crack growth analysis in piping structure with welding joint was conducted. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. Using S-FEM, two- and three-dimensional analyses are conducted, and crack growth behavior under thermal stress field is studied and discussed.
Nam, Taeksun. "Finite Analysis of Residual Stress Field Induced by Laser Shock Peening". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1216991714.
Kese, Kwadwo O. "Relaxation and nanomechanical studies of the Vickers residual stress field in glass /". Doctoral thesis, Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48.
Haggett, Michelle E. "Systematic review of UIT parameters on residual stresses of sensitized AA5456 and field based residual stress measurements for predicting and mitigating stress corrosion cracking". Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/41385.
Approved for public release; distribution is unlimited. This thesis focuses on the use of x-ray diffraction to measure residual stresses around welds in aluminum ship structures both in the laboratory and in the field. Tensile residual stresses are often generated during welding and, in sensitized aluminum structures, can cause extensive stress corrosion cracking. Peening techniques, such as ultrasonic impact treatment (UIT), can mitigate and even reverse these tensile residual stresses. This research uses x-ray diffraction to measure residual stresses around welds in AA5456 before and after UIT. In particular, we examined the importance of UIT parameters such as peening amplitude and pin size. We found that all combinations of UIT parameters removed the tensile residual stresses and resulted in compressive stress several hundred microns below the weld surface. The exact level of compressive residual stress was sensitive to the pin size used with a smaller, but measurable, dependence upon the displacement amplitude. In an effort to extend these measurement techniques to the field, we successfully performed the first x-ray residual stress measurements on a U.S. naval combatant.
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Sen, Debamoy. "Coupled Field Modeling of Gas Tungsten Arc Welding". Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/38820.
Welding is used extensively in aerospace, automotive, chemical, manufacturing, electronic and power-generation industries. Thermally-induced residual stresses due to welding can significantly impair the performance and reliability of welded structures. Numerical simulation of weld pool dynamics is important as experimental measurements of velocities and temperature profiles are difficult due to the small size of the weld pool and the presence of the arc. From a structural integrity perspective of welded structures, it is necessary to have an accurate spatial and temporal thermal distribution in the welded structure before stress analysis is performed. Existing research on weld pool dynamics simulation has ignored the effect of fluid flow in the weld pool on the temperature field of the welded joint. Previous research has established that the weld pool depth/width (D/W) ratio and Heat Affected Zone (HAZ) are significantly altered by the weld pool dynamics. Hence, for a more accurate estimation of the thermally-induced stresses it is desired to incorporate the weld pool dynamics into the analysis. Moreover, the effects of microstructure evolution in the HAZ on the mechanical behavior of the structure need to be included in the analysis for better mechanical response prediction. In this study, a three-dimensional model for the thermo-mechanical analysis of Gas Tungsten Arc (GTA) welding of thin stainless steel butt-joint plates has been developed. The model incorporates the effects of thermal energy redistribution through weld pool dynamics into the structural behavior calculations. Through material modeling the effects of microstructure change/phase transformation are indirectly included in the model. The developed weld pool dynamics model includes the effects of current, arc length, and electrode angle on the heat flux and current density distributions. All the major weld pool driving forces are included, namely surface tension gradient, plasma drag force, electromagnetic force, and buoyancy. The weld D/W predictions are validated with experimental results. They agree well. The effects of welding parameters (like welding speed, current, arc length, etc.) on the weld D/W ratio are documented. The workpiece deformation and stress distributions are also highlighted. The transverse and longitudinal residual stress distribution plots across the weld bead and their variations with welding speed and current are also provided. The mathematical framework developed here serves as a robust tool for better prediction of weld D/W ratio and thermally-induced stress evolution and distribution in a welded structure by coupling the different fields in a welding process. Ph. D.
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Song, Shaopin. "Analysis and Characterization of Residual Stresses in Pipe and Vessel Welds". ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1556.
This research sought to establish residual stress distribution characteristics in typical pipe and vessel welds by carrying out a comprehensive parametric study using an advanced sequentially coupled thermo-mechanical finite element procedure. The parametric study covered vessel and pipe components with a ranging radius to thickness ratio from r/t=2 to 100, for thickness ranging from t=1/4” to 10”. Component materials varied from low carbon steel to high alloy steels, such as stainless steel and titanium alloy. Furthermore, a structural mechanics based framework is proposed to generalize through-thickness residual stress distributions for a broad spectrum of joint geometry and welding conditions. The results of this study have been shown to provide both a significantly improved understanding of important parameters governing residual stresses in pipe and vessel welds, as well as a unified scheme for achieving consistent residual stress prescriptions for supporting fitness-for-service assessments of engineering structures. Specific contributions of this investigation may be summarized as follows:
(a) A welding heating input characterization procedure has been developed and validated to relate prescribed temperature thermal modeling procedure to conventional linear input definition. With this development, a large number of parametric analyses can be carried in a cost-effective manner without relying on the heat flux based weld pool model that can be exhaustive and time-consuming.
(b) A set of governing parameters controlling important residual stress distribution characteristics regardless of joint types, materials, and welding procedures have been identified. These are characteristic heat input intensity and radius over thickness ratio.
(c) A shell theory based residual stress estimation scheme has been developed to interrelate all parametric analysis results for circumferential girth welds, which can also be used to estimate residual stress distributions in both through-thickness and at any distance away from the weld, for cases that are not covered in the parametric study.
(d) In a similar manner, a curve bar theory based residual stress estimation scheme has also been developed for longitudinal seam welds.
These developments can significantly advance the residual stress profile prescription methods stipulated in the current national and international FFS Codes and Standards such as 2007 API 579 RP/ASME FFS-1 and BS 7910: 2011.
Fitzpatrick, Michael Edward. "A study of the effects of a quench residual stress field on fatigue in an Al/SiCâ†P metal matrix composite". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362987.
The correlatioin between residual stresses and the global properties from an indentation test, i.e. hardness and size of the contact area, has been studied frequently in recent years. The investigations presented have been based on experimental, theoretical and numerical methods and as a result, the basic features of the problem are fairly well understood in the case of residual equi-biaxial surface stresses. The more general case, when the principal surface stresses are not necessarily equi-biaxial, has received nuch less attention and it is therefore the aim of the present study to remedy this shortcoming. In doing so, qualitative results are of immediate interest in this initial study but possible ways of quantitative descriptions are also discussed for future purposes. The present analysis is based on numerical methods and in particular the finite element method (FEM) is relied upon. Classical Mises elastoplastic material behavior is assumed throughout the investigation.
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Djapic, Lilijana. "Determination of residual stress fields caused by shot peening". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338587.
Capítulos de libros sobre el tema "Residual stress field":
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Boag, J. M. y M. Brauss. "X-Ray Diffractometer Stress Measurements for Power Plant Field Applications". En International Conference on Residual Stresses, 381–86. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1143-7_64.
Lin, L., Y. Tao y N. S. Hu. "A Reformed Model For Fatigue Crack Growth Within Residual Stress Field". En International Conference on Residual Stresses, 815–19. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1143-7_136.
Namkung, M., D. Utrata, J. S. Heyman y S. G. Allison. "Low-Field Magnetoacoustic Residual Stress Measurement in Steel". En Solid mechanics research for quantitative non-destructive evaluation, 301–18. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3523-5_18.
Schajer, Gary S. "Judgement of Residual Stress Field Uniformity When Using the Hole-Drilling Method". En International Conference on Residual Stresses, 71–77. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1143-7_9.
Wang, Liang, Ya Zhi Li y Hong Su. "On the Stress Intensity Factor of Cracks in Residual Stress Field". En Key Engineering Materials, 1078–81. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.1078.
Wagner, L., G. Lütjering y V. Sedláček. "Fatigue Crack Growth Retardation in an Al Alloy 2024 in a Residual Compressive Stress Field". En International Conference on Residual Stresses, 803–8. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1143-7_134.
Seghir, R., F. Pierron y L. Fletcher. "Image-Based Stress Field Reconstruction in Complex Media". En Residual Stress, Thermomechanics & Infrared Imaging, Hybrid Techniques and Inverse Problems, Volume 7, 101–4. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95074-7_19.
Pantelakis, Sp y P. Papanikos. "Fatigue crack growth in the presence of residual stress field". En Problems of Fracture Mechanics and Fatigue, 461–64. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-2774-7_99.
Yousefi, Mohammad, Xavier Balandraud y Wael A. Samad. "Thermographic Stress Field Investigation of a Multiply-Loaded Disk". En Residual Stress, Thermomechanics & Infrared Imaging, Hybrid Techniques and Inverse Problems, Volume 7, 115–17. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95074-7_22.
Dattoma, V., M. De Giorgi y R. Nobile. "On the Residual Stress Field in the Aluminum Alloy Fsw Joints". En Experimental Analysis of Nano and Engineering Materials and Structures, 943–44. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6239-1_469.
Actas de conferencias sobre el tema "Residual stress field":
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"Residual Stress Field Prediction in Shot Peened Mechanical Parts with Complex Geometries". En Residual Stresses 10. Materials Research Forum LLC, 2016. http://dx.doi.org/10.21741/9781945291173-9.
"Elastic and Elastic-Plastic Behaviour of a Crack in a Residual Stress Field". En Residual Stresses 10. Materials Research Forum LLC, 2016. http://dx.doi.org/10.21741/9781945291173-34.
"Influence of Surface Pretreatment on Residual Stress Field of Heat-Treated Steel Induced by Laser Local Quenching". En Residual Stresses 2018. Materials Research Forum LLC, 2018. http://dx.doi.org/10.21741/9781945291890-28.
"Effect of Thermal and Mechanical Loadings on the Residual Stress Field in a Nickel Based Superalloy using X-Ray Laue Microdiffraction". En Residual Stresses 10. Materials Research Forum LLC, 2016. http://dx.doi.org/10.21741/9781945291173-89.
Price, A. J., P. Tsakiropoulos, M. R. Wenman y P. R. Chard-Tuckey. "Modelling Fatigue Crack Growth in a Residual Stress Field". En ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93174.
Tensile residual stresses can have a detrimental affect on the safe operating limits of components. In most cases, these residual stress fields can be relieved through various treatments but in many cases it is not realistic to expect the complete elimination of these stresses. When considering the Reactor Pressure Vessel (RPV) located within a Nuclear Reactor Plant (NRP), knowledge of fatigue and fracture within a residual stress field is essential in support of safety cases. This research has investigated the behaviour of flaws that lie within a residual stress field with emphasis on fracture toughness through a series of fracture toughness tests. Alongside this experimental series, a finite element model has been created to predict the stress distributions prior to fracture. To enable an accurate simulation of the residual stress field distribution before loading to fracture it is important that the introduction of a fatigue crack is accurately modelled. This paper details several methods of introducing a fatigue crack into a simulation. During this research it has been shown that the introduction of a crack in progressive stages will lead to a better representation of the residual stress distribution prior to fracture. It has been shown that it is essential to use experimentally determined crack front shapes for the final stage of crack growth as this shape can significantly alter the residual stress distribution.
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Bao, Sheng, Ashri Mustapha y Huangjie Lou. "Correlation Between Stress Concentration Degree and Residual Magnetic Field". En ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54715.
In this research, the correlation between the stress concentration degree and the residual magnetic field (RMF) of ferromagnetic steels is investigated. Tensile tests were carried out to measure the RMF signals on the surface of steel specimens with different stress concentration degrees. The effectivity of the metal magnetic memory (MMM) technique in defective specimens was investigated in comparison with a non-defective specimen. Analysis of the qualitative relationship between the stress concentration degree and the RMF components was subsequently performed on two types of defective specimens. The qualitative correlation between the planar distributions of the RMF components and the stress concentration degree was further studied. It was validated that both the RMF signal and its planar distribution are effective in characterizing the stress concentration degree. The results obtained in this research will be a complement to the MMM technique.
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Ni, Xin-Hua, Zhi-Hong y Shi Yan. "THE RESIDUAL STRESS FIELD OF MMCp WITH DEBONDING INTERPHASE". En 2015 International Conference on Energy and Mechanical Engineering. WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789814749503_0094.
Sherry, A. H., M. R. Goldthorpe, J. Fonseca y K. Taylor. "Residual Stress Effects on Ductile Tearing". En ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93677.
Residual stresses are internal stresses generated during the fabrication and/or operation of engineering structures. Such stresses can provide the major element of the driving force for crack initiation and growth. Structural integrity assessment procedures, provide guidance for the assessment of defects located within regions of high residual stress. However, such guidance may be conservative where the defect develops progressively during service. This paper describes recent experimental and numerical work aimed at quantifying such conservatisms and providing improved guidance for undertaking more realistic analyses. The results demonstrate that pre-loaded compact-tension specimens provide a useful means for studying the behaviour of cracks within residual stress fields. The magnitude of calculated crack driving forces due to residual stresses is influenced by the approach used to introduce cracks into the stress field, with progressive cracks providing lower levels of crack driving force than instantaneously introduced cracks. The J R-curve associated with cracks under primary or combined primary + secondary loading can apparently be rationalized when the total crack driving force is calculated using methods that take proper account of the influence of prior plasticity on the J-integral. However, it is noted that due to differences in the form of the crack-tip stress and strain fields for static and growing cracks, such values of J may be path dependent and influenced by the magnitude of the growth increment.
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Bao, Sheng, Li Lin, Da Zhang y Meili Fu. "Characterization of Stress-Induced Residual Magnetic Field in Ferromagnetic Steels". En ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41560.
In this research, tensile tests of three different steels were carried out to characterize the variation of the residual magnetic signals. To reduce the impact of initial magnetic field, all of the specimens were demagnetized before loaded. It was observed that the variations of magnetic signals along the surface of these steels demonstrate different characteristics both in the elastic and plastic stages. In the elastic stage, the magnetic field variation of Q235 and 45# steels had a nonlinear relationship with the applied stress and a simple linear relationship between stress and magnetic field appeared in Q345 steel. In the plastic stage, the magnetic field variation of Q235 was very complex and the magnetic field variations of Q345 and 45# steels demonstrated a process of systematic evolution. In addition, there existed a local dent of the magnetic curve in the necking position of the sample. When the sample was finally ruptured, one may evaluate the fracture position according to the features of the magnetic curve. Possible reasons were given for the different characteristics of magnetic field variations in different steels.
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Ng, Chi Seng, Yoke Chin Goh y Anand K. Asundi. "Whole field residual stress measurement using computer aided reflection grating". En Ninth International Symposium on Laser Metrology, editado por Chenggen Quan y Anand Asundi. SPIE, 2008. http://dx.doi.org/10.1117/12.814586.
Sparks, R. G., W. S. Enloe y M. A. Paesler. Mapping residual stress fields from Vickers hardness indents using Raman microprobe spectroscopy. Office of Scientific and Technical Information (OSTI), diciembre de 1988. http://dx.doi.org/10.2172/476629.
Litaor, Iggy, James Ippolito, Iris Zohar y Michael Massey. Phosphorus capture recycling and utilization for sustainable agriculture using Al/organic composite water treatment residuals. United States Department of Agriculture, enero de 2015. http://dx.doi.org/10.32747/2015.7600037.bard.
Objectives: 1) develop a thorough understanding of the sorption mechanisms of Pi and Po onto the Al/O- WTR; 2) determine the breakthrough range of the composite Al/O-WTR during P capturing from agro- wastewaters; and 3) critically evaluate the performance of the composite Al/O-WTR as a fertilizer using selected plants grown in lysimeters and test-field studies. Instead of lysimeters we used pots (Israel) and one- liter cone-tainers (USA). We conducted one field study but in spite of major pretreatments the soils still exhibited high enough P from previous experiments so no differences between control and P additions were noticeable. Due to time constrains the field study was discontinued. Background: Phosphorous, a non-renewable resource, has been applied extensively in fields to increase crop yield, yet consequently has increased the potential of waterway eutrophication. Our proposal impetus is the need to develop an innovative method of P capturing, recycling and reuse that will sustain agricultural productivity while concurrently reducing the level of P discharge from and to agricultural settings. Major Conclusions & Achievements: An innovative approach was developed for P removal from soil leachate, dairy wastewater (Israel), and swine effluents (USA) using Al-based water treatment residuals (Al- WTR) to create an organic-Al-WTR composite (Al/O-WTR), potentially capable of serving as a P fertilizer source. The Al-WTR removed 95% inorganic-P, 80% to 99.9% organic P, and over 60% dissolved organic carbon from the agro-industrial waste streams. Organic C accumulation on particles surfaces possibly enhanced weak P bonding and facilitated P desorption. Analysis by scanning electron microscope (SEM- EDS), indicated that P was sparsely sorbed on both calcic and Al (hydr)oxide surfaces. Sorption of P onto WW-Al/O-WTR was reversible due to weak Ca-P and Al-P bonds induced by the slight alkaline nature and in the presence of organic moieties. Synchrotron-based microfocused X-ray fluorescence (micro-XRF) spectrometry, bulk P K-edge X-ray absorption near edge structure spectroscopy (XANES), and P K-edge micro-XANES spectroscopy indicated that adsorption was the primary P retention mechanism in the Al- WTR materials. However, distinct apatite- or octocalciumphosphatelike P grains were also observed. Synchrotron micro-XRF mapping further suggested that exposure of the aggregate exteriors to wastewater caused P to diffuse into the porous Al-WTR aggregates. Organic P species were not explicitly identified via P K-edge XANES despite high organic matter content, suggesting that organic P may have been predominantly associated with mineral surfaces. In screen houses experiments (Israel) we showed that the highest additions of Al/O-WTR (5 and 7 g kg⁻¹) produced the highest lettuce (Lactuca sativa L. var. longifolial) yield. Lettuce yield and P concentration were similar across treatments, indicating that Al/O- WTR can provide sufficient P to perform similarly to common fertilizers. A greenhouse study (USA) was utilized to compare increasing rates of swine wastewater derived Al/O-WTR and inorganic P fertilizer (both applied at 33.6, 67.3, and 134.5 kg P₂O₅ ha⁻¹) to supply plant-available P to spring wheat (TriticumaestivumL.) in either sandy loam or sandy clay loam soil. Spring wheat straw and grain P uptake were comparable across all treatments in the sandy loam, while Al/O-WTR application to the sandy clay loam reduced straw and grain P uptake. The Al/O-WTR did not affect soil organic P concentrations, but did increase phosphatase activity in both soils; this suggests that Al/O-WTR application stimulated microorganisms and enhance the extent to which microbial communities can mineralize Al/O-WTR-bound organic P. Implications: Overall, results suggest that creating a new P fertilizer from Al-WTR and agro-industrial waste sources may be a feasible alternative to mining inorganic P fertilizer sources, while protecting the environment from unnecessary waste disposal.
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Pullammanappallil, Pratap, Haim Kalman y Jennifer Curtis. Investigation of particulate flow behavior in a continuous, high solids, leach-bed biogasification system. United States Department of Agriculture, enero de 2015. http://dx.doi.org/10.32747/2015.7600038.bard.
Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.
