Literatura científica selecionada sobre o tema "Cyclical bend"
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Artigos de revistas sobre o assunto "Cyclical bend"
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Izawa, Yasuhide, e Chikako Shingyoji. "Mechanical induction of oscillatory movement in demembranated, immotile flagella of sea urchin sperm at very low ATP concentrations". Journal of Experimental Biology 223, n.º 20 (13 de agosto de 2020): jeb225797. http://dx.doi.org/10.1242/jeb.225797.
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ABSTRACTOscillation is a characteristic feature of eukaryotic flagellar movement. The mechanism involves the control of dynein-driven microtubule sliding under self-regulatory mechanical feedback within the axoneme. To define the essential factors determining the induction of oscillation, we developed a novel experiment by applying mechanical deformation of demembranated, immotile sea urchin sperm flagella at very low ATP concentrations, below the threshold of ATP required for spontaneous beating. Upon application of mechanical deformation at above 1.5 µmol l−1 ATP, a pair of bends could be induced and was accompanied by bend growth and propagation, followed by switching the bending direction. For an oscillatory, cyclical bending response to occur, the velocity of bend propagation towards the flagellar tip must be kept above certain levels. Continuous formation of new bends at the flagellar base was coupled with synchronized decay of the preceding paired bends. Induction of cyclical bends was initiated in a constant direction relative to the axis of the flagellar 9+2 structure, and resulted in the so-called principal bend. In addition, stoppage of the bending response occasionally occurred during development of a new principal bend, and in this situation, formation of a new reverse bend did not occur. This observation indicates that the reverse bend is always active, opposing the principal bend. The results show that mechanical strain of bending is a central component regulating the bend oscillation, and switching of the bend direction appears to be controlled, in part, by the velocity of wave propagation.
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Shingyoji, C., e K. Takahashi. "Cyclical bending movements induced locally by successive iontophoretic application of ATP to an elastase-treated flagellar axoneme". Journal of Cell Science 108, n.º 4 (1 de abril de 1995): 1359–69. http://dx.doi.org/10.1242/jcs.108.4.1359.
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To elucidate the mechanism of oscillatory bending in cilia and flagella, we studied the effect of protease digestion on the response of axonemes to localized application of ATP. When the axonemes were treated with elastase and then reactivated locally by ATP iontophoresis, a pair of local bends were formed due to localized unidirectional sliding in the vicinity of the ATP pipette. Upon repeated application of ATP, the direction of bending with respect to the sperm head axis changed cyclically from side to side over several cycles. The bends were planar and similar to those observed in axonemes that had not been treated with elastase. In trypsin-treated axonemes, in contrast, repetitive local reactivation did not induce such cyclical bending; instead, it induced a bend that grew only in one direction upon repeated application of ATP. Moreover, the bends were not planar. Electron microscopy of these protease-digested axonemes showed that both the interdoublet (nexin) links and the radial spokes were disrupted, but the effects of these proteases were different; trypsin disrupted 60–70% of these structures whereas elastase disrupted 20–30% of them. In both cases, spokes no. 3 and no. 8 (and no. 7) were more resistant to digestion than the others, although they tended to be more resistant to elastase than to trypsin. The importance of radial spokes and interdoublet links in the generation of cyclical bending and the determination of the bending plane is discussed.
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Contreras-González, Aldo-Francisco, Manuel Ferre, Miguel Ángel Sánchez-Urán, Francisco Javier Sáez-Sáez e Fernando Blaya Haro. "Efficient Upper Limb Position Estimation Based on Angular Displacement Sensors for Wearable Devices". Sensors 20, n.º 22 (12 de novembro de 2020): 6452. http://dx.doi.org/10.3390/s20226452.
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Motion tracking techniques have been extensively studied in recent years. However, capturing movements of the upper limbs is a challenging task. This document presents the estimation of arm orientation and elbow and wrist position using wearable flexible sensors (WFSs). A study was developed to obtain the highest range of motion (ROM) of the shoulder with as few sensors as possible, and a method for estimating arm length and a calibration procedure was proposed. Performance was verified by comparing measurement of the shoulder joint angles obtained from commercial two-axis soft angular displacement sensors (sADS) from Bend Labs and from the ground truth system (GTS) OptiTrack. The global root-mean-square error (RMSE) for the shoulder angle is 2.93 degrees and 37.5 mm for the position estimation of the wrist in cyclical movements; this measure of RMSE was improved to 13.6 mm by implementing a gesture classifier.
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Zhang, Baozhuo, e Marcus L. Young. "High-energy synchrotron X-ray diffraction measurements of simple bending of pseudoelastic NiTi shape memory alloy wires". Powder Diffraction 31, n.º 2 (23 de maio de 2016): 104–9. http://dx.doi.org/10.1017/s0885715616000154.
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Many technological applications of austenitic shape memory alloys (SMAs) involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity. In this paper, we investigated the effect of mechanical bending of pseudoelastic NiTi SMA wires using high-energy synchrotron radiation X-ray diffraction (SR-XRD). Differential scanning calorimetry was performed to identify the phase transformation temperatures. Scanning electron microscopy images show that micro-cracks in compressive regions of the wire propagate with increasing bend angle, while tensile regions tend not to exhibit crack propagation. SR-XRD patterns were analyzed to study the phase transformation and investigate micromechanical properties. By observing the various diffraction peaks such as the austenite (200) and the martensite (${\bar 1}12$), (${\bar 1}03$), (${\bar 1}11$), and (101) planes, intensities and residual strain values exhibit strong anisotropy, depending upon whether the sample is in compression or tension during bending.
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Franklin, C. E., e I. A. Johnston. "Muscle power output during escape responses in an Antarctic fish". Journal of Experimental Biology 200, n.º 4 (1 de fevereiro de 1997): 703–12. http://dx.doi.org/10.1242/jeb.200.4.703.
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Escape responses (C-shaped fast-starts) were filmed at 500 frames s-1 in the Antarctic rock cod (Notothenia coriiceps) at 0 °C. The activation and strain patterns of the superficial fast myotomal muscle were measured simultaneously using electromyography and sonomicrometry respectively. In order to bend the body into the initial C-shape, the muscle fibres in the rostral myotomes (at 0.35L, where L is total length) shortened by up to 13 % of their resting length at a maximum velocity of 1.68 fibre lengths s-1. During the contralateral contraction, muscle fibres were stretched (by 5 % and 7 % at 0.35L and 0.65L, respectively) and were activated prior to the end of lengthening, before shortening by up to 12 % of resting fibre length (peak-to-peak strain). Representative strain records were digitised to create cyclical events corresponding to the C-bend and contralateral contraction. Isolated fibres were subjected to the abstracted strain cycles and stimulated at the same point and for the same duration as occurs in vivo. During the early phase of shortening, muscle shortening velocity (V) increased dramatically whilst the load was relatively constant and represented a substantial fraction of the maximum isometric stress. Pre-stretch of active muscle was associated with significant force enhancement. For the contralateral contraction, V exceeded that predicted by the steady-state force­velocity relationship for considerable periods during each tailbeat, contributing to relatively high maximum instantaneous power outputs of up to 290 W kg-1 wet muscle mass. In vitro experiments, involving adjusting strain, cycle duration and stimulation parameters, indicated that in vivo muscle fibres produce close to their maximum power. During escape responses, the maximum velocity and acceleration recorded from the centre of gravity of the fish were 0.71±0.03 m s-1 and 17.1±1.4 m s-2, respectively (mean ± s.e.m., N=7 fish). Muscle performance was sufficient to produce maximum velocities and accelerations that were within the lower end of the range reported for temperate-zone fish.
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Lizunov, Petro, e Valentyn Nedin. "THE PARAMETRIC OSCILLATIONS OF ROTATING ELASTIC RODS UNDER THE ACTION OF THE PERIODIC AXIAL FORCES". Management of Development of Complex Systems, n.º 44 (30 de novembro de 2020): 56–64. http://dx.doi.org/10.32347/2412-9933.2020.44.56-64.
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The paper presents the results of numerical investigation of the periodic axial forces’ influence on the transverse oscillations of long rotating rods. The gyroscopic inertia forces are taken to account and space oscillating process of rotating rods is considered with account of geometric nonlinearity. The study has been done with computer program with a graphical interface that is developed by authors. The process of numerical solution of the differential equations of oscillations of rotating rods using the method of numerical differentiation of rod’s bend forms by polynomial spline-functions and the Houbolt time integration method is described. A general block diagram of the algorithm is shown. This algorithm describes the process of repeated (cyclical) solving of the system of differential equations of oscillations for every point of mechanical system in order to find the new coordinates of the positions of these points in each next point of time t+∆t. The computer program in which the shown algorithm is realized allows to monitor for the behavior of moving computer model, which demonstrates the process of oscillatory motion in rotation. Moreover, the program draws the graphics of oscillations and changes of angular speeds and accelerations in different coordinate systems. Using this program, the dynamics of a range of objects which are modeled by long elastic rods have been studied. For investigated objects is shown that on various rotational speeds and beat frequencies the oscillatory motion of the rods occurs with different character of behavior. On certain speeds with different frequencies of axial load the oscillations have definite periodicity and occur with beats of amplitude which are the result of the periodic axial force action.
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Ritter, Scott M., James E. Barrick e M. Randall Skinner. "Conodont sequence biostratigraphy of the Hermosa Group (Pennsylvanian) at Honaker Trail, Paradox Basin, Utah". Journal of Paleontology 76, n.º 3 (maio de 2002): 495–517. http://dx.doi.org/10.1017/s0022336000037331.
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In cyclical Pennsylvanian strata, conodonts find their greatest stratigraphic utility as biotic signatures of physically defined stratigraphic entities (cycles, parasequences, high frequency sequences, etc.) rather then the primary means of stratigraphic subdivision (e.g., biostratigraphic interval zones). The practice of identifying depositional entities for purposes of regional correlation on the basis of their constituent conodont faunas is herein called conodont sequence biostratigraphy. In this paper, the concept is utilized to successfully correlate Pennsylvanian cycles of the Paradox basin with their Midcontinent counterparts.The Honaker Trail section is the most accessible and well-studied succession of carbonate shelf strata in the Paradox basin. Approximately 350 m of cyclically bedded limestone, sandstone, and shale comprising 53 fifth-order cycles are exposed along the cliffs of the deeply entrenched San Juan River. Maximum transgressive facies of 19 cycles yielded Idiognathodus-Neognathodus- and/or Streptognathodus-dominated conodont faunas. Those from the Chimney Rock, Gothic, LHT-5, UHT-3, UHT-5, UHT-8, unnamed limestone, and Shafer correspond to faunas from the Verdigris, Lower Fort Scott, Altamont (Lake Neosho), Lost Branch, Hertha (Mound City), Swope (Hushpuckney), Dennis (Stark), and South Bend cycles of the Midcontinent, respectively. By extrapolation, all minor cycles of the Marmaton, Pleasanton, and Bronson Groups (except for the Critzer) also appear to have counterparts at Honaker Trail.The position of the Desmoinesian–Missourian boundary in the Honaker Trail section can be approximated using conodonts in conjunction with fusulinids. The highest Desmoinesian conodont fauna, the Idiognathodus nodocarinatus fauna, occurs in cycle UHT-3 in the lower part of the Upper Honaker Trail sequence. The highest occurrence of Beedeina occurs in the same cycle. The lowest conodont fauna with the Missourian species I. eccentricus appears two cycles higher, in cycle UHT-5. Because in the Midcontinent region a small interval of strata separates the first appearance of I. eccentricus from the base of the Missourian, we place the base of the Missourian at the base of cycle UHT-4 (bed 105) at Honaker Trail. The appearance of Streptognathodus firmus and S. pawhuskaensis in the Shafer limestone indicates that the Missourian–Virgilian boundary lies slightly above or below this stratigraphic horizon.
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Lizunov, Petro, e Valentyn Nedin. "The gyroscopic forces influence on the oscillations of the rotating shafts". Strength of Materials and Theory of Structures, n.º 105 (30 de novembro de 2020): 223–31. http://dx.doi.org/10.32347/2410-2547.2020.105.223-231.
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The results of numerical investigation of shafts transverse oscillations with account of gyroscopic inertia forces are presented. It is shown what the action and how the gyroscopic forces influence on the transverse oscillations of the shafts during rotation. The study has been done with computer program with a graphical interface that is developed by authors. The process of numerical solution of the differential equations of oscillations of rotating rods using the method of numerical differentiation of rod's bend forms by polynomial spline-functions and the Houbolt time integration method is described. A general block diagram of the algorithm is shown. This algorithm describes the process of repeated (cyclical) solving the system of differential equations of oscillations for every point of mechanical system in order to find the new coordinates of positions of these points in each next point of time t+Dt. The computer program in which the shown algorithm is realized allows to monitor for the behavior of moving computer model, which demonstrates the process of oscillatory motion in rotation. Moreover, the program draws the graphics of oscillations and changes of angular speeds and accelerations in different coordinate systems. Defines the dynamic stability fields and draw the diagrams of found fields. Using this program, the dynamics of a range of objects which are modeled by long elastic rods have been studied. For some objects is shown that on special rotational speeds of shafts with different lengths, in the rotating with shaft coordinate system, the trajectories of center of the section have an ordered character in the form of n-pointed star in time interval from excitation to the start of established circular oscillation with amplitude that harmoniously changes in time. It is noted that such trajectories are fact of the action of gyroscopic inertia forces that arise in rotation.
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Abdalla, Hany F., Mohammad M. Megahed e Maher Y. A. Younan. "Determination of Shakedown Limit Load for a 90-Degree Pipe Bend Using a Simplified Technique". Journal of Pressure Vessel Technology 128, n.º 4 (9 de fevereiro de 2006): 618–24. http://dx.doi.org/10.1115/1.2349575.
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In this paper a simplified technique is presented to determine the shakedown limit load of a 90-degree pipe bend subjected to constant internal pressure and cyclic in-plane closing bending moment using the finite element method. The simplified technique determines the shakedown limit load without performing time consuming full elastic-plastic cyclic loading simulations or conventional iterative elastic techniques. Instead, the shakedown limit load is determined by performing two finite element analyses namely; an elastic analysis and an elastic-plastic analysis. By extracting the results of the two analyses, the shakedown limit load is determined through the calculation of the residual stresses developed in the pipe bend. In order to gain confidence in the simplified technique, the output shakedown limit moments are used to perform full elastic-plastic cyclic loading simulations to check for shakedown behavior of the pipe bend. The shakedown limit moments output by the simplified technique are used to generate the shakedown diagram of the pipe bend for a range of constant internal pressure magnitudes. The maximum moment carrying capacity (limit moment) the pipe bend can withstand and the elastic limit are also determined and imposed on the shakedown diagram of the pipe bend. In order to get acquainted with the simplified technique, it is applied beforehand to a bench mark shakedown problem namely, the Bree cylinder (Bree, J., 1967, J. Strain Anal., 3, pp. 226–238) problem. The Bree cylinder is subjected to constant internal pressure and cyclic high heat fluxes across its wall. The results of the simplified technique showed very good correlation with the analytically determined Bree diagram of the cylinder.
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Kim, Seung Mo, Eun Sook Shon, Yoon Hyun Ka, Yong Joon Kim, Jin Young Kim e Jae Dong Kim. "Reliability Characterization of Organic Solderability Preservatives (OSP) of IC Packages by Drop and Cyclic Bend Test". Key Engineering Materials 297-300 (novembro de 2005): 893–98. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.893.
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Cyclic bend test and drop test were carried out as a second level reliability test method in order to characterize the joint performance between electronic components and board. Two types of package substrates were used for the test. The one was NiAu plated, and the other one was organic solderability preservatives (OSP) finished. Drop test was done in accordance with JEDEC standard test method [1]. Drop impact and duration time was 1,500G and 0.5ms, respectively. Cyclic bend test was performed with Amkor internal specification because there is no international standard for the test. The Amkor internal specification was edited based on the IPC/JEDEC specification [2]. Board deflection and cyclic frequency was 3mm and 1Hz, respectively. NiAu substrate showed better mean life performance about by 30% in cyclic bend test. OSP substrate showed the same or better failure rate performance in drop test. Typical solder joint failures and intermetalic crack were found by failure analysis.
Teses / dissertações sobre o assunto "Cyclical bend"
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Juchnevičius, Žilvinas. "Cikliškai lenkiamų srieginių jungčių deformavimas ir stiprumas". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120206_165605-38518.
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Disertacijoje, taikant apkrovų pasiskirstymo sriegio vijose modeliavimą, nagrinėjamos lenkiamų srieginių jungčių mažaciklio stiprumo problemos. Mo-dernesnės daugiaciklio ir mažaciklio ilgaamžiškumo skaičiavimo metodikos detaliai kiekybiškai įvertina ašinės apkrovos pasiskirstymą vijose, kuris leidžia detaliau ir tiksliau įvertinti konstrukcijos ypatumų įtaką. Disertacijoje siekiama ir cikliškai lenkiamoms srieginėms jungtims sukurti apkrovos pasiskirstymo sriegyje skaičiavimo metodą ir pritaikyti jį ciklinio stiprumo skaičiavimui
Sudaryta lenkiamos srieginės jungties elementų poslinkių darnos lygtis įga-lino sukurti trijų ruožų ir daugiaruožį lenkimo apkrovos pasiskirstymo jung¬tyje modelius ir įdiegti juos į norminio mažaciklio ilgaamžiškumo skaičiavimo gran-dinę.
Pirmame skyriuje pateikta literatūros šaltinių analizė. Jame apžvelgiama sunkiai apkrautų srieginių jungčių taikymo sritis ir apkrovimo sąlygos, apžvel¬giami ir analizuojami atlikti tyrimai, susiję su srieginių jungčių cikliniu stipru-mu.
Antrame skyriuje pateikti sriegio vijų poros deformavimo savybių eksperi¬mentinio tyrimo rezultatai ir anksčiau literatūroje neminėtų nukraunamos ir pa-kartotinai apkraunamos vijų poros savybių analizė.
Trečiame skyriuje pateikta srieginės jungties elementų deformavimo sche¬ma, poslinkių darnos diferencialinės lygtys, diferencialinių lygčių analitiniai sprendiniai ir lenkiamos srieginės jungties modeliai – trijų ruožų ir daugiaruožis tamprieji modeliai lenkimo apkrovos... [toliau žr. visą tekstą]Industry equipment such as pressure vessels, mining equipment, heat exchang-ers, steam generators and other structures are provided with bolted closures for the purpose of in-service inspection and maintenance of internal components. Threaded connections often experience variable cyclic loads due to temperature, inner pressure and variation in the deformation of connection fittings. Often, studs and screws are not only affected by an axial load, but also by bending moments. More sophisticated high-cycle and low-cycle durability calculation meth-odologies have been already developed for threaded connections experiencing cyclic axial loads, and in these methodologies the distribution of axial load among turns is assessed quantitatively. The quantitative data of load distribu-tion in the thread enables a more accurate assessment of the influence of the constructional design particularities (connection length, material, nut and turn’s form) and the deformation stages of the connection element. These durability calculation methodologies are not applied for threaded connections that are cyclically bent, as the analytical models that are suitable for practical application in the load distribution of the turns have not been cre-ated for bent threaded connections. In this field, no models have been created to be calculated by the BE method. As the threaded connection is a complex node consisting of deformed el-ements, the load distribution among turns is influenced by the... [to full text]
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Juchnevičius, Žilvinas. "Deformation and strength of a cyclically bent threaded connection". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120206_165453-81433.
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Industry equipment such as pressure vessels, mining equipment, heat exchang-ers, steam generators and other structures are provided with bolted closures for the purpose of in-service inspection and maintenance of internal components. Threaded connections often experience variable cyclic loads due to temperature, inner pressure and variation in the deformation of connection fittings. Often, studs and screws are not only affected by an axial load, but also by bending moments.
More sophisticated high-cycle and low-cycle durability calculation meth-odologies have been already developed for threaded connections experiencing cyclic axial loads, and in these methodologies the distribution of axial load among turns is assessed quantitatively. The quantitative data of load distribu-tion in the thread enables a more accurate assessment of the influence of the constructional design particularities (connection length, material, nut and turn’s form) and the deformation stages of the connection element.
These durability calculation methodologies are not applied for threaded connections that are cyclically bent, as the analytical models that are suitable for practical application in the load distribution of the turns have not been cre-ated for bent threaded connections. In this field, no models have been created to be calculated by the BE method.
As the threaded connection is a complex node consisting of deformed el-ements, the load distribution among turns is influenced by the... [to full text]Srieginės jungtys dažnai patiria ciklinių lenkimo apkrovų dėl temperatū-ros, vidaus slėgio ir jungiamųjų detalių deformacijų kitimo. Srieginėms jung-tims, kurios patiria ašinių ciklinių apkrovų jau yra sukurtos modernesnės daugiaciklio ir mažaciklio ilgaamžiškumo skaičiavimo metodikos, kuriomis detaliai kiekybiškai įvertinamas ašinės apkrovos pasiskirstymas tarp vijų. Ap-krovos pasiskirstymo sriegyje kiekybiniai duomenys leidžia detaliau ir tiksliau įvertinti konstrukcijos ypatumų (jungties ilgio, medžiagos, veržlės ir vijų for-mos) ir jungties elementų deformavimo stadijų įtaką. Tokios ilgaamžiškumo skaičiavimo metodikos cikliškai lenkiamoms srieginėms jungtims netaikomos, nes lenkiamoms srieginėms jungtims nėra sukurtų apkrovos pasiskirstymo vijose analitinių modelių, tinkamų praktiniam naudojimui. Šioje srityje taip pat nėra sukurtų ir modelių, kurie skaičiuojami baigtinių elementų metodu. Kadangi srieginė jungtis yra kompleksinis mazgas, kurį sudaro deformuo-jami elementai, tai apkrovos pasiskirstymą tarp vijų lemia jungties elementų deformacijų ir poslinkių suderinamumas. Matematiškai aprašant jungties de-formuotą būvį, reikalingi teoriniai ir eksperimentiniai duomenys, kurie atspin-dėtų jungties elementų deformavimo specifinius ypatumus, pasireiškiančius veikiant lenkimui. Disertacijoje siekiama sukurti cikliškai lenkiamų srieginių jungčių apkro-vos pasiskirstymo sriegyje skaičiavimo metodą ir pritaikyti jį mažacikliam ilga-amžiškumui skaičiuoti.
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Utterström, Johanna. "One Bead One Compound Screening for Cyclic Peptide Binding Partners". Thesis, Linköpings universitet, Molekylär fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-152282.
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In recent years a significant research focus has been on the development of biomimicking three-dimensional substrates for cell culturing. Hydrogels mimicking the extracellular matrix is a well-suited scaffold for this purpose and there are many different ways these can be cross-linked to retain their shape. The group of Molecular Materials at IFM, Linköping University, is focusing on the development of physical hydrogels hybridized through peptide-peptide interactions but all peptides used for this today are created using rational design and on top of this very large, making them time-consuming and expensive to fabricate. The aim of this project was to evaluate if One Bead One Compound (OBOC) libraries could be used as an alternative to rational design in the finding of cyclic peptide binding partners used in the hybridization of hydrogels. The results were not very promising though since only seven peptides passed all screening steps and of these only two could be sequenced. Of these two, only one was water soluble enough to enable binding interactions analysis but was then found to be a false hit. Nevertheless, it should be noticed that only a fraction of all possible combinations was screened and the results cannot exclude OBOC libraries as an approach in the quest of finding new cyclic peptide binding partners.
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Mirza, Fahad. "Investigation of the impact response of Pb-free electronic assemblies and comparison of drop with cyclic 4-point bend test". Diss., Online access via UMI:, 2007.
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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2007.Includes bibliographical references.
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Aly, Hassan Ashraf. "Novel integrated scheme for destruction of hydrophobic hazardous air pollutants". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282569687.
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Appelsved, Peter. "Investigation of Mechanical Properties of Thermoplastics with Implementations of LS-DYNA Material Models". Thesis, KTH, Hållfasthetslära (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103790.
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The increased use of thermoplastics in load carrying components, especially in the automotive industry, drives the needs for a better understanding of its complex mechanical properties. In this thesis work for a master degree in solid mechanics, the mechanical properties of a PA 6/66 resin with and without reinforcement of glass fibers experimentally been investigated. Topics of interest have been the dependency of fiber orientation, residual strains at unloading and compression relative tension properties. The experimental investigation was followed by simulations implementing existing and available constitutive models in the commercial finite element code LS-DYNA. The experimental findings showed that the orientation of the fibers significantly affects the mechanical properties. The ultimate tensile strength differed approximately 50% between along and cross flow direction and the cross-flow properties are closer to the ones of the unfilled resin, i.e. the matrix material. An elastic-plastic model with Hill’s yield criterion was used to capture the anisotropy in a simulation of the tensile test. Residual strains were measured during strain recovery from different load levels and the experimental findings were implemented in an elastic-plastic damage model to predict the permanent strains after unloading. Compression tests showed that a stiffer response is obtained for strains above 3% in comparison to tension. The increased stiffness in compression is although too small to significantly influence a simulation of a 3 point bend test using a material model dependent of the hydrostatic stress.
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Liang, Xinxia. "Development of new approaches for the synthesis and decoding of one-bead one-compound cyclic peptide libraries". Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26760.
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La plupart des processus cellulaires et biologiques reposent, à un certain niveau, sur des interactions protéine-protéine (IPP). Leur manipulation avec des composés chimiques démontre un grand potentiel pour la découverte de nouveaux médicaments. Malgré la demande toujours croissante en molécules capables d'interrompre sélectivement des IPP, le développement d'inhibiteurs d’IPP est fortement limité par la grande taille de la surface d'interaction. En considérant la nature de cette surface, la capacité à mimer des structures secondaires de protéines est très importante pour lier une protéine et inhiber une IPP. Avec leurs grandes capacités peptidomimétiques et leurs propriétés pharmacologiques intéressan-tes, les peptides cycliques sont des prototypes moléculaires de choix pour découvrir des ligands de protéines et développer de nouveaux inhibiteurs d’IPP. Afin d’exploiter pleinement la grande diversité accessible avec les peptides cycliques, l’approche combinatoire «one-bead-one-compound» (OBOC) est l’approche la plus accessible et puissante. Cependant, l'utilisation des peptides cycliques dans les chimiothèques OBOC est limitée par les difficultés à séquencer les composés actifs après le criblage. Sans amine libre en N-terminal, la dégradation d'Edman et la spectrométrie de masse en tandem (MS/MS) ne peuvent pas être utilisées. À cet égard, nous avons développé de nouvelles approches par ouverture de cycle pour préparer et décoder des chimiothèques OBOC de peptides cycliques. Notre stratégie était d'introduire un résidu sensible dans le macrocycle et comme ancrage pour permettre la linéarisation des peptides et leur largage des billes pour le séquençage par MS/MS. Tout d'abord, des résidus sensibles aux nucléophiles, aux ultraviolets ou au bromure de cyanogène ont été introduits dans un peptide cyclique et leurs rendements de clivage évalués. Ensuite, les résidus les plus prometteurs ont été utilisés dans la conception et le développement d’approches en tandem ouverture de cycle / clivage pour le décodage de chimiothèques OBOC de peptides cycliques. Dans la première approche, une méthionine a été introduite dans le macrocycle comme ancrage pour simultanément permettre l’ouverture du cycle et le clivage des billes par traitement au bromure de cyanogène. Dans la seconde approche, un résidu photosensible a été utilisé dans le macrocycle comme ancrage pour permettre l’ouverture du cycle et le clivage suite à une irradiation aux ultraviolets. Le peptide linéaire généré par ces approches peut alors être efficacement séquencé par MS/MS. Enfin, une chimiothèque OBOC a été préparée et criblée la protéine HIV-1 Nef pour identifier des ligands sélectifs. Le développement de ces méthodologies permttra l'utilisation de composés macrocycliques dans les chimiothèques OBOC et constitue une contribution importante en chimie médicinale pour la découverte de ligands de protéines et le développement d'inhibiteurs d’IPP.A great number of cellular and biological processes depend, at some level, on protein-protein interactions (PPI). Their manipulation with chemical compounds has provided a great potential for the discovery of new drugs. Despite the increasing demand for molecules able to interrupt specific PPI, the development of small PPI inhibitors is beset by a number of challenges such as the large size of the interaction interface. Based on the interface’s nature, the ability to mimic protein secondary structures is very important to bind a protein and inhibit PPI. With their interesting peptidomimetic abilities and pharmacological properties, cyclic peptides are very promising templates to discover protein ligands and development new PPI inhibitors. To fully exploit the great diversity accessible with cyclic peptides, the one-bead-one-compound (OBOC) combinatorial method is certainly the most accessible and powerful approach. Unfortunately, the use of cyclic peptides in OBOC libraries is limited by difficulties in sequencing hit compounds after the screening. Lacking a free N-terminal amine, Edman degradation cannot be used on cyclic peptides and complicated fragmentation patterns are obtained by tandem mass spectrometry (MS/MS). In this regard we have designed and developed new convenient ring-opening approaches to prepare and decode OBOC cyclic peptide libraries. Our strategy was to introduce a cleavable residue in the macrocycle and as a linker to allow linearization of peptides and their release from the beads for sequencing by MS/MS. First, amino acid residues sensible to nucleophiles, ultraviolet irradiation or cyanogens bromide were introduced in a model cyclic peptide. Afterward, the most promising residues were used to design and develop tandem ring-opening/cleavage approaches to decode OBOC cyclic peptide libraries. In the first approach a methionine residue was introduced in the macrocycle and as a linker to allow a simultaneous ring-opening and cleavage from the beads upon treatment with cyanogens bromide. In the second approach, a photosensitive residue was used in the macrocycle and as a linker for a dual ring-opening/cleavage upon UV irradiation. The linear peptide generated by these approaches can be efficiently sequenced by tandem mass spectrometry. Finally, an OBOC library has been prepared and screened against the HIV-1 Nef protein to identify selective ligands. The development of these methodologies will prompt the use of macrocyclic compounds in OBOC libraries and be an important contribution in medicinal chemistry for the discovery of protein ligands and the development of PPI inhibitors.
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Wood, Kevin. "Development of Computational Tools for the Design, Simulation and Optimization of Cyclic Steady State (CSS) Adsorption and Chromatographic Processes". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/72854.
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This dissertation presents an analysis of two aspects of the chromatographic separation process known as Simulated Moving Bed (SMB) chromatography. The first aspect is system design, and the second is improving computer simulations to generate heuristics for choosing operational modes.
For the past 15-20 years, there has been a surge of interest in the use of Simulated Moving Bed systems for the chromatographic separation of chemicals¹. A wide variety of methods, nomenclatures, and conventions have been adopted over the years²⁻⁴, as teams from different backgrounds adopt and improve on the SMB technology. This work presents a unifying discussion of the two major design methods, Triangle Theory and Standing Wave Design, used in the SMB field. We provide the complete computer code required to execute both design methods. A sample problem is worked, which demonstrates the novelty and ease of use that such tools provide. Mathematica was chosen for the implementation of these design methods, because of its strong symbolic analysis capabilities, and simplicity of creating interfaces for new users. We present derivations of the classic Langmuir results in Mathematica, and proceed to extend those implementations. When analytic solutions are impossible, we use Mathematica's numerical methods.
This work also develops a distributed computing tool known as ChromRunner which allows large numbers of detailed numerical simulations to be run simultaneously. The motivations and benefits of this approach are discussed alongside implementation details. We apply the distributed computing system to two separate SMB separations in order to optimize them, as well as determine heuristics governing their operational modes. We wrote ChromRunner in C#, and took advantage of Visual Studio's Entity Framework to create the database backend. The user interface for this software was created using Microsoft's "Windows Presentation Foundation" (WPF) technologies.Ph. D.
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Liu, Tao. "Development Of Cyclic Peptidyl Ligands Through A Combinatorial Library Approach". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306865559.
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Yao, Hong Mei. "Wavelet based dynamic modelling of simulated moving bed chromatographic processes". Curtin University of Technology, Department of Chemical Engineering, 2009. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=128426.
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Simulated moving bed chromatography process (SMBCP) is the technical realisation of a countercurrent adsorption process through the cyclic port switching. SMB technology reduces the cost of packing material with high loading capacity and provides high purity and high recovery in a very short time. Major commodity applications have been found in the petroleum, food, biotechnology, pharmaceutical and fine chemical industries. The industrial applications bring an emergent demand to improve the SMBCP operation for higher product quality, productivity, efficiency and robustness. However, for this particular process, we encounter several challenges. Firstly, the interplay of the effects of strong nonlinearities, competition of solutes, mass transfer resistance and fluid dynamic dispersion produces steep concentration fronts. Mathematical model accounted for this particular property constitutes a serious difficulty for the solution procedure. Secondly, a dynamic SMB model consists of a set of partial differential, ordinary differential and algebraic equations, which are highly coupled. The large size is a problem due to its intensive computation when on-line optimisation and real-time control are necessary. Thirdly, the SMB unit operation exhibits complex dynamics. Process metrics for design and operation can be determined only when a cyclic steady state is reached after a certain number of switching. Achieving this steady state by solving the PDE models cycle after cycle involves expensive calculation. Studies have been carried out to solve these problems through process analysis, investigation on spatial discretisation techniques, and development of an accelerated integration scheme.Through a systematic study on the advances of SMB modelling, design and control, a set of functionally equivalent models for SMBCP are identified and summarized for their practical applications. The limitations of the existing modelling techniques in industrial applications are also identified. Furthermore, structural analysis of the existing models is conducted for a better understanding of the functionality and suitability of each model. Suggestions are given on how to choose an appropriate model with sufficient accuracy while keeping the computational demand reasonably low for real time control.
Effort is made on to the systematic investigation of different numerical methods for the solution of PDEs to circumvent the steep gradients encountered in chromatographic separation. Comprehensive studies are conducted on a single column chromatographic process represented by a transport-dispersive-equilibrium linear model. Numerical solutions from the upwind-1 finite difference, wavelet-collocation, and high resolution methods are evaluated by quantitative comparisons with the analytical solution for a range of Peclet numbers. It reveals that for a PDE system with a low Peclet number, all existing numerical methods work well, but the upwind finite difference method consumes the most time for the same degree of accuracy of the numerical solution. The high resolution method provides an accurate numerical solution for a PDE system with a medium Peclet number. The wavelet collocation method is capable of catching up steep changes in the solution, and thus can be used for solving PDE models with high singularity.
The advantages and disadvantages of the wavelet based approaches are further investigated through several case studies on real SMBCP system. A glucose-fructose separation process is firstly chosen with its relatively simple isotherm representations. Simulations are conducted using both wavelet collocation and upwind finite difference methods. For more complicated applications, an enantiomers separation process is selected. As the PDEs model exhibit a certain degree of singularity, wavelet collocation and high resolution methods are adopted for spatial discretisation. It is revealed that both the wavelet based approaches and high resolution methods are good candidates in terms of computation demand and prediction accuracy on the steep front. This is the first time that these two frontier numerical methods are used for such a complex SMB system models and our results are encouraging for the development of model-based online control scheme.
In developing a new scheme to rapidly obtain the solution at steady state for any arbitrary initial condition, the concept of Quasi-Envelope (QE) is adopted under the consideration that a SMBCP can be treated as a pseudo-oscillatory process because of a large number of continuous switching. The scheme allows larger steps to be taken to predict the slow change of starting state within each switching. Combined with previously developed wavelet-based technique, this method is successfully applied to the simulation of a SMB sugar separation process. Investigations are also carried out on the location of proper starting point for the algorithm and on the effect of changing stepsize to the convergence of iteration method. It is found that if the starting state of Quasi-Envelope is chosen to be the same as the original function, the multivalue algorithm would require similar computational effort to achieve the steady state prediction, regardless of the integration stepsize. If using constant stepsize, launching QE later is helpful when quasi-envelope displays steep change at the start-up period. A changing stepsize produces slow convergence compared to the constant stepsize strategy, thus increasing the work load where the stepsize change is occurring. Other iteration method is required to be imposed to achieve faster convergence right from the beginning. Potential applications can be seen for other chemical engineering processes with inherent cyclic behaviour.
Livros sobre o assunto "Cyclical bend"
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Oon, Su-Min. Synthesis and x-ray structure of iron stabilized strained cyclic allenes.: Valence isomerization between linear perpendicular and bent planar allene. 1987.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Cyclical bend"
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van Noorden, T. L., S. M. Verduyn Lunel e A. Bliek. "Direct Determination of Cyclic Steady States of Cyclically Operated Packed Bed Reactors". In Scientific Computing in Chemical Engineering II, 311–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-642-60185-9_36.
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Verruijt, Arnold. "Sea Bed Response to Cyclic Loads". In Theory and Applications of Transport in Porous Media, 35–52. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-017-1112-8_3.
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Carta, Giorgio. "Cyclic Fixed-Bed Sorption Processes for Bioseparations — Design Aspects". In Chromatographic and Membrane Processes in Biotechnology, 85–99. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3470-5_4.
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Qian, Ziqing, Punit Upadhyaya e Dehua Pei. "Synthesis and Screening of One-Bead-One-Compound Cyclic Peptide Libraries". In Peptide Libraries, 39–53. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-2020-4_3.
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Han, Long, Qinhui Wang, Qiang Ma, Jian Guan, Zhongyang Luo e Kefa Cen. "Hydration Reactivation of CaO-Based Sorbent for Cyclic Calcination-Carbonation Reactions". In Proceedings of the 20th International Conference on Fluidized Bed Combustion, 726–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02682-9_112.
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Lépore, Paula Ferreira, e Miguel Angel Buelta Martinez. "Cyclic-Bend-Over-Sheave Fatigue Testing of an Umbilical for Oil Production in Ultra-Deep Waters". In Advanced Structured Materials, 47–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-12667-3_4.
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Kim, Seung Mo, Eun Sook Shon, Yoon Hyun Ka, Yong Joon Kim, Jin Young Kim e Jae Dong Kim. "Reliability Characterization of Organic Solderability Preservatives (OSP) of IC Packages by Drop and Cyclic Bend Test". In Key Engineering Materials, 893–98. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-978-4.893.
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Mittal, Satyendra, e Anoop Bhardwaj. "Deformation Modulus Characteristics of Cyclically Loaded Granular Earth Bed for High-Speed Trains". In Latest Developments in Geotechnical Earthquake Engineering and Soil Dynamics, 423–31. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1468-2_19.
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Platte, Frank, Dmitri Kuzmin, Christoph Fredebeul e Stefan Turek. "Novel Simulation Approaches for Cyclic Steady-state Fixed-bed Processes Exhibiting Sharp Fronts and Shocks". In Trends and Applications in Constructive Approximation, 207–23. Basel: Birkhäuser Basel, 2005. http://dx.doi.org/10.1007/3-7643-7356-3_15.
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van Noorden, T. L., S. M. Verduyn Lunel e A. Bliek. "Direct determination of periodic states of cyclically operated packed bed reactors". In Reaction Kinetics and the Development and Operation of Catalytic Processes, Proceedings of the 3rd International Symposium, 263–70. Elsevier, 2001. http://dx.doi.org/10.1016/s0167-2991(01)81971-6.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Cyclical bend"
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Jin, Huan, Wu Yu, Feng Long, Min Yu, Qiyang Han e Yuhu Zhai. "Mechanical Performances of ITER In-Vessel Coil’s Conductor". In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16887.
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The design and R&D for ITER In-Vessel Coils (IVCs) is being deployed. The concerned issue of “Edge Localized Modes” (ELMs) and “Vertical Stabilization” (VS) of the ITER plasma can be addressed by the implemented IVCs. The ELM and VS coils will be installed in the vessel just behind the blanket shield modules to reach the requirement of keeping strong coupling with the plasma. The 59mm Stainless Steel Jacketed Mineral Insulated Conductor (SSMIC) using MgO as the insulation is being designed for the IVCs to resist the special challenges, including the nuclear radiation, high temperature, electromagnetic and thermal fatigue. It is necessary to take the mechanical performances of the SSMIC and the feasibility of fabrication techniques into consideration of the R&D program. The mechanical performances of the SSMIC close to the actual work conditions, including the three point bend modulus, three point bend cyclical performance and the cyclical performance with a U-bend sample of the SSMIC prototypes have been investigated and the results are presented in this paper.
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Cho, Nak-Kyun, e Haofeng Chen. "Cyclic Plasticity Behavior of 90° Back-to-Back Pipe Bends Under Cyclic Bending and Steady Pressure". In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-82386.
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Back-to-back pipe bends are widely adopted applications in many industries including nuclear sectors. Evaluation of their load bearing capability under complex cyclic loading is very important. Recently, a couple of research reported shakedown boundary of a 90° back-to-back pipe bends by adopting a conservative approach but no comprehensive post yield structural behaviors have been dealt with. In this research the concerning pipe bends subjected to cyclic opening in-plane (IP)/out-of-plane (OP) bending and steady internal pressures are analyzed to construct shakedown and ratchet limit boundary by means of the Linear Matching Method. Analyzed results present that the concerning pipe bends under out-of-plane bending has higher resistance to cyclic bending than under in-plane bending. In additions, the out-of-plane bending causes very small alternating plasticity areas, unlike the in-plane bending. Full cyclic incremental analyses known as step-by-step analysis are performed to verify the structural responses either side of each boundary and confirm correct responses. Parametric studies are carried out with respect to changes in geometry of the concerning pipe bends subjected to the same loading, and semi-empirical equations are derived from relationships of the reverse plasticity limit and the limit pressure with the bend characteristic. This paper offers broad understandings of structural responses of the 90° back-to-back pipe bends under the complex cyclic loading as well as providing key points to be considered for the life assessment of the piping system.
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Korba, Ahmed G., Mohammad M. Megahed, Hany F. Abdalla e Mohamed M. Nassar. "Prediction of Ratchet Boundary for 90-Degree Smooth and Mitred Pipe Bends". In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78673.
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The present paper attempts to predict ratchet boundary for 90-degree mitred and smooth pipe bends subjected to sustained pressure and cyclic in-plane bending. The methodology utilizes a recently published technique known as the “Uniform Modified Yielding” (UMY) technique, which relies on generation of a virtual structure with inhomogeneous reduced yield strength, whose magnitude and distribution depend on the elastic stress field due to the cyclic load. The collapse load of this virtual structure determines the threshold steady load necessary for commencement of “incremental collapse”. The technique is applied first to predict ratchet boundaries for two benchmark problems possessing analytical descriptions of ratchet boundary and uni-axial states of stress; the two-bar structure problem and the Bree cylinder. Predicted ratchet boundaries exactly coincided with the corresponding published analytical descriptions, and reasons for this correlation were discussed in this paper. The technique was then applied to three 90-degree pipe bends with similar geometries as follows: smooth pipe bend (SPB), single mitred pipe bend (SMPB), and three weld mitred pipe bend (3WMPB). Certain assumptions are adopted to enable treatment of the problem as a quasi-uniaxial one. Conservative estimates are obtained for ratchet boundaries in pipe bends that correlates well with elastic shakedown/ratchet boundary of the same problems as predicted by a recently developed non-cyclic direct technique.
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Banneyake, Ranil, Ayman Eltaher e Paul Jukes. "Effects of Cross-Section Ovalization of Subsea Thin-Walled Bends Under In-Plane Bending". In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-21098.
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Ovalization of the cross-section of bends under in-plane bending (a.k.a. Brazier effect) is a known phenomenon caused by the longitudinal stress acting on the cross-section as the pipe bends. Besides its tendency to induce stresses in the bend above what is predicted using simple beam theory, excessive cross-section ovalization is particularly critical to subsea pipes, as it can lead to collapse of the pipe under external pressure. Also, being in a plastic regime may cause the bend material to ratchet and undergo excessive strains under cyclic operational loads, especially under high-pressure high-temperature (HPHT) conditions. Ovalization normally results in local increase of stresses and could lead to failure of the bend before the bend globally reaches its limiting capacity. The offshore industry standards and design codes address the impact of initial ovality in straight pipes, but their applicability to bends is not clear. Therefore, this paper presents an investigation into the increased tendency of thin-walled bends to ovalize, and the effect of bend cross-section ovalization on their stiffness and yielding and collapse limit states, with emphasis on offshore applications. Due to the lack of analytical solutions for the bend response taking into account cross-section ovalization, finite element analysis (FEA) is used in this study. Predictions of the bend models are compared with those of straight pipe models and predictions of models of the bend made of beam elements (with pipe section) are compared with those of models made of brick /shell elements. The increased tendency of thin-walled bends to ovalize compared to straight pipes is investigated (e.g. 100 times in the linear range), and the impact and significance of ovalization in bends are assessed (e.g., stress increase of the order of 35% has been observed in some example situations). Also discussed in the paper is the selection of proper element specifications in order to accurately capture the ovalization response while keeping the computational cost manageable. Recommendations as to how to account for ovalization effects are presented. This paper helps to gain a better understanding of the response of subsea thin-walled bends under in-plane bending and their comparatively high tendency to ovalize compared to straight pipe, and emphasizes the significance of local effects such as cross-section ovalization, the overlooking of which may result in a significant underestimation of involved stresses and strains.
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Abdalla, Hany F., Mohammad M. Megahed e Maher Y. A. Younan. "Shakedown Limit Loads for 90-Degree Scheduled Pipe Bends Subjected to Constant Internal Pressure and Cyclic Bending Moments". In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61692.
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A simplified technique for determining the shakedown limit load for a long radius 90-degree pipe bend was previously developed [1, 2]. The simplified technique utilizes the finite element method and employs the small displacement formulation to determine the shakedown limit load (moment) without performing lengthy time consuming full cyclic loading finite element simulations or utilizing conventional iterative elastic techniques. The shakedown limit load is determined through the calculation of residual stresses developed within the pipe bend structure. In the current paper, a parametric study is conducted through applying the simplified technique on three scheduled pipe bends namely: NPS (Nominal Pipe Size) 10" Sch. No. 20, NPS 10" Sch. No. 40 STD, and NPS 10" Sch. No. 80. Two material models are assigned namely; an elastic-perfectly-plastic (EPP) material and an idealized elastic-linear strain hardening material obeying Ziegler’s linear kinematic hardening (KH) rule. This type of material model is termed in the current study as the KH-material. The pipe bends are subjected to a spectrum of constant internal pressure magnitudes and cyclic bending moments. The cyclic bending includes three different loading patterns namely: in-plane closing (IPC), in-plane opening (IPO), and out-of-plane (OP) bending moment loadings of the pipe bends. The shakedown limit moments output by the simplified technique are used to generate shakedown diagrams of the scheduled pipe bends for the spectrum of constant internal pressure magnitudes. A comparison between the generated shakedown diagrams for the pipe bends employing the EPP- and the KH-materials is presented. Relatively higher shakedown limit moments were recorded for the pipe bends employing the KH-material at the medium to high internal pressure magnitudes.
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Abdalla, Hany F. "Shakedown Boundary and Limit Load Determination of a 90-Degree Back to Back Pipe Bend Subjected to Steady Internal Perssures and Cyclic In-Plane Bending Moments". In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97336.
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Shakedown analysis of 90–degree back–to–back pipe bends is scarce within open literature. According the author’s knowledge, no shakedown analysis exists for such structure based on experimental data. Ninety degree back–to–back pipe bends are extensively utilized within piping networks of nuclear submarines and modern turbofan aero–engines where space limitation is considered a paramount concern. Additionally, on larger scales, 90–degree back–to–back pipe bend configurations are also found within piping networks of huge liquefied natural gas tankers. The structure analyzed is formed by bending a straight pipe to acquire the geometry of two 90–degree pipe bends set back–to–back each having a nominal pipe size (NPS) of 10 in. Schedule 40 Standard (STD). In the current research, the 90–degree back–to–back pipe bend setup analyzed is subjected to a spectrum of steady internal pressures and cyclic in–plane bending moments. A previously developed simplified technique for determining elastic shakedown limit loads is utilized to generate the elastic shakedown boundary of the 90–degree back–to–back pipe bend analyzed. In addition to determining the elastic shakedown boundary, elastic and post shakedown domains (Bree diagram), the maximum moment carrying capacities (limit moments) are also determined and imposed on the generated Bree diagram of the analyzed structure. The simplified technique outcomes showed excellent correlation with the results of full elastic–plastic cyclic loading finite element simulations.
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ElSaadany, Mostafa S., Maher Y. A. Younan e Hany F. Abdalla. "Determination of Shakedown Boundary and Fitness-Assessment-Diagrams of Cracked Pipe Bends". In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78320.
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Determination of shakedown boundaries of 90-degree plain smooth pipe bends has recently received substantial attention by several researchers. However, scarce or almost no solid information is found within the literature regarding the determination of the shakedown boundary of cracked pipe bends. The current research presents two additions to the literature namely: determination of shakedown boundary for a circumferentially cracked 90-degree pipe bend via a simplified technique utilizing the finite element method, and introduction of Fitness-Assessment-Diagrams (FAD) in compliance with the API 579 Fitness-for-Service assessment of pressure vessel and piping components. The analyzed cracked pipe bend is subjected to the combined effect of steady internal pressure spectrum and cyclic In-Plane Closing (IPC) and opening (IPO) bending moments. Line spring elements (LSE) are embedded in quadratic shell elements to model part through cracks. Fitness assessment diagrams (FAD) are obtained through linking the J-integral fracture mechanics parameter with the shakedown limit moments of the analyzed cracked 90-degree pipe bend. The LSE outcomes illustrated satisfactory results in comparison to the results of two verification studies: stress intensity factor and limit load. Additionally, full elastic-plastic cyclic loading finite element analyses are conducted and the outcomes revealed very good correlation with the results obtained via the simplified technique. The maximum load carrying capacity (limit moment) and the elastic domain are also computed thereby generating a Bree diagram for the cracked pipe bend.
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Duan, Xinjian, e Michael Kozluk. "Plastic Behaviour of Small Bore Piping Bend/Elbow Under Combined Internal Pressure and Bending Moment". In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57097.
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This paper presents some preliminary observations from six representative tests on the plastic behavior of small bore carbon steel piping bends/elbows with general and local wall loss subject to combined internal pressure and bending moment loading at typical CANDU® reactor operating temperature. These six tests include three materials (normalized elbow, stress relieved bend and cold worked bend), two piping sizes (NPS 2 and NPS 2 1/2), two loading modes (monotonic and cyclic) and three modes of failure (collapse, burst and leak). The test results show that a collapsed piping bend/elbow can still withstand five times design pressure without the loss of pressure boundary. The stress relieved bend appears to offer a compromise in the resistance to both environmental assisted cracking and plastic collapse relative to the normalized elbow and cold worked bend.
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Reinhardt, Wolf, e Xinjian Duan. "Comparison Between Cyclic Testing and Analysis of Piping Bends With Local Thinning". In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28894.
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A series of tests on small-bore Carbon steel piping specimens with bends has been performed within the Feeder Bend Testing Program. The objective of the tests was to explore the effect of global and local wall thinning on the structural behaviour of feeder pipes in CANDU® reactors. Tests involved both cyclic and monotonic bending loading together with static pressure in order to obtain information about both the ultimate load carrying capacity and the fatigue life. The specimens were thinned locally to below the NB-3600 pressure based wall thickness within or near the bend. Results of cyclic tests are reported and discussed. For one of the tests, a fatigue crack initiation and a fatigue crack growth analysis were performed. The results have relevance as an evaluation of the conservatism of traditional piping design methods, as well as a benchmark for fitness-for-service approaches, such as flaw tolerance evaluation.
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Zhao, K. M., e J. K. Lee. "Estimation of Material Properties from Cyclic Bend Test". In International Body Engineering Conference & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-2660.
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