Academic literature on the topic 'Crushing force'
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Journal articles on the topic "Crushing force"
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Polushyna, M. V., T. V. Moskalova, and V. F. Hankevich. "Static force analysis of a single toggle jaw crusher." Geo-Technical mechanics, no. 152 (2020): 254–62. http://dx.doi.org/10.15407/geotm2020.152.254.
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There are various recommendations in domestic and foreign literature regarding the law of distribution of the crushing load along the swing plate of jaw crushers: even, linear or nonlinear. The method of load distribution along the swing jaw affects the resultant crushing force, its application point and, therefore, the forces subjected to the jaw crusher links. A feature of a single toggle jaw crusher is the strong force exerted on the eccentric shaft since the crushing forces are directly transferred to the shaft. Therefore, it is important to determine the worst design case in order to calculate the strength of crusher parts. This article represents the static study of the influence of the application point of the crushing force on the forces acting on the eccentric shaft and the toggle plate of the single toggle jaw crusher. During the study, a kinematic scheme of the mechanism of the single toggle jaw crusher in the form of a four-link crank mechanism was worked out. The dependences of the angles of the rotation of the link on the angle of the eccentric shaft rotation of the crusher were obtained, which allowed determining the trajectories of different points of the swing jaw and the sections of the moving plate which crushed feeding material during the cycle. Static force analysis of the mechanism of a single toggle jaw crusher was carried out which made it possible to understand the mechanism of torque transmission to the links of crusher, determine the forces acting on the toggle plate and the eccentrics shaft bearings, as well as the shifting of application point position of the resultant crushing force along the swing plate during one stroke. The graphs of dependencies of the forces acting on the eccentric shaft and the toggle plate on the position of application point of the crushing load were built, which made it possible to determine the worst case for calculating the strength of crushers’ joints. It is established that maximum forces subjected to the eccentric shaft and the toggle plate occur when the crushing force is applied to the bottom zone of the moving plate. Such an application corresponds to the nonlinear distribution of the crushing load along the swing jaw.
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Zhangfeng, Zhao, Li Yanbiao, Li Wenhao, Zhan Xian, Zhu Xingliang, and Zhong Jiang. "Research on the biaxial compound pendulum jaw crusher based on seven-bar mechanism." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 11 (April 16, 2015): 1876–89. http://dx.doi.org/10.1177/0954406215583889.
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Traditional compound pendulum jaw crushers have many disadvantages such as low efficiency and uneven broken materials. This paper proposes a new biaxial compound pendulum jaw crusher to solve these problems. This paper presents the kinematic and dynamic performance of the new crushers, introduces its structure and layout features, derives the equations involving position, velocity, acceleration and kinetics, describes a workspace of the jaw crusher, analyzes the travel characteristic values and crushing force of movable jaw plates, and optimizes its structural and motion parameters through a multi-objective genetic algorithm. After the optimization process, the novel jaw crusher has little force on each hinge and large force on movable jaw plates. Specifically, the forces in the X-direction are 120,300 N for hinge C, 120,200 N for hinge D, and 195,000 N for hinge N; the forces in the Y-direction are 167,100 N, 162,800 N, and 197,900 N accordingly, while the breaking force of the movable jaw plate is 229,600 N. Experiments have been conducted. The results have clearly shown that the new biaxial compound pendulum jaw crusher has many advantages over conventional ones, such as the high crushing efficiency, even crushing, and large crushing force.
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Hussein, Rafea Dakhil, Dong Ruan, Guo Xing Lu, Jeong Whan Yoon, and Zhan Yuan Gao. "Dynamic Axial Compression of Square CFRP/Aluminium Tubes." Key Engineering Materials 794 (February 2019): 202–7. http://dx.doi.org/10.4028/www.scientific.net/kem.794.202.
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Carbon fibre composite tubes have high strength to weight ratios and outstanding performance under axial crushing. In this paper, square CFRP tubes and aluminium sheet-wrapped CFRP tubes were impacted by a drop mass to investigate the effect of loading velocity on the energy absorption of CFRP/aluminium tubes. A comparison of the quasi-static and dynamic crushing behaviours of tubes was made in terms of deformation mode, peak crushing force, mean crushing force, energy absorption and specific energy absorption. The influence of the number of aluminium layers that wrapped square CFRP tubes on the crushing performance of tubes under axial impact was also examined. Experimental results manifested similar deformation modes of tubes in both quasi-static and dynamic tests. The dynamic peak crushing force was higher than the quasi-static counterpart, while mean crushing force, energy absorption and specific energy absorption were lower in dynamic tests than those in quasi-static tests. The mean crushing force and energy absorption decreased with the crushing velocity and increased with the number of aluminium layers. The impact stroke (when the force starts to drop) decreased with the number of aluminium layers.
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Jusuf, Annisa, Fajri Syah Allam, Tatacipta Dirgantara, Leonardo Gunawan, and Ichsan Setya Putra. "Low Velocity Impact Analyses of Prismatic Columns Using Finite Element Method." Key Engineering Materials 462-463 (January 2011): 1308–13. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.1308.
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This paper presents the study of prismatic columns of different cross sections subjected to low velocity impact, which are commonly used as energy absorber components in vehicles. The impacts of the columns were numerically analyzed using FEM. Four cross sections were considered, i.e. square, hexagonal, octagonal and circular. For each cross section, columns with several combinations of perimeters and thicknesses were analyzed. The results showed that, for columns with equal perimeter and thickness, those with circular cross sections have the highest mean crushing force and those with square cross sections have the lowest crushing forces. Furthermore, keeping all other parameters constant, columns with thicker wall have significantly higher crushing force while columns with longer perimeter have only slightly higher crushing force. This parametric information will be very useful for modern automotive industry in designing front longitudinal members within an acceptable safety level.
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Wang, X., and G. Lu. "Axial crushing force of externally fibre-reinforced metal tubes." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 216, no. 9 (September 1, 2002): 863–74. http://dx.doi.org/10.1177/095440620221600901.
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Based on the classical Alexander solution for the axial collapse of bare metal tubes, a theoretical model is presented to predict the mean crushing force of arbitrarily fibre-reinforced metal tubes with a ring collapse mode. The derived mean crushing force and length of the local folding wave are more reasonable and are in better agreement with the experiments than previously obtained. The effect of wrapping direction of the reinforcing fibres is studied. This model for predicting the static mean crushing force can be extended for the dynamic mean crushing force of fibre-reinforced metal tubes under axial impact load.
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Wang, Wenkang, Shaoqing Shi, and Gaosheng Wang. "Comparative Study on Mechanical Properties of a Tube-Crushing Dissipator and a Symmetric Tube-Crushing Dissipator." Advances in Civil Engineering 2019 (April 3, 2019): 1–13. http://dx.doi.org/10.1155/2019/8156432.
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The tube-crushing dissipator is widely used in engineering, but it has the eccentricity problem. Therefore, a symmetric tube-crushing dissipator was proposed in this article, and quasistatic and dynamic tests were performed to compare mechanical properties of the tube-crushing dissipators and the symmetric tube-crushing dissipators. The results of the quasistatic tests show that the working force of the tube-crushing dissipators fluctuates around an average value which is about 20% smaller than the activation threshold after activation, while the working force fluctuates around an average value which is approximately equal to the activation threshold after activation. The results of the dynamic tests show that mean force at the crushing section of the tube-crushing dissipators and the symmetric tube-crushing dissipators increases with the increase of the impact velocity. Furthermore, the dynamic load-displacement curves are more volatile than those of the static tests. Therefore, dynamic tests which are more similar to the real working conditions of the dissipators are preferable over static tests. In addition, the metal tubes of the symmetric tube-crushing dissipators collapse vertically both in the quasistatic and dynamic tests; that is, the eccentricity problem of the tube-crushing dissipators is overcome by the symmetric tube-crushing dissipators.
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JI, XU, and ERKAN OTERKUS. "Physical mechanism of ice/structure interaction." Journal of Glaciology 64, no. 244 (February 28, 2018): 197–207. http://dx.doi.org/10.1017/jog.2018.5.
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ABSTRACTTo obtain the effect of velocity and structural natural frequency (structural stiffness) on ice failure, an extended dynamic Van der Pol-based single degree-of-freedom ice/structure interaction model is developed. Three basic modes of response were reproduced: intermittent crushing, frequency lock-in and continuous crushing. Further analysis on the physical mechanism of ice/structure interaction is presented on the basis of feedback mechanism and energy mechanism, respectively. Internal effect and external effect from ice and structure were both explained in the feedback branch. Based on reproduced results, energy exchanges at different configurations are computed from the energy conservation using the first law of thermodynamics. A general conclusion on the predominant type of vibration when the ice velocity increases during the interaction process is forced, self-excited and forced in each of the three modes of responses. Ice force variations also show that there is more impulse energy during the lock-in range. Moreover, ice-induced vibration demonstrates an analogy of friction-induced self-excited vibration. Finally, the similarity between strain-stress curve and Stribeck curve shows that static and kinetic friction force variations are attributed to ice force characteristic, and can be used to explain the lower effective pressure magnitude during continuous crushing than the peak pressure during intermittent crushing.
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Bai, Shenghe, Qizhi Yang, Kang Niu, Bo Zhao, Liming Zhou, and Yanwei Yuan. "Discrete Element-Based Optimization Parameters of an Experimental Corn Silage Crushing and Throwing Device." Transactions of the ASABE 64, no. 3 (2021): 1019–26. http://dx.doi.org/10.13031/trans.14463.
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HighlightsA discrete element simulation model was used to improve the performance of a corn silage crushing and throwing device.Feed rate, crushing speed, and dial speed were used as the test factors, and the average cutting force and average energy loss were used as the evaluation indexes in orthogonal testing.The order of significance of the factors was crushing speed > feed rate > dial speed for average cutting force and crushing speed > dial speed > feed rate for average energy loss.Abstract. To improve the performance of a corn silage crushing and throwing device and address the problems of low crushing quality and high power consumption, a discrete element simulation model of a corn silage crushing and throwing device and granular straw was established based on discrete element theory using EDEM, a general-purpose CAE software program designed with modern discrete element model technology to simulate and analyze particle processing and production operations. The average cutting force and average energy loss of the particles were the evaluation indexes, and the influence of feed rate, crushing speed, and dial speed on the evaluation indexes was analyzed using single-factor simulation tests. The order of significance was crushing speed > feed rate > dial speed for the average cutting force and crushing speed > dial speed > feed rate for the average energy loss. Using multi-objective optimization, the optimal combination of feed rate, crushing speed, and dial speed was 3.52 kg s-1, 892.06 rpm, and 1502 rpm, respectively. With the optimal parameters, the average cutting force was 58.20 N and the average energy loss was 0.85 J. To verify the feasibility of the EDEM simulation, field tests were conducted using a trial-produced device, with the acceptability of straw crushing and power consumption as the test indicators. During the field tests, the feed rate, crushing speed, and dial speed were set to 3.52 kg s-1, 890 rpm, and 1500 rpm, respectively. The field tests showed that the acceptability of straw crushing and the power consumption were 93.60% and 6.73 kW·h, respectively, with the optimal parameters, which satisfied the corn silage crushing standard and provides a theoretical and scientific basis for the design and optimization of the device. Keywords: Corn silage, Crushing and throwing device, Discrete element simulation, Motion simulation, Multi-objective optimization method.
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Mu, Fu Sheng, Hui Li, Xing Xue Li, and Hong Zhi Xiong. "Jaw Crusher Based on Discrete Element Method." Applied Mechanics and Materials 312 (February 2013): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amm.312.101.
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In order to analyze the force condition and crushing power of crusher teeth plate, the discrete element method models of jaw crusher and double-cavity jaw crusher are set up respectively using EDEM, a kind of software for discrete element analysis. Meanwhile, the working process, the loading force on the teeth plate and crushing power are simulated. The results show that: the rationality of the DEM simulation is declared, and the crushing process of the particles is also shown intuitively. The loading force condition and the crushing power of the moving jaw teeth plate serve as basis for its abrasion and energy consumption respectively.
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Panfilova, Olga, Olga Kalinina, Olga Golyaeva, Sergey Knyazev, and Mikhail Tsoy. "Physical and mechanical properties of berries and biological features of red currant growth for mechanized harvesting." Research in Agricultural Engineering 66, No. 4 (December 30, 2020): 156–63. http://dx.doi.org/10.17221/11/2020-rae.
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The physical and mechanical parameters of berries and the morphometric features of the structure of the bush growth habit are important criteria in predicting the use of berry harvesting equipment. In this research, six red currant cultivars have been studied. The berry separation force, the crushing force, and the strength of attachment of the berries to the stalk were assigned to the physical and mechanical parameters and were determined using the "PLODTEST-1" and "Dina-2" devices (Russia). For the optimal operation of the berry harvester, the crushing force of the berries must be more than 2 N, the berry separation force must be in the range of 0.5–1.5 N. A high correlation between the separation and crushing forces was determined (R = 0.71). During the period of technical maturity, the strength of the attachment of the berries in the raceme was more than 0.5 N and, by the end of maturation, this indicator decreased. Most of the studied cultivars have a compact, optimal bush volume. The red currant cultivars Niva, Asya and Vika are promising for mechanised harvesting.
Dissertations / Theses on the topic "Crushing force"
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Lu, Shuo. "Impact energy absorption analysis of different thin-walled tubes with and without reinforcement." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/impact-energy-absorption-analysis-of-different-thinwalled-tubes-with-and-without-reinforcement(4b8efa4c-9743-4574-993e-1b9df3a922d2).html.
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For an ideal impact energy absorber, the initial peak force should be low and the average crushing force should be high. Also, a long stroke and a stable force history are expected. The thin-walled tube under axial loads is a kind of energy absorber that can produce controlled progressive collapse during a crash. It is a promising collapse mechanism for energy absorption with demonstrated success in industry. But the conventional thin-walled tubes still have high initial peak force and force fluctuations during a crushing process. To help to achieve a better energy absorbing structure, a research work has been carried out in this thesis. The aim of the present research is to achieve an improved understanding of the crushing behaviour of thin-walled tubes under axial loads. In the study, the entire crushing process, including the initial stage of collapse, its localization and the subsequent progressive folding has been carefully investigated by experiment. The relation between the localized plastic deformation and the corresponding crushing force is built by comparing the cross section of series of specimens and their load-displacement curves, which give a deep insight of the collapse mechanism of circular thin-walled tube under axial loads. Then some trigger systems are proposed, which is proved to be a good way to reduce the initial peak force and influence the collapse behaviour. To achieve higher energy absorbing efficiency, the multi-cell thin-walled tube has been investigated. Finally, based on the analysis in this study, a new multi-cell profile which is composed of coaxial tubes with different lengths and dented grooves is proposed. The new design is proved to be a good energy absorber with low initial peak force and very high energy absorption efficiency.
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Konečný, Martin. "Pevnostní výpočet a optimalizace skříně válcového drtiče zrna S 900." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228058.
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This thesis deal with stress control of frame of crushing mill of grain with the aim of defining and consequent optimalization of undersized and overlarge parts of the construction. This frame is screwed assembly. Control is static analysis of frame. This analysis use Finite Element Method.
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Huňka, Jan. "Stavěcí mechanismus štěrbiny kuželového drtiče." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232135.
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This master’s thesis deals with the obtuse-angled cone crushers especially about design of the individual parts of the adjustment mechanism. Most space is devoted to functional calculation and subsequent technical construction of the new design of obtuse-angled crusher where the output setting is adjusted using the motion thread and hydraulic locking system for compensating the thread clearance. The parameters are chosen with regard to the already established older types of cone crushers produced by PSP Engineering, a.s. An inseparable part is the calculation verifying the functionality of the motion thread and gearing. Another essential part of this work are stress analysis of the slot adjusting mechanism design using finite element method and considering two states - adjusting of the slot and crushing itself.
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Staub, Déborah. "Étude du comportement mécanique à rupture des alumines de forte porosité : Application aux supports de catalyseurs d'hydrotraitement des résidus." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0089/document.
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La présente étude porte sur le comportement mécanique de deux types de supports de catalyseurs utilisés industriellement en hydrotraitement des résidus. Ces supports extrudés, fabriqués par IFPEN, sont constitués d’alumine de transition γ avec un taux de porosité proche de 70%. La porosité du premier matériau est uniquement constituée de mésopores (< 50 nm). La porosité du second matériau est constituée de mésopores et de macropores (jusqu’à 20 µm). Les niveaux de sollicitation en service étant très peu connus, cette étude s’attache à décrire de manière précise et exhaustive le comportement mécanique de ces supports sous une large gamme de sollicitations, et à identifier les différents mécanismes de ruine possibles. L’objectif final est de mieux comprendre les relations entre les paramètres microstructuraux et les propriétés mécaniques afin d’identifier des leviers d’amélioration de la tenue mécanique des supports. Dans un premier temps, une méthodologie adaptée de caractérisation mécanique est établie. Le comportement des supports est étudié d’une part en traction, à l’aide d’essais de flexion trois points et d’écrasement diamétral, et d’autre part, en compression sous différents taux de triaxialité, à l’aide d’essais de compression uniaxiale et hydrostatique et d’essais de micro-indentation sphérique. Les différents mécanismes responsables de la ruine des supports sont identifiés au moyen de techniques d’imagerie telles que la microscopie électronique à balayage et la micro-tomographie à rayons X. En traction, le comportement est fragile avec l’amorçage de la rupture sur un défaut critique. En compression, une transition fragile / quasi-plastique du comportement est observée avec l’augmentation du taux de confinement. Cette quasi-plasticité s’exprime en particulier à travers un phénomène de densification de la macroporosité. Dans un deuxième temps, un critère de rupture est identifié pour chaque type de matériau en vue de représenter sur une même surface de charge les différents types de comportement et phénomènes physiques observés. Cette identification est réalisée en couplant les essais d’indentation sphérique à une analyse numérique. Des critères faisant intervenir la pression hydrostatique permettent de rendre compte de la forte dissymétrie du comportement des matériaux en traction et en compression. Enfin, dans un souci de se rapprocher des sollicitations subies par les supports de catalyseurs dans un réacteur en service, le comportement d’un empilement de supports est étudié en compression œdométrique. L’analyse de cet essai par tomographie à rayons X permet de déterminer les différents mécanismes de ruine intervenant au sein d’un empilement, en particulier ceux responsables de la génération de fines. Les résultats illustrent la pertinence de la caractérisation en flexion et en indentation des supports de catalyseurs seuls pour prévoir leur comportement au sein d’un empilement en compressionIn this work, we study the mechanical behaviour of two types of catalysts supports produced by IFPEN and industrially used in residues hydrotreating. Those extruded supports are made of transition γ-alumina with about 70% of porous volume. The first material’s porosity is exclusively composed of mesopores (< 50 nm). The porosity of the second material is composed of both mesopores and macropores (up to 20 µm). Because of the limited knowledge of the stress fields in embedded catalysts supports in use in a reactor, this study aims at precisely and exhaustively describing the mechanical behaviour of those supports under a wide range of stresses, and identifying the possible damage mechanisms. The final objective is to better understand the influence of microstructural parameters on the mechanical properties of the supports in order to propose some leads about how to improve their mechanical strength. First, an adequate mechanical characterization methodology is set. On one hand, the tensile mechanical behaviour of the supports is studied with three-point bending and diametrical crushing tests. On the other hand, their compressive behaviour under various triaxiality rates is characterized in uniaxial and hydrostatic compression, and by spherical micro-indentation. The different damaging mechanisms are identified by imaging techniques such as scanning electronic microscopy and X-ray micro-tomography. Under tensile stresses, the supports exhibit a brittle behaviour and fracture initiates at a critical flaw. Under compressive stresses, a brittle/quasi-plastic transition is observed with increasing the triaxiality rate. The quasi-plasticity is mainly due to the densification of the macroporosity. The second part of the study consists in identifying, for each material, a fracture criterion able to represent every types of behaviour and physical phenomena observed on the same yield surface. This identification is achieved by coupling the spherical indentation tests to a numerical analysis. Fracture criteria involving hydrostatic pressure are well suited to describe the highly dissymmetric mechanical behaviour of the materials in tension and in compression. The last part of this work aims at studying the mechanical behaviour of a stack of supports under œdometric compression in order to produce stress fields more representative of those existing within the supports stacked in a reactor. This test is analysed by X-ray tomography, which allows us to determine/acknowledge the different damaging mechanisms involved in fragments and fines generation. The results illustrate the suitability of the bending and indentation tests to characterize the mechanical properties of a single support and relate them to its mechanical behaviour in a stack of supports under compression
Books on the topic "Crushing force"
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Chomp!: Fierce Facts about the Bite Force, Crushing Jaws, and Mighty Teeth of Earth's Champion Chewers. National Geographic Society, 2017.
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Spilsbury, Louise, and Richard Spilsbury. Crushing Avalanches (Awesome Forces of Nature). Heinemann, 2003.
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Spilsbury, Louise, and Richard Spilsbury. Crushing Avalanches (Awesome Forces of Nature). Tandem Library, 2003.
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Johansson, Jon. From Triumph to Tragedy. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198783848.003.0004.
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This chapter examines the paradox of Lyndon Johnson’s presidential leadership. Widely acclaimed for his brilliant transition to the presidency after the national trauma of President John F. Kennedy’s assassination, this chapter reveals how LBJ exploited his extraordinary high levels of leadership capital to achieve truly historic legislative successes, notably the passage of the Civil Rights Act (1964), the Voting Rights Act (1965), and a crushing electoral victory in 1964. The chapter also reveals how the very skills and character strengths that made Johnson a domestic tour de force did not translate into foreign policy, with fatal consequences for his presidency once his leadership capital collapsed around his failed policies in Vietnam. Ultimately, character-related weaknesses helped LBJ’s leadership descend into tragedy and collapse.
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Fredericks, Anthony D. Fizzle: The Hidden Forces Crushing Your Creativity. Blue River Press, 2020.
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Fredericks, Anthony D. Fizzle: The Hidden Forces Crushing Your Creativity. Blue River Press, 2020.
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Spilsbury, Louise, and Richard Spilsbury. Crushing Avalanches (Spilsbury, Louise. Awesome Forces of Nature.). Heinemann, 2003.
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Press, Abu Huraira. I Never Asked to Be the World's Best Boss but Here I Am Absolutely Crushing It: Of a Very High Standard;Excellent,Cute Line Journal, Diary, Notebook for Motive, Motivating Force, Incentive, Inspiration, Enthusiasm, Incitement, Motivational People. Independently Published, 2020.
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Press, Abu Huraira. I Never Asked to Be the World's Best Social Worker but Here I Am Absolutely Crushing I: Of a Very High Standard;Excellent,Cute Line Journal, Diary, Notebook for Motive, Motivating Force, Incentive, Inspiration, Enthusiasm, Incitement, Motivational People. Independently Published, 2020.
Find full textBook chapters on the topic "Crushing force"
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"Chapter Five. Repression: Crushing Terrorism with Force." In How Terrorism Ends, 115–45. Princeton University Press, 2009. http://dx.doi.org/10.1515/9781400831142-008.
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Hazelton, Jacqueline L. "Counterinsurgency Success." In Bullets Not Ballots, 147–54. Cornell University Press, 2021. http://dx.doi.org/10.7591/cornell/9781501754784.003.0007.
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This chapter argues that counterinsurgency success is about power, co-optation, building a coalition, and crushing opposition, not good governance. In the cases examined in the previous chapters, great power backing helped the client government achieve counterinsurgent success, and all six states remain at least nominally partnered with the West on important issues. But all six campaigns also had high human and moral costs. These findings force those who support great-power, liberal military intervention to consider unpalatable choices about national interests. Individually and collectively, these cases provide strong evidence of the explanatory power of the compellence theory, with its emphasis on coalition building among rival elites and a military campaign targeting civilians as well as insurgents. The chapter then looks at the implications of this analysis on peacekeeping and state-building efforts.
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Oliveira, Tiago, Carlos Páscoa, and José Tribolet. "Strategy Map." In Rethinking the Conceptual Base for New Practical Applications in Information Value and Quality, 250–65. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-4562-2.ch011.
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Evolution happens every moment–as every single moment of the present becomes the past, and the future becomes the present. As a consequence of the process of evolution, the world presents itself to us more complexly than ever. Information value, globalization, technological revolution, acceleration of innovation, and constant change characterize the contemporary challenges that are faced by organizations in what is called the Information Age and Knowledge-Based Economy. Today, to successfully accomplish their mission, organizations need to adapt, act, and think strategically. Alvin Toffler (1985) refers to the role of strategy in an organization: “An organization without strategy is like an airplane weaving through stormy skies, hurled up and down, slammed by the wind, lost in the thunderheads. If lightning or crushing winds do not destroy it, it will simply run out of gas.” Under the body of knowledge and principles of Organizational Engineering—and other theoretical-practical knowledge—this chapter proposes a Strategy Map for the Portuguese Air Force, a tool that clarifies strategy and provides the organization with a means of communication capable of generating motivation and creating focus and alignment, key features to “move” the organization towards its vision.
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Loveland, Ian. "6. The House of Lords." In Constitutional Law, Administrative Law, and Human Rights, 135–67. Oxford University Press, 2021. http://dx.doi.org/10.1093/he/9780198860129.003.0006.
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This chapter examines whether the House of Lords plays an effective anti-majoritarian legislative role. The chapter begins by discussing the changing nature of the relationship between the Commons and the Lords in the post-revolutionary era, focusing in particular on the emergence in the early nineteenth century of a political presumption that the Lords was becoming the inferior partner within Parliament and on the passage of the Parliament Act 1911 in which legal force was given to that political presumption. The chapter also addresses the various proposals put forward in the modern era to reform both the composition and the powers of the House of Lords, and suggests that most reform plans present a paradox. The more we ask a second chamber to perform functions complementary to those of the Commons, the more we demand of its members that they be (as individuals and as a body) ‘expert’, ‘experienced’, and ‘nonpartisan’, and so the more we reveal the crushing dominance of party politics in the lower house, and the incapacity and/or unwillingness of backbench MPs to exert a restraining influence on government activities. This suggests that the key division within the legislative process is now not Lords versus Commons, nor Labour versus Conservative, but party versus national interest. The final part of the chapter explores a more obviously ‘legal’ question; namely the implications of the Parliament Act 1911 for traditional understandings of the doctrine of Parliamentary sovereignty.
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Gross, Alan G. "Rachel Carson: The Ethical Sublime." In The Scientific Sublime. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190637774.003.0012.
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Rachel Carson has become Saint Rachel, canonized time and again by the environmental movement. May 27, 2007, marked the 100th anniversary of her birth. In that year, the Cape Cod Museum of Natural History in Brewster, Massachusetts, hosted a major Rachel Carson centennial exhibition. The show was a partnership project of the museum and the US Fish and Wildlife Service, and it featured artifacts, writings, photographs, and artwork from Carson’s life and career. In 2012, the 50th anniversary of the publication of Silent Spring was commemorated by a Coastal Maine Botanical Gardens event and exhibit. From September 7 through October 23, the exhibit presented artwork, photos, and interpretive panels in the visitor center. Canonization, and the posthumous fame it bestows, comes at a price: the disappearance of the Rachel Carson whose work was driven by two forces. The first was the love of nature. A perceptive review of The Sea Around Us compares Carson with great science writers who share with her a love of nature: . . . It is not an accident of history that Gilbert White and Charles Darwin described flora and fauna with genius, nor that the great mariners and voyagers in distant lands can re-create their experiences as part of our own. They wrote as they saw and their honest, questing eye, their care for detail is raised to the power of art by a deep-felt love of nature, and respect for all things that live and move and have their being. . . . The second force was the love of a woman, Dorothy Freeman, a person who in Carson’s view made her later life endurable and her later work possible: . . . All I am certain of is this: that it is quite necessary for me to know that there is someone who is deeply devoted to me as a person, and who also has the capacity and the depth of understanding to share, vicariously, the sometimes crushing burden of creative effort, recognizing the heartache, the great weariness of mind and body, the occasional black despair it may involve—someone who cherishes me and what I am trying to create, as well. . . .
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Lowenstam, Heinz A., and Stephen Weiner. "Mollusca." In On Biomineralization. Oxford University Press, 1989. http://dx.doi.org/10.1093/oso/9780195049770.003.0008.
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Mollusks have a well-deserved reputation for being expert mineralizers based only on their much-admired shell-making abilities. Table 6.1 shows that the reputation is deserved 10-fold as shell formation is just one of many different processes that these animals perform in which biogenic minerals are utilized. The table lists no less than 21 different minerals and about 17 different functions! The list contains both amorphous minerals (amorphous fluorite, calcium carbonate, calcium phosphate, calcium pyrophosphate, and silica) and many crystalline ones, including rather uncommon ones such as weddelite, calcium fluorite, barite, magnetite, lepidocrocite, and goethite. Weddelite, for example, is a calcium oxalate mineral frequently formed pathologically in vertebrates. Certain gastropods use the rather soft weddelite nonpathologically to cap pestlelike objects (gizzard plates) in their stomachs (Lowenstam 1968), which they use for crushing shelled prey. One mollusk, the chambered Nautilus, forms no less than five different minerals. An individual tooth of a chiton contains three different mature minerals that are products of two other transient minerals. In addition to the more familiar functions of mineralized tissues, mollusks use biogenic minerals as buoyancy devices, trap doors, egg shells, and love darts. The varieties of crystal shapes, sizes, organizational arrays, and tissue sites present a picture of overwhelming diversity all within one phylum. It is illustrative to compare the mollusks with the echinoderms. The echinoderms also use minerals for a wide variety of functions, but in contrast to the mollusks they use essentially the same “building material” for many different purposes. Thus, understanding how one echinoderm mineralized tissue forms provides insight into how most of the others form. This is not so with mollusks. It seems futile to expect that they too have adapted one basic process to form all their mineralized tissues. It seems just as futile to look for a different explanation for each type of mineralized product. The mollusks force us to seek a level of understanding of mineralization that identifies common approaches, strategies, and principles and, at the same time, appears to dispel any “dreams” about discovering the mechanism of mineralization. The mollusk phylum contains seven different taxonomic classes.
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McElroy, Michael B. "Hydro: Power From Running Water." In Energy and Climate. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780190490331.003.0016.
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As discussed in Chapter 4 and illustrated in Figure 4.1, close to 50% of the solar energy intercepted by the Earth is absorbed at the surface. Approximately half of this energy, 78 W m– 2, is used to evaporate water, mainly from the ocean. What this means is that evaporation of water accounts for as much as a third of the total solar energy absorbed by the Earth (atmosphere plus surface). The atmosphere has a limited ability to retain this water. Evaporation is balanced in close to real time by precipitation. A portion of this precipitation reaches the surface in regions elevated with respect to sea level— in mountainous locations, for example. It is endowed in this case with what we refer to as potential energy (Chapter 4). This potential energy can be stored (in lakes or dams, for instance), or it can be released, converted to kinetic energy (directed motion) as the water flows downhill on its return to the ocean. And along the way, energy can be captured and channeled to perform useful work. An early application involved exploiting the power of running water to turn a flat stone, one of two that constituted the apparatus used to grind grain, the other remaining stationary during the grinding process. The Domesday Book records that by AD 1086 as many as 5,624 water mills were operational in England south of the River Trent, deployed not just to grind grain but for a multitude of other tasks, including, but not confined to, sawing wood, crushing ore, and pumping the bellows of industrial furnaces (Derry and Williams 1960). Later, running water would provide the motive force for the textile industry that marked the beginning of the industrial age in North America, specifically in New England (Steinberg 1991; McElroy 2010). The most important contemporary application of water power involves the generation of electricity, the bulk of which is obtained by tapping the potential energy stored in high- altitude dams, a lesser fraction from the kinetic energy supplied by free- flowing streams (what is referred to as run- of- the- river sources).
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Rusnock, Paul, and Jan Šebestík. "Introduction." In Bernard Bolzano, 1–4. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198823681.003.0001.
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Bolzano’s life coincides almost exactly with what has been called the Age of Revolutions. Born in 1781, he lived through the revolution from above launched by Joseph II in 1780, the French Revolution, the triumphs and defeats of Napoleon, the conservative reaction embodied in the Metternich System, the beginnings of the Industrial Revolution, the July revolution of 1830, and finally the uprisings of 1848, the last year of his life. It was a time of exaggerations, of great hopes and fears, sudden reversals, and crushing disappointments, a time of vast enthusiasms and general confusion, as unprecedented forces were let loose upon a world almost completely unprepared for them. The world of letters was not spared, as authors strove to make their voices count in an ever more crowded and noisy public forum. Novelty was everywhere sought, overreach and passion common on all sides....
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Cohn, Samuel. "The French Revolution." In All Societies Die, 19–21. Cornell University Press, 2021. http://dx.doi.org/10.7591/cornell/9781501755903.003.0006.
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This chapter evaluates the causes of the French Revolution. The problem was not that Louis XVI was particularly wasteful, although he had a lavish lifestyle at Versailles. The issue was instead one of crushing military necessity. Before the revolution, France was dealing with invasion threats from Spain and England and was spending over twice as much as had been spent on the Seven Years' War. However, France was fiscally crippled by the fact that a substantial proportion of its financial base was exempt from paying taxes. The disputes within the elite about who was going to come up with the money to pay for extra military expenses led to revolution. The revolutionaries found divided conservative forces, as well as members of the elite willing to oppose the king if this would help them win their battles about future tax obligations. The result was the overthrow of the king and the entire noble class. But taxes were not the whole story: there was also a rising capitalist middle class resentful of the superior status of the aristocracy.
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Dalton, David R. "Yeasts." In The Chemistry of Wine. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190687199.003.0029.
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The yeast, Saccharomyces cerevisiae, is a fungus, one of the group of eukaryotes (organisms with membrane- enclosed organelles and nuclei in their cells) that lie on that branch of the tree of life that, as shown in Figure 18.1, includes plants and animals. Many years of debate preceded their notation as a separate branch on the tree while advocates forcing them into either plant or animal families battled. Thus, although the cell walls of yeast are strikingly similar to plants (save that yeasts utilize N-acetylglucosamine and related nitrogenous carbohydrate polymers [chitin-like] in place of polyphenols [lignin] for cross linking), it is clear that chloroplasts, common to plants, are missing. Similarly, while their organization and food disposition is similar to animals, the very presence of a cell wall, rather than a simple membrane, forces their exclusion from the family of animals. Of course, all life utilizes the same set of purine and pyrimidine bases bonded to a ribose or deoxyribose carbohydrate and amino acids. So while classifications are necessary, they may also be specious. A generic eukaryotic cell and a plant cell (seen before in Figure 7.1) are shown in Figure 18.2. Hundreds of yeasts and strains of those yeasts are available for use in the wine industry for fermenting the must obtained on crushing the grapes. Some of the yeasts are referred to as “wild” and are brought in with the grapes from the vineyard. Others, originally “wild,” have been isolated and maintained because it is held that their use adds value to the vintage. Indeed, it is here that a great deal of experience is required. Generally, the vintner has a good idea of the amount of sugar (measured as glucose) in the grapes harvested. However, different strains of yeast (some 1500 yeast species, including S. cerevisiae are a subgroup of 700,000 or so fungi), while probably processing glucose in the same way, will also process other sugars too and, in that vein, there are other issues to be faced.
Conference papers on the topic "Crushing force"
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Ka¨rna¨, Tuomo, Yan Qu, and QianJin Yue. "An Equivalent Lateral Force for Continuous Crushing." In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92648.
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This paper addresses a condition where a wide, vertical faced structure is subjected to dynamic actions posed by competent level ice. Loading conditions where the ice fails by continuous crushing are studied. It is widely accepted that the structure reacts reluctantly to very rapidly fluctuating forces. On the other hand, an external force caused by continuous ice crushing is often magnified within the structure. These two effects are considered by deriving an equivalent lateral force. The lateral force is obtained by using a magnification factor. This parameter can also be used as an indicator of the dynamic susceptibility of the structure.
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Anthony Opoku, Lope G Tabil, and Sana Talebi. "Crushing force, deformation modulus and crushing strength of timothy hay nodal stem segments." In ASABE/CSBE North Central Intersectional Meeting. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2006. http://dx.doi.org/10.13031/2013.22373.
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Jinxi, Cao, Qin Zhiyu, Rong Xingfu, and Yang Shichun. "Experimental Research on Crushing Force and its Distribution Feature in Jaw Crusher." In 2007 2nd IEEE Conference on Industrial Electronics and Applications. IEEE, 2007. http://dx.doi.org/10.1109/iciea.2007.4318789.
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Hou, Degao, Yan Chen, Jiayao Ma, and Zhong You. "Axial Crushing of Thin-Walled Tubes With Kite-Shape Pattern." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46671.
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Thin-walled tubes are widely used as energy absorption devices in automobiles, designed to protect the costly structures and people inside during an impact event through plastic deformation. They show excellent performance under axial loading in terms of weight efficiency, stroke distance and total energy absorption, but also have the disadvantage that the crushing force is not uniform during deformation process, especially with the existence of a high initial peak force. Recently, pattern design on tubular structures has received increasing attention. It has been found that, if the surface of a tube is pre-folded according to an origami pattern, the collapse mode of the tube can be altered, leading to changes in energy absorption performance. In this paper, we present a series of origami patterned tubes with a kite-shape pattern that is constructed by joining two pieces of Miura-ori. First of all, the geometry of the pattern is presented. We develop a theoretical model to predict the energy absorption associated with the axial crushing of the patterned tubes and derive a mathematical formula to calculate the mean crushing force accordingly. Secondly, a family of origami tubes with various profiles are designed, and their performances subjected to quasi-static axial crushing are numerically investigated. A parametric study is also conducted to establish the relationship between the pre-folded angle of the pattern and the initial peak force as well as the mean crushing force. Numerical results show that introducing patterns to thin-walled tubes offers three advantages in comparison with conventional tubes, i.e., a lower initial peak force, a more uniform crushing load, and a stable and repeatable collapse mode. A 36.0% increase in specific energy absorption and 67.2% reduction in initial peak force is achieved in the optimum case. The new origami patterned tubes show great promise as energy absorption devices.
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Jenson, Sean, Muhammad Ali, and Khairul Alam. "Composite Core Cross Tube Crushing Analysis." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23839.
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Abstract Thin walled axial members are typically used in automobiles’ side and front chassis to improve crashworthiness of vehicles. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of inclusion of functionally graded cellular structures in thin walled members under axial compressive loading. A compact functionally graded composite cellular core was introduced inside a cross tube with side length and wall thickness of 25.4 mm and 3.048 mm, respectively. The parameters governing the energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were evaluated. The results showed that the inclusion of composite graded cellular structure increased the energy absorption capacity of the cross tube significantly. The composite graded structure underwent progressive stepwise, layer by layer, crushing mode and provided lateral stability to the cross tube thus delaying local tube wall collapse and promoting large localized folds on the tube’s periphery as compared to highly localized and compact deformation modes that were observed in the empty cross tube under axial compressive loading. The variation in deformation mode resulted in enhanced stiffness of the composite structure, and therefore, high energy absorption by the structure. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.
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Sakai, I., A. Tsutai, M. Sahashi, and K. Inomata. "Coercive force of Co added Nd-Fe-B based prepared by crushing sintered magnets." In International Conference on Magnetics. IEEE, 1990. http://dx.doi.org/10.1109/intmag.1990.734857.
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Ali, Muhammad, Eboreime Ohioma, and Khairul Alam. "Study of Energy Absorption Characteristics of Square Tube With Composite Cellular Core." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86916.
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Square tubes are primarily used in automotive structures to absorb energy in the event of an accident. The energy absorption capacity of these structural members depends on several parameters such as tube material, wall thickness, axial length, deformation modes, locking strain, crushing stress, etc. In this paper, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. Here, the crushing response of composite cellular core tube was numerically studied using ABAQUS/Explicit module. The energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, crushing stroke, and energy curves were discussed. The composite cellular core tube shows promise for improving the crashworthiness of automobiles.
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Gao, Qiang, Liangmo Wang, Yuanlong Wang, Fuxiang Guo, and Zunzhi Zhang. "Crushing Analysis of Tapered Ellipse Tubes Under Oblique Impact Loading." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59045.
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In this paper, a class of axisymmetric thin-walled tubes with two types of geometries (straight and tapered) and four kinds of cross-sections (square, rectangle, circle, ellipse) are considered as energy absorbing components under oblique impact loading. The crash behavior of these tubes are first investigated by nonlinear finite element analysis through LS-DYNA. It is found that the tapered tubes has the better crashworthiness performance than the straight ones under oblique impact regarding both specific energy absorption (SEA) and peak crushing force (PCF). Among the tapered tubes, the tapered ellipse tube (TET) has the best crashworthiness performance. Then by calculating the overall SEA considering load angle uncertainty effect, it is found that the weighting factors for different load angles are critical for evaluating the crashworthiness performance of the tubes.
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Ali, M., J. Hoffman, J. Clark, and S. Takak. "Modeling of Impact Response of Composite Graded Structure." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64361.
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The work presented in this paper is a continuation of a study on exploring energy absorbing characteristics of a composite functionally graded structure found in a banana peel [1]. The impact behavior of peel structure under strain rates ranging from 4000 s−1 to 15000s−1 are studied. A modified mathematical model is presented, which calculates the initial dynamic crushing stresses of the structure at different impact velocities. The model outputs are compared with finite element simulations for the initial crushing stress, densification strain, global and local deformation modes, reactive force pulse, and total energy absorbed. A reasonable agreement is found between the proposed model and finite element simulations in determining the initial dynamic crushing stress and total energy absorbed by the structure.
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Faqiang, Yin, Pan Jin, Huang Shiwen, and Xu Mingcai. "Simplified Analytical Calculation and Modification of the Crushing Forces of Intersection Units in Vessel-Bridge Collisions." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18615.
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Abstract Because of the increasingly busy maritime trade, the number of bridges damaged by ship-bridge collision also increases. In order to reduce the serious losses caused by ship-bridge collision incidents, it is necessary to make a rapid estimation of ship collision forces. The simplified analytical formulas can be used to rapidly evaluate the collision force in ship collision accidents, but it is found that the existing simplified formulas are only applicable to bulb structures including small-angle inclined elements and not suitable for large-angle inclined elements which exist in ship-bridge collision. In this paper, the quasi-static crushing simulation of the bulbous structure with small-angle inclined angle elements is carried out, and the applicability of the simplified analytical formula of the intersection unit to the typical structure is verified. By comparing the simplified analytical results of the bow with the quasi-static simulation results and the ratio of the strength reduction factor to the effective crushing distance, it is found that the inclined angle of the inclined element will affect the impact force of the simplified analytical calculation. Then, finite element analysis of the truncated-type intersection structure with different element inclination angles are carried out, and the results show that the existing simplified analytical formula is no longer suitable for the calculation of collision force when the inclined angle is greater than 40°. For this reason, the existing simplified analytical formulas are modified for the large-angle inclined elements, and it can provide a certain reference calculation value for the collision force of vessel-bridge collision which includes large-angle inclined elements.
Reports on the topic "Crushing force"
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Terzic, Vesna, and William Pasco. Novel Method for Probabilistic Evaluation of the Post-Earthquake Functionality of a Bridge. Mineta Transportation Institute, April 2021. http://dx.doi.org/10.31979/mti.2021.1916.
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While modern overpass bridges are safe against collapse, their functionality will likely be compromised in case of design-level or beyond design-level earthquake, which may generate excessive residual displacements of the bridge deck. Presently, there is no validated, quantitative approach for estimating the operational level of the bridge after an earthquake due to the difficulty of accurately simulating residual displacements. This research develops a novel method for probabilistic evaluation of the post-earthquake functionality state of the bridge; the approach is founded on an explicit evaluation of bridge residual displacements and associated traffic capacity by considering realistic traffic load scenarios. This research proposes a high-fidelity finite-element model for bridge columns, developed and calibrated using existing experimental data from the shake table tests of a full-scale bridge column. This finite-element model of the bridge column is further expanded to enable evaluation of the axial load-carrying capacity of damaged columns, which is critical for an accurate evaluation of the traffic capacity of the bridge. Existing experimental data from the crushing tests on the columns with earthquake-induced damage support this phase of the finite-element model development. To properly evaluate the bridge's post-earthquake functionality state, realistic traffic loadings representative of different bridge conditions (e.g., immediate access, emergency traffic only, closed) are applied in the proposed model following an earthquake simulation. The traffic loadings in the finite-element model consider the distribution of the vehicles on the bridge causing the largest forces in the bridge columns.