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Статті в журналах з теми "EQUIVALENT STATIC FORCE TECHNIQUE"
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Zinco, Adamo, Fernando Fraternali, Gianmario Benzoni, and Enzo Martinelli. "On the Distribution in Height of Base Shear Forces in Linear Static Analysis of Base-Isolated Structures." Buildings 10, no. 11 (November 1, 2020): 197. http://dx.doi.org/10.3390/buildings10110197.
Повний текст джерелаАнотація:
Although base isolation is nowadays a well-established seismic-protection technique for both buildings and bridges, and several issues are still open and attract the interest of the research community. Among them, the formulation of computationally efficient and accurate analysis methods is a relevant aspect in structural design of seismic-isolated buildings. In fact, codes and guidelines currently in force in various parts of the world generally include the possibility for designers to utilize linear-elastic analysis methods based on equivalent linearization of the non-linear force-displacement response of isolators. This paper proposes a formula for defining the force distribution in height that should be considered in linear-static analyses to obtain a more accurate approximation of the actual structural response, supposedly simulated by means of non-linear time history analysis. To do that, it summarizes the results of a wide parametric analysis carried out on a batch of structures characterized by three different heights and various properties of base isolators. The reported results highlight that the equivalent static force distribution provided by both Italian and European codes tend to underestimate the actual seismic lateral forces acting on base-isolated buildings, whereas the inverted triangular distribution, proposed in various American codes and standards, is often conservative.
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Figliolini, Giorgio, and Massimo Sorli. "Open-loop Force Control of A Three-finger Gripper Through PWM Modulated Pneumatic Digital Valves." Journal of Robotics and Mechatronics 12, no. 4 (August 20, 2000): 480–93. http://dx.doi.org/10.20965/jrm.2000.p0480.
Повний текст джерелаАнотація:
This paper proposes an open-loop force control system for a three-finger gripper using small digital solenoid valves modulated using PWM (Pulse-Width-Modulation) technique. These valves are good candidates for this robotic application because of their small dimensions, low weight and cost, simple structure and easy operation by means of on/off signals. A linear model for pressure control in the pneumatic actuator's thrust chamber was developed and tested experimentally. A large dead-band was introduced in the PWM driver in order to investigate a suitable method for its correction. Good results were obtained by correcting the static characteristic curve of the three-way equivalent valve that controls the flow rate exchanged with the pneumatic cylinder thrust chamber. These results can be applied to similar solutions with larger digital valves. Gripping mechanism efficiency and the effects of friction forces were taken into account in developing the force control.
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Jiang, Shan, Fude Sun, Jiansheng Dai, Jun Liu, and Zhiyong Yang. "Design and analysis of a tendon-based MRI-compatible surgery robot for transperineal prostate needle placement." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 2 (May 7, 2014): 335–48. http://dx.doi.org/10.1177/0954406214533783.
Повний текст джерелаАнотація:
Tendon-based transmission has significant advantages in the development of a surgical robot, which is fully magnetic resonance imaging compatible and can work dexterously in the very limited space inside magnetic resonance imaging core. According to the requirements of magnetic resonance imaging compatibility, a novel 6 degrees of freedom tendon-based surgical robot composed of three independent modules is developed in this paper. After a brief introduction to the robot, the direct and inverse kinematic equations are deduced by applying the concept of screw displacements, and the reachable workspace of the robot is calculated. As to the static force analysis, we apply the principle of virtual work to derive a transmission between the equivalent joint torques and the tendon forces. By the use of the pseudoinverse technique, a systematic method is developed for the resolution of redundant tendon forces.
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Singh, A., N. Nawayseh, L. P. Singh, S. Singh, and H. Singh. "Investigation of Compressive Stress on Lumbar Spine due to Whole Body Vibration Exposure in Rotary Tillage Operation." International Journal of Automotive and Mechanical Engineering 16, no. 2 (July 4, 2019): 6684–96. http://dx.doi.org/10.15282/ijame.16.2.2019.16.0503.
Повний текст джерелаАнотація:
The aim of this study is to investigate the compressive stress on lumbar spine due to whole body vibration (WBV) exposure in real field rotary soil tillage operation. The spinal stress was evaluated in terms of daily equivalent static compression dose (Sed) with respect to various ride conditions (i.e. forward speed, pulling force and tilling depth). Taguchi's L9 orthogonal array was used to form a systematic set of experiments by varying each ride condition over three levels. Signal-to-noise (S/N) ratios were computed to analyse the holistic effect of ride conditions among all the experimental conditions. In addition, the power spectral density (PSD) of the acceleration at the seat pan was measured along the dominant axis for each experiment. A second order regression model was developed to predict the real experimental Sed response. Further, the ride conditions were optimised by using desirability technique with the aim of minimizing Sed response. The magnitude of daily equivalent static compression dose was found between 0.38 and 0.76 MPa which shows a moderate probability of an adverse health effects as per ISO2631-5: 2004. Statistically, forward speed and pulling force are found to significantly affect the Sed response with a contribution of 64.43% and 24.73%, respectively. The PSD indicated that the vibration energy of the acceleration measured on the seat pan depend on the ride conditions. The predicted response of regression model showed 4.56% error in obtaining the actual experimental values. The optimised forward speed, pulling force and tilling depth levels were found to be 0.6 m/s, 2 kN, and 0.10 m, respectively.
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Hu, Botao, Linan Cheng, Xiaobo Sun, and Fanchen Deng. "Design Technique of the Test Static for Large Curvature Composite Radome." Journal of Physics: Conference Series 2553, no. 1 (August 1, 2023): 012019. http://dx.doi.org/10.1088/1742-6596/2553/1/012019.
Повний текст джерелаАнотація:
Abstract The radome is an important component that maintains the aerodynamic shape of the aircraft, makes the electrical property stable, and ensures flight safety. Composite is used in most aircraft radome in the world to reduce the weight of the aircraft. For the sake of safety, a static strength test was usually conducted on the radome to verify whether its strength and stiffness meet the requirements. In this paper, the load was treated equivalently, and a lever loading system of nonparallel force was put forward considering the characteristics of the large curvature of the radome structure and that it was difficult to apply load. All test cases were completed successfully, and the test results indicate that the test system works stably and reliably, and the strength and stiffness of the radome meet the design requirements.
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Meena, Balveer Singh, Atul Kumar Shrivastava, and Kunal Bhelave. "A Finite-element Method of Solution for Optimization of Frame of Tractor Operated Single Row Maize Cobs Picker." International Journal of Plant & Soil Science 35, no. 3 (March 2, 2023): 154–59. http://dx.doi.org/10.9734/ijpss/2023/v35i32787.
Повний текст джерелаАнотація:
Finite element analysis (FEA) is a computational technique that divides complex structures into small elements and solves them numerically using various partial differential equations. In agriculture, engineers can use numerical simulation based on the FEA technique to study the behaviour of various input products in order to optimise the design of any machine without developing a prototype. The present study focused to design and simulates the frame of tractor operated single row maize cobs picker by employing the FEA technique. A 3D-CAD model of the frame of a tractor-operated single row maize cobs picker was created using the Solid Works software, and a static structural test was performed using the FEA technique in the ANSYS version 15.0 workbench software. A special fixture has been developed to calculate the force required to scrape the pulpy material of the leaves in the Universal Testing Machine. According to the simulation results, maximum deformation was observed as 0.051mm while maximum shear stress and Von Mises equivalent stress were found to be 0.246 MPaPa and 1. 47 MPa, respectively at 250 N scraping forces. Additionally, it was noted that the stress values fall within the material's yield strength. The FEA approach was found to be a scientific and highly effective method for designing and simulating the frame of a tractor-operated single row maize cobs picker.
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Boulkhiout, Radhwane. "Soil Densification Effect on The Seismic Response of Structures Taking into Consideration Soil-Structure Interaction." Civil Engineering Beyond Limits 2, no. 4 (September 21, 2021): 13–17. http://dx.doi.org/10.36937/cebel.2021.004.003.
Повний текст джерелаАнотація:
Soil compaction is a considerable construction activity to ensure safety and durability, notably in the transportation industry. This technique of compaction increases soil bulk density and soil strength, while decreases porosity, aggregate stability index, soil hydraulic conductivity, and nutrient availability, thus reduces soil health. Consequently, it lowers crop performance via stunted aboveground growth coupled with reduced root growth. Therefore, if the characteristics of the soil are changed, it will affect the response of the structures. In this work, the effect of improving soil characteristics by compaction techniques on the dynamic response of foundations and structures, taking into consideration the effect of soil-structure interaction was determined. The dynamic response of foundations is presented by the impedances functions, which are determined numerically by the CONAN program, based on the cone method. In addition, the response of the structure will be presented according to the lateral displacement in each level of it. This motion vector is a function of the forces in each level; for this, the equivalent static method was applied, which allows to calculate the seismic force at the base and its distribution on the height of the structure. The results obtained show the efficiency of soil densification on the seismic response of MDOF frames.
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Ahmad, Naveed, Qaisar Ali, and Muhammad Umar. "Seismic Vulnerability Assessment of Multistory Timber Braced Frame Traditional Masonry Structures." Advanced Materials Research 601 (December 2012): 168–72. http://dx.doi.org/10.4028/www.scientific.net/amr.601.168.
Повний текст джерелаАнотація:
Research carried out on the seismic investigation of timber braced frame (TBF) masonry structures of traditional construction practice is presented, essential for seismic performance evaluation of such construction type using engineering approaches. An innovative simplified equivalent frame method (EFM) based on macro modelling approach is presented for nonlinear dynamic seismic analysis of TBF masonry structures. The modelling include EFM idealization of wall using stiff elastic beam-column element assigned with moment-rotation (M-θ) nonlinear lumped plasticity hinges. Earlier, the approach i.e. the EFM idealization and M-θ constitutive law, is calibrated with the experimental results obtained through quasi-static cyclic test on full scale walls. The technique is further extended herein for seismic dynamic analysis of multistory structures. Generalization of the technique for modelling walls of various geometry and loading is performed. It included nonlinear static pushover analysis of various case study walls, by means of SAP2000 calibrated earlier with experimental results, for the derivation of lateral force-deformability behavior towards the development of generalized M-θ constitutive law for TBF masonry walls. Three representative structures, from one to three storeys, are analyzed using a suite of ten natural accelerograms and incremental dynamic analysis technique. Structure fragility and resilience functions are derived using a fully probabilistic and dynamic approach. The structures analyzed in the present study represent TBF masonry wall structures, called as Dhajji-Dewari structures, common in Northern areas of Pakistan.
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Yazdani, Aref. "Field Equations and Radial Solutions in a Noncommutative Spherically Symmetric Geometry." Advances in High Energy Physics 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/349659.
Повний текст джерелаАнотація:
We study a noncommutative theory of gravity in the framework of torsional spacetime. This theory is based on a Lagrangian obtained by applying the technique of dimensional reduction of noncommutative gauge theory and that the yielded diffeomorphism invariant field theory can be made equivalent to a teleparallel formulation of gravity. Field equations are derived in the framework of teleparallel gravity through Weitzenbock geometry. We solve these field equations by considering a mass that is distributed spherically symmetrically in a stationary static spacetime in order to obtain a noncommutative line element. This new line element interestingly reaffirms the coherent state theory for a noncommutative Schwarzschild black hole. For the first time, we derive the Newtonian gravitational force equation in the commutative relativity framework, and this result could provide the possibility to investigate examples in various topics in quantum and ordinary theories of gravity.
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Qureshi, Ramla Karim, Negar Elhami-Khorasani, and Thomas Gernay. "Adaption of active boundary conditions in structural fire testing." Journal of Structural Fire Engineering 10, no. 4 (December 9, 2019): 504–28. http://dx.doi.org/10.1108/jsfe-12-2018-0042.
Повний текст джерелаАнотація:
Purpose This paper aims to investigate the need for active boundary conditions during fire testing of structural elements, review existing studies on hybrid fire testing (HFT), a technique that would ensure updating of boundary conditions during a fire test, and propose a compensation scheme to mitigate instabilities in the hybrid testing procedure. Design/methodology/approach The paper focuses on structural steel columns and starts with a detailed literature review of steel column fire tests in the past few decades with varying axial and rotational end restraints. The review is followed with new results from comparative numerical analyses of structural steel columns with various end constraints. HFT is then discussed as a potential solution to be adapted for fire testing of structural elements. Challenges in contemporary HFT procedures are discussed, and application of stiffness updating approaches is demonstrated. Findings The reviewed studies indicate that axial and rotational restraints at the boundaries considerably influence the fire response of steel columns. Equivalent static spring technique for simulating effect of surrounding frame on an isolated column behavior does not depict accurate buckling and post-buckling response. Additionally, numerical models that simulate fire performance of a column situated in a full-frame do follow the trends observed in actual test results up until failure occurs, but these simulations do not necessarily capture post-failure performance accurately. HFT can be used to capture proper boundary conditions during testing of isolated elements, as well as correct failure modes. However, existing studies showed cases with instabilities during HFT. This paper demonstrates that a different stiffness updates calculated from the force-displacement response history of test specimen at elevated temperature can be used to resolve stability issues. Originality/value The paper has two contributions: it suggests that the provision of active boundary conditions is needed in structural fire testing, as equivalent static spring does not necessarily capture the effect of surrounding frame on an isolated element during a fire test, and it shows that force-displacement response history of test specimen during HFT can be used in the form of a stiffness update to ensure test stability.
Дисертації з теми "EQUIVALENT STATIC FORCE TECHNIQUE"
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Leaf, Timothy D. "Investigation of the vertical distribution of seismic forces in the static force and equivalent lateral force procedures for seismic design of multistory buildings /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1136093311&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Повний текст джерела
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Kassir, Wafaa. "Approche probabiliste non gaussienne des charges statiques équivalentes des effets du vent en dynamique des structures à partir de mesures en soufflerie." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1116/document.
Повний текст джерелаАнотація:
Afin d'estimer les forces statiques équivalentes du vent, qui produisent les réponses quasi-statiques et dynamiques extrêmes dans les structures soumises au champ de pression instationnaire induit par les effets du vent, une nouvelle méthode probabiliste est proposée. Cette méthode permet de calculer les forces statiques équivalentes du vent pour les structures avec des écoulements aérodynamiques complexes telles que les toitures de stade, pour lesquelles le champ de pression n'est pas gaussien et pour lesquelles la réponse dynamique de la structure ne peut être simplement décrite en utilisant uniquement les premiers modes élastiques (mais nécessitent une bonne représentation des réponses quasi-statiques). Généralement, les mesures en soufflerie du champ de pression instationnaire appliqué à une structure dont la géométrie est complexe ne suffisent pas pour construire une estimation statistiquement convergée des valeurs extrêmes des réponses dynamiques de la structure. Une telle convergence est nécessaire pour l'estimation des forces statiques équivalentes afin de reproduire les réponses dynamiques extrêmes induites par les effets du vent en tenant compte de la non-gaussianité du champ de pression aléatoire instationnaire. Dans ce travail, (1) un générateur de réalisation du champ de pression instationnaire non gaussien est construit en utilisant les réalisations qui sont mesurées dans la soufflerie à couche limite turbulente; ce générateur basé sur une représentation en chaos polynomiaux permet de construire un grand nombre de réalisations indépendantes afin d'obtenir la convergence des statistiques des valeurs extrêmes des réponses dynamiques, (2) un modèle d'ordre réduit avec des termes d'accélération quasi-statique est construit et permet d'accélérer la convergence des réponses dynamiques de la structure en n'utilisant qu'un petit nombre de modes élastiques, (3) une nouvelle méthode probabiliste est proposée pour estimer les forces statiques équivalentes induites par les effets du vent sur des structures complexes décrites par des modèles éléments finis, en préservant le caractère non gaussien et sans introduire le concept d'enveloppes des réponses. L'approche proposée est validée expérimentalement avec une application relativement simple et elle est ensuite appliquée à une structure de toiture de stade pour laquelle des mesures expérimentales de pressions instationnaires ont été effectuées dans la soufflerie à couche limite turbulenteIn order to estimate the equivalent static wind loads, which produce the extreme quasi-static and dynamical responses of structures submitted to random unsteady pressure field induced by the wind effects, a new probabilistic method is proposed. This method allows for computing the equivalent static wind loads for structures with complex aerodynamic flows such as stadium roofs, for which the pressure field is non-Gaussian, and for which the dynamical response of the structure cannot simply be described by using only the first elastic modes (but require a good representation of the quasi-static responses). Usually, the wind tunnel measurements of the unsteady pressure field applied to a structure with complex geometry are not sufficient for constructing a statistically converged estimation of the extreme values of the dynamical responses. Such a convergence is necessary for the estimation of the equivalent static loads in order to reproduce the extreme dynamical responses induced by the wind effects taking into account the non-Gaussianity of the random unsteady pressure field. In this work, (1) a generator of realizations of the non-Gaussian unsteady pressure field is constructed by using the realizations that are measured in the boundary layer wind tunnel; this generator based on a polynomial chaos representation allows for generating a large number of independent realizations in order to obtain the convergence of the extreme value statistics of the dynamical responses, (2) a reduced-order model with quasi-static acceleration terms is constructed, which allows for accelerating the convergence of the structural dynamical responses by using only a small number of elastic modes of the structure, (3) a novel probabilistic method is proposed for estimating the equivalent static wind loads induced by the wind effects on complex structures that are described by finite element models, preserving the non-Gaussian property and without introducing the concept of responses envelopes. The proposed approach is experimentally validated with a relatively simple application and is then applied to a stadium roof structure for which experimental measurements of unsteady pressures have been performed in boundary layer wind tunnel
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Uherek, Jan. "Statická a dynamická analýzy ocelové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409745.
Повний текст джерелаАнотація:
The thesis deals with a description and a static and dynamic analysis for an existing construction of lookout tower. The steel watchtower is located in Město Albrechtice and is made up of two lattice towers connected by a bridge. Main point was to create calculation models for the purpose of dynamic and static analysis, in the software SCIA Engineer 19.1, which is based on the principle of finite element method. Attention was paid to load created by winds according to Eurocode 1 and Eurocode 3, glaze and rime ice load and dynamic coefficient calculation. The thesis also includes an assesment of selected parts of the construction according to Eurocodes.
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Pečeliūnas, Robertas. "Automobilio svyravimai ekstremalaus stabdymo metu." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050224_192006-55801.
Повний текст джерелаАнотація:
The suspension of the motor vehicle is one of the most important elements of the flexible mounted and inflexible mounted masses of the vehicle bodywork, and most attention is paid to its exploration and improvement. Analysis of models of equivalent oscillation systems of motor vehicles testifies that the evaluation of motor vehicle oscillations and modelling of its motion modes is still very topical and requires further research. Suspension models of motor vehicles offered in publications regard only the influence of road irregularities, and the modernisation of these models is directed towards the improvement of passengers’ comfort. However not much research has been done on the influence of oscillations of flexible mounted and inflexible mounted masses of the bodyworks of vehicles in the process of braking; also there is not much investigation of the post-accident identification of the vehicle’s movement mode corresponding to the deformations of the suspension and the longitudinal pitch of the bodywork. Research of oscillations in the conditions of emergency braking is primarily important for the work in two practical directions:
1) improvement of calculation methods of motor vehicle’s response to external impact in the conditions of real operation;
2) further improvement of research methods on the road, and analysis of fait accompli road accidents related to oscillations in the emergency braking.
Methodology defining the oscillations occurring in the braking may be applied... [to full text]
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VISHWAKARMA, ADITYA. "ANALYSIS OF SEISMIC SUSCEPTIBILITY OF AN IRREGULARLY PLANNED SETBACK STRUCTURE WITH A SOFT STOREY ON SLOPING TERRAIN AND PLAIN TERRAIN." Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19972.
Повний текст джерелаАнотація:
The construction of multi-story setback buildings with soft storey, or open ground floor,
is in high demand and becoming more and more popular. This effort decreases the
setback configuration's vertical stability and the lateral load resisting system's rigidity.
When a building is supported on sloping land, there are several possibilities for short
and long columns inside the same structure. During earthquake shaking, all columns
and floor slabs at every level move horizontally by the same amount, which may result
in structural damage. In this study, an attempt is made to examine the seismic
performance of setback buildings standing on flat ground as well as on a slope, with
soft storey layout. ETABS, a widely used software programme, was used to analyse
simple 3-D frames of SETBACK structures. Using the study findings several graphs
were drawn for like base shear, storey drift, storey stiffness, displacement, rotation
about z axis are developed for both terrains i.e. plain and sloping. To create a technical
expertise two identical structure were examined on both terrains. All the modelled
structures with open ground storey have been analysed using two distinct methods:
equivalent static force technique, response spectrum method. To counteract this soft
storey impact and the severe reactions, mitigation approaches have been implemented,
and the most effective of these mitigation techniques is provided.
Частини книг з теми "EQUIVALENT STATIC FORCE TECHNIQUE"
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Paz, Mario. "Equivalent Static Lateral Force Method: Uniform Building Code-1985." In Structural Dynamics, 511–44. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-9907-0_23.
Повний текст джерела
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Paz, Mario. "Equivalent Static Lateral Force Method: Uniform Building Code-1988." In Structural Dynamics, 545–67. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-9907-0_24.
Повний текст джерела
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Paz, Mario. "Uniform Building Code-1994 Equivalent Static Lateral Force Method." In Structural Dynamics, 707–65. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4684-0018-2_24.
Повний текст джерела
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Paz, Mario. "Equivalent Static Lateral Force Method: Uniform Building Code—1985." In Structural Dynamics, 511–44. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-7918-2_23.
Повний текст джерела
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Paz, Mario. "Equivalent Static Lateral Force Method: Uniform Building Code—1988." In Structural Dynamics, 545–67. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-7918-2_24.
Повний текст джерела
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Echeverry Jaramillo, Sara, Marine Geers, Loïc Buldgen, Jean-Philippe Pecquet, and Philippe Rigo. "Resistance of Plane Lock Gates Subjected to Ship Impact." In Lecture Notes in Civil Engineering, 611–22. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_53.
Повний текст джерелаАнотація:
AbstractThis paper presents the analysis of lock gates submitted to ship impacts. This problem is generally approached in two different ways: firstly, by the use of an equivalent static method, in which the impact is modeled by a quasi-static force, or by the use of dynamic numerical simulations, during which the progress of the ship and the temporal evolution of the impact force is taken into account. The second approach requires extensive calculation and modeling efforts, which are generally prohibitive in the early design stage.A simplified analytical method is presented to evaluate the resistance of such structures when impacted by a ship. The principle is based in the super-element method, firstly evaluating the resistance of the lock gate in local deformation mode, assuming crushing only of certain structural elements in a limited zone, located in the close vicinity of the impact. Secondly, the entire resistance of the lock gate is calculated, considering the global deformation mode, assuming a bending of the entire structure.The scientific objective is to extend this approach to lock gates which cannot currently be treated with this method, in particular those where the layout of the stiffening elements can be highly irregular. This implies to study thoroughly the global deformation modes of the structure and the plastic mechanisms involved in the energy dissipation, in order to predict a correct displacement field and resistance force.
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Brock, Fred V., and Scott J. Richardson. "Barometry." In Meteorological Measurement Systems. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195134513.003.0004.
Повний текст джерелаАнотація:
The objective of barometry is to measure the static pressure exerted by the atmosphere. Static pressure is the force per unit area that would be exerted against any surface in the absence of air motion. It is an isotropic, scalar quantity. Dynamic pressure is the force per unit area due to air motion. It is a vector quantity, following the wind vector. This chapter is concerned with determining the static air pressure and doing so in the presence of air motion (wind) that requires special measurement techniques. The Earth’s atmosphere exerts a pressure on the surface of the Earth equal to the weight of a vertical column of air of unit cross-section. Since air is a fluid, this pressure, or force, is exerted equally in all directions. The static pressure at the surface is given by where g(z) = acceleration due to gravity at height z above sea level in ms-2, and ρ = density as a function of height, kg-3. The SI unit of pressure is the pascal, abbreviated as Pa. In meteorology, the preferred unit of pressure is the mb or the hPa (equivalent magnitude). Table 2-1 lists some conversion factors for units currently in use in pressure measurement and also for some units no longer favored. Standard sea level pressure in various units is shown in table 2-2. The last line of table 2-2 refers to the units of Ibf in-2,also called psi (pounds per square inch). Pressure measurements are often called absolute (psia), gauge (psig), or differential (psid). Absolute pressure is simply the total static pressure exerted by the gas (or fluid) and so the barometric pressure is also the absolute pressure. Gauge pressure is the pressure relative to ambient atmospheric pressure. Pressure in an automobile tire is measured relative to atmospheric pressure so it is gauge pressure, not absolute pressure. Differential pressure is the pressure relative to some other pressure. Gauge pressure is a special case of differential pressure. In addition to the static pressure there is a dynamic pressure exerted by wind flow.
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Sutton, Adrian P. "The force on a defect." In Physics of Elasticity and Crystal Defects, 163–78. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198860785.003.0008.
Повний текст джерелаАнотація:
This chapter is based on Eshelby’s static energy-momentum tensor which results in an integral expression for the configurational force on a defect. After elucidating the concepts of a configurational force and an elastic singularity the mechanical pressure on an interface, such as a twin boundary or a martensitic interface, is derived. Eshelby’s force on a defect is derived using both physical arguments and more formally using classical field theory. It is equivalent to the J-integral in fracture mechanics. The Peach–Koehler force on a dislocation is rederived using the static energy-momentum tensor. An expression for an image force is derived, where a defect interacts with a free surface.
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"Sample Calculations: To Compute Equivalent Static Lateral Forces and to Determine Vertical Force Distribution." In Earthquake-Resistant Structures, 381–84. Elsevier, 2013. http://dx.doi.org/10.1016/b978-1-85617-501-2.00024-9.
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Martinho Simões, José A., and Manuel Minas da Piedade. "Isoperibol Reaction-Solution Calorimetry." In Molecular Energetics. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195133196.003.0012.
Повний текст джерелаАнотація:
The determination of enthalpies of reaction in solution, using isoperibol reaction-solution calorimetry, is often the easiest and most accurate method of determining enthalpies of formation of compounds that cannot be studied by combustion calorimetry. The technique was pioneered by Thomsen who, between 1882 and 1886, performed thermochemical measurements involving the solution of various substances in liquids (e.g., diluted acids). Many types of isoperibol reaction-solution calorimeters have been developed since then. The designs vary according to the nature of the reactions of interest. One of the most widely used consists of a vessel, such as the one shown in figure 8.1, immersed in a thermostatic water bath. The sample is sealed inside a thin-walled glass ampule A, fixed to an ampule breaking system B in the calorimeter head C. The calorimeter head also supports the temperature sensor D, the stirrer E, and an electrical resistance F, used for calibration of the apparatus. The Dewar vessel G, containing the solution to be reacted with the sample, is adjusted to C. The assembled calorimetric vessel is transferred to the thermostatic bath, and from then on, the experimental procedure closely follows that already described in section 7.1 for isoperibol static-bomb combustion calorimetry. The reaction is initiated at the end of the fore period by pushing down the plunger H and breaking the ampule against a pin situated at the bottom of the ampule breaking system B. As a result of the calorimetric experiment, a temperature-time curve such as the one in figure 7.2 is obtained. Note that figure 7.2 is typical of an exothermic process. In the case of an endothermic process, a decrease of the temperature of the calorimetric system is observed during the reaction period. The experiments are usually carried out at atmospheric pressure and the initial goal is the determination of the enthalpy change associated with the calorimetric process under isothermal conditions, ΔHICP, usually at the reference temperature of 298.15 K. This involves the determination of the corresponding adiabatic temperature change, ΔTad, from the temperature-time curve just mentioned, by using one of the methods discussed in section 7.1; the determination of the energy equivalent of the calorimeter in a separate experiment.
Тези доповідей конференцій з теми "EQUIVALENT STATIC FORCE TECHNIQUE"
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Kumar, Saurabh, Anirban Mitra, and Haraprasad Roy. "Forced Vibration Analysis of Functionally Graded Plates With Geometric Nonlinearity." In ASME 2015 Gas Turbine India Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gtindia2015-1390.
Повний текст джерелаАнотація:
Forced vibration analysis has been carried out on functionally graded plates where the material properties vary along axial direction. The geometric nonlinearity is incorporated in the system using nonlinear strain displacement relations. An indirect methodology is adopted in which the dynamic system is assumed to satisfy the force equilibrium condition at peak excitation amplitude, thus reducing the problem to an equivalent static case. The computational points are selected and start functions are generated at those points by satisfying the flexural and membrane boundary conditions of the plate. The start functions are later used for generating higher order functions using Gram-Schmidt orthogonalisation procedure. The mathematical formulation is based on the variational form of energy principles and the governing equations are derived using Hamilton’s principle. The set of nonlinear governing equations is solved using an iterative direct substitution method employing an appropriate relaxation technique. The results are generated for combinations of clamped and simply supported boundary conditions and presented in amplitude-frequency plane. Three dimensional operational deflection shape plots along with contour plots are also provided for some cases. Results are validated with the works available in the literature.
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Eventoff, Arnold T. "Stress-Driven Cam Mechanism Synthesis Using the Phantom Linkage Method." In ASME 1994 Design Technical Conferences collocated with the ASME 1994 International Computers in Engineering Conference and Exhibition and the ASME 1994 8th Annual Database Symposium. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/detc1994-0262.
Повний текст джерелаАнотація:
Abstract The capability for automatically deriving the geometry of a cam and its driven linkage geometry as a function of critical design parameters is described. A technique developed called “The Phantom Linkage Method” enables instantaneous updating of a critical parameter (e.g. cam-follower contact stress) as a function of various system parameters. Linkage geometry and properties, timing diagram parameters, and static and dynamic loads in the system due to springs, gravity, and inertially-induced forces are included in the critical parameter calculation. The first part of the paper describes a method for instantly defining the shape of a cam surface as a function of linkage geometry and required output motion for a full cycle of motion. The second part adds static and dynamic forces to the analysis. The Phantom Linkage Method in conjunction with a series of equivalent drive ratios derived from the geometry is then used to determine cam-follower contact stress for a full cycle of motion. Finally, by including optimization capabilities, the mechanism and cam geometry, as well as the timing diagram, can be synthesized simultaneously to minimize an objective function describing a critical design parameter such as cam-follower contact stress.
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Underwood, James, Erick Alley, Jerolim Andric, Dario Boote, Zhen Gao, Ad Van Hoeve, Jasmin Jelovica, et al. "Committee II.1: Quasi-Static Response." In 21st International Ship and Offshore Structures Congress, Volume 1. SNAME, 2022. http://dx.doi.org/10.5957/issc-2022-committee-ii-1.
Повний текст джерелаАнотація:
Committee Mandate Concern for the quasi-static response of ship and offshore structures, as required for safety and serviceability assessments. Attention shall be given to uncertainty quantification of quasi-static load and response analysis approaches, and their limitations, including exact and approximate methods for derivation of different acceptance criteria. Introduction In the design of ship and offshore structures, Naval Architects and Structural Engineers require access to a wide range of analysis methods to successfully progress from concept brief through to a production ready design, that will safely operate for the duration of its service life. Significant development in computational analysis techniques have occurred over the preceding decades, coupled with increased availability of high-performance computing; however, computationally intensive methods regularly do not fit the requirements of a design team, particularly in the early design phases. Whilst some quasi-static methods may have arisen at times of lesser computational capabilities, quasi-static analysis methods remain relevant, providing an appropriate balance between accuracy and speed, often having an ability to provide a quick result based on minimal input data, facilitating rapid design iteration. In ship and offshore structures, the loading, whether local or global, is predominantly caused by a dynamic motion that is cyclic or oscillating, for example the wave loading of a ship hull girder in a seaway, the sloshing loading due to the motions of fluid in a tank, the loading on a deck or equipment foundation, etc. True dynamic analysis of such scenarios is complex and time consuming to undertake, and often can’t be successfully completed until the structural design details are in a progressed state. Therefore, quasi-static methods implementing a simplified approach that resembles the scenario, whether through a defined loading or to induce a seemingly equivalent structural response, have been developed. Not all loading scenarios can be suitably represented by quasi-static methods, particularly where loading is complex or structural response of the individual parts of the system may interact. However, where a quasi-static method can be implemented to develop a structure with sufficient reserve to facilitate safe operation, the benefits to the design process can be significant. In structural response analysis, a method may be considered to be quasi-static where the effects of structural dynamics (structural inertia and damping) may be neglected. In this regards the time component, or time derivatives, may be neglected. To adopt a quasi-static method, the true time dependant loading must be sufficiently slow in relation to the structural response not to coincide with resonant response frequencies. Due to this ‘slow’ progression, during analysis the system may be considered to be in static equilibrium at all time instances. These points are true for many quasi-static analyses, where loading may be through incremental application of force or displacement to a structure, and static equilibrium of the system is achieved before the next increment is applied. Therefore, time associated with the loading is only implied and not explicitly included in the assessment. In other words, the structural responses at any time instant will be only determined by the loads at that time instant, and the structural responses have no memory effect. Whilst the applied loading may be incremental, it need not be entirely linear, and in the same regard the structural response also need not be linear. For example, the loading and response could be coupled, such that as the structure deforms the load is iterated to reflect the new state of the system. However, in the application of quasi-static methods, the relative accuracy and therefore suitability of the method should always be considered. Quasi-static analysis covers a broad spectrum of methods from hand calculations to finite element analysis (FEA) and may even combine methods such as computational fluid dynamics (CFD). The methods may be used directly for structural assessment, or as part of broader method, such as the input to a reliability analysis or optimisation routine, or to derive a peak stress or stress sequence for fatigue assessment. For this reason, there may be perceived overlap between this and other ISSC committees. However, this committee has specifically focussed the presented report around methods that are quasi-static in nature, including where the topics, such as fatigue, ultimate and accidental limit states, that are covered in depth from a different perspective by other ISSC Technical Committees.
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Liu, K. J., and Keith E. Rouch. "An Application of Active Dynamic Absorber to the Milling Process and its Experimental Verification." In ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0225.
Повний текст джерелаАнотація:
Abstract In order to reach the inside surfaces of some workpieces, a prototype for milling extension is developed. The milling extension has a low static stiffness and is prone to machine tool chatter, therefore vibration control in this type of machining is of importance. The paper proposes the application of an active dynamic absorber to the milling process. A finite element model for the milling extension with consideration of the cutting dynamics is developed. An annular ring serving as the dynamic absorber mass is connected to the main system through active force generating systems which are piezoelectric translators functioning as actuators. The annular ring and the actuators are functioning as an active dynamic absorber in the theory to suppress the vibration of the milling system. Optimal control algorithms are used to calculate the Kalman feedback control for the equivalent lumped-mass milling structure model. Transient responses of the system are obtained. Oscillation of the milling extension equipped with the active dynamic absorber is attenuated appreciably, therefore the surface finish of a workpiece is improved. Harmonic responses are also obtained with and without the feedback control to show the superiority of the active control technique. A proof-of-concept experiment is designed and conducted to verify the theoretical prediction. Comparisons between the simulation and experimental results are made.
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Tang, Wenwu, Yaoguo Li, Douglas W. Oldenburg, and Jianxin Liu. "Magnetotelluric static shift correction using an equivalent source technique." In SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, 2014. http://dx.doi.org/10.1190/segam2014-1621.1.
Повний текст джерела
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Hu, Dianyin, and Rongqiao Wang. "Probabilistic Analysis on Turbine Disk Under LCF-Creep." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50722.
Повний текст джерелаАнотація:
This paper establishes a structural model of the turbine disk of a certain aero-engine subjected to loads due to centrifugal force and duration at elevated temperature, and calculates the plastic and creep deformation with finite element (FE) analysis software. During creep analysis, the Norton constitutive equation was taken into account. After the temperature field distribution of the turbine disk had been obtained, structural static analysis results showed that the maximum equivalent stress and strain appeared at the area near to the disk center, which was taken as the critical point. The Manson-Coffin formula was used to predict low cycle fatigue (LCF) life based on the calculations derived from cyclic plastic-creep analysis, and creep life was obtained by applying the Larson-Miller equation. Lognormal distributions of LCF life and creep life were used as pointed out in the literature, which mainly considered the uncertainties in material parameters. Taking the lives and loads as random variables including LCF life, creep life, fatigue load and hold time, a probabilistic analysis on the turbine disk was performed under LCF-Creep, in which a failure function was proposed based on linear cumulative damage rule (LCDR). The probabilistic method of response surface (RS) was applied to fit the regression model of the LCF-Creep life with a quadratic approximation function including cross-terms. The Monte Carlo Simulation sampling technique was employed to carry out probabilistic analysis on the turbine disk life, resulting in the conclusion that the life of turbine disk under LCF-Creep follows a lognormal distribution. Furthermore, the effect of different random variables on the disk life was investigated through sensitivity analysis in order to increase the component’s life and improve its reliability. However, studies on the distributions of loads and damage theory of the component under LCF-Creep still need to be discussed in future study.
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Dayal, Vinay, Gohar M. Mir, and David K. Hsu. "Damage Modeling in Honeycomb Panels for Tap Testing." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1627.
Повний текст джерелаАнотація:
Abstract Effect of damage on Composite Honeycomb panel due to low speed impact is of significance. The result of such impact is damage such as crushing or buckling of the core, core to face de-bonding and local de-lamination of the plies. The damage, however, may be invisible to human eye but can result in significant degradation of stiffness and strength of Honeycomb structure. Of all the NDE techniques available, Tap Test seems to be the cheapest and most suited for the detection of damage in face-sheets, the face-sheet to core de bonding, and core damage. Instrumented Tap Testing with scanning capability makes it a very attractive NDE tool. This work is concerned with modeling the Tap Test on composite honeycomb panels by Finite Elements in both static and dynamic modes. Interactive Finite Element model has been developed having option of creating multiple defects of varying size at desired location within the core material. Model is generated using Graphite/Epoxy quasi-isotropic laminate as face sheet material with Nomex paper core, simulating condition of crushed core. The model was analyzed by applying point load (equivalent force of the impacting projectile) at the node of concern. The defect is modeled as a gap in the core. Samples were made having defects at different core height and were analyzed using Finite Element Methods (ANSYS) and by Tap Testing under same boundary conditions and loading. The sensitivity of FE model and Tap Test to damage location and size has been studied and the results are presented.
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Kianirad, Ehsan, Ronald W. Gamache, David Brady, and Akram N. Alshawabkeh. "Equivalent Quasi-Static Estimation of Dynamic Penetration Force for Near Surface Soil Characterization." In Geo-Frontiers Congress 2011. Reston, VA: American Society of Civil Engineers, 2011. http://dx.doi.org/10.1061/41165(397)238.
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Udoh, Ikpoto E. "A Concise Methodology for the Design of Statically-Equivalent Deep-Offshore Mooring Systems." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23054.
Повний текст джерелаАнотація:
Model testing of deepwater offshore structures often requires the use of statically-equivalent deepwater mooring systems. The need for such equivalent systems arises due to the spatial limitations of wave basins in accommodating the dimensions of the direct-scaled mooring system. With the equivalent mooring system in place and connected to the model floater, the static global restoring forces and global stiffness of the prototype floating structure can be matched (to within some tolerance) by those of the model for specified offsets in the required degrees of freedom. A match in relevant static properties of the system provides the basis for comparisons of dynamic responses of the model and prototype floaters. Although some commercial programs are capable of designing equivalent mooring systems, the physics applied in these programs are protected by intellectual property, and their methodologies are generally inflexible. This paper illustrates a concise approach to the design of statically-equivalent deepwater mooring systems. With this approach, either manual or advanced optimization techniques can be applied as needed based on the complexity of the equivalent system to be designed. A simple iterative scheme is applied in solving the elastic catenary equations for the optimal static configuration of each mooring line. Discussions cover the approach as applied in developing a fit-for-purpose tool called STAMOORSYS, its validation, and its application to the design of an equivalent mooring system for a spar platform in deepwater. The spar model parameters are representative of a structure which could be tested in the Offshore Technology Research Center, College Station, Texas, USA. Results show that the method is capable of producing good design solutions using manual optimization and a genetic algorithm.
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Ereke, I. Murat, and Kubilay Yay. "Theoretical Analysis of Fatigue Strength of a Double-Deck Bus Body Using FEM." In ASME 2002 Engineering Technology Conference on Energy. ASMEDC, 2002. http://dx.doi.org/10.1115/etce2002/struc-29023.
Повний текст джерелаАнотація:
Modern design techniques primarily consist of finite element analysis of the vehicle body in a computational media. In this study, an actual double-deck bus body of domestic production has been modeled in three-dimensions by means of IDEAS program in order to calculate its fatigue strength. In other words, an approximation algorithm has been developed to obtain service loads. The effects of dynamic and static loads on the bus body have been calculated and included to the FEM analysis. As a new approximation technique, during the service life of a vehicle under dynamic loads (straight good road, straight bad road, cornering bad road and singular obstacle road) arising from the road conditions as taking into account, load spectrum has been constituted. In the design spectrum that has been utilized in our calculations, considering the equivalence damage effect rule, instead of using straight good road conditions, other fifty percent of forces that have been mentioned above, accepted as hundred percent of dynamic and static forces caused by bad road conditions acting on the bus body. As a result of this study, the calculated results have been compared to the theoretical and experimental data taken from literature review. It can be seen that this approximation technique that we used in our calculations can be used for this kind of fatigue analysis of vehicle components or bodies.