Journal articles: 'Load stability'

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Ackerman, Jeffrey, Karna Potwar, and Justin Seipel. "Suspending loads decreases load stability but may slightly improve body stability." Journal of Biomechanics 52 (February 2017): 38–47. http://dx.doi.org/10.1016/j.jbiomech.2016.12.001.

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Mohd Rosli, Hazwani, Hazlie Mokhlis, Nurulafiqah Nadzirah Mansor, Norazliani Md Sapari, Syahirah Abd Halim, Li Wang, and Mohamad Fani Sulaima. "A Binary Archimedes Optimization Algorithm and Weighted Sum Method for UFLS in Islanded Distribution Systems Considering the Stability Index and Load Priority." Energies 16, no. 13 (July 3, 2023): 5144. http://dx.doi.org/10.3390/en16135144.

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This study proposes an under-frequency load-shedding (UFLS) scheme based on a binary Archimedes Optimization Algorithm (BAOA) and the Weighted Sum Method (WSM) to maintain the stability of an islanded distribution system. These methods consider stability indices and load priorities to ensure effective load shedding during frequency deviations. The BAOA determines the optimal load shedding based on the stability index and power mismatch that minimizes the impact on critical loads while maintaining system stability in an islanded distribution system. The WSM determines the rank of the load to be shed based on four criteria: the load priority, the load category, the stability index, and the load size. Each load is assigned a weight based on its priority. These weight variables determine the order in which loads are shed during frequency deviations. The effectiveness of the proposed UFLS was tested on an 11 kV Malaysian distribution network with two mini hydro distributed generation systems. A comparative study was conducted based on five result outputs, including the number of loads shed, the size of the loads shed, the frequency undershoot, the frequency overshoot, and the time taken to achieve a stable frequency in three cases: base load, peak load, and peak load with photovoltaics (PV). The proposed UFLS showed the best results for 11 of 15 outputs (73.3%) for islanding events and 9 of 15 outputs (60%) for overloading events. The voltage profile and stability index, also, were improved after the proposed UFLS was applied.

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Singh, Lovepreet, Arun Kaushal, and Amritpal Digra. "A review on stability of polyhouse structures." INTERNATIONAL JOURNAL OF AGRICULTURAL SCIENCES 17, AAEBSSD (July 15, 2021): 319–25. http://dx.doi.org/10.15740/has/ijas/17-aaebssd/319-325.

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Naturally ventilated polyhouse is popular all over the world for growing high value cropssuch as capsicum, tomato, lettuce, herbs etc. and these polyhouses are available in different designs as per different climatic conditions. Structure failure is the major problem faced by farmers throughout the world. The several studies carried out throughout the world shows that the single design of polyhouse cannot be adopted throughout the country due to different agro-climatic conditions.As per differentstudies, polyhousestability designs are analyzed for dead load, live load, snow load, wind load and load combination and Loads were calculated by adoptingdifferent National Standards. Moreover, Truss members, columns and foundation stability analysis is carried out by considering dead loads, live loads and wind loads in most of the studies. Support reactions arealso calculated on truss joints and column joints. The optimum design of any polyhouse generally depends on its structural design, specific mechanical and physical properties of the individual structural components i.e., foundation, hoops, lateral support, polygrip, assembly and end frame. From all the studies it is reported that in most parts of the world, wind is the major force responsible for the failure of any polyhouse structure.

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Lee, Wei-Jen, Mo-Shing Chen, and Lucas B. Williams. "Load Model for Stability Studies." IEEE Transactions on Industry Applications IA-23, no. 1 (January 1987): 159–65. http://dx.doi.org/10.1109/tia.1987.4504881.

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Arif, Hina, and Jaan Lellep. "Stability of nanobeams and nanoplates with defects." Acta et Commentationes Universitatis Tartuensis de Mathematica 25, no. 2 (November 17, 2021): 221–38. http://dx.doi.org/10.12697/acutm.2021.25.15.

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The sensitivity of critical buckling load and critical stress concerning different geometrical and physical parameters of Euler-Bernoulli nanobeams with defects is studied. Eringen’s nonlocal theory of elasticity is used for the determination of critical buckling load for stepped nanobeams subjected to axial loads for different support conditions. An analytical approach to study the impact of discontinuities and boundary conditions on the critical buckling load and critical stress of nanobeams has been developed. Critical buckling loads of stepped nanobeams are defined under the condition that the nanoelements are weakened with stable crack-like defects. Simply supported, clamped and cantilever nanobeams with steps and cracks are investigated in this article. The presented results are compared with the other available results and are found to be in a close agreement.

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Kiss, László. "Stability of pinned-rotationally restrained arches." Theoretical and Applied Mechanics, no. 00 (2020): 10. http://dx.doi.org/10.2298/tam200402010k.

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The article aims to find the buckling loads for pinned-rotationally restrained shallow circular arches in terms of the rotational end stiffness, geometry and material distribution. The loading is a concentrated vertical force placed at the crown. A geometrically nonlinear model is presented which relates not only the axial force but also the bending moment to the membrane strain. The nonlinear load-strain relationship is established between the strain and load parameters. This equation is then solved and evaluated analytically. It turns out that the stiffness of the end-restraint has, in general, a significant effect on the lowest buckling load. At the same time, some geometries are not affected by this. As the stiffness becomes zero, the arch is pinned-pinned and as the stiffness tends to infinity, the arch behaves as if it were pinned-fixed and has the best load-bearing abilities.

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Cagan, J., and L. A. Taber. "Large Deflection Stability of Spherical Shells With Ring Loads." Journal of Applied Mechanics 53, no. 4 (December 1, 1986): 897–901. http://dx.doi.org/10.1115/1.3171878.

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Large deflections of shallow and deep spherical shells under ring loads are studied. The axisymmetric problem is solved through a Newton-Raphson technique on discretized nonlinear shell equations. Comparison of computed load-deflection curves to experimental data from both thick and thin shells generally shows good agreement in peak loads and the type of instability. For a point load, the load increases monotonically with deflection; as the ring radius increases, transition-type (snap-through) and then local buckling occurs. In addition, the pre- and post-buckled mechanical behaviors of the shell are examined.

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Holbein, Mary Ann, and Mark S. Redfern. "Postural Stability While Holding Loads in Various Postures." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 37, no. 10 (October 1993): 697–700. http://dx.doi.org/10.1177/154193129303701011.

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Stability while handling loads is an important issue in the prevention of injuries. This study investigated the effects of load positioning on recovery from an unexpected balance disturbance while standing upright holding loads. Fifteen subjects were tested while holding a box in one of five postures. An empty box and a 25 lb box were tested. Subjects stood on a posture platform while perturbations of the supporting surface were induced. Postural sway was recorded via center of pressure displacements calculated from three dimensional foot forces. It was found that laden standing with the heavier load resulted in increased sway magnitude and slower sway velocities than unladen standing. The load position also affected stability. Raising the center of gravity of the body-and-load system appears to increase sway. These results require consideration when designing safe material handling tasks, especially if the supporting surface is unstable or if slip potential is present.

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LaGoy, Alice D., Caleb Johnson, Katelyn F. Allison, Shawn D. Flanagan, Mita T. Lovalekar, Takashi Nagai, and Chris Connaboy. "Compromised Dynamic Postural Stability Under Increased Load Carriage Magnitudes." Journal of Applied Biomechanics 36, no. 1 (February 1, 2020): 27–32. http://dx.doi.org/10.1123/jab.2018-0473.

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Warfighter performance may be compromised through the impact of load carriage on dynamic postural stability. Men and women may experience this impact to differing extents due to postural stability differences. Therefore, the authors investigated the effect of load magnitude on dynamic postural stability in men and women during a landing and stabilization task. Dynamic postural stability of 32 subjects (16 women) was assessed during the unilateral landing of submaximal jumps under 3 load conditions: +0%, +20%, and +30% body weight. Dynamic postural stability was measured using the dynamic postural stability index, which is calculated from ground reaction force data sampled at 1200 Hz. Two-way mixed-measures analysis of variance compared dynamic postural stability index scores between sexes and loads. Dynamic postural stability index scores were significantly affected by load (P = .001) but not by sex or by the sex by load interaction (P > .05). Dynamic postural stability index scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034), and 30% (0.420 ± 0.028) body weight conditions. Increased load negatively affects dynamic postural stability with similar performance decrements displayed by men and women. Men and women warfighters may experience similar performance decrements under load carriage conditions of similar relative magnitudes.

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Le, Trong Nghia, Hoang Minh Vu Nguyen, Thai An Nguyen, Trieu Tan Phung, Thi Thu Hien Huynh, and Quang Tien Nguyen. "Optimize Ranking and Load Shedding in Microgrid Considering Improved Analytic Hierarchy Process Algorithm and Power Stability Index." Mathematical Problems in Engineering 2023 (November 29, 2023): 1–14. http://dx.doi.org/10.1155/2023/6074287.

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This paper proposes a load shedding model for the island microgrid based on the ranking of loads and the power stability index (PSI). Loads are ranked based on the improved analytic hierarchy process (AHP) algorithm. Real-time measurement systems have the function of collecting data for very important, important, and less-important loads at each bus load. From this data, the improved AHP method is applied to rank the loads. The advantage of this method is that the subjectivity is eliminated and not depending on the expertise of the system operator when implementing the traditional AHP method. Besides, the minimum amount of load shedding power is calculated, taking into account both primary and secondary control methods. The objective is to minimize the impact on power consumers and ensure that the frequency returns to an acceptable range. In addition, when implementing load shedding, voltage quality, and stability are considered. The PSI serves as a crucial parameter for assessing the voltage stability of microgrid buses. This index is combined with load ranking weights to obtain combined weights for the load shedding plan. Consequently, the proposed load shedding plan prioritizes minimizing damage to customers, improving voltage quality and stability, and ensuring frequency is within permissible limits. The 16-bus microgrid system is applied to compare with traditional methods and to prove the efficiency of the suggested technique.

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Sharma, Mamta R., Arbind K. Singh, and Gurmail S. Benipal. "Elastic Stability of Concrete Beam-Columns." International Journal of Structural Stability and Dynamics 17, no. 01 (January 2017): 1750094. http://dx.doi.org/10.1142/s0219455417500948.

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Following the empirical-computational methodology, the contemporary investigations deal with inelastic stability and dynamics of concrete beam-columns. Even under service loads, the concrete structures exhibit physical nonlinearity due to presence of axio-flexural cracks. The objective of the present paper is to analyze the static and dynamic stability of conservative physically nonlinear fully cracked flanged concrete beam–columns. In this paper, using proper reference frames, analytical expressions are developed for the lateral displacement and stiffness of a flanged concrete cantilever under axial compressive and lateral forces. Two critical values of both the axial and lateral loads are identified. For constant lateral force smaller than its first critical value, the concrete beam–columns exhibit brittle buckling mode. Higher lateral forces lesser than the second critical value introduce alternate stable and unstable domains with increase in axial force. The lateral stiffness is predicted to vanish when the axial loads reach the critical values and when the limiting displacement is reached for axial load exceeding its second critical value. The load-space is partitioned into stable and unstable regions. Accessibility of these equilibrium states in the load space has been investigated. Such distinguishing aspects of the predicted behavior of elastic concrete beam–columns are discussed. Their dynamic stability is investigated in second part of the paper.

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Chattopadhyay, Tapan Kumar, Sumit Banerjee, and Chandan Kumar Chanda. "Voltage Stability Index of Radial Distribution Networks by Considering Distributed Generator for Different Types of Loads." International Journal of Energy Optimization and Engineering 5, no. 1 (January 2016): 1–22. http://dx.doi.org/10.4018/ijeoe.2016010101.

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The paper presents an approach on voltage stability analysis of distribution networks for loads of different types. A voltage stability index is proposed for identifying the node, which is most sensitive to voltage collapse. It is shown that the node, at which the value of voltage stability index is maximum, is more sensitive to voltage collapse. For the purpose of voltage stability analysis, constant power, constant current, constant impedance and composite load modeling are considered. Distributed generation can be integrated into distribution systems to meet the increasing load demand. It is seen that with the insertion of distributed generator (DG), load capability limit of the feeder has increased for all types of loads. By using this voltage stability index, one can measure the level of voltage stability of radial distribution systems and thereby appropriate action may be taken if the index indicates a poor level of stability. The effectiveness of the proposed method is demonstrated through two examples.

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Sarwar, Sohail, Hazlie Mokhlis, Mohamadariff Othman, Munir Azam Muhammad, J. A. Laghari, Nurulafiqah Nadzirah Mansor, Hasmaini Mohamad, and Alireza Pourdaryaei. "A Mixed Integer Linear Programming Based Load Shedding Technique for Improving the Sustainability of Islanded Distribution Systems." Sustainability 12, no. 15 (August 3, 2020): 6234. http://dx.doi.org/10.3390/su12156234.

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In recent years significant changes in climate have pivoted the distribution system towards renewable energy, particularly through distributed generators (DGs). Although DGs offer many benefits to the distribution system, their integration affects the stability of the system, which could lead to blackout when the grid is disconnected. The system frequency will drop drastically if DG generation capacity is less than the total load demand in the network. In order to sustain the system stability, under-frequency load shedding (UFLS) is inevitable. The common approach of load shedding sheds random loads until the system’s frequency is recovered. Random and sequential selection results in excessive load shedding, which in turn causes frequency overshoot. In this regard, this paper proposes an efficient load shedding technique for islanded distribution systems. This technique utilizes a voltage stability index to rank the unstable loads for load shedding. In the proposed method, the power imbalance is computed using the swing equation incorporating frequency value. Mixed integer linear programming (MILP) optimization produces optimal load shedding strategy based on the priority of the loads (i.e., non-critical, semi-critical, and critical) and the load ranking from the voltage stability index of loads. The effectiveness of the proposed scheme is tested on two test systems, i.e., a 28-bus system that is a part of the Malaysian distribution network and the IEEE 69-bus system, using PSCAD/EMTDC. Results obtained prove the effectiveness of the proposed technique in quickly stabilizing the system’s frequency without frequency overshoot by disconnecting unstable non-critical loads on priority. Furthermore, results show that the proposed technique is superior to other adaptive techniques because it increases the sustainability by reducing the load shed amount and avoiding overshoot in system frequency.

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Teng, Zhen Chao, and Jing Ji. "Nonlinear Stability Analysis on Vessels Subjected to External Pressure." Advanced Materials Research 243-249 (May 2011): 5214–18. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.5214.

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To determine stability performance and the critical load of the short cylinder vessel which is made of steel, this paper carried out the finite element linear buckling analysis for 5 meters long steel pressure vessel and obtained buckling critical load. Then performed the nonlinear instability analysis by the arc-length method and obtained the load-displacement curves of the overall stability of the pressure vessel structure. The critical load can be got by twice the elastic slope method and double-tangent intersection method, and the loads are slightly higher than the result of the theoretical calculation, so the result of the theoretical calculation is safe and reliable. Finally, several measures keeping stability of short cylinder pressure vessel are proposed.

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Liu, J., J. L. Ge, H. Yang, W. S. Chen, J. H. Wu, and Q. L. Qu. "Analysis of Aircraft Parking Stability Based on Atmosphere Boundary Theory." Journal of Physics: Conference Series 2458, no. 1 (March 1, 2023): 012026. http://dx.doi.org/10.1088/1742-6596/2458/1/012026.

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Abstract Based on numerical simulation technology, the aerodynamic load research of civil aircraft parked on the ground is conducted. The CRM model parked on the ground is established by CFD software. Based on the atmospheric boundary layer theory, the seven incoming flow conditions for numerical calculation are designed. And the aerodynamic loads’ change of the aircraft model is calculated when the -90° sideslip angle. The result shows that the mooring load on the nose landing gear mainly comes from the longitudinal load caused by the upwards pitching moment on the flat tail and the lateral load caused by the yaw moment; since the rolling moment coefficient is less than the pitching moment coefficient by two orders of magnitude, which hardly affects the mooring load. The study provides a reference for reducing the mooring load of civil aircraft under heavy wind conditions.

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Damodhar, Sunil S., and S. Krishna. "A Novel Load Shedding Scheme for Voltage Stability." International Journal of Emerging Electric Power Systems 17, no. 6 (December 1, 2016): 649–61. http://dx.doi.org/10.1515/ijeeps-2015-0159.

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Abstract Undervoltage load shedding serves to maintain voltage stability when a majority of loads are fast acting. An undervoltage load shedding scheme should address two tasks: the detection of voltage instability following a large disturbance and the determination of the amount of load to be shed. Additionally, in case of short-term voltage instability, the scheme should be fast. This paper proposes a method to predict voltage instability arising due to a large disturbance. The amount of load to be shed to maintain voltage stability is then determined from the Thevenin equivalent of the network as seen from the local bus. The proposed method uses local measurements of bus voltage and power, and does not require knowledge of the network. The method is validated by simulation of three test systems subjected to a large disturbance. The proposed scheme is fairly accurate in estimating the minimum amount of load to be shed to maintain stability. The method is also successful in maintaining stability in cases where voltage collapse is detected at multiple buses.

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Fan, Jun Jian, and Kuan Tang Xi. "Out-of-Plane Elastic Stability Analysis of Parabolic and Circular Arches." Applied Mechanics and Materials 638-640 (September 2014): 190–96. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.190.

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Effects of different load modes, rise-span ratios and support conditions on out-of-plane buckling and differences between parabolic and circular arches were studied. With the increase of rise-span ratio, buckling loads of arches under vertical load uniformly distributed along the horizontal line get bigger and bigger compared with those of vertical load uniformly distributed along the axis. With increase of rise-span ratio, the buckling loads of hingeless and two-hinged arch increase after decrease, then decrease. The buckling load of three-hinged arch decreases after increases. When rise-span ratio is small, support condition has a great influence on out-of-plane buckling. The parabolic arch is better than circular arch in out-of-plane stability and economy. But circular arch is better than parabolic arch in manufacture.

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BURGESS, KEVIN L., and KEVIN M. PASSINO. "Stability analysis of load balancing systems." International Journal of Control 61, no. 2 (February 1995): 357–93. http://dx.doi.org/10.1080/00207179508921907.

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Versele, Vickà, Peter Clarys, Benedicte Deforche, Johan Lefevre, Evelien Mertens, Ruben Charlier, Sara Knaeps, and Dirk Aerenhouts. "Stability of potential renal acid load." Nutrition & Dietetics 77, no. 1 (May 6, 2018): 139–43. http://dx.doi.org/10.1111/1747-0080.12432.

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Pal, M. K. "Voltage stability conditions considering load characteristics." IEEE Transactions on Power Systems 7, no. 1 (1992): 243–49. http://dx.doi.org/10.1109/59.141710.

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Begovic, M. M., and R. Q. Mills. "Load identification and voltage stability monitoring." IEEE Transactions on Power Systems 10, no. 1 (1995): 109–16. http://dx.doi.org/10.1109/59.373933.

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Salunke, Minal S., Ramesh S. Karnik, Angadi B. Raju, and Vinayak N. Gaitonde. "Analysis of Transmission System Stability with Distribution Generation Supplying Induction Motor Loads." Mathematics 12, no. 1 (January 2, 2024): 148. http://dx.doi.org/10.3390/math12010148.

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A distributed-power-generating source (DPGS) is intended to locally supply the increased power demand at a load bus. When applied in small amounts, a DPGS offers many technical and economic benefits. However, with large DPGS penetrations, the stability of the transmission system becomes a significant issue. This paper investigates the stability of a transmission system equipped with a DPGS at load centres supplying power to both a constant power (CP) and induction motor (IM) load. The DPGSs considered in the present study are microturbine and diesel turbine power generators (MTGS and DTGS), both interfaced with synchronous generators. The influence of an IM load supplied by the DPGS on small-signal stability is studied by a critical damping ratio analysis. On the other hand, time-domain indicators of the transient response following a short circuit are employed in the analysis. Further, a variance analysis test (VAT) is performed to determine the contribution of IM and CP loads on the system stability. The study revealed that large penetration levels of IM loads significantly affect the stability and depend on the kind of DPGS technology used.

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Zhang, Lei, and Gengshu Tong. "Elastic Stability of Two-Span Continuous Beams under Moving Loads." Advances in Structural Engineering 8, no. 2 (April 2005): 157–72. http://dx.doi.org/10.1260/1369433054037994.

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The elastic stability of two span continuous beams has been studied using FEA methods. Two formulae for estimating the critical loads are proposed, one is suitable for two-span beams with one span loaded, while the other is suitable for two-span beams with both spans equally loaded. Two identical concentrated loads symmetrically located about the mid-span of each loaded span were considered in the derivation of both formulae, and the effect of the height of loaded points for doubly symmetric beams was included. The formulae presented are also accurate enough in calculating the critical loads for two-span continuous beams with the mono-symmetric sections used in practice if the point of load application is at or above the shear centre. A linear approximation is suggested for the interaction of two spans when the two spans of the beam are not equally loaded. For a two-span continuous runway girder supporting moving cranes, the minimum critical load and the maximum absolute moment were investigated, some possible combination of wheel forces on beams considered, and approaches to calculating the critical load for each load combination are suggested when the girder has either one or two cranes moving along it.

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Pogonowska-Płatek, Sylwia, and Wojciech Dornowski. "Stability analysis of steel frames according to Eurocode 3." Bulletin of the Military University of Technology 68, no. 2 (June 28, 2019): 145–63. http://dx.doi.org/10.5604/01.3001.0013.3008.

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In the paper, the qualitative and quantitative comparison of EC3 methods to verify the global stability of the structure is presented. The steel portal frame subjected to varied loads is considered. The initial global sway imperfection and the initial local bow imperfections of member frame are taken into account. The sensitivity of a structure to the 2nd order effects is assessed indirectly using the elastic critical load. The elastic critical load of a frame is calculated according to the buckling mode. The 2nd order effects are taken into account using the finite element method. Keywords: second order effects, steel frame, global stability, critical load.

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Suleiman, Osama Mohammed Elmardi, Mahmoud Yassin Osman, and Tagelsir Hassan. "Stability of thin laminated decks plates under plane compressive loading." International research journal of engineering, IT & scientific research 5, no. 2 (March 21, 2019): 1–28. http://dx.doi.org/10.21744/irjeis.v5n2.607.

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It was found that symmetric laminates are stiffer than the anti – symmetric one due to coupling between bending and stretching which decreases the buckling loads of symmetric laminates. The buckling load increases with increasing aspect ratio, and decreases with increase in modulus ratio. The buckling load will remain the same even when the lamination order is reversed. The buckling load increases with the mode number but at different rates depending on the type of end support. It is also observed that as the mode number increases, the plate needs additional support.

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Nugraha, Jutika Aditya Nugraha, I. Gde Budi Indrawan, and Dwikorita Karnawati. "Numerical Evaluation of Earthquake Effect on Cisumdawu Tunnel Stability." Journal of Applied Geology 4, no. 2 (December 31, 2019): 73. http://dx.doi.org/10.22146/jag.53207.

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Cisumdawu Tunnel is located approximately 3.95 km southeast of the activeLembang Fault. Earthquakes induced by movement of the the active the strike-slip fault may influence stability of the twin tunnel. This paper presents results of numerical analyses carried out to demonstrate effect of a worst-case scenario of earthquake load potentially induced by the Lembang Fault on the stability of the Cisumdawu Tunnel. Static and pseudo-static tunnel stability analyses were carried out at 11 observation stations of tunnel face mapping using RS2 finite element package (Rocscience, Inc.). In the pseudo-static analyses, a 0.48 horizontal seismic load coefficient, which was obtained from a deterministic seismic hazard analysis (DSHA) based on a 6.8 maximum magnitude of estimated earthquake sourced from the Lembang Fault using Campbell-Bozorgnia (2014) attenuation relationship, was applied to the finite element models. The numerical analysis results showed that strength factors of the rock masses around the twin tunnel were greater than unity, both under the static and earthquake loads. The forepolling zones, however, appeared to be under an overstressed condition. Reduction of rock strength factor around the tunnel roof due to application of the earthquake load occurred at all observation stations. Total displacement contours of rock masses around the twin tunnel indicated an increased rock mass displacement due to the earthquake load, as compared to that due to the static load. Under the static load, the largest displacement occurred at the tunnel inverts. The predicted roof displacements obtained from this study were in a reasonably good agreement with those obtained from the field measurements. Number of yielded elements and extend of shear and tension failure zones in the rock masses around the twin tunnel also appeared to increase due to the earthquake load. Despite slight tunnel displacement as predicted in the numerical analyses, the worst-case scenario of earthquake load potentially induced by the Lembang Fault may only cause failures of the rock masses around the Cisumdawu Tunnel. To prevent the twin tunnel displacement caused by such relatively severe earthquake loads, however, stabilizing surrounding the relatively poor ground condition may be necessary.

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Lu, Si Ping, and Qing Yuan Zeng. "An ANSYS-Based Approach for Nonlinear Dynamic Stability Analysis." Applied Mechanics and Materials 166-169 (May 2012): 2876–82. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2876.

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Study on dynamic stability of structure is a hot subject in the fields of engineering mechanics, but its basic theory and analytical method still need to be further improved. This paper improved the current method for dynamic stability analysis called “dynamic eigenvalue method”, and the method for nonlinear dynamic stability analysis based on ANSYS platform is proposed. A long column under harmonic loads is taken as the research objective, dynamic eigenvalues affected by the load frequency, load amplitude and damping ratio are studied. Results show that, the increasing of load frequency or dynamic load amplitude will lead to the increase of maximum dynamic eigenvalue and decrease of minimum dynamic eigenvalue, which is not beneficial to dynamic stability of structure. The increasing of damping ratio will lead to the decrease of maximum dynamic eigenvalue and increase of minimum dynamic eigenvalue, this make the dynamic eigenvalue more stable. Therefore, the high damping is beneficial to dynamic stability of structure.

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Bosich, Daniele, Giovanni Giadrossi, Stefano Pastore, and Giorgio Sulligoi. "Weighted Bandwidth Method for Stability Assessment of Complex DC Power Systems on Ships." Energies 15, no. 1 (December 31, 2021): 258. http://dx.doi.org/10.3390/en15010258.

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In shipboard DC grids, tightly controlled load converters can impair the system stability, thus provoking the ship blackout. Conversely, load converters regulated by low control bandwidths are capable of inducing a stabilizing action. This compensation is verifiable if the loads are few. On the contrary, the balancing of control dynamics is hardly evaluated if the bus feeds multiple (i.e., hundreds or more) DC controlled loads. In this paper, the weighted bandwidth method (WBM) is presented to assess the small-signal stability of a complex shipboard power system by aggregating the multiple converters into two sets of controlled loads. Once the validity of the aggregation is proven, a stability study is performed on the two-loads system. As the last system is more inclined to instability than the initial multiple-loads system, the verification of the two-loads stability criterion guarantees that the shipboard DC grid also remains stable. Finally, emulations on HIL verify the proposed stability assessment thus providing the first unique verification of WBM.

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Holbein, M. A., and M. S. Redfern. "Postural Stability While Walking and Carrying Loads in Various Postures." Proceedings of the Human Factors and Ergonomics Society Annual Meeting 38, no. 10 (October 1994): 564–67. http://dx.doi.org/10.1177/154193129403801005.

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Falls, over-exertion injuries and other potential consequences of balance losses continue to be serious ergonomic concerns. Stability issues are important in the prevention of these injuries, especially when the task is complicated by handling loads. However, stability analyses are not typical components of ergonomic job analyses. This study demonstrated that stability assessments can be effective in recommending load-carrying strategies. In particular, the effects of load positioning and magnitude on stability were investigated. Unladen walking was also tested for comparison. Several stability measures were defined based on the body-and-load's center of mass displacement in the frontal plane. Statistical differences among the load positions and magnitudes were found and are discussed. Results were consistent across measures. Additional work is needed to better define the limits of stability while carrying and to relate these, or other, stability measures to the likelihood of a balance loss.

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Zhang, Jing, Li Sui, Xu Hong Guo, and Guo Hua Liu. "Buckling Stability Analysis of Parallel Micro-Spring." Advanced Materials Research 989-994 (July 2014): 2859–64. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.2859.

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Compression deformation will cause a micro-spring to buckle, and structural parameters, constraint conditions and structural forms of a micro-spring will affect its critical load and buckling mode. In order to study the influence on the micro-spring’s stability caused by structural forms and find a structure to improve its critical load in the end, this paper designs a new kind of parallel micro-springs, which consists of two same-structured S-shaped planar micro-springs. We have carried on eigenvalue buckling analysis on the parallel micro-spring by software ANSYS, and have gotten its six orders’ buckling mode. Because the critical load of the parallel micro-spring may change with the length of the beam connecting the two sub-springs, this paper studies the effect of the beam’s length on the parallel micro-spring’s critical loads and buckling mode. From comparing the analysis results between parallel micro-spring and single micro-spring with same stiffness, this paper concludes the stability’s degree of improvement.

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Zhou, Xue Song, Huan Liang, and You Jie Ma. "Review of Electric Load Modeling Research." Advanced Materials Research 811 (September 2013): 627–30. http://dx.doi.org/10.4028/www.scientific.net/amr.811.627.

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The effect of load model on the analyses of load flow, transient stability, small disturbance stability and voltage stability is analyzed. The importance of the load modeling research is emphasized. The development of component-based method and measurement-based method is reviewed. The advances on the load model research including the select ion of load model structure, model parameters identification, load model with the voltage stability analysis and the sensitivity of load model to the transient stability is summarized.

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Huang, You-Qin, Han-Wen Lu, Ji-Yang Fu, Ai-Rong Liu, and Ming Gu. "Dynamic Stability of Euler Beams under Axial Unsteady Wind Force." Mathematical Problems in Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/434868.

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Dynamic instability of beams in complex structures caused by unsteady wind load has occurred more frequently. However, studies on the parametric resonance of beams are generally limited to harmonic loads, while arbitrary dynamic load is rarely involved. The critical frequency equation for simply supported Euler beams with uniform section under arbitrary axial dynamic forces is firstly derived in this paper based on the Mathieu-Hill equation. Dynamic instability regions with high precision are then calculated by a presented eigenvalue method. Further, the dynamically unstable state of beams under the wind force with any mean or fluctuating component is determined by load normalization, and the wind-induced parametric resonant response is computed by the Runge-Kutta approach. Finally, a measured wind load time-history is input into the dynamic system to indicate that the proposed methods are effective. This study presents a new method to determine the wind-induced dynamic stability of Euler beams. The beam would become dynamically unstable provided that the parametric point, denoting the relation between load properties and structural frequency, is located in the instability region, no matter whether the wind load component is large or not.

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Al-Sadooni, Hussein Hadi Abdul-Wahid, and Rashid Hamid Al-Rubayi. "Combinational load shedding using load frequency control and voltage stability indicator." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 5 (October 1, 2022): 4661. http://dx.doi.org/10.11591/ijece.v12i5.pp4661-4671.

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This paper proposes a load shedding program for evaluating and distributing the minimum load power to be curtailed required to bring the frequency and voltage, after the system was subjected to a heavy disturbance, to the allowable range for each load bus. The quantity of load shedding was estimated to restore the power system's frequency, taking into account the turbine governor's primary control and the generators' reserve power for secondary control. Calculation and review of the load bus's voltage stability indicator (Li) to prioritize the load shedding quantity at these locations. The lower the voltage stability indicator on the load bus, the less load shedding can occur, and vice versa. The frequency and voltage values are still within allowable ranges with this approach, and a significant amount of load shedding can be prevented, resulting in a reduction in customer service interruption. The proposed method's efficacy was demonstrated when it was checked against the IEEE 30 bus 6 generators power system standard simulated in MATLAB environment and it minimize the power to be shed by around 20% of the conventional load shedding schemes.

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., Abdullah I. Al-Odien. "The Automatic Load Shedding for Stability Security at the Load Buses." Journal of Applied Sciences 2, no. 9 (August 15, 2002): 903–6. http://dx.doi.org/10.3923/jas.2002.903.906.

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Guran, A., and R. H. Plaut. "Stability of Ziegler's pendulum with eccentric load and load-dependent stiffness." Archive of Applied Mechanics 63, no. 3 (March 1993): 170–75. http://dx.doi.org/10.1007/bf00794891.

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Kacalak, Wojciech, Zbigniew Budniak, and Maciej Majewski. "Crane stability for various load conditions and trajectories of load translocation." Mechanik, no. 12 (December 2016): 1820–23. http://dx.doi.org/10.17814/mechanik.2016.12.571.

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Bekirova, М. "STABILITY OF RODS WITH INITIAL IMPERFECTIONS IN THE FORM OF ECCENTRICITY OF LOAD APPLICATION UNDER LINEAR AND NON-LINEAR CREEP CONDITIONS." Mechanics And Mathematical Methods 5, no. 1 (June 30, 2023): 110–20. http://dx.doi.org/10.31650/2618-0650-2023-5-1-110-120.

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Stability of a compressed rod having initial imperfections in the form of eccentricity of applied load under conditions of linear and nonlinear creep is considered. It is noted that all real elements have some initial imperfections in the form of technological deflections, eccentricities of applied loads, etc., so they begin to bulge from the very beginning of loading. Another important factor in stability theory is the consideration of material creep. In this regard, the loading process is divided into two phases: the instantaneous loading process and the creep phase under constant external load. Moreover, creep can be time-limited or unrestricted. In the paper formulas for determination of critical forces of stability loss of the rod having initial imperfections, under short-term and long-term action of load are obtained. The equation allowing to determine time of the first crack appearance is derived. Derived are equations the roots of which are loads at action of which the first cracks appear at initial moment of time and at arbitrarily long period of load action. Analysis of acting force determining the character of rod deformation is executed. From the constructed stability equation it is possible to determine the critical force corresponding to the critical length of the section with cracks. For similar problems in nonlinear formulation formulas for determining critical force and critical displacement corresponding to maximum load are obtained. For the case of long duration load the equation which establishes relationship between load and displacement is obtained. Equation for determination of critical force under prolonged action of load has been derived. It has been established that critical displacement is the same under short- and continuous action of load. It is shown that at any intermediate moment critical displacement can be achieved under load lying in certain interval. Keywords: stability, rod, initial imperfection, eccentricity, linear creep, non-linear creep, critical force, crack, critical displacement.

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Keshav, Vasanth, Shuvendu Narayan Patel, and Rajesh Kumar. "Stability and Failure Study of Suddenly Loaded Laminated Composite Cylindrical Panel." International Journal of Applied Mechanics 11, no. 10 (December 2019): 1950093. http://dx.doi.org/10.1142/s1758825119500935.

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In this paper, nonlinear dynamic buckling of laminated composite cylindrical panels subjected to in-plane impulsive compressive load is studied along with the failure analysis. Balanced and symmetric angle-ply laminated composite curved panels are considered. Convergence study is performed, and results are validated with the results from the existing literature, and then the dynamic buckling loads are calculated. The failure index of laminated composite curved panel is also calculated to check the precedence of first ply failure load over nonlinear dynamic buckling load. The effect of aspect ratio, loading function, and radius of curvature is studied. The analysis is carried out using finite element method. It is observed that the first ply failure for balanced and symmetric angle-ply laminated composite curved panels occurs after the panel has buckled due to dynamic impulse loads.

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CAI, JIANGUO, and JIAN FENG. "EFFECT OF SUPPORT STIFFNESS ON STABILITY OF SHALLOW ARCHES." International Journal of Structural Stability and Dynamics 10, no. 05 (December 2010): 1099–110. http://dx.doi.org/10.1142/s0219455410003919.

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The nonlinear behavior and in-plane stability of parabolic shallow arches with elastic rotational supports are investigated. A central concentrated load is applied to create the compression in the supports. Nonlinear buckling analysis based on the virtual work formulation is carried out to obtain the critical load for both symmetric snap-through buckling and anti-symmetric bifurcation buckling. It is found that the effect of rotational stiffness of the elastic supports on the critical loads is significant. The critical load increases as either the initial stiffness coefficient α or the stiffening rate β increases. The effect of the stiffening rate β on the critical loads decreases, as the initial stiffness coefficient α increases. In addition, the influence of rotational stiffness on the bifurcation buckling is larger than that on the snap-through buckling. The limit of the geometric parameter λ between the bifurcation and snap-through buckling modes also increases with the increase in the stiffening rate β. In addition, the snap-through buckling mode governs the buckling of the arch with larger stiffening rates.

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Song, Dun Wen, Qian Miao, Xue Tao Yang, and Li Hua Wu. "Under Voltage Load Shedding Clustering Control Based on PV Curve." Advanced Materials Research 816-817 (September 2013): 702–6. http://dx.doi.org/10.4028/www.scientific.net/amr.816-817.702.

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In order to prevent voltage collapse while the voltages drops, adopts under voltage load shedding (UVLS) clustering control to recover voltage stability. First using the method of sensitivity sorting to cluster the load node, then using PV curve to calculate and determine the number of loads to be shed, finally the same cluster taking the same control parameters to shed the loads, the simulation validate it could recovery voltage stability and embodies the rationality and economical efficiency of this method.

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Amrutheswara Krishnamurthy and Dr.Suresh Nagesh. "Aerodynamic Effect on Stability and Lift Characteristics of an Elevated Sedan Car." ARAI Journal of Mobility Technology 2, no. 2 (May 13, 2022): 205–13. http://dx.doi.org/10.37285/ajmt.1.2.6.

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There is a strong interaction between air and vehicle components. Aerodynamics plays a significant role in a vehicle's fuel efficiency. The contact patch load between the tire and road is directly related to the vehicle load. In this research, the lift forces generated due to the additional wing attached to the car model with different spans and heights of the wing location from the car body is considered for study. The loads due to change in Angle of Attack (AOA) and their effect on the tire loads are studied. The upward vertical force produced from aerodynamic loads reduces the wheel load of the car virtually. A tire's coefficient of friction would decrease with upward vertical force. This balance load implies that a lightweight car would make more efficient use of its tires than a heavier car. ANSYS Fluent is used for the Computational Fluid Dynamics (CFD) study. The validation of airflow characteristics, lift and drag forces from simulations are done with wind tunnel testing data. Varying the angle of attack, wingspan, height between the car and the wing's lower surface, one can increase the capacity of the payload by 10% or fuel efficiency by 10% to 20%.

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Tan, Bo, Tao Yang, Heying Qin, and Qi Liu. "Laboratory Study on the Stability of Large-Size Graded Crushed Stone under Cyclic Rotating Axial Compression." Materials 14, no. 7 (March 24, 2021): 1584. http://dx.doi.org/10.3390/ma14071584.

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In this paper, the stability of large-size graded crushed stone used for road base or cushioning under repeated load is investigated. Using an in-house developed device, large-size crushed stone mix was compacted and molded by the vibration and rotary compaction method. Cyclic rotating axial compression was applied, and the shakedown theory was used to study the cumulative deformation of the large-size crushed stone specimens. The effects of gradation parameters on the cumulative strain and stability behavior were analyzed, and the critical stability and failure loads were determined according to the shakedown theory. The test results indicate that there are three obvious instability behavior stages of large-size graded crushed stone under cyclic rotating axial compression: elastic stability, plastic creep, and incremental plastic failure. Large-size graded crushed stone has a higher critical stability load stiffness than conventional-size graded crushed stone. The critical shakedown load of the specimen is mainly affected by the skeleton structure performance, and the critical failure load by the properties of the crushed stone material. Increasing the content and compactness of large-size crushed stone in the specimen can improve the stiffness and stability performance, and to achieve improvements, the content of large-size crushed stone should be controlled between 22% and 26%. The critical shakedown load increases with the increase in the California bearing ratio (CBR) value, while, on the other hand, the CBR value has little relationship with the critical failure load.

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Wang, Xueke, Steven A. Lavender, and Carolyn Sommerich. "The Effects of Load Stability and Visual Access During Asymmetric Lifting Tasks on Back and Upper Extremity Biomechanical Responses." Human Factors: The Journal of the Human Factors and Ergonomics Society 61, no. 5 (December 6, 2018): 712–21. http://dx.doi.org/10.1177/0018720818814107.

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Objective: To explore the change of muscular and biomechanical responses in different load stability and visual access conditions during an asymmetric lifting task. Background: Previous studies found that lifting unstable loads resulted in changes to the biomechanical loads experienced by the spine and upper extremities. However, researchers have not extensively investigated behaviors when people lift potentially unstable loads. It was hypothesized that lifting a potentially unstable load can lead to changes in lifting behavior, which may be mitigated by visual access to the load. Method: Fourteen volunteers lifted either a stable load or a potentially unstable load that could move within the container during the lifting task. In half of the lifting conditions, the box was covered to restrict visual access when lifting. Spine kinematic and kinetic measures and surface electromyographic (EMG) signals from back, shoulder, and arm muscles were obtained. Results: Lifts of the stable load were faster and generally had higher peak muscle activations than lifts of the potentially unstable load. Participants had less spine flexion when handling the potentially unstable load without visual access. Conclusion: When lifting and moving a potentially unstable load that could lead to a perturbation, people tended to lift the container more slowly comparing with lifting a stable load, which in turn reduced the peak muscle activities. Application: In industry, there are many work situations where workers need to lift or carry unstable loads that can shift during transport. Providing visual access to the load may help mitigate some of these effects.

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He, Lin, Cong Liu, and Zhen Yu Wu. "Parametric Modeling and Stability Analysis of Temporary Grandstand." Applied Mechanics and Materials 578-579 (July 2014): 907–16. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.907.

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Temporary grandstands bear crowd load, which is created when spectators jumping on the structure. The simplified loads applied to temporary grandstand have been obtained based on experiment data of human body jumping forces. By the ABAQUS software, the parametric and automatic modeling of three-dimensional (3D) temporary grandstand structures has been realized with Python scripting. The linear buckling analysis and nonlinear buckling analysis of the structure have been carried out. The ultimate bearing capacity and the structural deformation under crowd load have been acquired. Results show that the nonlinear effect of the structure under crowd load is very obvious; the linear buckling analysis cannot get the ultimate bearing capacity of the structure and the first order buckling mode cannot simulate the final deformation of the structure either. The research of this paper greatly improve the efficiency of the construction and automation design of temporary structures and reveal the mechanical behavior of such structure to a certain degree.

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Zhu, D. Y., C. F. Lee, D. H. Chan, and H. D. Jiang. "Evaluation of the stability of anchor-reinforced slopes." Canadian Geotechnical Journal 42, no. 5 (October 1, 2005): 1342–49. http://dx.doi.org/10.1139/t05-060.

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The conventional methods of slices are commonly used for the analysis of slope stability. When anchor loads are involved, they are often treated as point loads, which may lead to abrupt changes in the normal stress distribution on the potential slip surface. As such abrupt changes are not reasonable and do not reflect reality in the field, an alternative approach based on the limit equilibrium principle is proposed for the evaluation of the stability of anchor-reinforced slopes. With this approach, the normal stress distribution over the slip surface before the application of the anchor (i.e., σ0) is computed by the conventional, rigorous methods of slices, and the normal stress on the slip surface purely induced by the anchor load (i.e., λpσp, where λp is the load factor) is taken as the analytical elastic stress distribution in an infinite wedge approximating the slope geometry, with the anchor load acting on the apex. Then the normal stress on the slip surface for the anchor-reinforced slope is assumed to be the linear combination of these two normal stresses involving two auxiliary unknowns, η1 and η2; that is, σ = η1σ0 + η2λpσp. Simultaneously solving the horizontal force, the vertical force, and the moment equilibrium equations for the sliding body leads to the explicit expression for the factor of safety (Fs)or the load factor (λp), if the required factor of safety is prescribed. The reasonableness and advantages of the present method in comparison with the conventional procedures are demonstrated with two illustrative examples. The proposed procedure can be readily applied to designs of excavated slopes or remediation of landslides with steel anchors or prestressed cables, as well as with soil nails or geotextile reinforcements.Key words: slopes, factor of safety, anchors, limit equilibrium method.

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SAITO, Katsuhiko, and Masato ASAOKA. "Study on Evaluation of Pallet Load Stability." Journal of Japan Institute of Navigation 112 (2005): 247–53. http://dx.doi.org/10.9749/jin.112.247.

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Didit, Micke, Xiwen Zhang, and Weidong Zhu. "Slope Stability Considering the Top Building Load." Open Journal of Civil Engineering 12, no. 03 (2022): 292–300. http://dx.doi.org/10.4236/ojce.2022.123017.

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Omer, Hosam A., Khalid O. Mahjoub, and Abdelrahman A. Karrar. "On The Stability of Generators Load Sharing." IFAC Proceedings Volumes 47, no. 3 (2014): 8210–17. http://dx.doi.org/10.3182/20140824-6-za-1003.02791.

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Georgiadis, Michael. "Load-Path Dependent Stability of Shallow Footings." Soils and Foundations 25, no. 1 (March 1985): 84–88. http://dx.doi.org/10.3208/sandf1972.25.84.

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Ha, Junhong, Semion Gutman, Sudeok Shon, and Seungjae Lee. "Stability of shallow arches under constant load." International Journal of Non-Linear Mechanics 58 (January 2014): 120–27. http://dx.doi.org/10.1016/j.ijnonlinmec.2013.08.004.

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Journal articles on the topic 'Load stability'

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