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Artykuły w czasopismach na temat "Small strain dynamic properties"
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Sas, Wojciech, Katarzyna Gabryś, Emil Soból i Alojzy Szymański. "Nonlinear dynamic properties of silty clay from Warsaw area". Annals of Warsaw University of Life Sciences – SGGW. Land Reclamation 48, nr 3 (1.09.2016): 201–20. http://dx.doi.org/10.1515/sggw-2016-0016.
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Abstract In this work, the small-strain and nonlinear dynamic properties of silty clay samples were studied by means of the low- and high-amplitude resonant column (RC) tests at various mean effective stresses (p’). The tested specimens were collected from the centre of Warsaw, district Śródmieście. Initially, the low-amplitude tests (below 0.001%) were conducted. Subsequently, the nonlinear testing was performed, at shearing strains greater than 0.001%. These tests were carried out in order to receive the dynamic properties of silty clay specimens in the nonlinear shear strain range. The small-strain material damping ratios (Dmin) of silty clay samples were also measured during the low-amplitude resonant column testing. The results show that increasing shear strain (γ) above the elastic threshold (γte) causes a decrease of the shear modulus (G) and normalized shear modulus (G/Gmax) of analyzed soil samples. Simultaneously, it is observed a increase of its damping ratio (D) and normalized damping (D/Dmin) with increasing shear strain (γ). Predictive equations for estimating normalized shear modulus and material damping of silty clay soils were presented here as well. The equations are based on a modified hyperbolic model and a statistical analysis of the RC tests results. The influence of unloading process on dynamic properties of the tested material was also discussed in the paper.
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Song, Binghui, Angelos Tsinaris, Anastasios Anastasiadis, Kyriazis Pitilakis i Wenwu Chen. "Small to medium strain dynamic properties of Lanzhou loess, China". Soil Dynamics and Earthquake Engineering 163 (grudzień 2022): 107454. http://dx.doi.org/10.1016/j.soildyn.2022.107454.
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Kyei-Manu, William Amoako, Charles R. Herd, Mahatab Chowdhury, James J. C. Busfield i Lewis B. Tunnicliffe. "The Influence of Colloidal Properties of Carbon Black on Static and Dynamic Mechanical Properties of Natural Rubber". Polymers 14, nr 6 (16.03.2022): 1194. http://dx.doi.org/10.3390/polym14061194.
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The influence of carbon black (CB) structure and surface area on key rubber properties such as monotonic stress-strain, cyclic stress–strain, and dynamic mechanical behaviors are investigated in this paper. Natural rubber compounds containing eight different CBs were examined at equivalent particulate volume fractions. The CBs varied in their surface area and structure properties according to a wide experimental design space, allowing robust correlations to the experimental data sets to be extracted. Carbon black structure plays a dominant role in defining the monotonic stress–strain properties (e.g., secant moduli) of the compounds. In line with the previous literature, this is primarily due to strain amplification and occluded rubber mechanisms. For cyclic stress–strain properties, which include the Mullins effect and cyclic softening, the observed mechanical hysteresis is strongly correlated with carbon black structure, which implies that hysteretic energy dissipation at medium to large strain values is isolated in the rubber matrix and arises due to matrix overstrain effects. Under small to medium dynamic strain conditions, classical strain dependence of viscoelastic moduli is observed (the Payne effect), the magnitude of which varies dramatically and systematically depending on the colloidal properties of the CB. At low strain amplitudes, both CB structure and surface area are positively correlated to the complex moduli. Beyond ~2% strain amplitude the effect of surface area vanishes, while structure plays an increasing and eventually dominant role in defining the complex modulus. This transition in colloidal correlations reflects the transition in stiffening mechanisms from flexing of rigid percolated particle networks at low strains to strain amplification at medium to high strains. By rescaling the dynamic mechanical data sets to peak dynamic stress and peak strain energy density, the influence of CB colloidal properties on compound hysteresis under strain, stress, and strain energy density control can be estimated. This has considerable significance for materials selection in rubber product development.
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KREN, Alexander P. "IMPACT INDENTATION OF METALS AT THE SMALL ELASTOPLASTIC STRAIN". Mechanics of Machines, Mechanisms and Materials 1, nr 58 (marzec 2022): 56–63. http://dx.doi.org/10.46864/1995-0470-2022-1-58-56-63.
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The aim of this paper is to study and describe the behavior features of metals under impact loading in the area of elastic-plastic transition, with strains not exceeding 3–4 %, which are typical for measuring the hardness of materials during dynamic indentation. It has been established that until the state of full plasticity is reached, the excess of the dynamic hardness over the static one cannot be explained only by an increase of the strain rate and requires taking into account the elastic properties of the material. It is shown that a grow of the yield stress and the part of elastic deformation leads to a significant increase in the dynamic hardness of the material. This is due to the feature of measurements, which consists in fixing the value of the initial impact energy, which is distributed between elastic and plastic part of strain, depending on the characteristics of the material: yield stress, elastic modulus, strain-hardening coefficient.
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Jafarian, Yaser, i Hamed Javdanian. "Small-strain dynamic properties of siliceous-carbonate sand under stress anisotropy". Soil Dynamics and Earthquake Engineering 131 (kwiecień 2020): 106045. http://dx.doi.org/10.1016/j.soildyn.2020.106045.
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Lei, Xudong, Kailu Xiao, Xianqian Wu i Chenguang Huang. "Dynamic Mechanical Properties of Several High-Performance Single Fibers". Materials 14, nr 13 (25.06.2021): 3574. http://dx.doi.org/10.3390/ma14133574.
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High-performance fiber-reinforced composites (FRCs) are widely used in bulletproof structures, in which the mechanical properties of the single fibers play a crucial role in ballistic resistance. In this paper, the quasi-static and dynamic mechanical properties of three commonly used fibers, single aramid III, polyimide (PI), and poly-p-phenylenebenzobisoxazole (PBO) fibers are measured by a small-scale tensile testing machine and mini-split Hopkinson tension bar (mini-SHTB), respectively. The results show that the PBO fiber is superior to the other two fibers in terms of strength and elongation. Both the PBO and aramid III fibers exhibit an obvious strain-rate strengthening effect, while the tensile strength of the PI fiber increases initially, then decreases with the increase in strain rate. In addition, the PBO and aramid III fibers show ductile-to-brittle transition with increasing strain rate, and the PI fiber possesses plasticity in the employed strain rate range. Under a high strain rate, a noticeable radial splitting and fibrillation is observed for the PBO fiber, which can explain the strain-rate strengthening effect. Moreover, the large dispersion of the strength at the same strain rate is observed for all the single fibers, and it increases with increasing strain rate, which can be ascribed to the defects in the fibers. Considering the effect of strain rate, only the PBO fiber follows the Weibull distribution, suggesting that the hypothesis of Weibull distribution for single fibers needs to be revisited.
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Gao, Shuling, i Guanhua Hu. "Experimental Study on Biaxial Dynamic Compressive Properties of ECC". Materials 14, nr 5 (6.03.2021): 1257. http://dx.doi.org/10.3390/ma14051257.
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An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.
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Deng, Ji Wei, Chang Wu Liu i Jian Feng Liu. "Effect of Dynamic Loading on Mechanical Properties of Concrete". Advanced Materials Research 568 (wrzesień 2012): 147–53. http://dx.doi.org/10.4028/www.scientific.net/amr.568.147.
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Concrete structures have to bear dynamic loads in daily work, strength and deformation characteristics of concrete under dynamic loads differ from the characteristics under static loads, and this difference may become a key factor to restrict the structural safety under certain conditions. Using the MTS815 test system, the dynamic uniaxial compression tests of concrete specimens were conducted. The mechanical characteristic parameters of strength, elastic modulus, peak strain and the stress-strain curves at different loading rates of concrete specimens have been studied. The results reveal that concrete is a rate-sensitive material, as a small loading rate may lead to the rapid growth of strength; the variation rule of peak strain is not obvious with the increase of loading rate, thus the peak strain can be regarded as a fixed value in actual projects; the higher the loading rate is, the greater the concrete strength and the elastic modulus are; the elastic modulus increases essentially due to the improvement of structural stiffness; concrete specimens with the same mix proportion have similar stress-strain curves and the loading rate has little effect on the shape of the curve.
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Yang, Jie, Xin Cai, Yangong Shan, Miaomiao Yang, Xingwen Guo i Jinlei Zhao. "Small-Strain Dynamic Properties of Lean Cemented Sand and Gravel Materials under Different Cementing Agent Contents". Advances in Civil Engineering 2020 (24.11.2020): 1–13. http://dx.doi.org/10.1155/2020/8878506.
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Lean cemented sand and gravel (LCSG) materials are increasingly being used in dams, embankments, and other civil engineering applications. Therefore, their mechanical properties and stress-strain behavior should be systematically understood. In this study, the small-strain dynamic properties of LCSG materials were examined. A series of dynamic triaxial tests were performed to investigate the effects of the confining pressure and cementing agent content of the material on its dynamic shear modulus (Gd) and damping ratio (λ). The results show that Gd increased and λ decreased with increasing confining pressure and cementing agent content; however, under the same confining pressure and cementing agent content, Gd decreased gradually in accordance with shear strain. Furthermore, new expressions were derived for Gd and λ, as well as for their maxima. The results of this study could provide a reference for practical engineering applications, including the construction of dams using LCSG materials.
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Kang, Gyeong-o., Woong Choi i Changho Lee. "Prediction of Small-Strain Dynamic Properties on Granulated Spherical Glass Bead-Polyurethane Mixtures". Advances in Civil Engineering 2019 (12.09.2019): 1–12. http://dx.doi.org/10.1155/2019/6348326.
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This paper aims to propose predictive equations for the small-strain shear modulus (Gmax) and small-strain damping ratio (Dmin) of a granulated mixture with plastic and nonplastic materials to reduce the dynamic energy of the ground. Polyurethane bead (PB) and glass bead (GB) were used as the plastic and nonplastic materials, respectively. 180 resonant-column tests were conducted with various conditions affecting the dynamic properties, such as nonplastic particle content (PC), void ratio (e), particle-size ratio (sr), and mean effective confining pressure (σm′). The results showed that Gmax and Dmin, respectively, increased and decreased as e decreased with increasing σm′ of material mixtures. In addition, Gmax decreased with an increase in PC, whereas Dmin increased. It was also found that sr of materials affected the changes in Gmax and Dmin. With an increase in sr, Gmax increased while Dmin decreased because small particles do not hinder the behavior of large particles as the size of larger particles increases. Finally, based on the results, new equations for estimating Gmax and Dmin of a granulated mixture with PB and GB were proposed as functions of PC, e, median grain size (D50), and σm′.
Rozprawy doktorskie na temat "Small strain dynamic properties"
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Beyerlein, Kenneth Roy. "Simulation and Modeling of the Powder Diffraction Pattern from Nanoparticles: Studying the Effects of Faulting in Small Crystallites". Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/368693.
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Accurate statistical characterization of nanomaterials is crucial for their use in emerging technologies. This work investigates how different structural characteristics of metal nanoparticles influence the line profiles of the corresponding powder diffraction pattern. The effects of crystallite size, shape, lattice dynamics, and faulting are all systematically studied in terms of their impact on the line profiles.
The studied patterns are simulated from atomistic models of nanoparticles via the Debye function. This approach allows for the existing theories of diffraction to be tested, and extended, in an effort to improve the characterization of small crystallites. It also begins to allow for the incorporation of atomistic simulations into the field of diffraction. Molecular dynamics simulations are shown to be effective in generating realistic structural models and dynamics of an atomic system, and are then used to study the observed features in the powder diffraction pattern.
Furthermore, the characterization of a sample of shape controlled Pt nanoparticles is carried out through the use of a developed Debye function analysis routine in an effort to determine the predominant particle shape. The results of this modeling are shown to be in good agreement with complementary characterization methods, like transmission electron microscopy and cyclic voltammetry.
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Venables, R. "Dynamic strain ageing and the fatigue behaviour of nimonic 901". Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376646.
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Voorhies, Katherine Desiree. "Static and Dynamic Stress/Strain Properties for Human and Porcine Eyes". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31867.
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Every year, more than 2.4 million eye injuries occur in the United States, with over 30,000 of those injured left blind in at least one eye as a result. Computer modeling is one of the most versatile ways to study ocular trauma, however, existing models lack accurate stress and strain properties for ocular globe rupture. A pressure system was built to examine static and dynamic globe rupture pressures for healthy postmortem human and porcine (pig) eyes. Maximum rupture stress for the quasi-static tests was found to be 11.17MPa for human tissue and 12.08MPa for porcine tissue, whereas stress for the dynamic tests was found to be 30.18MPa for human tissue and 26.01MPa for porcine tissue. Maximum rupture stress results correlate well with static material properties used in published research (9.4MPa), and dynamic properties of 23MPa found in published research. Healthy postmortem human eyes were ruptured statically and dynamically to determine the relationship between stress and strain for the ocular globe under intraocular pressure loading. Stress-strain relationships were investigated and values for the elastic modulus were found to be slightly lower than that previously published. This research shows that it is important to differentiate between tissue type, and static versus dynamic failure properties before drawing conclusions from computer models and other published research. Now that rupture can be accurately determined, safety systems designed to protect eyesight in automotive, sports, and military applications can also be applied to protect the quality of life for humans in these applications.Master of Science
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Wang, J., S. Dong, Ashraf F. Ashour, X. Wang i B. Han. "Dynamic mechanical properties of cementitious composites with carbon nanotubes". Elsevier, 2019. http://hdl.handle.net/10454/17465.
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YesThis paper studied the effect of different types of multi-walled carbon nanotubes (MWCNTs) on the dynamic mechanical properties of cementitious composites. Impact compression test was conducted on various specimens to obtain the dynamic stress-strain curves and dynamic compressive strength as well as deformation of cementitious composites. The dynamic impact toughness and impact dissipation energy were, then, estimated. Furthermore, the microscopic morphology of cementitious composites was identified by using the scanning electron microscope to show the reinforcing mechanisms of MWCNTs on cementitious composites. Experimental results show that all types of MWCNTs can increase the dynamic compressive strength and ultimate strain of the composite, but the dynamic peak strain of the composite presents deviations with the MWCNT incorporation. The composite with thick-short MWCNTs has a 100.8% increase in the impact toughness, and the composite with thin-long MWCNTs presents an increased dissipation energy up to 93.8%. MWCNTs with special structure or coating treatment have higher reinforcing effect to strength of the composite against untreated MWCNTs. The modifying mechanisms of MWCNTs on cementitious composite are mainly attributed to their nucleation and bridging effects, which prevent the micro-crack generation and delay the macro-crack propagation through increasing the energy consumption.
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Lo, Kai Fung. "Small-strain shear modulus and damping ratio determination by bender element /". View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20LOK.
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Kemper, Andrew Robb. "Material Properties of Human Rib Cortical Bone from Dynamic Tension Coupon Testing". Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/43709.
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The purpose of this study was to develop material properties of human rib cortical bone using dynamic tension coupon testing. This study presents 117 human rib cortical bone coupon tests from six cadavers, three male and three female, ranging in age from 18 to 67 years old. The rib sections were taken from the anterior, lateral, and posterior regions on ribs 1 through 12 of each cadaver's rib cage. The cortical bone was isolated from each rib section with a low speed diamond saw, and milled into dog bone shaped tension coupons using a small computer numerical control machine. A high-rate servo-hydraulic Material Testing System equipped with a custom slack adaptor, to provide constant strain rates, was used to apply tension loads to failure at an average rate of 0.5 strains/sec. The elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, and strain energy density were determined from the resulting stress versus strain curves. The overall average of all cadaver data gives an elastic modulus of 13.9 GPa, a yield stress of 93.9 MPa, a yield strain of 0.883 %, an ultimate stress of 124.2 MPa, an ultimate strain of 2.7 %, and a strain energy density of 250.1 MPa-strain. For all cadavers, the plastic region of the stress versus strain curves was substantial and contributed approximately 60 strain % to the overall response and over 80 strain % in the tests with the 18 year old cadaver. The rib cortical bone becomes more brittle with increasing age, shown by an increase in the modulus (p < 0.01) and a decrease in peak strain (p < 0.01). In contrast to previous three-bending tests on whole rib and rib cortical bone coupons, there were no significant differences in material properties with respect to rib region or rib level. When these results are considered in conjunction with the previous three-point bending tests, there is regional variation in the structural response of the human rib cage, but this variation appears to be primarily a result of changes in the local geometry of each rib while the material properties remain nearly constant within an individual.Master of Science
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Kates, Gina L. "Development and implementation of a seismic flat dilatometer test for small-and high-strain soil properties". Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/20234.
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Bisplinghoff, Jill Aliza. "Biomechanical Response of the Human Eye to Dynamic Loading". Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31880.
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Blindness due to ocular trauma is a significant problem in the United States considering that each year approximately 500,000 years of eyesight are lost. The most likely sources of eye injuries include sports related impacts, automobile accidents, consumer products, and military combat. Out of the 1.9 million total eye injuries in the country, more than 600,000 sports injuries occur each year and 40,000 of them require emergency care. In 2007, approximately 66,000 people suffered from vehicle related eye injuries in the United States. Of the vehicle occupants sustaining an eye injury during a crash, as many as 15% to 25% sustained severe eye injuries and it was shown that within these severe eye injuries as many as 45% resulted in globe rupture.
The purpose of this thesis is to characterize the biomechanical response of the human eye to dynamic loading. A number of test series were conducted with different loading conditions to gather data. A drop tower pressurization system was used to dynamically increase intraocular pressure until rupture. Results for rupture pressure, stress and strain were reported. Water streams that varied in diameter and velocity were developed using a customized pressure system to impact eyes. Intraocular pressure, normalized energy and eye injury risk were reported. A Facial and Ocular Countermeasure Safety (FOCUS) headform was used to measure the force applied to a synthetic eye during each hit from projectile shooting toys. The risk of eye injury for each impact was reported. These data provide new and significant research to the field of eye injury biomechanics to further the understanding of eye injury thresholds.
Master of Science
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Almaari, Firas, i Essam Aljbban. "Strain Rate Effect on Fracture Mechanical Properties of Ferritic-Pearlitic Ductile Iron". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-78858.
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This study investigates the effect of strain rate on fracture properties of Ferritic-Pearlitic Ductile Iron. A series of dynamic three point bending tests, with various load application rates, are conducted on Charpy V-notch specimens, in room temperature and approximately -18 °C. The tests are performed in a custom-made fixture and during the tests, force and displacement data are recorded. A XFEM (Extended Finite Element Method) model of the test setup has been established and material data from the tests are used as input to the model. The test results show a strong dependency of the strain rate regarding the force needed for crack initiation. Moreover, it can be concluded that low temperature makes the material very brittle, even at low load application rates.
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Sears, Nicholas C. "Investigations into the Quasi-Static and Dynamic Properties of Flexible Hybrid Electronic Material Systems". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525278328687427.
Pełny tekst źródłaKsiążki na temat "Small strain dynamic properties"
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Antos, R., i Y. Otani. The dynamics of magnetic vortices and skyrmions. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198787075.003.0022.
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This chapter argues that control of magnetic domains and domain wall structures is one of the most important issues from the viewpoint of both applied and basic research in magnetism. Its discussion is however limited to static and dynamic properties of magnetic vortex structures. It has been revealed both theoretically and experimentally that for particular ranges of dimensions of cylindrical and other magnetic elements, a curling in-plane spin configuration is energetically favored, with a small region of the out-of-plane magnetization appearing at the core of the vortex. Such a system, which is sometimes referred to as a magnetic soliton, is characterized by two binary properties: A chirality and a polarity, each of which suggests an independent bit of information in future high-density nonvolatile recording media.
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White, Robert, i Mark Krstic. Healthy Soils for Healthy Vines. CSIRO Publishing, 2019. http://dx.doi.org/10.1071/9781486307395.
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Healthy Soils for Healthy Vines provides a clear understanding of vineyard soils and how to manage and improve soil health for best vineyard performance. It covers the inherent and dynamic properties of soil health, how to choose which soil properties to monitor, how to monitor soil and vine performance, and how vineyard management practices affect soil health, fruit composition and wine sensory characters. It also covers the basic tenets of sustainable winegrowing and their significance for business resilience in the face of a changing climate.
This book will be of practical value to anyone growing grapevines, managing a vineyard or making wine, from the small individual grower to the large wine company employee. It will be of special interest to winegrowers employing organic, natural or biodynamic methods of production, where the primary focus is on the biological health of the soil.
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Webb, Andrew. Colloids in critical illness. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0056.
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Colloid solutions are homogenous mixtures of large molecules suspended in a crystalloid solution. The efficacy of colloids as volume substitutes or expanders, and length of effect are determined by their physicochemical properties. Smaller volumes of colloid than crystalloid are required for resuscitation. The primary use of colloids is in the correction of circulating volume. Rather than using fixed haemodynamic endpoints, fluid can be given in small aliquots with assessment of the dynamic haemodynamic response to each aliquot. The aim of a fluid challenge is to produce a small, but significant (200 mL) and rapid increase in plasma volume with changes in central venous pressure or stroke volume used to judge fluid responsiveness. Colloid fluids give a reliable increase in plasma volume to judge fluid responsiveness.
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Romagnoli, Stefano, i Giovanni Zagli. Blood pressure monitoring in the ICU. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199600830.003.0131.
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Two major systems are available for measuring blood pressure (BP)—the indirect cuff method and direct arterial cannulation. In critically-ill patients admitted to the intensive care unit, the invasive blood pressure is the ‘gold standard’ as a tight control of BP values, and its change over time is important for choosing therapies and drugs titration. Since artefacts due to the inappropriate dynamic responses of the fluid-filled monitoring systems may lead to clinically relevant differences between actual and displayed pressure values, before considering the BP value shown as reliable, the critical care giver should carefully evaluate the presence/absence of artefacts (over- or under-damping/resonance). After the arterial pressure waveform quality has been verified, the observation of each component of the arterial wave (systolic upstroke, peak, systolic decline, small pulse of reflected pressure waves, dicrotic notch) may provide a number of useful haemodynamic information. In fact, changes in the arterial pulse contour are due the interaction between the heart beat and the whole vascular properties. Vasoconstriction, vasodilatation, shock states (cardiogenic, hypovolaemic, distributive, obstructive), valve diseases (aortic stenosis, aortic regurgitation), ventricular dysfunction, cardiac tamponade are associated with particular arterial waveform characteristics that may suggest to the physician underlying condition that could be necessary to investigate properly. Finally, the effects of positive-pressure mechanical ventilation on heart–lung interaction, may suggest the existence of an absolute or relative hypovolaemia by means of the so-called dynamic indices of fluid responsiveness.
Części książek na temat "Small strain dynamic properties"
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Song, Binghui, Angelos Tsinaris, Anastasios Anastasiadis, Kyriazis Pitilakis i Wenwu Chen. "Small to Medium Strain Dynamic Properties of Lanzhou Loess". W Proceedings of the 4th International Conference on Performance Based Design in Earthquake Geotechnical Engineering (Beijing 2022), 2141–50. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11898-2_197.
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Chiaro, Gabriele, Ali Tasalloti, Alessandro Palermo i Laura Banasiak. "Small-Strain Shear Stiffness and Strain-Dependent Dynamic Properties of Gravel-Rubber Mixtures". W Lecture Notes in Civil Engineering, 467–77. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1579-8_36.
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Khan, K. A., Sukanta Das i B. K. Maheshwari. "Effect of Degree of Saturation on Dynamic Properties of Solani Sand in Small Strain". W Lecture Notes in Civil Engineering, 223–31. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6564-3_20.
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Miralbes, R., D. Ranz i D. Zouzias. "Study of the Use of Sawdust and Mycelium Composite as a Substitute of EPS". W Lecture Notes in Mechanical Engineering, 67–72. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_12.
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AbstractExpanded polystyrene foams are a petroleum-origin material that is usually used in some applications such as motorcyclist helmets. Despite it notably mechanical properties, it low density and its capability to absorb energy during an impact, it is necessary to find a renewable-origin substitute material. Thus, it has been studied the use of a sawdust and mycelium composite material under quasi-static and dynamic efforts. Sawdust is a waste material that has very small grains that are totally disaggregated so it has very low material properties. The use of oyster mushroom mycelium generates an internal structure that joins grains and, consequently, the resultant material has notably high mechanical properties. Then it has been compared the resultant properties (stress-strain curve, absorbed energy, decelerations, etc.) with the different densities EPS ones and it has been concluded that this composite material, despite it high density, it could be a suitable substitute material and in some cases it has better properties.
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Tsuji, Nobuhiro, Shigenobu Ogata, Haruyuki Inui, Isao Tanaka i Kyosuke Kishida. "Proposing the Concept of Plaston and Strategy to Manage Both High Strength and Large Ductility in Advanced Structural Materials, on the Basis of Unique Mechanical Properties of Bulk Nanostructured Metals". W The Plaston Concept, 3–34. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7715-1_1.
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AbstractAdvanced structural materials are required to show both high strength and large ductility/toughness, but we have not yet acquired the guiding principle for that. The bulk nanostructured metals are polycrystalline metallic materials having bulky dimensions and average grain sizes smaller than 1 μm. Bulk nanostructured metals show very high strength compared with that of the coarse-grained counterparts, but usually exhibit limited tensile ductility, especially small uniform elongation below a few %, due to the early plastic instability. On the other hand, we have recently found that particular bulk nanostructured metals can manage high strength and large tensile ductility. In such bulk nanostructured metals, unusual deformation modes different from normal dislocation slips were unexpectedly activated. Unusual <c+a> dislocations, deformation twins with nano-scale thickness, and deformation-induced martensite nucleated from grain boundaries in the bulk nanostructured Mg alloy, high-Mn austenitic steel, and Ni-C metastable austenitic steel, respectively. Those unexpected deformation modes enhanced strain hardening of the materials, leading to high strength and large tensile ductility. It was considered that the nucleation of such unusual deformation modes was attributed to the scarcity of dislocations and dislocation sources in each recrystallized ultrafine grain, which also induced discontinuous yielding with clear yield drop universally recognized in bulk nanostructured metals having recrystallized structures. For discussing the nucleation of different deformation modes in atomistic scales, the new concept of plaston which considered local excitation of atoms under singular dynamic fields was proposed. Based on the findings in bulk nanostructured metals and the concept of plaston, we proposed a strategy for overcoming the strength-ductility trade-off in structural metallic materials. Sequential nucleation of different deformation modes would regenerate the strain-hardening ability of the material, leading to high strength and large tensile ductility. The strategy could be a guiding principle for realizing advanced structural materials that manage both high strength and large tensile ductility.
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Pelleg, Joshua. "Dynamic Deformation—The Effect of Strain Rate". W Mechanical Properties of Nanomaterials, 181–255. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-74652-0_6.
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Fei, Kang, Jinxin Xu, Jian Qian i Wei Hong. "Strain dependent dynamic properties of clay–gravel mixtures". W Advances in Energy Science and Equipment Engineering II, 1203–10. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2017. http://dx.doi.org/10.1201/9781315116174-69.
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Chiu, Y. W., X. H. Zhang, H. Hao i N. Salter. "Dynamic Tensile Properties of Clay Brick at High Strain Rates". W Lecture Notes in Civil Engineering, 677–85. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-8079-6_64.
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Wang, Yingchun, Shukui Li i Jinxu Liu. "Strain rate-dependent and temperature- dependent compressive properties of 2DCf/SiC Composite". W Dynamic Behavior of Materials, Volume 1, 287–94. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-8228-5_41.
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Ott, Kyle A., R. S. Armiger, A. C. Wickwire, A. S. Iwaskiw i Andrew C. Merkle. "Determination of Simple Shear Material Properties of the Brain at High Strain Rates". W Dynamic Behavior of Materials, Volume 1, 139–47. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4238-7_18.
Pełny tekst źródłaStreszczenia konferencji na temat "Small strain dynamic properties"
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Ajmera, Beena, Binod Tiwari i Quoc-Hung Phan. "Small Strain Dynamic Properties of Silt-Clay Mixtures". W Geo-Congress 2020. Reston, VA: American Society of Civil Engineers, 2020. http://dx.doi.org/10.1061/9780784482810.021.
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Bonifasi-Lista, Carlos, Spencer P. Lake, Michael S. Small i Jeffrey A. Weiss. "Viscoelastic Properties of Human MCL in the Transverse Direction". W ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32621.
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Ligament viscoelasticity is an important determinant of tissue response to rapid loading and potential for injury, and may also play a role in tissue nutrition via fluid movement during loading/unloading. Because ligaments are anisotropic multiphase structures, it is likely that their viscoelastic response is direction-dependent. Previous efforts to describe ligament viscoelasticity have either reported experimental data without theoretical interpretation (e.g., [1]), or assumed a particular form for the viscoelastic response a priori [2–4]. Small sinusoidal perturbations about an equilibrium strain value allow application of linear viscoelasticity theory for determination of storage modulus (dynamic stiffness) and loss modulus (phase, or damping) as a function of frequency and equilibrium strain level. With these data, one can assess the appropriateness of different viscoelastic and/or poroelastic models to describe time- and rate-dependent constitutive behavior.
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Shilo, Doron, Amir Mendelovich i Haika Drezner. "Electromechanical Response of Large Strain Ferroelectric Actuators". W ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59107.
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One of the desired properties of actuators is large actuation strains, which also correlates with large work output per volume. This property becomes especially important in micro systems where small devices are required to produce relatively large strokes. The existing mechanisms for electromechanical actuation are limited to small actuation strains and hence recent years have seen a variety of attempts at achieving larger strain actuation. One such attempt, basing on 90 degree domain switching in ferroelectric crystals subjected to compression load and cyclic electric field, has recently been demonstrated. In this presentation we explore the dynamics of 90 degree domain switching at high frequencies. For this purpose a novel ferroelectric actuator and experimental system were developed, which allow measuring the response of a BaTiO3 single crystal to a combination of constant tensile stress and cyclic electric field at frequencies of up to 100 kHz. Experimental results are compared with theoretical calculations basing on a new model which considers the motion of discrete domain walls. Current results exhibit actuation strains of up to 0.8% (an order of magnitude larger than piezoelectric strains) and no decrease of actuation strains up to several kHz.
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Valle, Celestino, Beatriz I. Camacho, Kenneth H. Stokoe i Alan F. Rauch. "Comparison of the Dynamic Properties and Undrained Shear Strengths of Offshore Calcareous Sand and Artificially Cemented Sand". W ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37091.
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Calcareous sand specimens were obtained from Campeche Bay in the southern Gulf of Mexico. The dynamic properties of these specimens were measured in resonant column and torsional shear (RCTS) tests, while the undrained shear strength was measured in unconsolidated-undrained (UU) triaxial compression tests. For weakly cemented, natural materials like this, it is difficult to obtain reliable properties from laboratory tests because sampling and handling of the soil specimens damages the particle cementation to an unknown degree. Artificially cemented specimens can be studied to better understand this problem. In this work, the strength and dynamic properties of artificially cemented sand were also measured using RCTS and UU tests. The artificially cemented specimens were formed by mixing uniform sand with a sodium silicate solution. The degree of cementation was varied by using different sodium silicate concentrations. This approach could be used to reproduce cemented test specimens in the laboratory with similar mechanical properties as cemented offshore soils. The results from this limited study show that the small-strain dynamic properties measured in the laboratory, and their variation with confining pressure, clearly identifies disturbance in the calcareous soils.
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Valle, Celestino, i Kenneth H. Stokoe. "Laboratory Measurements of the Dynamic Properties of Intact and Remolded Offshore Clays From Campeche Bay". W ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37248.
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Comparisons of the dynamic properties of intact and remolded offshore clay specimens has been carried out. The clay specimens were obtained from Campeche Bay, offshore Mexico. Combined resonant column and torsional shear (RCTS) equipment at the University of Texas at Austin was used to determine the dynamic soil properties. Each soil specimen was tested twice, first in the intact condition and second as remolded material. Remolding was done by kneading the intact material and then reforming the specimen by compacting in a mold. The effects on the dynamic properties, expressed by shear modulus and material damping ratio, between intact and remolded conditions are discussed. As expected, shear modulus and material damping at small and large strains are affected by remolding. Interestingly, the normalized modulus degradation curves were changed very little by remolding up to strains between 0.06 and 0.1%. The results offer insight into the effects of sampling disturbance on linear and nonlinear dynamic soil properties.
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McClure, Michael J., Scott A. Sell i Gary L. Bowlin. "Multi Layered Polycaprolactone-Elastin-Collagen Small Diameter Conduits for Vascular Tissue Engineering". W ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192895.
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The architecture of the vascular wall is highly intricate and requires unique biomechanical properties in order to function properly. Native artery is composed of a mix of collagens, elastin, endothelial cells (ECs), smooth muscle cells (SMC), fibroblasts, and proteoglycans arranged into three distinct layers: the intima, media, and adventitia. Throughout artery, collagen and elastin play an important role, providing a mechanical backbone, preventing vessel rupture, and promoting recovery while undergoing pulsatile deformations [1]. The low-strain mechanical response of artery to blood flow is dominated by the elastic behavior, of elastin, which prevents pulsatile energy from being dissipated as heat [2]. A higher amount of energy loss indicates a decrease in recoverability, which could lead to eventual disruption of blood flow. An effective way to quantify recoverability is through hysteresis and compliance measurement. The hypothesis of this study was that the fabrication of a multi-layered electrospun tissue engineering scaffold composed of polycaprolactone (PCL), elastin, and collagen would demonstrate dynamic mechanical properties indicative of a highly elastic material, similar to the three distinct layers of native arterial tissue, while remaining conducive to tissue regeneration. PCL was chosen, in this case, to provide mechanical integrity and elasticity, while elastin and collagen would provide further elasticity and bioactivity [3,4].
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Darvish, Kurosh, Erik G. Takhounts i Jeff R. Crandall. "A Dynamic Method to Develop Nonlinear Viscoelastic Model of Brain Tissue". W ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0122.
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Abstract The objective of this paper is to present an instrumentation and data analysis method developed to determine a nonlinear viscoelastic model of brain tissue using a forced vibration technique. The application of this model is mainly for studying the injury mechanisms of brain tissue resulting from impacts to the head. Since the early 1950s several attempts have been recorded to model the mechanical behavior of brain tissue. Investigators have used a variety of quasi-static and dynamic experimental techniques in their studies and there is a general agreement that brain exhibits viscoelastic characteristics (Galford and McElhaney, 1969). However, there are three major limitations associated with most of the previous studies. First is the limitation of boundary and environmental conditions. By applying small strains (less than 10%), most researchers have explained their experimental results with linear models (Shuck and Advani, 1972). However, biomechanical models show that shear strains up to 100% occur in brain in impact situations (Ueno et al., 1996). To include finite deformation, a nonlinear model is needed to characterize the biomechanics of impact and injury of the brain tissue. Although viscoelastic material properties are generally very sensitive to temperature (Haddad, 1995), the effect of temperature on brain material properties has not been investigated in the previous studies. Most in vitro tests have been performed in the room temperature and only a few in vivo studies have been reported (Fallenstein et al., 1969; Wang and Wineman, 1972). The effect of gravity has not been addressed in the previous studies. The brain sample is so soft that it creeps under its own weight, which causes pre-stress and pre-strain in the sample (Takhounts, 1998). The second limitation is with regard to the constitutive models. A few researchers, who have investigated the nonlinear behavior of the brain tissue, have presented the results of their studies in some special forms of stress-strain relationships (Donnely, 1993). These relationships are generally dependent on the type of experiment and can not be used for other types of loading and deformation. In order to develop an analytical or numerical model of brain, a three-dimensional constitutive relation is required that is independent of the type of experiment. The third limitation is the experimental methods. In the stress relaxation test method, due to hardware and inertial limitations, the jump of ideal step input is usually simulated with high-speed ramp input (Takhounts, 1998). Therefore, time constants that are shorter than the ramp time interval (about 0.04 s) can not be identified in the relaxation response. The small time constants have a significant effect in the short time response of the material, which is of primary interest in the biomechanics of impact and injury. On the other hand, due to inertial effects, the transient vibration of the system perturbs the first portion (about 400 ms) of the relaxation curve (Takhounts, 1998). In the ramp test method also, due to the initial acceleration period, the short time constants can not be measured correctly (Donnely, 1993). Previous studies based on the forced vibration technique, due to hardware limitations, have been performed in the frequency range of 5–350 Hz with strain levels of up to 35% (Shuck and Advani, 1972; Arbogast et al., 1997). These results have been used to develop linear viscoelastic models for shear with time constants in the range of 0.4 to 32 milliseconds. In the method presented in this paper, the goal was to develop a viscoelastic model of brain tissue that is free from the constraints discussed above. The samples are taken from fresh human and bovine brain tissues (maximum 24 hours after death or slaughter). Samples are cut with cylindrical metal cores (5–20 mm diameter) from different parts of the brain tissue and in transverse and vertical anatomic directions. Using the same experimental apparatus, cylindrical samples with the length of 5–30 mm are studied in both simple extension and in simple shear modes. In order to study the effect of temperature, canceling the effect of gravity and minimizing material deterioration, each sample is placed in a temperature controlled slow flow of saline solution throughout the experiment. An electromechanical vibrator with frequency response of dc-6500 Hz and maximum force of 65lb is used to apply the input displacement to one end of the specimen. The characteristics of the vibrator allow the identification of a wide range of time constants of the brain tissue (from 80 μs to 1.6 s) in a wide range of strain inputs (infinitesimal to 100%). The reaction force at the other end of the specimen is recorded via a miniature high precision load cell. As shown in figure 1, the analog signals of the load cell, an accelerometer that measures the motion of the vibrator, and a thermocouple that measures the temperature of the sample are collected via an isolated analog to digital converter in a personal computer. Via a digital to analog converter, the computer also controls the motion of the vibrator. The whole system works as a closed loop control system. The resultant forces of a simple harmonic displacement input and also the superposition of a series of simple harmonic inputs are analyzed in the frequency domain to generate linear, quasilinear and nonlinear third order Green-Rivlin viscoelastic models of the brain tissue (Fung, 1993 and Lockett, 1972). In addition, square wave and triangular wave inputs are applied to study the relaxation and hysteresis phenomena. The lateral movement of the samples is recorded with a high-speed camera and digital image analysis. The results obtained from the samples in transverse and vertical directions are used to develop three-dimensional transversely isotropic models. Preliminary experiments, as shown in figure 2, show that for low strain levels below 10%, linear viscoelastic model describes the short time behavior of brain tissue to a high degree of accuracy. For strain levels between 10% to 40% and short relaxation times below 100 ms, a quasilinear model can be used that only considers the strain nonlinearity of the material. Assuming that the effect of a single relaxation exponential function, after passing four time constants, is negligible, 100 ms relaxation time corresponds to the frequency of 6.4 Hz. For higher strain levels (up to 100%) and longer relaxation times (up to 5 s) or lower frequencies (below 6.4 Hz), a third order Green-Rivlin model, which includes both strain and time nonlinearity, should be used. The discrete spectrum approximation is used to represent the relaxation functions. It is shown that by using this form, the nonlinear models can be easily implemented in numerical algorithms that can be used in finite element programs (Puso and Weiss, 1998). A complete set of tests on a single specimen takes between 15–30 minutes. Therefore, multiple sections from a whole brain can be analyzed in a few hours, which minimizes the effect of material deterioration.
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Tang, Weihan, Seunghun Baek i Bogdan I. Epureanu. "Reduced Order Models for Blisks With Small and Large Mistuning and Friction Dampers". W ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57850.
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In operation, rotating bladed disks (blisks) are often subject to high levels of dynamic loading, resulting in large amplitudes of forced vibrations especially at resonance. Moreover, variations in structural properties of individual sectors, referred to as mistuning, can lead to strain energy localization and can amplify forced responses. To prevent damages caused by high cycle fatigue, various frictional damping sources are introduced to dissipate vibration energy. Due to the nonlinear behavior of frictional contacts, conventional methods to study the dynamics of the blisk-damper systems are based often on numerical time integration, which is time-consuming and can be computationally prohibitive due to the large sizes of commercial blisk models. Existing techniques for model reduction either rely heavily on cyclic symmetry of the blisk-damper system, or are based on component mode synthesis (CMS). However, in the presence of mistuning, cyclic symmetry no longer exists. Also, mistuning is random and best studied statistically. Repetitive CMS condensation for a large amount of random mistuning patterns can lead to a computationally formidable task. This paper presents a reduced-order modeling technique to efficiently capture the nonlinear dynamic responses of blisk-damper systems with both small perturbations in blade material properties (small mistuning), and significant changes in the blisk geometries (large mistuning). The reduced-order models (ROMs) are formed by projecting the blisk-damper systems onto a novel mode basis that mimics the contact behavior. This mode basis contains normal mode shapes of the mistuned blisk-damper systems with either sliding or sticking conditions enforced on the contact surfaces. These mode shapes are computed through the N-PRIME method, a technique recently developed by the authors to efficiently obtain mode shapes for blisks with simultaneous large and small mistuning. The resulting modal nonlinear equations of motion are solved by a hybrid frequency/time (HFT) domain method with continuation. In the HFT method, the contact status and friction forces are determined in the time domain by a quasi-two-dimensional contact model at each contact point, whereas the modal equations of motion are solved in the frequency domain according to a harmonic balance formulation. The forced responses computed by the proposed ROMs are validated for two systems with distinct mistuning patterns. A statistical analysis is performed to study the effectiveness of the frictional dampers under random mistuning patterns.
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Daghash, Sherif, Osman E. Ozbulut i Muhammad M. Sherif. "Shape Memory Alloy Cables for Civil Infrastructure Systems". W ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7562.
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Shape memory alloys (SMAs) have attracted a great deal of attention as a smart material that can be used in various civil engineering applications due to their favorable mechanical properties such as ability to undergo large deformations, high corrosion and fatigue resistance, good energy dissipating capacity, and excellent re-centering ability. In contrast to the use of SMAs in the biomedical, mechanical and aerospace applications, which requires mostly small diameter of material, the larger size bars are usually needed in a civil engineering application. It is well known that properties of large-section SMA bars are generally poorer than those of wires due to difficulties in material processing. Furthermore, large diameter SMA bars are more expensive than thin SMA wires. Shape memory alloy cables have been recently developed as an alternative and new structural element. They leverage the superior mechanical characteristics of small diameter SMAs into large-size structural tension elements and possess several advantages over SMA bars. This study explores the performance of NiTi SMA cables and their potential use in civil engineering. The SMA cable, which has a diameter of 8 mm, is composed of 7 strands and each strand has 7 wires with a diameter of 0.885 mm. The uniaxial tensile tests are conducted at various loading rates and strain amplitudes to characterize the superelastic properties of the SMA cable and study the rate-dependent mechanical response of the SMA cable under dynamic loads. An optical digital image correlation measurement system and an infrared thermal imaging camera are employed to obtain the full-field strain and temperature fields. Potential applications of SMA cables in civil infrastructure applications are discussed and illustrated.
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Lall, Pradeep, Di Zhang i Vikas Yadav. "High Strain-Rate Constitutive Behavior of SAC305 Solder During Operation at High Temperature". W ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-39518.
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Leadfree solders have been used as interconnects in electronic packaging, due to its environmental friendly chemical property. However, those materials may experience high strain rates when subjected to shock and vibration. Consequently, failure will occur to electronics in those situations. Therefore, knowing the material properties of lead-free solders are extremely important, but research on mechanical behaviors of those solder alloys at high strain rates are scarce. Anand’s viscoplastic constitutive model has been widely used to describe the inelastic deformation behavior of solders in electronic components under thermo-mechanical deformation. However, Anand’s model constants for the transient dynamic strain rates are scarce. In this paper, the nine material parameters to fit the Anand viscoplastic model at high strain rates have been presented. In order to develop the constants for this model, uniaxial tensile tests at several strain rates and temperatures have been completed. A constant strain rate impact hammer which enables attaining strain rates around 1 to 100 per sec has been employed to implement tensile tests and a small thermal chamber is applied to control testing temperature. High speed cameras operating at 70,000 fps have been used to capture images of specimen and then digital image correlation method is used to calculate tensile strain. Uniaxial stress-strain curves have been plotted over a wide range of strain rates (ε̇ = 10, 35, 50, 75 /sec) and temperatures (T = 25, 50, 75, 100, 125°C). Anand viscoplasticity constants have been calculated by nonlinear fitting procedures. In addition, the accuracy of the extracted Anand constants has been evaluated by comparing the model prediction and experimental data.
Raporty organizacyjne na temat "Small strain dynamic properties"
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Murray, Matthew, Trace Thornton, Stephen Rowell i Clifford Grey. Dynamic material properties of Grade 50 steel : effects of high strain rates on ASTM A992 and A572 Grade 50 steels. Engineer Research and Development Center (U.S.), sierpień 2023. http://dx.doi.org/10.21079/11681/47445.
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Uniaxial tensile tests were conducted on American Society for Testing Materials International (ASTM) A992 and A572 Grade 50 steels at increasing strain rates to determine the material strength properties of structural members subjected to dynamic loadings. The increase in dynamic yield strength and ultimate tensile strength was determined to update design criteria within UFC 3-340-02, which are currently limited to ASTM A36 and A514 steels. The proposed updates will provide the necessary information required to design blast-resistant structures utilizing modern-day structural steels. The dynamic material properties determined by high-rate tensile tests were compared to static values obtained from ASTM E8 standard tensile tests. The comparisons were used to calculate dynamic increase factors (DIFs) for each steel at strain rates from 2E-3 to 2E0 inch/inch/second. The experiments revealed that the A992 steel exhibited an increase in yield strength up to 45% and ultimate tensile strength up to 20% as strain rate increased over the range tested. The A572-50 steel exhibited a similar increase in yield strength up to 35% and ultimate tensile strength up to 20%. The DIF design curves developed during this research will allow engineers to more efficiently design structural steel components of hardened structures for the protection of our nation’s critical infrastructure.
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Subramanian, K. H. Test Plan to Update SRS High Level Waste Tank Material Properties Database by Determining Synergistic Effects of Dynamic Strain Aging and Stress Corrosion Cracking. Office of Scientific and Technical Information (OSTI), marzec 2002. http://dx.doi.org/10.2172/799694.
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Christman. L51577 Prediction of SCC Susceptibility Based on Mechanical Properties of Line Pipe Steels. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), sierpień 1988. http://dx.doi.org/10.55274/r0010278.
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If a relationship between the deformation properties of a line pipe steel and its stress-corrosion cracking resistance can be established, then steels may be selected or designed for improved stress-corrosion resistance, based on their mechanical properties. Benefit: In this research program three line pipe steels, removed from long-term service, were examined to determine if there is a correlation between their mechanical properties and stress-corrosion cracking resistance. The hypothesis was that the steel with the greatest tendency for strain hardening, under cyclic and monotonic stress conditions would also have the highest threshold stress for stress-corrosion crack initiation. This hypothesis was verified by the laboratory experiments, which showed the steel with the greatest tendency for strain hardening to have the highest resistance to stress-corrosion. Two other steels, with distinctly lower resistance to plastic deformation, had lower threshold stresses for stress-corrosion. This observation is consistent with the present concept of stress-corrosion crack growth, which holds that crack tip dissolution, and hence crack propagation, occurs because localized plastic deformation ruptures passive films or prevents film formation resulting in crack growth. Result: The cyclic strain behavior of these three steels is consistent with their monotonic stress-strain curves. Both Steels A and B showed a point of extreme strain as the cyclic stress was increased. Their monotonic stress-strain curves both showed well pronounced yield points above which a considerable strain accompanied a small stress increment (low strain hardening). For both steels the rapid increase in cyclic strain occurred at approximately the elevated temperature yield point (\45 ksi for Steel A
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Upadhyaya, Shrini, Dan Wolf, William J. Chancellor, Itzhak Shmulevich i Amos Hadas. Traction-Soil Compaction Tradeoffs as a Function of Dynamic Soil-Tire Interation Due to Varying Soil and Loading Conditions. United States Department of Agriculture, październik 1995. http://dx.doi.org/10.32747/1995.7612832.bard.
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The objectives of this study were to investigate soil-pneumatic tire interaction and develop traction-soil compaction prediction model. We have developed an inverse solution technique that employs a response surface methodology to determine engineering properties of soil in-situ. This technique is useful in obtaining actual properties of soil in-situ for use in traction and soil compaction studies rather than using the values obtained in the laboratory by employing remolded and/or disturbed soil samples. We have conducted extensive field tests i the U.S. to develop semi-empirical traction prediction equation for radial ply tires. A user friendly traction-soil compaction program was developed to predict tractive ability of radial ply tires using several different techniques and to estimate soil compaction induced by these tires. A traction prediction model that incorporates strain rate effects on the tractive ability of tires was developed in Israel. A mobile single wheel tester and an in-situ soil test device were developed i Israel to significantly enhance the ability of Israeli investigators to conduct traction-soil compaction research. This project has resulted in close cooperation between UCD, Technion, and ARO, which will be instrumental in future collaboration.
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Groeneveld, Andrew, i C. Crane. Advanced cementitious materials for blast protection. Engineer Research and Development Center (U.S.), kwiecień 2023. http://dx.doi.org/10.21079/11681/46893.
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Advanced cementitious materials, commonly referred to as ultra-high performance concretes (UHPCs), are developing rapidly and show promise for civil infrastructure and protective construction applications. Structures exposed to blasts experience strain rates on the order of 102 s-1 or more. While a great deal of research has been published on the durability and the static properties of UHPC, there is less information on its dynamic properties. The purpose of this report is to (1) compile existing dynamic property data—including compressive strength, tensile strength, elastic modulus, and energy absorption—for six proprietary and research UHPCs and (2) implement a single-degree-of-freedom (SDOF) model for axisymmetric UHPC panels under blast loading as a means of comparing the UHPCs. Although simplified, the model allows identification of key material properties and promising materials for physical testing. Model results indicate that tensile strength has the greatest effect on panel deflection, with unit weight and elastic modulus having a moderate effect. CEMTECmultiscale® deflected least in the simulation. Lafarge Ductal®, a commonly available UHPC in North America, performed in the middle of the five UHPCs considered.
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Tyson. L52337 Weld Design Testing and Assessment Procedures for High Strength Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), grudzień 2011. http://dx.doi.org/10.55274/r0010448.
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This is the last report of a�c reports detailing the small-scale mechanical testing performed on the trial welds in this consolidated program. This report summarizes and compares the results of all of the mechanical tests applied primarily to welds of rounds 1 and 2, including tensile results and their correlation with microstructure, Charpy test results, conventional (through-thickness-notched) toughness tests, and low-constraint toughness tests. The reports contains a summary of the mechanical properties of the experimental single and dual torch GMAW-P X100 pipe welds prepared for this consolidated program. It summarizes the detailed results reported in Final Reports 277-T-05, 277-T-06 and 277-T-07. The intent of this summary is to provide insight and understanding of the significance of the results and the implications for mechanical testing of weldments to extract properties essential for strain-based design (SBD).
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Michalopoulos, C. D. PR-175-420-R01 Submarine Pipeline Analysis - Theoretical Manual. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), grudzień 1985. http://dx.doi.org/10.55274/r0012171.
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Describes the computer program SPAN which computes the nonlinear transient response of a submarine pipeline, in contact with the ocean floor, to wave and current excitation. The dynamic response of a pipeline to impact loads, such as loads from trawl gear of fishing vessels, may also be computed. In addition, thermal expansion problems for submarine pipelines may be solved using SPAN. Beam finite element theory is used for spatial discretization of the partial differential equations governing the motion of a submarine pipeline. Large-deflection, small-strain theory is employed. The formulation involves a consistent basis and added mass matrix. Quadratic drag is computed using a nonconventional approach that involves the beam shape functions. Soil-resistance loads are computed using unique pipeline-soil interaction models which take into account coupling of axial and lateral soil forces. The nonlinear governing equations are solved numerically using the Newmark Method. This manual presents the discretized equations of motion, the methods used in determining hydrodynamic and soil-resistance forces, and the solution method.
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Snyder, Victor A., Dani Or, Amos Hadas i S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, kwiecień 2002. http://dx.doi.org/10.32747/2002.7580670.bard.
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Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.
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Moghtadernejad, Sara, Ehsan Barjasteh, Ren Nagata i Haia Malabeh. Enhancement of Asphalt Performance by Graphene-Based Bitumen Nanocomposites. Mineta Transportation Institute, czerwiec 2021. http://dx.doi.org/10.31979/mti.2021.1918.
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As the State of California continues to grow, demand for enhanced infrastructure such as roadways and highways escalates. In view of the current average highway lifespan of 15–20 years, the improvement of asphalt binders leads to material sustainability by decreasing required maintenance and increasing the lifespan of roadways. In the present investigation, enhancement of asphalt binder properties was achieved by different methods of mixing varying compositions of graphene nanoparticles with an SBS polymer and asphalt binder. Additionally, experimental evaluation and comparison of the rheological and mechanical properties of each specimen is presented. Graphene nanoparticles have attracted great curiosity in the field of highway materials due to their incredible rigidity, even in small quantities. Addition of as little as 1.0%nanoparticles in combination with polymers in an asphalt binder is expected to increase the rigidity of the material while also maintaining the beneficial polymer characteristics. Evaluation of the effect of the mixing design established that the methods for application of graphene to the polymer-modified asphalt binder are critical in the improvement of a roadway, resulting in resistance to premature aging and strain from constant road operation.
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Leveque, E., M. Zarea, R. Batisse i P. Roovers. IPC-BST-R01 Burst Strength of Gouges in Low Toughness Gas Transmission Pipes. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), wrzesień 2006. http://dx.doi.org/10.55274/r0011781.
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EPRG research aimed at establishing a limit on the toughness value that separates toughness-dependent from toughness-independent failure behavior. More specifically, one objective is to evaluate the toughness-dependent Battelle formula for burst resistance of gouges for (very) low toughness values. This mainly experimental project checks this behavior on several gas transmission pipes, a small diameter one, 150 mm, a medium diameter one, 350 mm, and a large diameter one, 900 mm. Pipe material is carefully characterized in terms of tensile properties, Charpy energy, and shear area. Then, based on the toughness independent criterion, a set of gouges is defined, of different depths/lengths, so as to span the different regions of the criterion, covering both short and long defects. These defects are manufactured by spark erosion, resulting in thin slits. Each such slit is incorporated into a vessel that is submitted to a burst test, with a number of additional measurements, like strain gauges on the pipe surface, a clip gauge et the center of the defect. For the small and medium sized pipes, temperature is also controlled during the test, to ensure it is as low as practically feasible, without heavy infrastructure. The results are interpreted both in terms of comparison with the criteria, and also in terms of analysis of the failure surface, to identify failure mechanisms.