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1
Sharma, Jyotsna, S. B. B. Inwood, and A. R. R. Kovscek. "Experiments and Analysis of Multiscale Viscous Fingering During Forced Imbibition." SPE Journal 17, no. 04 (November 27, 2012): 1142–59. http://dx.doi.org/10.2118/143946-pa.
Повний текст джерелаАнотація:
Summary Immiscible displacement of one fluid by another in porous media has practical applications when viscous oil is produced by water injection. A greater understanding of the flow patterns that evolve during such unstable displacements yields insights into improving predictive capability and increasing oil recovery. Immiscible multiphase displacement exhibits a wide range of behaviors depending on the relative magnitude of viscous, capillary, and gravity forces. Using flow-visualization images from forced-imbibition experiments carried out in etched-silicon micromodels, we show that the conventional Darcy-type modeling of fluid flux is not predictive under unstable, immiscible, forced-imbibition conditions at the scale of interest. When a less viscous fluid displaces a more viscous fluid at low capillary numbers, the displacement patterns show viscous instabilities in the form of fingers and local capillary control of interface movement. We show that such complex displacement patterns are well modeled using statistical theories. We derive a scaling model to describe quantitatively the functional forms for saturation, fractional flow, and capillary dispersion profiles using the self-similar characteristics inherent in the displacement patterns. For the specific range of flow rates (Nc ~ 10−7) and oil/water viscosity ratios (M ~ 8–400) considered in our experiments, both capillary and viscous forces are important, and the displacement pattern indicates fractal features. Results show that functional relations of the scaling model are in considerable agreement with our experimental data.
2
Wang, Hao, Wen-Zhi Zheng, Jian Li, and Yu-Qi Gao. "Effects of temperature and lead core heating on response of seismically isolated bridges under near-fault excitations." Advances in Structural Engineering 22, no. 14 (June 11, 2019): 2966–81. http://dx.doi.org/10.1177/1369433219855914.
Повний текст джерелаАнотація:
Seismic responses of bridges isolated by lead rubber bearings under near-fault excitations are presented in this article. A bilinear force-deformation model is employed to represent the hysteretic behaviors of lead rubber bearings. The joint effects of ambient temperature, initial displacement, and lead core heating on the responses of seismically isolated bridges are investigated. Nonlinear time history analyses are conducted with the employed hysteretic models of lead rubber bearings. Comparisons of the responses with and without the joint effects are performed, in terms of maximum isolator displacements, maximum isolator forces, and base forces of the piers. Results show that ambient temperature, initial displacement, and lead core heating have significant joint effects on the responses of seismically isolated bridges. When such joint effects are ignored at low temperatures, the maximum isolator displacements could be overestimated, whereas the maximum isolator forces and the base forces could be underestimated. However, as for ambient temperatures above 20°C, the maximum isolator displacements could be underestimated, whereas the maximum isolator forces and the base forces could be overestimated with small maximum isolator displacements and underestimated with large maximum isolator displacements.
3
Fong, Chun-Man, J. Troy Blackburn, Marc F. Norcross, Melanie McGrath, and Darin A. Padua. "Ankle-Dorsiflexion Range of Motion and Landing Biomechanics." Journal of Athletic Training 46, no. 1 (January 1, 2011): 5–10. http://dx.doi.org/10.4085/1062-6050-46.1.5.
Повний текст джерелаАнотація:
Abstract Context: A smaller amount of ankle-dorsiflexion displacement during landing is associated with less knee-flexion displacement and greater ground reaction forces, and greater ground reaction forces are associated with greater knee-valgus displacement. Additionally, restricted dorsiflexion range of motion (ROM) is associated with greater knee-valgus displacement during landing and squatting tasks. Because large ground reaction forces and valgus displacement and limited knee-flexion displacement during landing are anterior cruciate ligament (ACL) injury risk factors, dorsiflexion ROM restrictions may be associated with a greater risk of ACL injury. However, it is unclear whether clinical measures of dorsiflexion ROM are associated with landing biomechanics. Objective: To evaluate relationships between dorsiflexion ROM and landing biomechanics. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: Thirty-five healthy, physically active volunteers. Intervention(s): Passive dorsiflexion ROM was assessed under extended-knee and flexed-knee conditions. Landing biomechanics were assessed via an optical motion-capture system interfaced with a force plate. Main Outcome Measure(s): Dorsiflexion ROM was measured in degrees using goniometry. Knee-flexion and knee-valgus displacements and vertical and posterior ground reaction forces were calculated during the landing task. Simple correlations were used to evaluate relationships between dorsiflexion ROM and each biomechanical variable. Results: Significant correlations were noted between extended-knee dorsiflexion ROM and knee-flexion displacement (r = 0.464, P = .029) and vertical (r = −0.411, P = .014) and posterior (r = −0.412, P = .014) ground reaction forces. All correlations for flexed-knee dorsiflexion ROM and knee-valgus displacement were nonsignificant. Conclusions: Greater dorsiflexion ROM was associated with greater knee-flexion displacement and smaller ground reaction forces during landing, thus inducing a landing posture consistent with reduced ACL injury risk and limiting the forces the lower extremity must absorb. These findings suggest that clinical techniques to increase plantar-flexor extensibility and dorsiflexion ROM may be important additions to ACL injury-prevention programs.
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Bjarnesen, Jesper. "Between Labor Migration and Forced Displacement." Conflict and Society 2, no. 1 (June 1, 2016): 52–67. http://dx.doi.org/10.3167/arcs.2016.020107.
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The significant number of involuntary returns of labor migrants to Burkina Faso is a relatively neglected aspect of the armed conflict in Côte d’Ivoire. Between 500,000 and 1 million Burkinabe migrants were forced to leave Côte d’Ivoire between 2000 and 2007, placing tremendous pressure on local communities in Burkina Faso to receive and integrate these mass arrivals, and causing those returning labor migrants an acute sense of displacement. Th is article analyzes the experiences of displacement and resettlement in the context of the Ivorian crisis and explores the dialectics of displacement and emplacement in the lives of involuntary labor migrant returnees; their young adult children; and Burkinabe recruits returning aft er their service in the Forces Nouvelles rebel forces in Côte d’Ivoire.
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Gluck, J., Y. Ribakov, and A. N. Dancygier. "Selective Control of Base-Isolated Structures with CS Dampers." Earthquake Spectra 16, no. 3 (August 2000): 593–606. http://dx.doi.org/10.1193/1.1586129.
Повний текст джерелаАнотація:
Addition of dampers to a base isolator reduces base displacements but may increase floor accelerations and interstory drifts. This paper presents a “selective control approach” for the design of base-isolated active controlled structures with Controlled Stiffness Dampers (CSD). According to this approach the dampers are activated only within a given range of the base displacement. The optimal damping forces are calculated according to structure's displacements and velocities. However, because of the CS dampers' structure the actual application of the forces is independent of the displacement and the velocity that are transferred to the device. These forces depend only on the geometry and on the mechanical properties of the devices' springs. The efficiency of the proposed method is demonstrated in a numerical example.
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Jarosz, Jakub. "The effect of braking forces on displacement of integral bridges." Budownictwo i Architektura 12, no. 2 (June 11, 2013): 023–30. http://dx.doi.org/10.35784/bud-arch.2069.
Повний текст джерелаАнотація:
The paper presents the results of numerical analyses of the lateral displacement for reinforced concrete and single span integral bridge with foundations constructed on piles. The lateral displacement due to braking forces was analysed. Then, the results were compared to analogical displacement caused by the temperature increase. The following changeable bridge parameters were assumed: span length, deck height, piles length and piles diameter. The results of the lateral displacements were compared on concerning the fixing of the pile top. In the first case, the piles were fixed by pile cap, and in the second one, the piles were fixed directly to the deck. Moreover, two options of soil were considered. The first option in which soil was composed of sand and sandy silt, and the second one in which soil was composed of sand and clay. In the analysed cases, the displacement caused by braking forces accounts for 10% - 20% of the total lateral displacement of the ,construction. The research presented in this paper shows that the main determinants of the lateral displacement of integral bridges are piles diameters and the type of surrounding ground. Pile length is of small importance.
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De Troyer, André, and Theodore A. Wilson. "Mechanism of the increased rib cage expansion produced by the diaphragm with abdominal support." Journal of Applied Physiology 118, no. 8 (April 15, 2015): 989–95. http://dx.doi.org/10.1152/japplphysiol.00016.2015.
Повний текст джерелаАнотація:
When the abdomen in quadriplegic subjects is given a passive mechanical support, the expansion of the lower rib cage during inspiration is greater and the inward displacement of the upper rib cage is smaller. These changes have traditionally been attributed to an increase in the appositional force of the diaphragm, but the mechanisms have not been assessed. In this study, the inspiratory intercostal muscles in all interspaces were severed in anesthetized dogs, so that the diaphragm was the only muscle active during inspiration, and the displacements of the ribs 10 and 5 and the changes in pleural and abdominal pressure were measured during unimpeded breathing and during breathing with a plate applied on the ventral abdominal wall. In addition, external forces were applied to the 10th rib pair in the cranial and lateral directions, and the rib trajectories thus obtained were used as the basis for a vector analysis to estimate the relative contributions of the insertional and appositional forces to the rib 10 displacements during breathing. Application of the abdominal plate caused a marked increase in the inspiratory cranial and outward displacement of rib 10 and a decrease in the inspiratory caudal displacement of rib 5. Analysis of the results showed, however, that 1) the insertional and appositional forces contributed nearly equally to the increased inspiratory displacement of rib 10 and 2) the decrease in the expiratory displacement of rib 5 was the result of both the greater displacement of the lower ribs and the decrease in pleural pressure.
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Schultheis, Michael J. "Introduction." African Studies Review 32, no. 1 (April 1989): 1–2. http://dx.doi.org/10.1017/s0002020600012750.
Повний текст джерелаАнотація:
In recent months the international news media has again focused on refugees and internally displaced people in Mozambique, Angola and the Horn of Africa. Many of these are “hunger migrants,” people on the move in search of food. But hunger is only one form of forced displacement. It is clear that drought and famine are the companions of war and civil conflict, which disrupts water supply, planting, harvesting and the patterns of economic life in the countryside. In some instances, this disruption is chosen as the means of warfare carried on against the population.The papers in this symposium develop different aspects of the dynamics of displacement and repatriation. The first paper focuses on forced displacement in Africa, with special consideration of the situation in southern Africa. The second two papers take up the questions of repatriation and reintegration of refugees into their home communities. Together they raise the central issues, which governments and international agencies often are unwilling, or unable, to address.The first paper presents a general overview of the refugee/displacement map in Africa and develops the general thesis that contemporary displacements in Africa, as elsewhere, are caused by economic and political forces which generate oppressive and dehumanizing situations. It evaluates the instruments which the international community has developed to protect refugees and notes the politics of refugee definition. The central thesis analyzes the geo-political forces involved in refugee generation in Africa, specifically in the southern African context. The conclusion looks at implications for collaborative action on the part of the university and nongovernmental communities in both northern and southern countries.
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Huang, Shiping, and Anil Misra. "Path-dependent analysis of elastic sphere contact subjected to tangential loading with varying directions." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 226, no. 8 (March 7, 2012): 678–86. http://dx.doi.org/10.1177/1350650112440414.
Повний текст джерелаАнотація:
The Cattaneo–Mindlin solutions of contact between elastic spheres and their recent extensions do not consider the sequential application of arbitrarily directed shear forces in the contact tangential plane. For this loading condition, the contact tractions simultaneously undergo loading and unloading. This article presents a path-dependent analysis wherein we use superposition at each loading step to obtain the contact tangential traction, and, subsequently the tangential displacement and compliance. The methodology is illustrated by example calculation of contact shear force–displacement relationship, which shows the formation of hysteretic loop and the noncoaxiality of the shear forces and displacements.
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Zhou, Yanzhou, Ricky D. Wildman, and Jonathan M. Huntley. "Measurement of the mechanical properties of granular packs by wavelength-scanning interferometry." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2115 (November 11, 2009): 789–808. http://dx.doi.org/10.1098/rspa.2009.0297.
Повний текст джерелаАнотація:
A wavelength-scanning interferometer has been constructed to observe both the normal and in-plane displacements particle by particle at the base of a model granular pack. The pack comprised 25 000 steel beads supported by a thick glass substrate and was subjected to local disturbing forces on its upper surface. The system allows measurement of normal displacements of the beads to a precision of ca 0.1 nm, thereby providing highly accurate determination of contact forces while minimizing artefacts due to substrate and grain compliance. The probability distribution of the normalized contact force was found to be approximately independent of the applied load on the upper surface of the granular pack and has an exponential tail. The probability distributions of the normalized response force and lateral displacement have similar power-law tails. The interactions between contact forces and lateral displacements suggest that significant internal rearrangement occurs in the granular pack as the load is increased, and particle displacement plays an important role in the mechanics of the granular material.
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Wang, Haifei, and Junjie Gong. "Dynamic analysis of coupling misalignment and unbalance coupled faults." Journal of Low Frequency Noise, Vibration and Active Control 38, no. 2 (January 8, 2019): 363–76. http://dx.doi.org/10.1177/1461348418821582.
Повний текст джерелаАнотація:
Misalignment is a common fault occurring in the rotor system. However, the response characteristics have not been understood comprehensively, especially the relation between forces or torques and displacements, accelerations, or moments. First, misalignment modeling is investigated in this paper. Two coupled rotor system is modeled by six degrees of freedom. Misalignment effects are considered at coupling location using nodal force vectors and moment vectors. Second, Newmark- β method is used to solve the nonlinear equations. Acceleration, displacement, and force or moment response characteristics are discussed. Some results are obtained as follows: (1) 2× will appear in the parallel misalignment forces spectrum, and 0× will appear in the vertical force spectrum; 2×, 4×, 6× will appear in the angular misalignment moment spectrum. (2) In parallel misalignment simulation, it is found that multifrequency components are more obvious, static components are showed in vertical forces and displacements, 1× is dominated and 2× is weak in the displacement spectrum, and 2× is obvious in the force spectrum; acceleration is periodic impulse signal and 1× and 2× are dominated in its spectrum; vertical displacement is truncated and its values are positive, the orbit looks like an inverted triangle. (3) In angular misalignment simulation, it is found that multifrequency components of response are more obvious, 2× is obvious in the vertical displacement spectrum, and 2× is dominated in the moment spectrum; acceleration is periodic impulse signal, horizontal and vertical displacements are periodic, the orbit looks like a moon or an eight shape, and 2× is obvious in the moment spectrum.
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BOSAKOV, S. V., and Y. N. KOTOV. "CONTACT PROBLEM FOR INCLINED PLATE CONDITIONS OF EQUALITY OF ITS SOME DISPLACEMENT." STRUCTURAL MECHANICS AND ANALYSIS OF CONSTRUCTIONS 303, no. 4 (February 28, 2022): 54–58. http://dx.doi.org/10.37538/0039-2383.2022.1.54.58.
Повний текст джерелаАнотація:
Porpose. Calculation of the plate on flexible base where one part of the points of the plate base are in the same inclined plane during bending. The concrete foundation where a base plate is located is an flexible semi-infinite foundation. Method. To determine a contact voltage between the plate and the foundation the Zhemochkin method is used. The system of canonical equations includes the equations of the Zhemochkin method and the equation to find single points of the slab in the inclined plane. The result of solving the system determines the forces in the method of Zhemochkin and unknown forces causing the displacement of the base plate of the foundation in the same inclined plane. Then the displacement of the base plate and the forces in it are found. Results. Calculation of the metal foundation of an eccentrically compressed metal column with an I-beam cross-section based on a concrete surfacing. Isolines of equal contact voltages and displacements, graphs of voltage and displacement with the typical sections of the foundation are shown.
13
Khosravi, Farshad, Seyyed Amirhosein Hosseini, and Abdelouahed Tounsi. "Forced Axial Vibration of a Single-Walled Carbon Nanotube Embedded in Elastic Medium under Various Moving Forces." Journal of Nano Research 63 (June 2020): 112–33. http://dx.doi.org/10.4028/www.scientific.net/jnanor.63.112.
Повний текст джерелаАнотація:
The dynamic free and forced axial vibrations subjected to moving exponential and harmonic axial forces of a single-walled carbon nanotube (SWCNT) embedded in an elastic medium, are studied in this paper. Two different boundary conditions of SWCNT, including clamped-clamped and clamped-free, are taken into account. Eringen’s nonlocal elasticity theory is used to show the nonlocality for the model. The constitutive equations and their boundary conditions are derived by Hamilton’s principle. Employing the general solution, the derived equations are analytically solved to obtain two items. Firstly, the axial natural frequencies, secondly, the time-domain axial displacements at the middle of the carbon nanotube (CNT), and then the maximum axial displacements. The responses are validated with previous works, and the results demonstrates good agreement to them to verify the influence of the nonlocal parameter on the nondimensional natural frequencies for three various mode numbers. In the time-domain section, the effects of the nonlocal parameter, length, nondimensional stiffness of the elastic medium, and velocity of the moving load on the axial displacement are investigated. Also, the influences of the excitation frequency to natural frequency for the harmonic moving load, as well as the time constant for the exponential moving load on the axial displacement, are illustrated. Finally, the effect of the nonlocal parameter on the maximum axial deflection versus velocity parameter is schematically indicated.
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RAGULSKIS, Kazimieras, Bronislovas SPRUOGIS, Marijonas BOGDEVIČIUS, Arvydas MATULIAUSKAS, Vygantas MIŠTINAS, and Liutauras RAGULSKIS. "Investigation of Dynamics of a Pipe Robot with Nonlinear Interactions of Its Elements." Mechanics 28, no. 5 (October 21, 2022): 394–400. http://dx.doi.org/10.5755/j02.mech.30467.
Повний текст джерелаАнотація:
Systems in which vibrational displacements are limited because elastic forces increase practically up to unlimited values, are investigated. Here systems having one degree of freedom are investigated in which vibrations have specific qualities for the case of conservative systems as well as for the case of forced harmonic excitations. Typical expressions for nonlinear stiffness are proposed. Model of a pipe robot with limited values of displacements is presented and investigated. The model has two degrees of freedom: the displacement of the vibrating mass inside the pipe robot and the displacement of the pipe robot itself. Motion of the pipe robot in the negative direction as well as motion of the pipe robot in the positive direction for different parameters of the system is observed. For high amplitude of excitation, the distance travelled by the pipe robot is much greater than for low amplitude of excitation. The obtained results are used in the process of design of pipe robots.
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Fedulov, A. I. "Calculation of displacement forces on percussive tool." Journal of Mining Science 30, no. 5 (September 1994): 491–94. http://dx.doi.org/10.1007/bf02047341.
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Mahardika, Mohammad Azis, Yun She, Tomotaka Koe, Anindityo Patmonoaji, Muhammad Nasir, Shintaro Matsushita, and Tetsuya Suekane. "Competition of gravity and viscous forces in miscible vertical displacement in a three-dimensional porous medium." Physics of Fluids 34, no. 7 (July 2022): 073102. http://dx.doi.org/10.1063/5.0090387.
Повний текст джерелаАнотація:
When viscosity and density contrast exist in the vertical miscible displacement in porous media between two fluids, the interplay between the viscous force and gravity determines the interface stability. Two stability criteria are derived to determine the interface stability. Hill's and Dumore's stability criteria are used to determine the interface stability of the sharp and diffused interface, respectively. In this study, we visualized the crossover between unstable displacement and stable displacement for a vertical displacement in porous media using microfocused x-ray computed tomography. The experiments were divided into four possible configurations: (1) unconditionally stable (gravitationally stable-viscously stable), (2) unconditionally unstable (gravitationally unstable-viscously unstable), (3) conditionally stable (gravitationally stable-viscously unstable), and (4) conditionally stable (gravitationally unstable, viscously stable). The structure of the displacement interface was visualized for the critical velocity ratio (V/Vc) in the range of 0.5–11.9. In the conditionally stable configurations 3 and 4, a crossover between stable and unstable displacements was observed. We found that Dumore's stability criterion is more appropriate for predicting interface stability than Hill's stability criterion. Viscous fingering occurs in configuration 3 when V/Vc is higher than Dumore's critical velocity, whereas gravity fingering occurs in configuration 4 when V/Vc is lower than Dumore's critical velocity. Similar events in two-dimensional experiments, such as tip-splitting, shielding, and coalescence, were also observed three-dimensionally. The significant changes in the mixing length and sweep efficiency signify the crossover between the stable and unstable displacements.
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Auersch, L. "Characteristics of train passages over slab tracks from measurements and different track–soil models: Damage detection and ground vibration reduction." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 2 (March 6, 2019): 142–60. http://dx.doi.org/10.1177/0954409719835036.
Повний текст джерелаАнотація:
The characteristics of train passages over intact or damaged slab tracks on different soils have been calculated by the finite-element boundary-element method or the wavenumber-domain method. The influence of track and soil parameters on the distribution of track displacements and soil forces has been analysed. The measured and calculated displacement time histories of train passages could be used to identify track damages such as loose sleepers or a loose track plate. The time histories and spectra of soil forces can explain the measured ground vibration reduction in the slab tracks. The calculated displacement and force distributions of slab tracks on continuous soils do not fulfil the Winkler hypothesis, and Winkler models should not be used for track analysis.
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Dado, M., and A. H. Soni. "Complete Dynamic Analysis of Elastic Linkages." Journal of Mechanisms, Transmissions, and Automation in Design 109, no. 4 (December 1, 1987): 481–86. http://dx.doi.org/10.1115/1.3258821.
Повний текст джерелаАнотація:
A complete dynamic analysis procedure to analyze elastic linkages is presented in this study. Forward and inverse dynamics techniques are developed for elastic linkages with revolute and prismatic pairs. The techniques utilize finite-line-element method in solving for the elastic displacements and system internal forces. The analysis procedure is applicable to multiloop and multidegree-of-freedom systems. The driving forces and torques may be functions of time, displacement, and/or velocity. In forward dynamic analysis, an integration procedure is developed to evaluate the system coordinate velocities and displacements. Numerical examples are presented to illustrate the analysis techniques and their features.
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Ucun, İsmail. "INVESTIGATION OF EFFECT ON LATERAL DISPLACEMENT AND FORCES OF CUTTING MODE IN SAWABILITY OF METAL PROFILE USING CUTTING DISC." Transactions of the Canadian Society for Mechanical Engineering 36, no. 1 (March 2012): 23–35. http://dx.doi.org/10.1139/tcsme-2012-0003.
Повний текст джерелаАнотація:
In this study, the cutting performance of cutting discs used to cut metal materials depending on the cutting modes is determined with an experimental study. Tests are performed using a computer-controlled cutting machine. For the tests, peripheral speeds of 40, 60 and 80 m/sec and feed speeds of 0.3, 0.4, 0.5, 0.6, and 0.7 m/min. are preferred as cutting parameters. Up cutting and down cutting are taken into consideration as cutting modes. A three-point dynamometer is used to determine the forces applied on the disc during cutting. A KEYENCE laser displacement measuring device is used to measure lateral displacements of the cutting disc. According to the test results, feed speed is observed as a significant parameter in determining the cutting forces and lateral displacements. Up and down cutting modes used in the study has a significant effect on determining the forces applied on the cutting disc and lateral displacements of the disc. In particular, lateral displacements obtained in down cutting mode are observed to be greater than the displacements obtained in up cutting mode.
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Lenormand, Roland, Eric Touboul, and Cesar Zarcone. "Numerical models and experiments on immiscible displacements in porous media." Journal of Fluid Mechanics 189 (April 1988): 165–87. http://dx.doi.org/10.1017/s0022112088000953.
Повний текст джерелаАнотація:
Immiscible displacements in porous media with both capillary and viscous effects can be characterized by two dimensionless numbers, the capillary number C, which is the ratio of viscous forces to capillary forces, and the ratio M of the two viscosities. For certain values of these numbers, either viscous or capillary forces dominate and displacement takes one of the basic forms: (a) viscous fingering, (b) capillary fingering or (c) stable displacement. We present a study in the simple case of injection of a non-wetting fluid into a two-dimensional porous medium made of interconnected capillaries. The first part of this paper presents the results of network simulators (100 × 100 and 25 × 25 pores) based on the physical rules of the displacement at the pore scale. The second part describes a series of experiments performed in transparent etched networks. Both the computer simulations and the experiments cover a range of several decades in C and M. They clearly show the existence of the three basic domains (capillary fingering, viscous fingering and stable displacement) within which the patterns remain unchanged. The domains of validity of the three different basic mechanisms are mapped onto the plane with axes C and M, and this mapping represents the ‘phase-diagram’ for drainage. In the final section we present three statistical models (percolation, diffusion-limited aggregation (DLA) and anti-DLA) which can be used for describing the three ‘basic’ domains of the phase-diagram.
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Ladeve`ze, P., and J. G. Simmonds. "The Exact One-Dimensional Theory for End-Loaded Fully Anisotropic Beams of Narrow Rectangular Cross Section." Journal of Applied Mechanics 68, no. 6 (June 2, 2001): 865–68. http://dx.doi.org/10.1115/1.1412238.
Повний текст джерелаАнотація:
The exact theory of linearly elastic beams developed by Ladeve`ze and Ladeve`ze and Simmonds is illustrated using the equations of plane stress for a fully anisotropic elastic body of rectangular shape. Explicit formulas are given for the cross-sectional material operators that appear in the special Saint-Venant solutions of Ladeve`ze and Simmonds and in the overall beamlike stress-strain relations between forces and a moment (the generalized stress) and derivatives of certain one-dimensional displacements and a rotation (the generalized displacement). A new definition is proposed for built-in boundary conditions in which the generalized displacement vanishes rather than pointwise displacements or geometric averages.
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Gromysz, Krzysztof. "Stiffness test in lateral direction of temporary wooden building supports." MATEC Web of Conferences 262 (2019): 10004. http://dx.doi.org/10.1051/matecconf/201926210004.
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Temporary supports consisting of a jack, a stack of wooden cubic elements and a iron plate are used during the removal of buildings deflections by uneven raising. Where the weight of a building is rested on temporary supports with a considerable length, unintentional displacements of buildings in the horizontal direction are seen. The displacements are connected with supports deformations caused by horizontal forces acting on the building part being raised. Non-vertically installed jacks, being part of the supports, are the most frequent reason for the occurrence of such forces. The jacks are not vertical due to deformations in the stack of wooden elements, upon which they are rested. In such case, the stiffness of temporary supports is essential for the safety of the deflection removal process. Laboratory tests of temporary supports were carried out and they showed that their stiffness, understood as a horizontal force divided by a displacement in the acting direction of the force, is not constant. The stiffness of supports is decreasing as the displacement amplitude grows. A considerable decrease in supports stiffness was experienced when positive longitudinal deformations occurred in the cross section of the support elements. As a result, the unconnected elements of the supports were unable to transmit positive stresses of this number. For the investigated range of loads, the deformations of the material of the supports elements were elastic. Inelastic forces were however generated along the contact points of the elements forming part of the supports, and such forces were responsible for creating a hysteresis loop and energy dissipation by the supports. The system, when a full load-unload cycle was applied, was returning to the initial position. Higher values of the energy dissipation coefficient correspond to higher values of a displacement amplitude.
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Feng, Wenkai, Zhichun Lu, Xiaoyu Yi, and Shan Dong. "A Dynamic Method to Predict the Earthquake-Triggered Sliding Displacement of Slopes." Mathematical Problems in Engineering 2021 (November 15, 2021): 1–11. http://dx.doi.org/10.1155/2021/4872987.
Повний текст джерелаАнотація:
The earthquake-induced permanent displacement is an important index of the potential damage to a slope during an earthquake. The Newmark method assumes that a slope is a rigid-plastic body, and the seismic responses of sliding masses or seismic forces along the slide plane are ignored. The decoupled method considers no relative displacement across the sliding plane, so it overpredicts the seismic response of the sliding mass. Both dynamic and sliding analyses are performed in the coupled method, but when Ts/Tm is large, the results are unconservative. In this paper, a method is proposed to predict the earthquake-triggered sliding displacement of slopes. The proposed method is based on the Newmark rigid method, coupled method, and decoupled method considering both the forces at the sliding interface and the system dynamics under critical conditions. For the flexible system, the displacements are calculated with different stiffness values, and the results show that as the stiffness increases and tends to infinity, the critical acceleration and displacements of the proposed method are close to those of the Newmark method. The proposed method is also compared with the Newmark method with the period ratio Ts/Tm. At small values of Ts/Tm, the flexible system analysis results of the displacement are more conservative than those of the rigid block model; at larger values of Ts/Tm, the rigid block model is more conservative than the flexible system.
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Li, Peixing, Helei Zhu, and Leijie Lai. "An Improved Dynamic Model and Matrix Displacement Model for Distributed-Compliance Bridge-Type Amplification Mechanism." Actuators 11, no. 12 (December 7, 2022): 368. http://dx.doi.org/10.3390/act11120368.
Повний текст джерелаАнотація:
This paper establishes a matrix displacement model and an improved dynamic model for the static and dynamic performances analysis for a kind of bridge-type displacement amplification mechanism with distributed-compliance, which has better performances than traditional lumped-compliance bridge-type mechanisms. In the matrix displacement model, the stiffness matrix for two rigid bodies connected by flexures is first obtained by regarding the displacements and the forces on two mass centers of the rigid bodies as the node displacements and node forces. By extending and superimposing each elemental stiffness matrix, the global stiffness matrix for the flexure mechanism can be obtained to calculate the displacement amplification ratio and input stiffness of the bridge-type mechanism. In the improved dynamic model, in order to establish the Lagrangian dynamic model more accurately, the deflectional, axial, and rotational velocities of any point on the beam flexure are calculated by solving the derivatives of the deformation curves of beam flexures versus time to obtain the expression of the kinetic energy in the vibrating beams. On this basis, the three-degree-of-freedom vibration differential equation for the bridge-type mechanism is established by using the Lagrange method, and the natural frequency in the working direction is obtained accurately. The presented models are compared with the finite element analysis, and experiments for two case studies of the bridge-type distributed-compliance mechanism are presented. The comparisons results demonstrate the high prediction accuracy of the improved dynamic model.
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Currano, Luke J., Danny Gee, Wayne A. Churaman, Madan Dubey, Paul Amirtharaj, Miao Yu, and Balakumar Balachandran. "MEMS Rotational Actuator for High Force and Large Displacement." Advances in Science and Technology 54 (September 2008): 372–77. http://dx.doi.org/10.4028/www.scientific.net/ast.54.372.
Повний текст джерелаАнотація:
A MEMS thermal actuator that provides rotational or near-linear translational displacements is investigated. This actuator provides a solution to applications that require highforces and large displacements. Output moments up to 7x10-7 N-m and free rotations of up to 3 degrees were measured. These correspond to forces of up to 1.44mN at a displacement of 23.7μm, yielding a work of 3.41x10-8 N-m. An electrothermal-mechanical model that considers temperature dependence of material properties is presented, and the model predictions show good agreement with actuator test data.
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Wei, Wei, Zhi Dong Yang, Jun Wei Han, and Ting Gao. "Internal Force Decoupling Control of Hyper-Redundant Shaking Table Based on Stiffness Matrix." Applied Mechanics and Materials 681 (October 2014): 115–20. http://dx.doi.org/10.4028/www.scientific.net/amm.681.115.
Повний текст джерелаАнотація:
A novel internal force decoupling control strategy of hyper-redundant shaking table based on stiffness matrix is proposed in this paper. The linear models of electro-hydraulic servo system and mechanical system are built by considering the shaking table moving in a small range around the zero point. Internal forces are given through a transformation of cylinder forces which can be acquired from the pressure sensors. By meshing top platform of the shaking table in different directions, the stiffness matrix between the redundancy displacements and internal forces are given through dynamics equations including inertia and shear parts. The IFDC controller is designed to feedback the redundancy displacement caused by internal forces to the input current of the servovalve. Simulation results show that the proposed method is capable to reduce internal forces effectively.
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Shen, Li, Shi Qiao Gao, An Ran Jiang, and Cai Feng Wang. "Analysis of Micro Structure’s Elastic Stiffness." Applied Mechanics and Materials 184-185 (June 2012): 890–95. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.890.
Повний текст джерелаАнотація:
Based on the calculation and analysis of three kinds of elastic beam’s stiffness coefficient in micro machined gyroscope, the results show: in the condition of small displacement，forces and displacement are linear relationship in clamped-clamped beam, crab-foot beam and bow beam; but as the displacement increases, the relationship between forces and displacement are obvious non-linear in clamped-clamped beam. When the displacement is three times the length of beam’s width, the bow beam’s force and displacement are linear relationship. By ANSYS crab-foot beam and bow beam’s stiffness is obtained, the simulation results and the polynomial fitting coefficient are all credible.
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Eshel, D., C. Shingyoji, K. Yoshimura, I. R. Gibbons, and K. Takahashi. "Evidence for an inequality in the forces that generate principal and reverse bends in sperm flagella." Journal of Cell Science 100, no. 1 (September 1, 1991): 213–18. http://dx.doi.org/10.1242/jcs.100.1.213.
Повний текст джерелаАнотація:
The response of the mechanism initiating flagellar bends to imposed mechanical transients has been studied by holding the head of a sea urchin sperm in the tip of a sinusoidally vibrating micropipet and then displacing the micropipet laterally at a speed of up to 1.15 micron ms-1 for 1.5 beat cycle, without vibration, before resuming sinusoidal vibration with the initial phase, frequency and amplitude at the new location of the pipet. This transient displacement of the micropipet delays the initiation of the bend that was due to initiate 0.5 beat cycle after onset of the displacement. The amount of this delay increases with the speed of the displacement, for speeds up to 1 micron ms-1. Analysis of the flagellar waveforms during the transient showed that with imposed displacements at speeds of equal magnitude, the initiation of a principal bend was delayed to a longer extent than that of a reverse bend. At a micropipet speed of 0.75 micron ms-1, there was an average delay of 0.21 beat cycle in the initiation time of a principal bend as compared to a delay of only about 0.04 beat cycle in the initiation time of a reverse bend during displacements in the opposite direction. For both principal and reverse bends, the second bend due to initiate during the transient displacement initiated in most of the cases with no delay, regardless of the micropipet speed. Our results suggest that the force generated by microtubule sliding to initiated a new reverse bend is greater than that generated to initiate a principal bend.
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Lara Valencia, Luis Augusto, Yamile Valencia Gonzalez, and David Marcelo Bedoya Zambrano. "Study of a Semi-Active Control System to Reduce Lateral Displacement in Framed Structures under Seismic Load." Ingeniería e Investigación 42, no. 3 (February 10, 2022): e85937. http://dx.doi.org/10.15446/ing.investig.85937.
Повний текст джерелаАнотація:
This study presents the numerical implementation of a semi-active control system used to reduce lateral displacements in framed structures under seismic loads. To manage forces in the structures, two controllable fluid devices called magnetorheological (MR) dampers were used, and a fuzzy logic (FL) algorithm was employed to determine the optimal control forces. The FL controller has been programmed based on a set of 49 inference rules using two input parameters: displacement and velocity of the first story of the uncontrolled structure. The voltage to be applied to the MR dampers was the output parameter of the control algorithm, thus altering the damping forces in the system. To evaluate the performance of the proposed controller, three plane frame structures with different geometric configurations were modeled and subjected to four different real ground accelerations records. The results obtained in this study showed considerable reductions in displacement, acceleration, and interstory drift for all the structures studied, demonstrating the effectiveness and efficiency of the controller to improve the damping characteristics in structures.
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Yu, Xiao Jin. "Solution of Statically Indeterminate Beam with Straight Axis by Section-Conversion Method." Applied Mechanics and Materials 744-746 (March 2015): 292–97. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.292.
Повний текст джерелаАнотація:
For computation of reaction, internal force and displacement of a beam, the displacement equation from Conversion Method is used in establishing compatibility condition of deformation. In the process of Section-Conversion Method, the joints without sway is set as the coordinate criterion. Cutting the part between two joints as a base element with the method of section, it becomes a simply supported beam in form. The internal forces at the section cut are those which equivalent forces from other side of the beam. According to the axiom of action and reaction, the equivalent forces react to the other part of the beam. The displacement equations are used for all parts one by one. The precision resolutions of reaction, internal force and displacement of a beam are achieved.
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Pan, Wen Jun, Xian Guo Ye, and Lei Chang. "Application of QR Method for Analysis of Spatial-Mega Frame Structure." Advanced Materials Research 243-249 (May 2011): 6049–52. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.6049.
Повний текст джерелаАнотація:
With the generalized displacement parameters of spline knots chosen as basic unknowns, the node displacement functions of spatial mega frames were built up, then element node displacements could be expressed by these parameters. New stiffness equation of spatial mega frame was deduced according to energy variational principle. The nodal displacement and nodal forces were worked out by the displacement parameters of spline knots. Process of block assembling for spline-discretization matrix was introduced briefly. One spatial mega frame was calculated by QR method and different finite element softwares. Comparation among the results and those of references proves that QR method is exactly an economical, effective and reliable method for computation of spatial mega frames. It provides a new approach for simplified calculation to spatial mega structures, so has good theoretical and practical value.
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Qing, Ming, Zhan Liu, and Tinghui Zheng. "Fast and Accurate Computation of the Displacement Force of Stent Grafts after Endovascular Aneurysm Repair." Bioengineering 9, no. 9 (September 6, 2022): 447. http://dx.doi.org/10.3390/bioengineering9090447.
Повний текст джерелаАнотація:
Purpose: Currently, the displacement force of stent grafts is generally obtained using computational fluid dynamics (CFD), which requires professional CFD knowledge to perform the correct simulation. This study proposes a fast, simple, and clinician-friendly approach to calculating the patient-specific displacement force after endovascular aneurysm repair (EVAR). Methods: Twenty patient-specific post-EVAR computed tomography angiography images were used to reconstruct the patient-specific three-dimensional models, then the displacement forces were calculated using CFD and the proposed approaches, respectively, and their numerical differences were compared and analyzed. Results: Based on the derivation and simplification of the momentum theorem, the patient-specific displacement forces were obtained using the information of the patient-specific pressure, cross-sectional area, and angulation of the two stent graft ends, and the average relative error was no greater than 1.37% when compared to the displacement forces calculated by CFD. In addition, the linear regression analysis also showed good agreement between the displacement force values calculated by the new approach and CFD (R = 0.999). Conclusions: The proposed approach can quickly and accurately calculate the patient-specific displacement force on a stent graft and can therefore help clinicians quickly evaluate the post-EVAR displacement force.
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Suresh, Srinivasan A., Amar Hajj-Ahmad, Elliot W. Hawkes, and Mark R. Cutkosky. "Forcing the issue: testing gecko-inspired adhesives." Journal of The Royal Society Interface 18, no. 174 (January 2021): 20200730. http://dx.doi.org/10.1098/rsif.2020.0730.
Повний текст джерелаАнотація:
Materials are traditionally tested either by imposing controlled displacements and measuring the corresponding forces, or by imposing controlled forces. The first of these approaches is more common because it is straightforward to control the displacements of a stiff apparatus and, if the material suddenly fails, little energy is released. However, when testing gecko-inspired adhesives, an applied force paradigm is closer to how the adhesives are loaded in practice. Moreover, we demonstrate that the controlled displacement paradigm can lead to artefacts in the assumed behaviour unless the imposed loading trajectory precisely matches the deflections that would occur in applications. We present the design of a controlled-force system and protocol for testing directional gecko-inspired adhesives and show that results obtained with it are in some cases substantially different from those with controlled-displacement testing. An advantage of the controlled-force testing approach is that it allows accurate generation of adhesive limit curves without prior knowledge of the expected behaviour of the material or the loading details associated with practical applications.
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Aydın, Adem, Levent Uğur, and Halil Atmaca. "The effect of anterolateral ligament integrity on the tibia displacement and reaction forces of anterior cruciate ligament." Orthopaedic Journal of Sports Medicine 5, no. 2_suppl2 (February 1, 2017): 2325967117S0010. http://dx.doi.org/10.1177/2325967117s00108.
Повний текст джерелаАнотація:
Objective: Recent studies focused on rotational instability and remained positive pivot test in patients with anterior cruciate ligament (ACL) reconstruction. Clinical, radiological and biomechanical studies showed the importance of the anterolateral ligament (ALL) integrity. ALL is one of the stabilization structures against the internal rotation of the tibia under forces which was associated with Segond fracture previously. Even some authors claimed that ACL failure and risk of re-rupture increased if only ACL reconstruction performed in patients with simultaneous ALL injury. The aim of the study is to evaluate the importance of ALL on knee biomechanics during anterior drawer test and internal rotation forces with different flexion angles in terms of reaction forces on ACL and the amount of tibia displacement via finite element analysis. Methods: Three dimensional (3D) solid model of knee joint and ALL injured models were constructed based on DICOM formatted computed tomography (CT) images. 0°, 15°,30°,45°,60°,75° and 90° flexion angles were applied respectively to reference models. Then varied anterior drawer and internal rotational forces were used to investigate the effect of ALL. ANSYS ®Version 17 was used in analyses and same boundary conditions were used in all models. Results: In critical analyzing the all results; medial displacement and the amount of anterior drawer distance were increased in all ALL injured models when compared with references. Therewithal the rotational displacements were increased by increasing the knee flexion angle and rotational torque. But, it was not a significant change in the amount of displacement between the models with respect to anteroposterior displacement when the anterior drawer force was increased. Conclusion: ALL particular has an important role in the stability of the internal rotation occurs against the force and with increased contribution rate to the knee joint stability by increasing the knee flexion angle. But the reaction forces were not affected by ALL integrity. So this study do not support the previous studies which suggest simultaneously reconstruction of both ligaments to avoid re rupture of ACL in cases with ALL injured.
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Çoşut, Muhammed, Gebrail Bekdaş, and Sinan Melih Nigdeli. "Optimization of reinforced concrete frame structures and matrix displacement method." Challenge Journal of Concrete Research Letters 14, no. 1 (March 7, 2023): 10. http://dx.doi.org/10.20528/cjcrl.2023.01.002.
Повний текст джерелаАнотація:
In this study, reinforced concrete frame system is generated, and all structural elements which are beam and columns are optimized according to the applied distributed loads and different concrete classes by using Matlab program. Jaya algorithm which is a Metaheuristic Algorithm that enables to optimization process and finds the best cross sections, reinforcement area as well as cost of the system, is proposed. It is observed that cross-section, reinforced area as well as cost of the system are changed when concrete classes are used differently. After finding the optimum design values for frame system, the matrix displacement method is utilized to specify the system displacements and all nodes forces. Furthermore, columns and beam displacement results are not similar, and also internal forces are different for nodes. TS500 (2000) (Reinforced concrete structures design and construction rules) and TBDY (2018) (Turkey Building Earthquake Regulation) are used together to specify variables, constraints and also necessity values. The proposed method is feasible for frame structures consisting of different members.
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Malesińska, Agnieszka, Mariusz Rogulski, Pierfabrizio Puntorieri, Giuseppe Barbaro, and Beata Kowalska. "Displacements of the pipe system caused by a transient phenomenon using the dynamic forces measured in the laboratory." Measurement and Control 51, no. 9-10 (September 14, 2018): 443–52. http://dx.doi.org/10.1177/0020294018799370.
Повний текст джерелаАнотація:
Background: When transporting liquids, in particularly over long distances, dynamic forces in the system can present a risk. The larger the system size, and the greater the pressure, the more harmful the impact is of such forces. Water is transported in this way for domestic, industrial, and fire-fighting purposes. One of the impulses of dynamic force application may be the transition of the pressure wave in the water hammer. Methods: In this paper, the results of measured dynamic forces and associated displacements recorded on the model caused by transient flow conditions are presented. For measured forces, the displacements of the pipe were also calculated by using the oscillation motion equations. Force measurements and displacement analyses were carried out in laboratory on the model of a simple fire protection system equipped with three nozzles. Results and Conclusions: The measurement results and calculations were used to calibrate a mathematical model created using MATLAB software.
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Burd, S. C., R. Srinivas, J. J. Bollinger, A. C. Wilson, D. J. Wineland, D. Leibfried, D. H. Slichter, and D. T. C. Allcock. "Quantum amplification of mechanical oscillator motion." Science 364, no. 6446 (June 20, 2019): 1163–65. http://dx.doi.org/10.1126/science.aaw2884.
Повний текст джерелаАнотація:
Detection of the weakest forces in nature is aided by increasingly sensitive measurements of the motion of mechanical oscillators. However, the attainable knowledge of an oscillator’s motion is limited by quantum fluctuations that exist even if the oscillator is in its lowest possible energy state. We demonstrate a technique for amplifying coherent displacements of a mechanical oscillator with initial magnitudes well below these zero-point fluctuations. When applying two orthogonal squeezing interactions, one before and one after a small displacement, the displacement is amplified, ideally with no added quantum noise. We implemented this protocol with a trapped-ion mechanical oscillator and determined an increase by a factor of up to 7.3 (±0.3) in sensitivity to small displacements.
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WANG, D., A. QU, H. ZHOU, and M. WANG. "BIOMECHANICAL ANALYSIS OF THE APPLICATION OF ZYGOMA IMPLANTS FOR PROSTHESIS IN UNILATERAL MAXILLARY DEFECT." Journal of Mechanics in Medicine and Biology 16, no. 08 (November 25, 2016): 1640030. http://dx.doi.org/10.1142/s0219519416400303.
Повний текст джерелаАнотація:
The objective of this research is to evaluate the biomechanical effect of zygomatic implant-supported obturator prostheses in unilateral maxillary defect. Based on CT data, four 3D numerical models were built. One model was a normal craniofacial complex (model 1) and other three models were structures with unilateral maxilla defect reconstructed using clasp-retained obturator prosthesis (model 2), one zygomatic implant-supported and clasp-retained prosthesis (model 3), two zygomatic implant-supported and clasp-retained prosthesis (model 4). Bilateral vertical loads of 300[Formula: see text]N were imposed and the stress and displacement distribution were calculated, analyzed and compared. The bilateral occlusal forces dispersed along the three-mechanical-pillar of the maxillofacial region and the displacement distributed symmetrically in model 1. Because of mechanical pillars break on the affected side, all occlusal forces were transferred by clasps and abutment teeth in model 2, which induced the increase in stress and displacement level. The zygomatic implant restored mechanical pillars and greatly reduced the stress and displacements levels in models 3 and 4. The stress and displacement distributions on clasps, bones, teeth and periodontal ligaments were more reasonable with the support of zygomatic implants. Therefore, the zygomatic implant-supported and clasp-retained prostheses were found to be more effective for unilateral maxillary defect reestablishment.
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Han, Xingbo, Yongxu Xia, Xing Wang, and Lunlei Chai. "Complex Variable Solutions for Forces and Displacements of Circular Lined Tunnels." Mathematical Problems in Engineering 2018 (September 16, 2018): 1–12. http://dx.doi.org/10.1155/2018/2037845.
Повний текст джерелаАнотація:
A complex variable method for solving the forces and displacements of circular lined tunnels is presented. Complex potentials for the stresses and displacements are expressed in the term of series expression. The undetermined coefficients of the complex potentials are obtained according to the stress boundary conditions along the lining inner surface and the displacement and surface traction boundary condition along the lining and rock-mass interface. Solutions for the stresses and displacements of the tunnel lining and rock-mass are then established by applying Muskhekishvili’s complex variable method. In addition, forces solutions for linings are presented based on the tangential stress at the two boundaries. Examples are finally established to reveal the applicability and accuracy of the proposed method. The effects of the degrees from the tunnel crown to the invert, coefficient of the lateral earth pressure, and distance from the rock-mass to the interface on the regulations of the lining forces and rock-mass stresses are also thoroughly investigated.
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Sun, Lianwei, Zhong-chao Li, and Rong-zhu Liang. "Simplified Analytical Method for Predicting the Lateral Ground Displacements due to Shield Tunnelling." Advances in Civil Engineering 2021 (June 21, 2021): 1–10. http://dx.doi.org/10.1155/2021/5524557.
Повний текст джерелаАнотація:
Earth pressure balance or slurry shield tunnelling will squeeze the subsoils and lead to lateral outward ground displacement. However, current methods to estimate the shield tunnelling-induced ground displacements generally use the methods based on the face unsupported tunnelling (e.g., New Austrian tunnelling and open shield excavation), which cannot predict the lateral ground movement due to shield tunnelling. In this paper, a novel simplified analytical method is proposed to predict the ground lateral displacement during the shield advancing process. The key shield tunnelling operation factors, including the additional pressure of cutter head, the friction forces around shield body, the back-fill grouting pressure, and the soil volume loss are all considered. The lateral ground displacements induced by the four former factors are calculated by using Mindlin’s solutions. The soil volume loss-induced lateral ground displacement is calculated by employing the expression introduced by Pinto and Whittle. Combining with the displacement obtained from all the factors, the analytical method for lateral ground displacement induced by shield tunnelling is obtained. The applicability of the proposed analytical approach is verified with three well-documented case histories involving slurry shield and EPB shield machines.
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Ratnayake, Jithendra, Guangzhao Guan, Ajith Polonowita, Andrew R. Gray, Carolina Loch, Kai Chun Li, John Neil Waddell, Karl Lyons, and Paul A. Brunton. "Measuring Changes in Jaw Opening Forces to Assess the Degree of Improvement in Patients with Temporomandibular Disorders." Applied Sciences 12, no. 3 (January 24, 2022): 1224. http://dx.doi.org/10.3390/app12031224.
Повний текст джерелаАнотація:
Background: Currently, the degree of improvement in patients with TMDs is measured through subjective questionnaires and clinical examination This study aimed to investigate the properties of an objective quantitative measure of jaw-opening forces to assess clinical improvement in temporomandibular disorder (TMD) patients following treatment. Methods: Baseline jaw-opening forces were recorded for TMD-patients (n = 62) and a comparison group of TMD-free participants (n = 56), using a jaw-opening forces measuring device. TMD patients were divided into three subcategories (myofascial pain, disc-displacement, and myofascial pain and disc-displacement combined) and received a combination of treatment for six months; meanwhile, TMD-free participants did not receive treatment. Jaw-opening forces for each participant in both groups were measured at their six-month review appointment. Results: Jaw-opening forces were reliable at baseline (single measure ICC 0.98, 95% CI 0.97–0.98, ICC ≥ 0.94 for all groups and subcategories). Jaw-opening forces increased in the TMD group following treatment at six-months (18.6 N at baseline and 32.4 N at six-months, p < 0.001) and did not change significantly in the TMD-free group (49 N at baseline and 48.3 N at six-months). There was a small improvement in the disc displacement group (27.8% higher forces, p = 0.002). However, the myofascial-pain and myofascial-pain-and-disc-displacement groups showed significant improvement following treatment (93.5% higher forces, p < 0.001; 91.1% higher forces, p < 0.001; respectively). Conclusion: This study demonstrated that the measurement of jaw-opening forces could potentially be used to assess the clinical improvement in TMD patients following diagnosis and treatment.
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Tanne, Kazuo, Susumu Matsubara, and Mamoru Sakuda. "Location of the Centre of Resistance for the Nasomaxillary Complex Studied in a Three-Dimensional Finite Element Model." British Journal of Orthodontics 22, no. 3 (August 1995): 227–32. http://dx.doi.org/10.1179/bjo.22.3.227.
Повний текст джерелаАнотація:
The purpose of this study was to investigate the location of the centre of resistance (CRe) for the nasomaxillary complex by the use of finite element analysis. A three-dimensional finite element model of the craniofacial complex, consisting of 2918 nodes and 1776 elements, was used for displacement analyses. Anteriorly and inferiorly directed forces of 9·8 N were applied at five different levels, parallel and perpendicular to the functional occlusal plane, respectively. For each loading condition, horizontal and vertical displacements of eight anatomic points in the complex and on the maxillary dentition were analysed. The complex exhibited an almost translatory displacement of approximately 1·0 µm in the forward direction when the horizontal force was applied at a point on the horizontal plane, passing through the superior ridge of the pterygomaxillary fissure, whereas the complex experienced clockwise or counter clockwise rotation when the forces were applied at the remaining levels. Furthermore, the downward forces produced anteriorly upward, or posteriorly upward rotation. However, the force applied at a point on the vertical plane passing through the posterior wall of the pterygomaxillary fissure, produced almost equal displacements of approximately 6·0 µm in an inferior direction for all the anatomic points. It is suggested that CRe of the nasomaxillary complex is located on the posterosuperior ridge of the pterygomaxillary fissure, registered on the median sagittal plane.
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Yang, Dong Quan, and Hong Peng. "Elasto-Plastic Analysis of Frame Structures under Large Displacement-Rotation Deformations." Advanced Materials Research 243-249 (May 2011): 5968–74. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.5968.
Повний текст джерелаАнотація:
A finite element program for elasto-plastic analysis of 3D beams and frame structures under large displacement/rotations is developed. The element is Timoshenko beam element based on mechanics of continuum. Constitutive equations for large displacements/rotations in elastic stage are expressed in an explicit way which is suitable for programming. The modification of constitutive equation is presented for the analysis of elasto-plastic problems. A fiber model is adopted for the calculation of stiffness matrix and internal forces. For solution of nonlinear finite element equations, general displacement control method and semi-modified stiffness matrix method is adopted. The results of numerical experimentation show that the program work well for 3D beams and frame structures under elasto-plastic large displacement/rotations.
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Djukic, Djordje. "Generalized Lagrange-D’Alembert principle." Publications de l'Institut Math?matique (Belgrade) 91, no. 105 (2012): 49–58. http://dx.doi.org/10.2298/pim1205049d.
Повний текст джерелаАнотація:
The major issues in the analysis of the motion of a constrained dynamic system are to determine this motion and calculate constraint forces. In the analytical mechanics, only the first of the two problems is analyzed. Here, the problem is solved simultaneously using: 1) Principle of liberation of constraints; 2) Principle of generalized virtual displacement; 3) Idea of ideal constraints; 4) Concept of generalized and ?supplementary" generalized coordinates. The Lagrange-D?Alembert principle of virtual work is generalized introducing virtual displacement as vectorial sum of the classical virtual displacement and virtual displacement in the ?supplementary" directions. From such principle of virtual work we derived Lagrange equations of the second kind and equations of dynamical equilibrium in the ?supplementary" directions. Constrained forces are calculated from the equations of dynamic equilibrium. At the same time, this principle can be used for consideration of equilibrium of system of material particles. This principle simultaneously gives the connection between applied forces at equilibrium state and the constrained forces. Finally, the principle is applied to a few particular problems.
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Maximiano, Dalilah Pires, Ricardo A. M. Silveira, Andréa R. D. Silva, and Paulo B. Gonçalves. "An Efficient Strategy for Solving Structural Nonlinear Equations by Combining the Orthogonal Residual Method and Normal Flow Technique." International Journal of Structural Stability and Dynamics 19, no. 04 (April 2019): 1950039. http://dx.doi.org/10.1142/s0219455419500391.
Повний текст джерелаАнотація:
This paper presents a new procedure for solving structural nonlinear problems by combining the orthogonal residual method (ORM) and normal flow technique (NFT). The perpendicularity condition to the Davidenko flow, introduced by the NFT, which must be satisfied during the iterative process, overcome the difficulties, i.e. the poor convergence and inefficiency of the ORM close to the limit points, particularly the displacement limit points (snap-back behavior). Basically, the idea of the proposed strategy is to adjust the load parameter, which is treated as a variable in the nonlinear incremental-iterative solution process, assuming that the unbalanced forces (residual forces) must be orthogonal to the incremental displacements. This constraint is used together with the NFT perpendicularity condition. The proposed procedure is tested, and its efficiency is corroborated through the analyses of slender shallow and nonshallow arches and an L-frame since they exhibit highly nonlinear behaviors under certain loading conditions. It is concluded that the proposed procedure can overcome the numerical instability problems in the neighborhood of critical points when using only the conventional OR process, and the procedure compares favorably with the arc-length method, minimum residual displacement method, and generalized displacement control method.
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Xu, Qiang, and Xing Jun Qi. "Analysis on Seismic Pounding of Curved Bridge." Applied Mechanics and Materials 90-93 (September 2011): 800–804. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.800.
Повний текст джерелаАнотація:
Based on the impact phenomenon between the end of the beam and the bridge abutment of the curved continuous bridge during earthquakes, a spatial finite element calculating model with collision element is presented. The law of collision is studied by the nonlinear contact time history analysis method under two three-dimensional ground motions. The variation laws of relative displacement and the internal force at the bottoms of piers are researched. In addition the changing of displacement and internal force at the end diaphragm are studied. The results show that the pounding action can easily lead to significant collision forces between the end beam and the abutment of the curved bridge which increases the axial force of girder evidently. The collision forces and longitudinal displacements from the inner to outer of the diaphragm generally are showed by an increasing trend, and the pounding action is more fierce under Elcentro ground motion than that under Tianjin ground motion.There is no relative displacement of consolided pier, bending moment and shear force of the consolided pier are greater than that of the mobile pier.The conclusions from the present study may serve as a reference base for seismic design of continuous curved bridges.
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Sazonova, Svetlana, Viktor Asminin, and Alla Zvyaginceva. "Modeling of dangerous internal forces in the calculation by the mixed method of statically indeterminate frames with bars of a given stiffness." Modeling of systems and processes 14, no. 2 (July 26, 2021): 44–54. http://dx.doi.org/10.12737/2219-0767-2021-14-2-44-54.
Повний текст джерелаАнотація:
The features of using the mixed method for calculating internal forces in statically indeterminate frames with rods of a given stiffness are considered. The substantiation of the choice for the calculation of frames of the mixed method, methods of forces or displacements is given. The condition of equivalence of the main and the given systems is provided. The calculations took into account the mechanical meaning of the canonical equations and individual terms of the canonical equations of the mixed method. The corresponding reactions and displacements have been determined. It has been substantiated which part of the frame when calculating by the mixed method is more rational to calculate by the method of displacement, and which part by the method of forces. Used "tabular" data in the process of calculating the frame by the mixed method. If necessary, frame parts are designed to be statically determinate.
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Saiki, Naoya, Kazuaki Inaba, Kikuo Kishimoto, Hideo Seno, and Kazuhiro Takahashi. "Investigation of the Correlation between IC Chip Pick-Up Performance and Peeling Behavior of Adhesive Tapes." Key Engineering Materials 462-463 (January 2011): 807–11. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.807.
Повний текст джерелаАнотація:
It was investigated that the influences of the peeling behavior of adhesive tapes in peeling tests on IC chip pick-up performance. Needles peel off an IC chip with an adhesive film from the base material in the pick-up process, by sticking out the backside of the base material. In the case that the peeling forces of the adhesive tape decrease as the peeling speeds increase in peeling tests, only two kinds of behaviors were observed in pick-up test; the peeling propagated little and the IC chip was not peeled off under critical needle displacement while the pick-up was completed instantaneously over critical needle displacement. In the case that the peeling forces of the adhesive tape increase as the peeling speeds increase, the pick-up time decreased as the needle displacement increased. As a result, it can be concluded that the needle displacement where the peeling propagates instantaneously is critical for succeeded pick-up if the peeling forces of the adhesive tape decrease as the peeling speeds increase. If the peeling forces of the adhesive tape increase as the peeling speeds increase, the information of peeling speeds at each needle displacement are needed to estimate how long it takes to pick-up a chip.
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Lee, M. W. "Particle displacements on the wall of a borehole from incident plane waves." GEOPHYSICS 52, no. 9 (September 1987): 1290–96. http://dx.doi.org/10.1190/1.1442389.
Повний текст джерелаАнотація:
Particle displacements from incident plane waves at the wall of a fluid‐filled borehole are formulated by applying the seismic reciprocity theorem to far‐field displacement fields. Such displacement fields are due to point forces acting on a fluid‐filled borehole under the assumption of long wavelengths. The displacement fields are analyzed to examine the effect of the borehole on seismic wave propagation, particularly for vertical seismic profiling (VSP) measurements. When the shortest wavelength of interest is approximately 25 times longer than the borehole’s diameter, the scattered displacements are proportional to the first power of incident frequency and borehole diameter. The maximum scattered energy occurs when an incident P‐wave propagates perpendicular to the borehole. Borehole effects on VSP measurements, such as waveform distortion, amplitude variation, and time delay, have been analyzed using the concept of a transfer function. When the shortest wavelength of interest is about 40 times longer than the borehole’s diameter, borehole effects on VSP measurements using a wall‐locking geophone are negligible.
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Zeng, Zhiping, Ji Hu, Qiang Zeng, Zhibin Huang, Huatuo Yin, and Hui Huang. "Analysis of Longitudinal Force of Beam and Rail of Continuously Welded Rails (CWR) on Railway Bridge." Journal of Physics: Conference Series 2148, no. 1 (January 1, 2022): 012065. http://dx.doi.org/10.1088/1742-6596/2148/1/012065.
Повний текст джерелаАнотація:
Abstract To study the longitudinal force of CWR on viaduct, a track-bridge-pier finite element model is established. Taking a multi-span simply supported beam with a maximum span of 32.7m of an elevated CWR as an example, the additional expansion and contraction forces, displacement between rail and beam and the force of pier are calculated, and whether the rail stress meets the requirements when setting constant resistance fasteners is checked. The results show that: (1) For the left and right lines, the maximum additional expansion forces of single strand rail are both 211.13kN, and the maximum relative displacements between beam and rail are both 6.572mm. (2) The maximum value of the additional expansion and contraction forces and the relative displacement between beam and rail of the same line occur at the same position. The left line is at ZFZ29 pier and the right line is at ZFS31 pier. (3) The maximum force of pier in this section is 500.80kN, and the pier numbers are ZFZ27 and ZFS29. (4) The rail stress is less than the allowable stress of 352MPa, and the rail strength meets the requirements.