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Journal articles on the topic 'Longitudinal static stability'

Author: Grafiati
Published: 4 June 2021
Last updated: 15 February 2022

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1

WANG, KeMu, ChenAn ZHANG, FaMin WANG, and ZiAn JIA. "Longitudinal static stability analysis of hypersonic waveriders." SCIENTIA SINICA Technologica 44, no. 10 (October 1, 2014): 1114–22. http://dx.doi.org/10.1360/n092014-00058.

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2

Bloy, A. W. "An Aircraft Longitudinal Static Stability and Control Experiment." International Journal of Mechanical Engineering Education 24, no. 3 (July 1996): 183–90. http://dx.doi.org/10.1177/030641909602400305.

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3

ANDO, Shigenori, and Hiroshi KAJITA. "Evaluation Method of Longitudinal Static Stability of Tailless Airplane." Journal of the Japan Society for Aeronautical and Space Sciences 40, no. 456 (1992): 14–22. http://dx.doi.org/10.2322/jjsass1969.40.14.

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4

Su, Xin Bing, Zhou Zhou, Jing Cheng Shi, and Xu Wang. "Research on Longitudinal Static Stability for VFSW Tailless Configuration UAV." Applied Mechanics and Materials 543-547 (March 2014): 348–53. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.348.

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The Variable Forward-Swept Wing (VFSW) Tailless configuration UAV can well satisfy multipurpose demands. However, this kind of unconventional morphing aircraft lacks tail, which brings great challenge to stability analysis. The connatural aero-elasticity divergence and the strong aerodynamic coupling as well as many uncertain factors in mechanical environment, give the VFSW Tailless configuration UAV complicated dynamic characteristics. During the process of transformation, the variation of dynamic shape will inevitably lead to the variation about aerodynamic center and barycentre positions of airplane, then make the angle of attack static stability margin variable, and directly influence stability of aircraft. On the basis of introduction of the VFSW Tailless configuration UAV, according to its geometric shape, positions of aerodynamic center and barycentre, in different states with different forward-swept angle, were calculated, so as to obtain variation curve of longitudinal static stability margin, which provided preferences for dynamics analysis, position of barycentre adjustment and design of flight control system (FCS).
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5

Choi, Jung-Kyu, and Hyoung-Tae Kim. "Evaluation of Longitudinal Static Stability of Human Powered Hydrofoil Boat." Journal of the Society of Naval Architects of Korea 46, no. 4 (August 20, 2009): 391–97. http://dx.doi.org/10.3744/snak.2009.46.4.391.

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6

Yang, Wei, Zhigang Yang, and Maurizio Collu. "Longitudinal static stability requirements for wing in ground effect vehicle." International Journal of Naval Architecture and Ocean Engineering 7, no. 2 (March 2015): 259–69. http://dx.doi.org/10.1515/ijnaoe-2015-0018.

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7

Bai, Ming, He Xu, Long He, Wei Xing Guo, and Chang Hua Qiu. "Longitudinal Associated Stability Analysis of Mobile Robot in Rough Terrain." Key Engineering Materials 572 (September 2013): 632–35. http://dx.doi.org/10.4028/www.scientific.net/kem.572.632.

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Focusing on the longitudinal adaptability of a three-fuselage articulated with separated differential mechanism in rough terrain, the associated factor which could be a criterion for the judgment of longitudinal associated stability of mobile robot has been proposed, and the analysis results of the longitudinal associated stability under different situation have been obtained based on static stability theory of mobile robot.
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8

Cook, M. V. "The theory of the longitudinal static stability of the hang-glider." Aeronautical Journal 98, no. 978 (October 1994): 292–304. http://dx.doi.org/10.1017/s0001924000026798.

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Abstract This paper describes the development of a simple theory of the longitudinal static stability of the hang-glider. The classical theory, as developed for the conventional aeroplane, is modified to accommodate the particular features of the hang-glider. When the appropriate assumptions are made, the theory provides simple insight into the controls fixed and controls free stability and control characteristics of the hang-glider. The validity of the theoretical models is successfully demonstrated by application to a typical fifth generation hang-glider wing for which good quality aerodynamic data were available.
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9

Yang, Wei, Zhigang Yang, and Chengjiong Ying. "Effects of design parameters on longitudinal static stability for WIG craft." International Journal of Aerodynamics 1, no. 1 (2010): 97. http://dx.doi.org/10.1504/ijad.2010.031705.

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10

Xiao, Hou Di, Pan Pan Mi, Long Bin Liu, and Shuai Cao. "A New Method of Strengthening Longitudinal Static Stability of Airship in Ascent." Applied Mechanics and Materials 687-691 (November 2014): 212–15. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.212.

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To improve the controllability and maneuverability, airship is usually designed as static instability. But the airship is vulnerable to sudden wind interference in its ascent, resulting in divergent pitching motion. A new aerodynamic shape was put forward which added a inflatable aerodynamic-lift wing at backward of the airship hull. With the method of Computational Fluid Dynamics (CFD), aerodynamic characteristics and longitudinal static stability of the conventional airship and new winged airship were comparative investigated. It can be concluded that the new winged airship was longitudinal stable whereas the conventional airship was instable. It can be applied for restraining the sudden wind interference for airship in ascent.
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11

Ayers, Paul, John B. Conger, Rob Comer, and Paul Troutt. "Stability Analysis of Agricultural Off-Road Vehicles." Journal of Agricultural Safety and Health 24, no. 3 (2018): 167–82. http://dx.doi.org/10.13031/jash.12889.

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Abstract. Vehicle rollovers cause many agricultural work-related fatalities each year. Tractors, off-road utility vehicles (ORUVs), zero turn radius (ZTR) mowers, and all-terrain vehicles (ATVs) can all become involved in fatal rollovers. The rollover tendency of these vehicles was evaluated using static lateral and longitudinal stability angles. Center of gravity locations were measured with the lift axle method, and lateral and longitudinal stability angles were calculated for four ATVs, five ORUVs, four ZTR mowers, and four lawn tractors. Stability angles were calculated for loaded and unloaded vehicle conditions. Loading vehicles with ballast and operators can substantially decrease lateral and longitudinal stability angles. Stability angles for these vehicles and for five full-size agricultural tractors were compared. All loaded and unloaded, lateral and longitudinal stability angles determined met the appropriate ANSI requirements. Keywords: ATVs, Off-road utility vehicles, Stability angles, Tractors.
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12

Wilshin, Simon, Michelle A. Reeve, G. Clark Haynes, Shai Revzen, Daniel E. Koditschek, and Andrew J. Spence. "Longitudinal quasi-static stability predicts changes in dog gait on rough terrain." Journal of Experimental Biology 220, no. 10 (March 6, 2017): 1864–74. http://dx.doi.org/10.1242/jeb.149112.

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13

Collu, Maurizio, Minoo H. Patel, and Florent Trarieux. "The longitudinal static stability of an aerodynamically alleviated marine vehicle, a mathematical model." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2116 (December 2, 2009): 1055–75. http://dx.doi.org/10.1098/rspa.2009.0459.

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An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles highlights a gap that can be usefully filled by a new vehicle concept, utilizing both hydrodynamic and aerodynamic forces. A high-speed marine vehicle equipped with aerodynamic surfaces is one such concept. In 1904, Bryan & Williams (Bryan & Williams 1904 Proc. R. Soc. Lond. 73 , 100–116 (doi:10.1098/rspl.1904.0017)) published an article on the longitudinal dynamics of aerial gliders, and this approach remains the foundation of all the mathematical models studying the dynamics of airborne vehicles. In 1932, Perring & Glauert (Perring & Glauert 1932 Reports and Memoranda no. 1493) presented a mathematical approach to study the dynamics of seaplanes experiencing the planing effect. From this work, planing theory has developed. The authors propose a unified mathematical model to study the longitudinal stability of a high-speed planing marine vehicle with aerodynamic surfaces. A kinematics framework is developed. Then, taking into account the aerodynamic, hydrostatic and hydrodynamic forces, the full equations of motion, using a small perturbation assumption, are derived and solved specifically for this concept. This technique reveals a new static stability criterion that can be used to characterize the longitudinal stability of high-speed planing vehicles with aerodynamic surfaces.
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14

Mohammed, Tariq O., Naser M. Elkhmri, and Hamza AboBakr. "Analysis and Simulation of UAV Aircraft Flight Dynamics." Advanced Materials Research 915-916 (April 2014): 7–11. http://dx.doi.org/10.4028/www.scientific.net/amr.915-916.7.

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The objective of the present work is to evaluate the static and dynamic stability of the Flying Wing Unmanned Aircraft Vehicle (UAV) model using the Tornado software. The longitudinal and the lateral-directional aerodynamics were studied using the model with incompressible flow, asymmetric, conditions. The stability coefficients were calculated and give proof that the aircraft is statically stable. Using the stability coefficients, the longitudinal and lateral-directional equations of motion were written to evaluate the dynamic stability of the vehicle. Good flying qualities were obtained, rating in Level 1 for the Cooper and Harper scale.
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15

Lasi, Fahad, Bakhtawar Samejo, Atif Mehmood, and Muhammad Waseem. "Impact of medial longitudinal arch height on static stability of undergraduate physiotherapy students." International Journal of Health and Rehabilitation Sciences (IJHRS) 8, no. 2 (2019): 78. http://dx.doi.org/10.5455/ijhrs.0000000171.

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16

Opala-Berdzik, Agnieszka, Janusz W. Błaszczyk, Bogdan Bacik, Joanna Cieślińska-Świder, Dariusz Świder, Grzegorz Sobota, and Andrzej Markiewicz. "Static Postural Stability in Women during and after Pregnancy: A Prospective Longitudinal Study." PLOS ONE 10, no. 6 (June 8, 2015): e0124207. http://dx.doi.org/10.1371/journal.pone.0124207.

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17

Czyż, Z., T. Łusiak, P. Karpiński, and J. Czarnigowski. "Numerical investigation of the gyroplane longitudinal static stability for the selected stabilizer angles." Journal of Physics: Conference Series 1101 (October 2018): 012003. http://dx.doi.org/10.1088/1742-6596/1101/1/012003.

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18

Bykerk, Tamas, Dries Verstraete, and Johan Steelant. "Low speed longitudinal aerodynamic, static stability and performance analysis of a hypersonic waverider." Aerospace Science and Technology 96 (January 2020): 105531. http://dx.doi.org/10.1016/j.ast.2019.105531.

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19

Pang, Mei Sa, Deng Hua Li, Jun Fang Fan, and Xue Fei Li. "Double Loop Autopilot Design Based on Frequency Domain." Advanced Materials Research 301-303 (July 2011): 1724–29. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.1724.

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The static stability of missile pitching movement is one of the important performances in guidance and control systems. In this paper, a method which consists of the single and double loop longitudinal autopilot using frequency domain approach is proposed to solve the problem efficiently. Single-loop autopilot is used to simplify the system design when the missile is highly static stable; the double-loop autopilot is employed to stabilize the system and improve frequency performance when the missile is static stable or static unstable. Control gain of the system is determined by aerodynamic parameters and frequency domain indexes. The simulation result shows that double-loop autopilot based on frequency domain simplified the system design and improved the stability and robustness of missile system.
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20

Sun, De Xin, and Xin Hui Liu. "Analysis of Static Stability of Articulated Hydraulic Excavator with Two Degree of Freedom." Advanced Materials Research 430-432 (January 2012): 1663–66. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.1663.

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In this paper, the geometric model of the hydraulic excavator with two degree of freedom was built, and then the dynamic model based on the multi-body dynamic software RecurDyn was built, and then the lateral stability and longitudinal stability of the hydraulic excavator on different gradients were analyzed, the result showed the tipping feather of the hydraulic excavator truly, and this paper provides guidance for choosing the hydraulic excavator’s working conditions.
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21

Bromfield, M. A., and G. B. Gratton. "Factors affecting the apparent longitudinal stick-free static stability of a typical high-wing light aeroplane." Aeronautical Journal 116, no. 1179 (May 2012): 467–99. http://dx.doi.org/10.1017/s0001924000006990.

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Abstract Flying a light aeroplane involves a combination of pilot and aeroplane performing a set task, within a specific environment. The pilot is continuously sampling and selecting available sensory cues, interpreting those cues, making decisions and manipulating the primary controls (stick and rudder) to safely achieve flying objectives. The ‘feel’ of an aeroplane (a flying quality) is directly associated with the stick and rudder forces and how the aeroplane responds to control inputs. Classical theory has been applied to estimate the apparent (as felt by the pilot) longitudinal stick-free static stability (change of stick force with airspeed) of a typical, two-seat, high-wing light aeroplane. The theory has been extended to consider the effects of tail downwash and flap deflection. The results are compared with actual flight tests and show that the method may be used for the initial assessment of longitudinal stick-free static stability and more importantly, tendencies towards neutral or negative stability affecting flight safety.
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22

Asendorpf, Jens B. "Beyond stability: Predicting inter‐individual differences in intra‐individual change." European Journal of Personality 6, no. 2 (June 1992): 103–17. http://dx.doi.org/10.1002/per.2410060204.

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Demonstration of a high longitudinal stability of inter‐individual diferences in behaviour has been one traditional goal of personality psychology. In recent years, impressively high longitudinal correlations have been reported for self‐and other‐ratings of behaviour in adulthood, indicating a high overall stability of personality differences in that period of development. However, even 5‐year correlations around 0.70 do not exclude major deviations of some of the subjects from this overall stability (i.e. differential stability in the sample). Furthermore, the younger a sample is, the lower will be the longitudinal stability observed, and the less suficient is the explanation of inter‐individual diferences by static traits. This article goes beyond the notion of stability at the sample level by asking from a developmental perspective (a) whether systematic inter‐individual differences in intra‐individual change exist, (b) how they can be assessed, and (c) whether these inter‐individual differences can be explained by characteristics of the person or of the environment.
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23

Perez, Ruben E., Hugh H. T. Liu, and Kamran Behdinan. "Relaxed Static Stability Aircraft Design via Longitudinal Control-Configured Multi-disciplinary Design Optimization Methodology." Canadian Aeronautics and Space Journal 52, no. 1 (March 2006): 1–14. http://dx.doi.org/10.5589/q06-004.

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24

Bloy, A. W., J. T. Turner, and A. Rizzi. "An Interactive Multimedia Computer Program on Aircraft Stability and Control." International Journal of Mechanical Engineering Education 25, no. 3 (July 1997): 231–39. http://dx.doi.org/10.1177/030641909702500308.

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A pilot interactive multimedia computer program on aircraft longitudinal static stability and trim is described. The module simulates typical features of an undergraduate course and has been evaluated by third-year undergraduate students familiar with the topic. In general, favourable comments have been made, particularly concerning the ease of use, overall presentation, level of interactivity and the simulation of a wind-tunnel experiment. Applications of the program are suggested.
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25

Brzuzy, Aneta, and Grzegorz Bąk. "Stability analysis of steel compression members under shock loads." Bulletin of the Military University of Technology 67, no. 1 (April 3, 2018): 107–25. http://dx.doi.org/10.5604/01.3001.0011.8051.

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This paper presents the results of a numerical analysis of the elastic-plastic behaviour of steel compression members subjected to compression with a permanent pre-deformation in the longitudinal axis by a longitudinal indispensable shock load. A differential load intensity was considered up to the loss of stability. A finite difference method was applied, with an explicit integration schema for the time of the dynamic stability equations. It was assumed that the precursor to the unstable behaviour of a steel compression member was a continuous deformation of the rod axis, which was defined according to current industry-standard design procedures. Cases of flexible and stiff rods, varying in slenderness, were considered. It was demonstrated that a significant load on the performance of the steel compression members and their buckling mechanisms is attributable to longitudinal wave effects. These longitudinal wave effects cause high-frequency changes in the axial forces with a significant stress concentration due to the effect of reflection from a pinned support. This is critical for the dissipation of internal energy by plastic deformation. The applied research method facilitated an estimation of the dynamic critical forces and their relationships with static values. Keywords: steel rods with pre-deformation of axis, elastic-plastic behaviour, dynamic stability of rods, differential approximation, effects of axial wave response
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26

Yan, Hui, Tong Ge, and Jian Min Liu. "Analysis of Motion in Longitudinal Plane of Negative Buoyancy Vehicle." Advanced Materials Research 457-458 (January 2012): 1367–76. http://dx.doi.org/10.4028/www.scientific.net/amr.457-458.1367.

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This article described a novel type of autonomous underwater vehicle and modeled the dynamics. This kind of vehicle looked like an air-plane with large wings and worked under the condition of negative buoyancy. The motions of negative-buoyancy-vehicle (NBV) in the longitudinal plane were analyzed through linear system theory. This paper divided motion of NBV into a few modes in the longitudinal plane and provided a method of reduction of order to simplify the analysis, as well as gave the criterion of static stability under constant load in longitudinal plane. It had been found that the maneuverability and stability of NBV was related to many factors such as the velocity, lift-drag ratio, buoyancy and metacentric height. All of the conclusions could be applied on NBV design.
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27

Guerrero, J. E., C. Pacioselli, J. O. Pralits, F. Negrello, P. Silvestri, A. Lucifredi, and A. Bottaro. "Preliminary design of a small-sized flapping UAV: I. Aerodynamic performance and static longitudinal stability." Meccanica 51, no. 6 (October 14, 2015): 1343–67. http://dx.doi.org/10.1007/s11012-015-0298-6.

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28

Zhu, Jianxu, Shupei Zhang, Guolin Wang, Wei Zhang, and Sheng Zhang. "Research on vehicle stability region under critical driving situations with static bifurcation theory." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 8 (February 23, 2021): 2072–85. http://dx.doi.org/10.1177/0954407021993941.

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A strategy for solving the static bifurcation points of the 5DOF vehicle nonlinear system is proposed to research the stability region of the system. The bifurcation characteristics of the system is changed by the coupling of the steering and the engine braking torques under the high-speed emergency steering conditions, and the corresponding vehicle stability region must be redefined. The stability region of the vehicle which is influenced by the engine braking torque is determined with the static bifurcation theory, and the equilibrium points of the 5DOF vehicle system are solved with the phase space method and the random weight particle swarm optimization (RWPSO) algorithm. The vehicle stability is verified with different initial longitudinal speeds and different steering angles, and the simulation results validate the effectiveness of the stability region under the critical driving conditions. The study is conducive to the development of the active safety control systems and the application of nonlinear system dynamics in the automotive field. Furthermore, it provides the theoretical support for the application of the vehicle-handling stability.
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29

KWIEK, Agnieszka. "STUDY ON THE STATIC AND DYNAMIC STABILITY OF A MODULAR AIRPLANE SYSTEM." Aviation 20, no. 4 (December 20, 2016): 160–67. http://dx.doi.org/10.3846/16487788.2016.1235849.

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The purpose of this research is an analysis of the static and dynamic stability of the Modular Airplane System (MAS). The MAS is designed to perform suborbital space flights. The concept assumes that two tailless vehicles bonded together form a conventional aircraft where the wing of the second one is used as the horizontal tail of the whole system. The CFD calculations, and the stability and control derivatives were conducted by the PANUKL package, which uses a low order panel method for the aerodynamic analysis. The analysis of the static and dynamic stability was performed by the SDSA package. Only the selected part of the MAS mission was investigated. The results that will be presented have been divided into three parts: static stability, longitudinal dynamic stability and lateral dynamic stability. The MAS has a few possible applications. The first one is a suborbital space tourism flight. Moreover, it can be used as a lunching vehicle for micro satellites or as a testing platform for new space technology to improve their TRL level. Finally, in the far future, it could be used as a fast point-to-point travel system. The paper presents the results of the static and dynamic stability of a unique aircraft configuration which consists of two tailless vehicles. The research focuses on a situation where the vehicles are just before separation and their mass is similar. Moreover, the influence of the second vehicle’s position with respect to the first one is included.
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30

Mi, Bai-gang, Hao Zhan, and Bai-bing Chen. "New Systematic CFD Methods to Calculate Static and Single Dynamic Stability Derivatives of Aircraft." Mathematical Problems in Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/4217217.

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Several new systematic methods for high fidelity and reliability calculation of static and single dynamic derivatives are proposed in this paper. Angle of attack step response is used to obtain static derivative directly; then translation acceleration dynamic derivative and rotary dynamic derivative can be calculated by employing the step response motion of rate of the angle of attack and unsteady motion of pitching angular velocity step response, respectively. Longitudinal stability derivative calculations of SACCON UCAV are taken as test cases for validation. Numerical results of all cases achieve good agreement with reference values or experiments data from wind tunnel, which indicate that the proposed methods can be considered as new tools in the process of design and production of advanced aircrafts for their high efficiency and precision.
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31

Liu, Xiao Xiong, Yan Wu, Peng Hui Li, and Heng Xu. "Dynamic Optimization Genetic Algorithms for Flight Control Laws Design." Applied Mechanics and Materials 278-280 (January 2013): 1581–84. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.1581.

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The general flight control laws are designed by static designs and dynamic fits. To improve the adaptive capability, the method of control laws design was introduced by using dynamic optimization genetic algorithms. The control parameters were adjusted online in the flight envelope. The dynamic optimization model was built for aircraft longitudinal function. The fitness was set up by applying order track. And then the control parameters were regulated by dynamic optimization genetic algorithms. Finally an example of a longitudinal control augmented stability system of an aircraft is used with a simulation.
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32

Chen, Wenjie, K. H. Low, and S. H. Yeo. "Adaptive gait planning for multi-legged robots with an adjustment of center-of-gravity." Robotica 17, no. 4 (July 1999): 391–403. http://dx.doi.org/10.1017/s0263574799000958.

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Adaptive gait planning is an important aspect in the development of control systems for multi-legged robots traversing on rough terrain. The problem of adaptive gait generation can be viewed as one of finding a sequence of suitable foothold on rough terrain so that legged systems maintain static stability and motion continuity. Due to the limit of static stability, deadlock situation may occur in the process of searching for a suitable foothold, if terrain contains a large number of forbidden zones. In this paper, an improved method for adaptive gait planning is presented by active compensation of stability margin, through center of gravity (CG) adjustment in the longitudinal axis and/or body translation in the lateral direction. An algorithm for the proposed method is developed and embedded in a computer program. Simulation results show that the method provides legged machines with a much larger terrain adaptivity and better deadlock-avoidance ability.
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33

Nikitenko, M. I., and N. А. Shanshabayev. "Resistance of models of pyramidal-prismatic piles to static pulling load." BULLETIN of L.N. Gumilyov Eurasian National University. Technical Science and Technology Series 134, no. 1 (2021): 7–19. http://dx.doi.org/10.32523/2616-7263-2021-134-1-7-19.

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The article presents results of testing models of piles with different longitudinal shapes under the action of a static pulling load, performed in laboratory conditions. The article reveals resistance of the pyramidal-prismatic piles can be either more or less than the resistance of the prismatic and pyramidal piles. It was found that an increase in the length of the pyramidal part of the pile, as well as the size of its cross-section at the top, affect the resistance of the pile to pull-out load. So, the resistance of these piles is 1.28-1.85 times higher than the resistance of a prismatic pile with a section size of 20×20 cm, and 8-36% lower than the resistance of a prismatic pile with a section size of 30×30 cm and a pyramidal pile (with a top section size of 30×30 cm and at the bottom - 20×20 cm). Correlation dependencies are obtained to assess the stability of pyramidal-prismatic piles in relation to the bearing capacity of piles with traditional longitudinal section shape (prismatic and pyramidal piles).
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34

Champagne, Yves, and Nathalie McCarthy. "Analysis of the stability of multiple-phase-shift distributed-feedback semiconductor lasers." Canadian Journal of Physics 71, no. 1-2 (January 1, 1993): 29–38. http://dx.doi.org/10.1139/p93-006.

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The effects of the longitudinal spatial hole burning on the static lasing characteristics of a specific configuration of distributed-feedback semiconductor laser with three phase-shift regions are investigated using a numerical approach. A serious degradation of the stability of the optimum design, having the flattest axial intensity distribution at low output power, is predicted for drive levels beyond a critical value. The lasing wavelength exhibits a sudden shift (wavelength chirping), along with a significant degradation of the single-mode character of the longitudinal-mode spectrum. Thus, the potentialities of this multiple-phase-shift structure to provide a stable narrow-linewidth emission at high output power appear to be less than expected from results calculated for the near-threshold regime. Nevertheless, it is found that a multiple-phase-shift configuration that departs slightly from the optimum case suffices to recover most of the promises expected from this distributed-feedback laser design.
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35

Babcock, J., and R. Lind. "Aeroelastic effects of battens on the flight dynamics of a MAV." Aeronautical Journal 118, no. 1207 (September 2014): 985–1008. http://dx.doi.org/10.1017/s0001924000009714.

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Abstract Wing flexibility is well established as providing gust rejection and delayed onset of stall for micro air vehicles. As such, many designs adopt wings of a flexible material mounted onto a skeleton comprised of a stiff leading-edge spar and stiff chordwise strips, called battens. These battens are shown to provide additional strength at localised regions of the wing and thus improve the gust rejection and delay stall; however, their effect on the flight dynamics is less studied. Using a numerical modeling approach, this paper explores a design space of vehicles with a varied number of wing battens mounted onto a baseline vehicle with a flexible wing. The battens are modelled as stepwise changes in torsional stiffness along the wing span. The resulting trim characteristics, static stability metrics and flight dynamics are evaluated. The battens are shown to improve gust rejection but otherwise have a complicated effect across the design space. A reduction in the number of battens improves the longitudinal static stability derivative slightly but lowers the lateral and directional static stability. The damping is decreased for the short period mode and increased for the phugoid and dutch roll modes as the number of battens is reduced.
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36

Fang, Hui. "Influence of Pier Settlement on Structural Stress of Longitudinal Connected Track in High-Speed Railways." Advances in Civil Engineering 2020 (May 22, 2020): 1–12. http://dx.doi.org/10.1155/2020/8102637.

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Pier settlement is unavoidable in the construction and operation of high-speed railways. This paper presents a work on the influence of pier settlement on additional structural stress of longitudinal connected track (LCT). First of all, the generation mechanism of additional structural stress of LCT caused by pier settlement is described in detail. On this basis, the deformation of LCT caused by pier settlement is analytically deduced and a dynamic model of high-speed train-LCT-bridge coupled system considering pier settlement is established based on the train-track-bridge dynamic interaction theory, adopting which the additional structural stresses of LCT are discussed from static and dynamic perspectives. Results show that pier settlement has a great influence on the stability of LCT. Additional tensile stresses of LCT appear at settlement pier location and two adjacent pier locations. Tensile stresses on top surface of slab and on bottom surface of base should be paid attention to. The behaviors of LCT at adjacent pier locations cannot be ignored in studying the influence of pier settlement on the system. To ensure the stability of LCT and running performance of train, the control value of pier settlement is suggested to be 10.5 mm from the static and dynamic perspectives in practical engineering.
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Kang, Chi-Hang, Hwan-Kee Cho, Young-Il Jang, Sang-Hyun Lee, and Kwang-Youn Kim. "Analysis of the Longitudinal Static Stability and the Drop Trajectory of a Fighter Aircraft's External Fuel Tank." Journal of the Korean Society for Aeronautical & Space Sciences 38, no. 3 (March 1, 2010): 274–79. http://dx.doi.org/10.5139/jksas.2010.38.3.274.

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38

Guerrero, J. E., C. Pacioselli, J. O. Pralits, F. Negrello, P. Silvestri, A. Lucifredi, and A. Bottaro. "Erratum to: Preliminary design of a small-sized flapping UAV: I. Aerodynamic performance and static longitudinal stability." Meccanica 52, no. 9 (November 7, 2016): 2245. http://dx.doi.org/10.1007/s11012-016-0571-3.

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39

Martsinkovsky, V. A., A. Zhulyov, and C. Kundera. "Static and Dynamics of a Pump Impeller with a Balancing Device Part II: Dynamic Analysis." International Journal of Applied Mechanics and Engineering 19, no. 3 (August 1, 2014): 621–31. http://dx.doi.org/10.2478/ijame-2014-0043.

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Abstract This paper presents the theoretical study of the system comprising an impeller and a balancing device. It deals with the dynamic analysis of the system, i.e., the axial vibrations of the impeller, and the system stability. The dynamic analysis took into account linearized hydrodynamic forces and moments generated in the longitudinal clearances of the seals of the impeller. The theoretical analysis was supplemented with a numerical example with characteristics determined for a real single-stage centrifugal pump
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40

Peeters, Maarten W., Martine A. Thomis, Hermine H. M. Maes, Gaston P. Beunen, Ruth J. F. Loos, Albrecht L. Claessens, and Robert Vlietinck. "Genetic and environmental determination of tracking in static strength during adolescence." Journal of Applied Physiology 99, no. 4 (October 2005): 1317–26. http://dx.doi.org/10.1152/japplphysiol.00021.2005.

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The purpose of this study was to determine whether the observed phenotypic stability in static strength during adolescence, as measured by interage correlations in arm pull, is mainly caused by genetic and/or environmental factors. Subjects were from the Leuven Longitudinal Twin Study ( n = 105 pairs, equally divided over 5 zygosity groups). Arm-pull data were aligned on age at peak height velocity to attenuate the temporal fluctuations in interage correlations caused by differences in timing of the adolescent growth spurt. Developmental genetic models were fitted using structural equation modeling. After the data were aligned on age at peak height velocity, the annual interage correlations conformed to a quasi-simplex structure over a 4-yr interval. The best-fitting models included additive genetic and unique environmental sources of variation. Additive genetic factors that already explained a significant amount of variation at previous measurement occasions explained 44.3 and 22.5% of the total variation at the last measurement occasion in boys and girls, respectively. Corresponding values for unique environmental sources of variance are 31.2 and 44.5%, respectively. In conclusion, the observed stability of static strength during adolescence is caused by both stable genetic influences and stable unique environmental influences in boys and girls. Additive genetic factors seem to be the most important source of stability in boys, whereas unique environmental factors appear to be more predominant in girls.
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41

Cook, M. V., and H. V. de Castro. "The longitudinal flying qualities of a blended-wing-body civil transport aircraft." Aeronautical Journal 108, no. 1080 (February 2004): 75–84. http://dx.doi.org/10.1017/s0001924000005029.

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Abstract This paper describes an evaluation of the longitudinal flying qualities of a generic blended-wing-body (BWB) transport aircraft at low speed flight conditions. Aerodynamic data was obtained from several sources and integrated into the equations of motion of a typical BWB configuration in order to provide a reasonable basis for flying qualities assessment. The control requirements to trim are enumerated for a representative range of cg position and static margin over the typical range of approach speeds for both stable and unstable configurations. The linear dynamic characteristics of the unaugmented airframe are also described for the same range of stability margin. Subsequent work describes the development of a rate command-attitude hold command and stability augmentation system configured to comply with representative modern handling criteria. Finally, the flight dynamics of the augmented aircraft are described after refinement of the control law by means of piloted simulation in a fixed base flight simulator.
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42

QUINN, D., A. MURPHY, and C. GLAZEBROOK. "AEROSPACE STIFFENED PANEL INITIAL SIZING WITH NOVEL SKIN SUB-STIFFENING FEATURES." International Journal of Structural Stability and Dynamics 12, no. 05 (October 2012): 1250060. http://dx.doi.org/10.1142/s0219455412500605.

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The introduction of skin sub-stiffening features has the potential to modify the local stability and fatigue crack growth performance of stiffened panels. Proposed herein is a method to enable initial static strength sizing of panels with such skin sub-stiffening features. The method uses bespoke skin buckling coefficients, automatically generated by Finite Element analysis and thus limits the modification to the conventional aerospace panel initial sizing process. The approach is demonstrated herein and validated for prismatic sub-stiffening features. Moreover, examination of the generated buckling coefficient data illustrates the influence of skin sub-stiffening on buckling behavior, with static strength increases typically corresponding to a reduction in the number of initial skin longitudinal buckle half-waves.
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43

Irsyad Lukman, E., and M. Agoes Moelyadi. "Longitudinal Static Stability and wake visualization of high altitude long endurance aircraft developed in Bandung institute of technology." Journal of Physics: Conference Series 1005 (April 2018): 012050. http://dx.doi.org/10.1088/1742-6596/1005/1/012050.

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44

Andrews, SA, and RE Perez. "Analytic study of the conditions required for longitudinal stability of dual-wing aircraft." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 5 (May 11, 2017): 958–72. http://dx.doi.org/10.1177/0954410017704215.

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Recent studies of new, fuel-efficient transport aircraft have considered designs, which make use of two principal lifting surfaces to provide the required lift as well as trim and static stability. Such designs include open tandem-wings as well as closed joined and box-wings. As a group, these aircraft can be termed dual-wing designs. This study developed a new analytic model, which takes into account the downwash from the two main wings and is sensitive to three important design variables: the relative areas of each wing, the streamwise separation of the wings, and the center of gravity position. This model was used to better understand trends in the dual-wing geometry on the stability, maneuverability, and lift-to-drag ratio of the aircraft. Dual-wing aircraft have been shown to have reduced the induced drag compared to the conventional designs. In addition, further drag reductions can be realized as the horizontal tail can be removed if the dual-wings have sufficient streamwise stagger to provide the moments necessary for trim and longitudinal stability. As both wings in a dual-wing system carry a significant fraction of the total lift, trends in such designs that led to longitudinal stability can differ from those of the conventional aircraft and have not been the subject of detailed investigation. Results from the analytic model showed that the longitudinal stability required either a reduction of the fore wing area or shifting the center of gravity forward from the midpoint of both wings' aerodynamic centers. In addition, for wing configurations of approximately equal fore and aft wing areas, increasing the separation between the two wings decreased the stability of the aircraft. The source of this unusual behavior was the asymmetric distribution of downwash upstream and downstream of the wing. These relationships between dual-wing geometry and stability will provide initial guidance on the conceptual design of dual-wing aircraft and aid in the understanding of the results of more complex studies of such designs, furthering the development of future transport aircraft.
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Zhang, GQ, LC Ji, Y. Xu, and J. Schlüter. "Parametric study of different fins for a rocket at supersonic flow." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 18 (June 24, 2015): 3392–404. http://dx.doi.org/10.1177/0954406215590642.

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Various parameters including the fins with variable span to chord ratio, curvature radius, and setting angle have been investigated between the flat fin and wrap around fin (WAF) rocket configurations at supersonic flow. The results show that under the same flight condition, the flat fins can provide a higher lift and pitching moments than the WAFs. Due to the symmetric effect, any extra side forces, moments as well as the self-induced rolling characteristics will be not generated as compared to the WAF configurations. The WAFs can greatly improve the longitudinal stability and enhance the longitudinal aerodynamic characteristics for the whole rocket. The static pressure distributions at different chordwise positions together with the force variations around the fins have been obtained computationally and analyzed in detail.
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46

Peşman, Emre, Deniz Can Kolukısa, and Metin Taylan. "Numerical and Analytical Approaches for Roll Motion Analysis in Regular Longitudinal Waves." Polish Maritime Research 22, no. 3 (September 1, 2015): 28–35. http://dx.doi.org/10.1515/pomr-2015-0053.

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Abstract In this study numerical and analytical approaches were investigated in terms of accuracy of their results, practicality of solution and ability to reproduce the main features of the parametric roll phenomenon such as loss of stability and bifurcations in parametric roll motion analysis of ships. In general, single-degree-of-freedom analytical approach is based on reducing number of degrees of freedom from 3 to 1 by using the quasi-static Froude-Krylov assumption, incorporating heave and pitch effects by means of a time varying restoring moment. On the other hand, numerical approaches to motion of six and four degrees of freedom are based on three dimensional diffraction/radiation and potential flow theories. In summary, this paper reveals that analytical approaches are sufficiently adequate to obtain accurate practical results for this relatively complex phenomenon.
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Funk, Shany, T. Jacob, D. Ben-Dov, E. Yanovich, O. Tirosh, and N. Steinberg. "A balance and proprioception intervention programme to enhance combat performance in military personnel." Journal of the Royal Army Medical Corps 164, no. 1 (September 14, 2017): 52–57. http://dx.doi.org/10.1136/jramc-2017-000809.

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BackgroundOptimal functioning of the lower extremities under repeated movements on unstable surfaces is essential for military effectiveness. Intervention training to promote proprioceptive ability should be considered in order to limit the risk for musculoskeletal injuries. The aim of this study was to assess the effect of a proprioceptive intervention programme on static and dynamic postural balance among Israel Defense Forces combat soldiers.MethodsTwenty-seven male soldiers, aged 18–20 years, from a physical fitness instructor’s course, were randomly divided into two groups matched by age and army unit. The intervention group (INT) underwent 4 weeks of proprioceptive exercises for 10 min daily; the control group underwent 4 weeks of upper body stretching exercises for 10 min daily. All participants were tested pre and postintervention for both static and dynamic postural balance.ResultsSignificant interaction (condition*pre-post-test*group) was found for static postural balance, indicating that for the INT group, in condition 3 (on an unstable surface—BOSU), the post-test result was significantly better compared with the pretest result (p<0.05). Following intervention, the INT group showed significant correlations between static postural stability in condition 2 (eyes closed) and the dynamic postural stability (length of time walked on the beam following fatigue) (r ranged from 0.647 to 0.822; p<0.05).ConclusionsThe proprioceptive intervention programme for combat soldiers improved static postural balance on unstable surfaces, and improved the correlation between static postural balance in the eyes closed condition and dynamic postural balance following fatigue. Further longitudinal studies are needed to verify the relationship between proprioception programmes, additional weight bearing and the reduction of subsequent injuries in combat soldiers.
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48

Ubertalli, Graziano, Paolo Matteis, Sara Ferraris, Caterina Marcianò, Fabio D’Aiuto, Michele Maria Tedesco, and Daniele De Caro. "High Strain Rate Behavior of Aluminum Alloy for Sheet Metal Forming Processes." Metals 10, no. 2 (February 12, 2020): 242. http://dx.doi.org/10.3390/met10020242.

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Aluminum alloy sheets are gaining increasing interest in the construction of some or all components of the car body in view of their lightweight properties which can allow significant fuel consumption reduction. In order to be suitable for car body application, aluminum alloy sheets should have sufficient mechanical properties both in static (e.g., structural stability and durability) and dynamic conditions (e.g., crash test). Static and dynamic mechanical tests (strain rates: ε ˙ ≈ 1 × 10−3 s−1 and ε ˙ ≈ 5 × 102 s−1 respectively) were conducted on AA6016 alloy sheet (1 mm thick), in T4 and T6 temper and for the longitudinal, transverse, and diagonal rolling directions by means of standard static tensile test and modified Hopkinson bar dynamic tests. Microstructural and fracture morphology observations are also reported. The results show that the ultimate tensile strength increases by 13−14%, and the elongation at fracture increases by 75−105%, depending on the temper, by increasing the strain rate.
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49

Bakar, Abu, Li Ke, Haobo Liu, Ziqi Xu, and Dongsheng Wen. "Design of Low Altitude Long Endurance Solar-Powered UAV Using Genetic Algorithm." Aerospace 8, no. 8 (August 16, 2021): 228. http://dx.doi.org/10.3390/aerospace8080228.

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This paper presents a novel framework for the design of a low altitude long endurance solar-powered UAV for multiple-day flight. The genetic algorithm is used to optimize wing airfoil using CST parameterization, along with wing, horizontal and vertical tail geometry. The mass estimation model presented in this paper is based on structural layout, design and available materials used in the fabrication of similar UAVs. This model also caters for additional weight due to the change in wing airfoil. The configuration is optimized for a user-defined static margin, thereby incorporating static stability in the optimization. Longitudinal and lateral control systems are developed for the optimized configuration using the inner–outer loop strategy with an LQR and PID controller, respectively. A six degree-of-freedom nonlinear simulation is performed for the validation of the proposed control scheme. The results of nonlinear simulations are in good agreement with static analysis, validating the complete design process.
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Nguyen, Nang Van, Yasuhiro Harada, Hiroki Takimoto, and Kota Shimomoto. "Measurement of Static Lateral Stability Angle and Roll Moment of Inertia for Agricultural Tractors with Attached Implements." Journal of Agricultural Safety and Health 26, no. 1 (2020): 15–29. http://dx.doi.org/10.13031/jash.13610.

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Highlights Keywords: Implement, Inertial parameter, Lateral stability, Moment of inertia, Rollover, Tractor.Static lateral stability of agricultural tractors with mounted rotary tillers was analyzed. Keywords: Implement, Inertial parameter, Lateral stability, Moment of inertia, Rollover, Tractor.The mounted implement increased static lateral stability of tractors in phase I rollover but decreased static lateral stability in phase II rollover. Keywords: Implement, Inertial parameter, Lateral stability, Moment of inertia, Rollover, Tractor.A mounted implement may significantly reduce the static lateral stability of agricultural tractors and increase the risk of tractor side overturn. Keywords: Implement, Inertial parameter, Lateral stability, Moment of inertia, Rollover, Tractor. ABSTRACT. Each year, many fatalities result from rollovers of agricultural tractors in Japan. In addition to rollover protective structures (ROPS) and seat belts, a warning device that alerts the operator of impending rollover based on the tractor stability index is a measure used to prevent rollovers. The stability index requires inertial parameters, which have been measured only for the single body of the tractor, to calculate the warning threshold. In this study, the center of gravity (CoG) and lateral stability angles of three agricultural tractors were measured, and lateral stability angles were also calculated and compared with measured values for three tractor-tiller combinations to analyze the effect of the attached implement on the tractor stability as well as to verify the accuracy of the calculation methods. The roll moment of inertia (RMI) was also measured for two tractors and two rotary tillers, and RMI values for tractor-tiller combinations were calculated. The measurement and calculation results show that the attached implement increased the lateral stability angle of tractors in phase I rollover and decreased the lateral stability angle in phase II rollover, and for a certain tractor-tiller combination, there was no transition from phase I to phase II rollover. The difference between the measured and calculated lateral stability angles in phase I ranged from -3.5° to 2.5°, while that in phase II ranged from 0.2° to 5.2°. The RMI about the longitudinal axis through the CoG was 203 and 433 kg m-2 for tractors A and B, respectively, and 52 and 94 kg m-2 for rotary tillers D and F, respectively. The calculated RMI values were 265 and 540 kg m-2 for tractor-tiller combinations A-D and B-E, respectively. Keywords: Implement, Inertial parameter, Lateral stability, Moment of inertia, Rollover, Tractor.
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