Journal articles: 'Pinned-ends'

1

Li, Xiao Fei, Ying Hua Zhao, Chun Yang Zhu, and Chen Chen. "Exact Solutions of Stiffness Matrix for Curved Beams with Pinned-Pinned Ends." Advanced Materials Research 368-373 (October 2011): 3117–20. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.3117.

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Based on the theory of virtual work and principle of thermal elasticity, exact solutions for in-plane displacements of curved beams with pinned-pinned ends are derived explicitly. In the case of infinite limit of radius, these equations coincide with that of the straight beams. Compared with the results of FEM, the analytical solutions by the proposed formulae are accurate. The stiffness matrix of statically indeterminate curved beams at three freedom direction is derived explicitly. The exact solutions of stiffness matrix obtained in this paper would provide a scientific base for further study and design of the curved bridges

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2

Li, Xiao Fei, Wei Ming Yan, and Hao Xiang He. "Exact Solutions of Dynamic Characteristics for Curved Beams with Pinned-Pinned Ends." Applied Mechanics and Materials 405-408 (September 2013): 702–5. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.702.

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Based on the theory of virtual work and principle of thermal elasticity, exact solutions for in-plane displacements of curved beams with pinned-pinned ends are derived explicitly. In the case of infinite limit of radius, these equations coincide with that of the straight beams. Compared with the results of FEM, the analytical solutions by the proposed formulae are accurate. Basing on the stiffness matrix of statically indeterminate curved beams at three freedom direction, the dynamic characteristics are derived explicitly. The analytic method of dynamic characteristics for curved beam performed in this paper would provide a scientific base for further study and design of the curved bridges.

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3

Zhang, Hua, and Xiang Fang Li. "On Buckling Loads of Timoshenko Columns with Elastically Supported Ends." Advanced Materials Research 446-449 (January 2012): 578–81. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.578.

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The stability of Timoshenko columns with elastically supported ends under axially compressive force is analyzed. Characteristic equations are obtained according to an intermediate state between Haringx’s and Engesser’s models. For clamped-free, clamped-clamped, and pinned-pinned columns, buckling loads are given in closed form. The influences of elastic restraint stiffness on the critical loads are elucidated. Haringx’s and Engesser’s models are two extreme cases of the present. Critical buckling loads using Haringx’s model are upper bound, and those using Engesser’s model are lower bound.

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4

Kim, Heung Youl, Kyung Hoon Park, and Ki Hyuk Kwon. "Experimental Study on the Influence of Boundary Condition on the Behavioral Characteristics of CFT Square Columns under Constant Axial Load upon a Fire." Applied Mechanics and Materials 82 (July 2011): 521–26. http://dx.doi.org/10.4028/www.scientific.net/amm.82.521.

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The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-section size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-section size was 360mm by 360mm. In the specimens with cross-section size of 280 mm × 280mm, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.

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5

Kim, Hyung Jun, Heung Youl Kim, and In Hwan Yeo. "An Experimental Study on the Fire Behavior of CFT Columns under the Constant Axial Loading Condition in Fire." Advanced Materials Research 446-449 (January 2012): 1298–306. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.1298.

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The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-sectional size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-sectional size was 360 by 360. In the specimens with cross-sectional size of 280 x 280, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.

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6

Foda, Mosad A. "On Non-linear Free Vibrations of a Beam with Pinned Ends." Journal of King Saud University - Engineering Sciences 7, no. 1 (1995): 93–106. http://dx.doi.org/10.1016/s1018-3639(18)30619-6.

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7

Peng, Li, and Ying Wang. "Transverse Free Vibration of Timoshenko Beams Resting on Viscoelastic Foundations." Advanced Materials Research 919-921 (April 2014): 275–79. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.275.

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The complex modal analysis is developed to study the transverse vibration of Timoshenko beams resting on viscoelastic Pasternak foundation. Complex frequency equations and modal function expressions are obtained for pinned-pinned ends. In numerical examples, the characteristics of natural frequencies and decrement coefficients of Timoshenko beams are compared with Euler-Bernoulli beams. The numerical results show that with increase in the length, the natural frequencies of Timoshenko beams are slightly less than Euler-Bernoulli beams, and the decrement coefficients of Timoshenko beams are not constant as that of Euler-Bernoulli beams.

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8

Sun, Jian Peng, and Qing Ning Li. "The Precise Transfer Matrix Method for Dynamic Characteristic Analysis of Curved Box Beams." Advanced Materials Research 255-260 (May 2011): 1721–24. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.1721.

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The dynamic characteristic as one key feature determines the earthquake response and seismic performance of structures.Curved box beams occur coupling of flexural and torsional modes,which companied with warping.Based on the precise transfer matrix method,precise transfer matrixs for solving the natural frequencies and modes of curved box beam out plane have been derivated.The analysis of vibration characteristics of single-span curved box beam with pinned-pinned ends has been done. Example shows that the precise transfer matrix method is a simple and effective method for dynamic characteristic analysis of curved box beams.

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9

Goy, T. P., M. Negrych, and I. Ya Savka. "On nonlocal boundary value problem for the equation of motion of a homogeneous elastic beam with pinned-pinned ends." Carpathian Mathematical Publications 10, no. 1 (2018): 105–13. http://dx.doi.org/10.15330/cmp.10.1.105-113.

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In the current paper, in the domain $D=\{(t,x): t\in(0,T), x\in(0,L)\}$ we investigate the boundary value problem for the equation of motion of a homogeneous elastic beam $$ u_{tt}(t,x)+a^{2}u_{xxxx}(t,x)+b u_{xx}(t,x)+c u(t,x)=0, $$ where $a,b,c \in \mathbb{R}$, $b^2<4a^2c$, with nonlocal two-point conditions $$u(0,x)-u(T, x)=\varphi(x), \quad u_{t}(0, x)-u_{t}(T, x)=\psi(x)$$ and local boundary conditions $$u(t, 0)=u(t, L)=u_{xx}(t, 0)=u_{xx}(t, L)=0.$$ Solvability of this problem is connected with the problem of small denominators, whose estimation from below is based on the application of the metric approach. For almost all (with respect to Lebesgue measure) parameters of the problem, we establish conditions for the solvability of the problem in the Sobolev space. In particular, if $\varphi\in\mathbf{H}_{q+\rho+2}$ and $\psi \in\mathbf{H}_{q+\rho}$, where $\rho>2$, then for almost all (with respect to Lebesgue measure in $\mathbb{R}$) numbers $a$ exists a unique solution $u\in\mathbf{C}^{\,2}([0,T];\mathbf{H}_{q})$ of the problem considered.

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10

Li, Shirong, You-He Zhou, and Xiaojing Zheng. "THERMAL POST-BUCKLING OF A HEATED ELASTIC ROD WITH PINNED-FIXED ENDS." Journal of Thermal Stresses 25, no. 1 (2002): 45–56. http://dx.doi.org/10.1080/014957302753305862.

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11

Li, Baohui, Zhengzhong Wang, and Lina Jing. "Dynamic Response of Pipe Conveying Fluid with Lateral Moving Supports." Shock and Vibration 2018 (November 4, 2018): 1–17. http://dx.doi.org/10.1155/2018/3295787.

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The Galerkin method is proposed to reveal the dynamic response of pipe conveying fluid (PCF), with lateral moving supports on both ends of the pipe. Firstly, the dynamic equation is derived by the Newtonian method after calculating the acceleration of the fluid element via the dynamics approach. Secondly, the discrete form of the dynamic equation is formulated by the Galerkin method. Thirdly, the numerical analysis of the system is carried out through the fourth-order Runge–Kutta method, and the effectiveness of the proposed method is validated by comparison with the analytical results obtained by the mode superposition method. In the example analysis, the responses of the lateral deflection and bending moment are investigated for the pinned-pinned, clamped-pinned, and clamped-clamped PCF. The effects of fluid velocity and the moving frequencies of supports are discussed. Especially, the deflection responses are analyzed under extreme condition; i.e., the moving frequency of a support is identical to the natural frequency of PCF.

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12

Şcedilakar, Gürkan. "The Effect of Axial Force on the Free Vibration of an Euler-Bernoulli Beam Carrying a Number of Various Concentrated Elements." Shock and Vibration 20, no. 3 (2013): 357–67. http://dx.doi.org/10.1155/2013/735061.

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In this study, free vibration analysis of beams carrying a number of various concentrated elements including point masses, rotary inertias, linear springs, rotational springs and spring-mass systems subjected to the axial load was performed. All analyses were performed using an Euler beam assumption and the Finite Element Method. The beam used in the analyses is accepted as pinned-pinned. The axial load applied to the beam from the free ends is either compressive or tensile. The effects of parameters such as the number of spring-mass systems on the beam, their locations and the axial load on the natural frequencies were investigated. The mode shapes of beams under axial load were also obtained.

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13

Pearson, D. "Modelling the Ends of Compression Helical Springs for Vibration Calculations." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 200, no. 1 (1986): 3–11. http://dx.doi.org/10.1243/pime_proc_1986_200_088_02.

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The squared ends of compression helical springs are modelled as fixed ends with adjacent pinned supports. A theory is developed for the calculation of the natural frequencies, its predictions being compared with experiments on springs with about 2 1/2, 4 and 8 1/2 active turns, using two new designs of test rig. The discrepancy between theory and experiment is typically 1 per cent. The paper contains discussions of the application of the theory to forced vibration calculations, and the modelling of other types of end. Two methods are reviewed for the design of helical springs with the object of avoiding vibration problems.

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14

King, W. W. "Displacement-Limited Buckling of an Optical Fiber." Journal of Electronic Packaging 115, no. 1 (1993): 39–43. http://dx.doi.org/10.1115/1.2909300.

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Buckling of an optical fiber within a confining connector housing is analyzed under the restriction that the transverse deflection profile be shallow. Fibers with pinned ends and with clamped ends are treated. The three stages of buckling are discussed: sufficiently small transverse displacements that contact is not made with the housing wall; point contact with the wall; and finite-length contact with the wall. Explicit expressions for responses as functions of relative longitudinal displacement of ends are obtained for the first and third stages. For the second stage, longitudinal displacement and maximum fiber curvature are expressed in terms of buckling load. Except for a portion of the point-contact stage, contact with a confining wall causes more severe stresses in the fiber than would otherwise be the case.

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15

Jin, Ji Duo, Xiao Dong Yang, and Yu Fei Zhang. "Stability and Natural Characteristics of a Supported Beam." Advanced Materials Research 338 (September 2011): 467–72. http://dx.doi.org/10.4028/www.scientific.net/amr.338.467.

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The stability, natural characteristics and critical axial force of a supported beam are analyzed. The both ends of the beam are held by the pinned supports with rotational spring constraints. The eigenvalue problem of the beam with these boundary conditions is investigated firstly, and then, the stability of the beam is analyzed using the derived eigenfuntions. According to the analytical expression obtained, the effect of the spring constants on the critical values of the axial force is discussed.

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16

Moradifard, Reza, Mohammad Gholami, and Elnaz Zare. "Nonlinear free vibration analysis of a bi-directional functionally graded microbeam on nonlinear elastic foundation using modified couple stress theory." International Journal of Computational Materials Science and Engineering 10, no. 01 (2021): 2150001. http://dx.doi.org/10.1142/s2047684121500019.

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In this research, a size-dependent Euler–Bernoulli beam model is proposed for nonlinear free vibration of a bi-directional functionally graded (BFG) based on a three-layered nonlinear elastic foundation within the framework of the modified couple stress (MCS) theory. The nonlinearity due to the stretching effect of the mid-plane of the BFG microbeam is the source of the nonlinearity of the assumed free vibration issues. The motion governing equations and the corresponding boundary conditions are derived by applying the principle which is associated to Hamilton, under the assumption that the axial inertia is negligible. By applying cubic nonlinearity via Galerkin’s method, the partial nonlinear differential equation can be reduced and turned into an ordinary nonlinear equation of the differential. Then, Galerkin’s variational method is used to gain proximate analytical expressions for the nonlinear frequency of microbeams with boundary conditions of pinned–pinned ends and clamped–clamped ends. The precision of the present solution is evaluated through comparing the nonlinear frequency provided by the proposed approach with the results available from previous studies. The influence of changes in some parameters such as amplitude ratio, the material length scale parameter, material gradient parameters, end supports and stiffness coefficients of the foundation with nonlinearity on the normalized fundamental frequency is studied in detail. As a main result, it is observed that the nonlinear vibration frequencies are higher than their linear counterparts.

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17

Yidris, Noorfaizal, Mohamed Thariq Hameed Sultan, Mohammad Yazdi Harmin, and Azmin Shakrine Mohd Rafie. "Local-Overall Flexural Interaction of Pinned-Ended Thin-Walled I-Section Columns." Applied Mechanics and Materials 564 (June 2014): 444–48. http://dx.doi.org/10.4028/www.scientific.net/amm.564.444.

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The structural performance of thin-walled compression members are subject to the effects of local buckling, interaction between buckling modes, loading end conditions and material yielding and that due to these effects the compressive carrying capability of thin-walled members can be significantly diminished. This paper employs the finite element simulation to examine the local-overall flexural interaction response of pinned-ended thin-walled I-section columns that covers the complete compressed loading history from the onset of elastic local buckling through the nonlinear elastic and elasto-plastic post-buckling interactive phases of behaviour to final collapse and unloading. A detailed account of the growth and redistribution of stresses on the surfaces is given in the paper. Pinned-ended conditions means, of course, simply supported conditions at the column ends with respect to global rotations and the ends of the constituent plates of the cross-section can be treated as either locally rotationally constrained or locally rotationally free. The numerical simulations take into account the influence of material nonlinearity and geometrical imperfections on the compressive ultimate failures of the sections, however, the study is limited to the interaction of local buckling with overall flexural bending as well as locally rotationally constrained condition. This paper shows that the ultimate failure of the columns is related with yielding on the compression sides of the outer surfaces of the section walls at the web, flanges and section junctions mostly located along the length of the columns.

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18

Teng, Xiaoyan, Nan Liu, and Xudong Jiang. "Analytical model of high-frequency energy flow response for a beam with free layer damping." Advances in Mechanical Engineering 12, no. 12 (2020): 168781402098459. http://dx.doi.org/10.1177/1687814020984596.

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Energy flow analysis (EFA) is developed to predict the vibrational energy density of beam structures with both full free layer damping (FFLD) and partial free layer damping (PFLD) treatments in the high frequency range. Both equivalent flexural stiffness and structural damping loss factor of a beam with free layer damping are obtained using the equivalent complex stiffness method. Then the energy density governing equation considering high damping effect is derived for a beam with FFLD treatment. Following obtainment of the energy transfer coefficients at both ends of free damping layer, the energy density within a beam with PFLD treatment is evaluated by solving the presented energy governing equation. To verify the proposed formulation, numerical simulations are performed for the pinned-pinned beams with FFLD and PFLD treatments. The EFA results are compared with the exact solutions from wave analysis at various frequencies, and good correlations are observed between the developed EFA results and the exact solutions.

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19

Corrado, Virginia, Berardino D'Acunto, Nicola Fontana, and Maurizio Giugni. "Inertial Effects on Finite Length Pipe Seismic Response." Mathematical Problems in Engineering 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/824578.

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A seismic analysis for soil-pipe interaction which accounts for length and constraining conditions at the ends of a continuous pipe is developed. The Winkler model is used to schematize the soil-structure interaction. The approach is focused on axial strains, since bending strains in a buried pipe due to the wave propagation are typically a second-order effect. Unlike many works, the inertial terms are considered in solving equations. Accurate numerical simulations are carried out to show the influence of pipe length and constraint conditions on the pipe seismic strain. The obtained results are compared with results inferred from other models present in the literature. For free-end pipelines, inertial effects have significant influence only for short length. On the contrary, their influence is always important for pinned pipes. Numerical simulations show that a simple rigid model can be used for free-end pipes, whereas pinned pipes need more accurate models.

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20

Fan, Feng, Yu Jin Wang, Li Lin, and Hong Liang Qian. "Experimental Study on Axial Compression Performance of High-Strength Aluminum-Alloy Columns with H-Section." Applied Mechanics and Materials 274 (January 2013): 459–62. http://dx.doi.org/10.4028/www.scientific.net/amm.274.459.

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This paper presents an experimental investigation of aluminum alloy H-type sections subjected to axial compression between two pinned ends. The specimens were fabricated using 6082-T6 heat-treated aluminum alloy. 26 material tensile tests were performed then a test program included 12 column tests which were separated into 6 test series of different geometry and ranged from 990 to 1840 mm in length in order to obtain a column curve. All the observed failure modes for the column tests were overall buckling and the axial capacities were obtained.

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21

Li, Xiao Fei, Ying Hua Zhao, and De Hai Yu. "Analytical Solutions at Three Freedom Direction for Curved Beams with Clamped-Pinned Ends under Thermal Load." Applied Mechanics and Materials 94-96 (September 2011): 322–25. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.322.

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The purpose of the paper is to present analytical solution of curved beam with clamped-pinned ends under thermo load based on the principle of thermal expansion and theory of virtual work. A class of equations for in-plane displacements at three freedom direction and internal forces in the cross-section of statically indeterminate curved beams under thermo load are derived explicitly. In the case of infinite limit of radius, these equations coincide with that of the straight beams. Compared with the results of FEM, the analytical solutions by the proposed formulae are accurate. The analytical solutions obtained in this paper would provide a scientific base for further study and design of the curved bridges.

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22

Civalek, Omer, and Baki Ozturk. "Free vibration analysis of tapered beam-column with pinned ends embedded in Winkler-Pasternak elastic foundation." Geomechanics and Engineering 2, no. 1 (2010): 45–56. http://dx.doi.org/10.12989/gae.2010.2.1.045.

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23

Bochicchio, Ivana, Claudio Giorgi, and Elena Vuk. "Long-Term Damped Dynamics of the Extensible Suspension Bridge." International Journal of Differential Equations 2010 (2010): 1–19. http://dx.doi.org/10.1155/2010/383420.

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This work is focused on the doubly nonlinear equation , whose solutions represent the bending motion of an extensible, elastic bridge suspended by continuously distributed cables which are flexible and elastic with stiffness . When the ends are pinned, long-term dynamics is scrutinized for arbitrary values of axial load and stiffness . For a general external source , we prove the existence of bounded absorbing sets. When is time-independent, the related semigroup of solutions is shown to possess the global attractor of optimal regularity and its characterization is given in terms of the steady states of the problem.

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24

Foda, Mosaad A. "Influence of shear deformation and rotary inertia on nonlinear free vibration of a beam with pinned ends." Computers & Structures 71, no. 6 (1999): 663–70. http://dx.doi.org/10.1016/s0045-7949(98)00299-5.

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25

Foda, Mosaad A. "Influence of Shear Deformation and Rotary Intertia on Nonlinear Free Vibration of a Beam with Pinned Ends." Journal of King Saud University - Engineering Sciences 10, no. 1 (1998): 87–103. http://dx.doi.org/10.1016/s1018-3639(18)30689-5.

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26

Cetin, Dogan, and Mesut Simsek. "Free vibration of an axially functionally graded pile with pinned ends embedded in Winkler-Pasternak elastic medium." Structural Engineering and Mechanics 40, no. 4 (2011): 583–94. http://dx.doi.org/10.12989/sem.2011.40.4.583.

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27

Merli, R., C. Lázaro, S. Monleón, and A. Domingo. "Comparison of two linearization schemes for the nonlinear bending problem of a beam pinned at both ends." International Journal of Solids and Structures 47, no. 6 (2010): 865–74. http://dx.doi.org/10.1016/j.ijsolstr.2009.12.001.

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28

Balazs, Anna C., Chandralekha Singh, Ekaterina Zhulina, Dilip Gersappe, and Galen Pickett. "Patterned Polymer Films." MRS Bulletin 22, no. 1 (1997): 16–21. http://dx.doi.org/10.1557/s0883769400032280.

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Polymer films that contain well-defined patterns can be used in a variety of novel applications. For example such films can serve as the scaffolding in fabricating organic/inorganic composites with controlled architectures. One means of forming patterned films is to anchor the ends of homopolymers onto a substrate (so that the ends are fixed and cannot move) and immerse the system in a poor solvent. The incompatibility between the polymer and solvent drives the system to phase-separate. Since the ends are immobilized however, the polymers can only escape the unfavorable solvent by clustering with neighboring chain s into distinct aggregates or “pinned micelles.” These micelles have a uniform size and spacing, and form a regular array on the surface. In this article, we use theoretical models to extend this concept and show that, by tethering copolymers—chains that contain more than one type of monomer—we can drive the system to form more complicated surface patterns. These copolymer patterns provide a handle for engineering the interaction between surfaces and thus facilitate the fabrication of novel optical devices. If the copolymer films are composed of both hydrophilic and hydrophobic domains, the surface can also be used as a template for growing biological cells with tailored shapes and sizes.

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Chang, Xue Ping, Jun Liu, and Ji Hong Ren. "Exact Mathematical Model and its Numerical Solution of a Two-Layer Beam Subjected to Non-Uniform Temperature Rise." Applied Mechanics and Materials 130-134 (October 2011): 3163–68. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3163.

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Based on accurately considering the axial extension, geometrically nonlinear governing equations for a two-layer beam subjected to thermal load were formulated. By using a shooting method, the strongly nonlinear ordinary differential equations with two-point boundary conditions were solved and numerical solution for thermal post-buckling and bending deformation of a two-layer beam with pinned-pinned ends and subjected to transversely non-uniform temperature rising were obtained. As an example, equilibrium paths and configuration for a beam laminated by brass and steel are presented and characteristic curves of the nonlinear deformation changing with the thermal load were plotted. Effects of the geometric and material parameters on the deformation of the beam were discussed and analyzed in detail. The theoretical analysis and numerical results show that the bending deformation and the stretching-bending coupling terms of beam subjected to uniform or non-uniform temperature rising can be produced because of the non-homogenous distribution of the material properties. The bending deformation resulted from transversely temperature rise is primary deformation when values of average temperature rise parameter is under critical temperature, however, the curves become the thermal post-buckling equilibrium paths with the increment of average temperature rise when values of average temperature rise parameter exceed critical temperature.

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30

Blostotsky, Boris, Elia Efraim, and Yuri Ribakov. "Tensile Buckling of a Rod with an End Moving along a Circular Guide: Improved Experimental Investigation Based on a Dynamic Approach." Applied Sciences 11, no. 16 (2021): 7277. http://dx.doi.org/10.3390/app11167277.

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Investigation of buckling under tension is highly important from theoretical and practical viewpoints to ensure safety and the proper performance of mechanical systems. In the present work, tensile buckling is investigated experimentally, and the critical force is measured in systems where one end of an elastic tensile rod slides along a straight guide, while the other slides along a curve. An experimental setup is proposed and developed for determining the critical tensile load of the elastic rod by a dynamic method. This setup allows measuring free vibrations and frequency with the required accuracy. Improvement of the critical load accuracy is achieved by approaching the maximum load to the critical one. Limitations in selecting the test parameters are found according to the required extrapolation accuracy of the dominant natural vibration frequency dependence on tensile load. Theoretical analysis and tests are performed for the rod connection schemes pinned–rigid, rigid–pinned, and rigid–rigid, considering imperfections in the fixation of the rod ends. It is experimentally shown that the system buckling at tensile load is possible and that experimental and theoretical values of the critical load are in good agreement. The achieved accuracy, estimated by the discrepancy between the calculated and the experimental values, is 2.1–3.5%.

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31

Hołubowski, Ryszard, and Andrzej Merena. "Multiple shooting method in stability analysis of non-prismatic multi-segment columns." Budownictwo i Architektura 12, no. 4 (2013): 225–32. http://dx.doi.org/10.35784/bud-arch.1977.

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The application of multiple shooting method in stability analysis of non-prismatic multi-segment columns with pinned ends loaded with a concentrated force applied to the upper node has been presented. Numerical analyses were carried out for an exemplary three-segment column by solving the system of differential equations with variable coefficients and parameter. The results were compared with the solution obtained by using SOFiSTiK software based on the finite element method. The analyses show that considering the stiffness changes along the length can have a significant influence on the values of critical loads and thus change the resistance of the column. The advantage of the proposed method is its high efficiency and easy description of stiffness changes.

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32

Zhang, Zijun, Yongshou Liu, Hailong Zhao, and Wei Liu. "Topology Optimized Vibration Control of a Fluid–Conveying Carbon Nanotube with Non-Uniform Magnetic Field." International Journal of Applied Mechanics 07, no. 06 (2015): 1550092. http://dx.doi.org/10.1142/s1758825115500921.

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This paper presents an approach to control the fluid-induced vibration of the carbon nanotubes (CNTs) embedded in viscoelastic medium with topology non-uniform magnetic field. Non-local continuum theory and homogenization equivalence are employed to conclude small-scale effects of the carbon nanotube (CNT) and the nanofluid, respectively. Simply supported, fixed–fixed and fixed–pinned fluid–conveying carbon nanotubes (FCCNTs) with sliding and no-sliding ends are chosen as samples to illustrate the control effect of the magnetic field, and the optimal magnetic field distributions are obtained through genetic algorithm (GA). Dynamic characteristics (the eigen-frequencies and the critical velocities) of different FCCNT models are calculated through differential quadrature (DQ) method. The control effects of the magnetic field can be validated through examining the stiffness enhancement of the Ampere’s force. Results present that the eigen-frequencies and critical velocities of different FCCNTs are all raised by 3–13% through the given magnetic fields. Contrasts between different models illustrate that the dynamic stiffness of simply supported FCCNT with no-sliding ends is enhanced mostly by the magnetic field.

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33

Michaello, R. Da S., D. Helbig, L. A. O. Rocha, M. V. Real, E. D. Dos Santos, and L. A. Isoldi. "COMPUTATIONAL MODELING APPLIED TO THE STUDY OF THERMAL BUCKLING OF COLUMNS." Revista de Engenharia Térmica 14, no. 1 (2015): 34. http://dx.doi.org/10.5380/reterm.v14i1.62111.

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Buckling is an instability phenomenon that can happen in slender structural components when subjected to a compressive axial load. This phenomenon can occur due to an externally applied force, which when exceed a certain limit, called critical load, will promote the mechanical buckling on the structural member. Another buckling possibility happens to statically indeterminate structural elements when submitted to a positive temperature variation. As the axial displacements are restricted, if the temperature gradient is larger than the critical temperature variation, it will be generated a compressive axial load higher than the critical load of the structural component and the thermal buckling will occur. In this context, the present work presents a computational model to solve the thermal buckling problem of columns. A thin shell finite element, called SHELL93, was adopted for the computational domain discretization. It was employed a solution involving homogeneous algebraic equations, where the critical temperature variation is determined by the smallest eigenvalue and the buckled configuration is defined by its associated eigenvector. A case study was performed considering a steel column with three different support conditions at its ends: fixed-fixed, fixed-pinned, and pinned-pinned. The numerical results obtained for the critical temperature variation showed a maximum absolute difference around 2% when compared to the analytical solutions. Moreover, the buckled shape of the column, for each case, was defined in agreement with the configurations found in literature. Therefore, the computational model was verified, i.e., it is able to satisfactorily predict the mechanical behavior of the thermal buckling of columns. So, it is possible to use this numerical model in practical situations that do not have an analytical solution, as is the case of the thermal buckling of columns with cutouts.

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Mamandi, Ahmad, and Mohammad H. Kargarnovin. "Nonlinear Dynamic Analysis of an Inclined Timoshenko Beam Subjected to a Moving Mass/Force with Beam’s Weight Included." Shock and Vibration 18, no. 6 (2011): 875–91. http://dx.doi.org/10.1155/2011/794254.

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In this study, the nonlinear vibrations analysis of an inclined pinned-pinned self-weight Timoshenko beam made of linear, homogenous and isotropic material with a constant cross section and finite length subjected to a traveling mass/force with constant velocity is investigated. The nonlinear coupled partial differential equations of motion for the rotation of warped cross section, longitudinal and transverse displacements are derived using the Hamilton's principle. These nonlinear coupled PDEs are solved by applying the Galerkin's method to obtain dynamic responses of the beam. The dynamic magnification factor and normalized time histories of mid-point of the beam are obtained for various load velocity ratios and the outcome results have been compared to the results with those obtained from linear solution. The influence of the large deflections caused by a stretching effect due to the beam's fixed ends is captured. It was seen that existence of quadratic-cubic nonlinear terms in the nonlinear governing coupled PDEs of motion causes stiffening (hardening) behavior of the dynamic responses of the self-weight beam under the act of a traveling mass as well as equivalent concentrated moving force. Furthermore, in a case where the object leaves the beam, its planar motion path is derived and the targeting accuracy is investigated and compared with those from the rigid solution assumption.

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35

Modarres-Sadeghi, Yahya, Michael P. Païdoussis, and Christian Semler. "The nonlinear behaviour of a slender flexible cylinder pinned or clamped at both ends and subjected to axial flow." Computers & Structures 85, no. 11-14 (2007): 1121–33. http://dx.doi.org/10.1016/j.compstruc.2006.08.006.

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Wang, Zhihao, Fangfang Yue, Hao Wang, Hui Gao, and Buqiao Fan. "Refined Study on Free Vibration of a Cable with an Inertial Mass Damper." Applied Sciences 9, no. 11 (2019): 2271. http://dx.doi.org/10.3390/app9112271.

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To accurately predict the optimum supplemental modal damping ratio of the cable and the corresponding size of the inertial mass damper (IMD), combined effects of the cable sag, the cable flexural rigidity, and the boundary conditions on the control performance of the cable with the IMD are well investigated in this refined study. An analytical model of the cable-IMD system considering these effects is developed. The equation of motion of the cable-IMD system is transformed into a complex eigenvalue problem through the finite difference method. Experimental results from a scaled cable model with an IMD are then used to verify theoretical solutions. Three typical cables in actual cable-stayed bridges are selected for case studies. The results show that the theoretically predicted modal damping ratios of the cable with an IMD, taking into account the sag and the flexural rigidity, agree well with those identified from experimental results, while would be often overestimated with a taut-cable model. Moreover, experimental damping ratios of the cable always fall between those theoretically calculated with fixed ends or pinned ends for each case. Finally, to be conservative in actual design, it is recommended to use the cable-IMD system model with fixed ends to calculate the required damper size and predict the resulting modal damping ratio of the cable, since the corresponding theoretical solution often gives the lower bound of supplemental damping ratio of the cable.

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Li, Guo Hua, Cheng Zhi Qi, and Jian Luo. "Nonlinear Finite Element Analysis of Steel Frame with Semi-Rigid Connections." Applied Mechanics and Materials 226-228 (November 2012): 1199–202. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1199.

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In conventional analysis and design, the beam-column connections are divided into two categories: fully rigid joints and perfectly pinned joints. Actually, most beam-column connections exhibit flexibility. Idealized connections may diverge from the real reaction of structures. This article presents a hybrid finite-element model that consists of a beam element with two semi-rigid connections at the ends for studying the effect of the flexibility on the structures. Based on the theory of finite deformation, the first-order and the second-order stiffness matrix and the equilibrium equation of hybrid beam element were got. A nonlinear finite element analysis program was developed to analysis the steel frames with semi-rigid connections. At last, one-bay, two-story semi-rigid planar steel frame was analyzed using the program, and some conclusions about the effect of semi-rigid connections flexibility were obtained.

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38

ZHANG, QI-YI, XUN XIANG, and KAI-YAN HU. "HYSTERESIS EFFECT OF SINGLE DOUBLE-END ANCHORED POLYELECTROLYTE IN AC ELECTRIC FIELD." Modern Physics Letters B 26, no. 14 (2012): 1250089. http://dx.doi.org/10.1142/s0217984912500893.

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We investigate the dynamics of a single flexible and semiflexible polyelectrolyte (PE) chain, fixed at both ends under the action of spatially uniform alternating-current (AC) electric fields using Brownian dynamics simulations. The results show that the shapes of the orbits in the position-electric field plane are strongly influenced by the factors such as the frequencies of the AC electric fields, the whole chain length, the pinned chain length, the friction coefficient of polymer beads and the elasticity constant of polymer chain. These orbits transform from hysteretic cycles to single curves when the frequencies are smaller than the characteristic frequency ω*. The influences of the above factors on ω* have been explored. The physical mechanism and the values of the characteristic frequency have been explored in detail within the Rouse-mode analysis. The values of ω* can be roughly predicted from Rouse-mode analysis.

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39

Putra, Ichsan Setya, Pham Hoang Nam, Hendri Syamsudin, Tatacipta Dirgantara, and Le Xuan Truong. "Design, Manufacturing and Testing Process of Buckling and Bending Testing Machine Using Systematic Method." Applied Mechanics and Materials 393 (September 2013): 441–46. http://dx.doi.org/10.4028/www.scientific.net/amm.393.441.

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In this work, a new testing machine is designed and manufactured with two main functions, i.e., buckling and bending experiment. This machine is designed for classroom demonstrations, or students working in pairs or small groups. The buckling experiment is used to show the buckling phenomenon and to determine critical buckling load for struts with pinned and clamped ends for various strut lengths. The struts for buckling test are made from aluminum alloys with section 2 mm × 20 mm and various lengths of 300mm, 350mm, 400mm, 450mm, 500mm. The bending experiment is carried out to find the flexural rigidity of a strut. The supports of strut in bending test can be changed to fixed, pinned, and rolled supports. The strut of bending test is made from aluminum alloys and common steel with section 3 mm × 20 mm and length 600 mm. Using a systematic method, the development of the machine is broken downinto 3 stages. The first stageof the systematic process is to define the specification based on requirements and objectives. In the second stage, the conceptual design is performed. It comprises the evaluation of the function to find advantages and disadvantages of the components based on the design requirements setup earlier and the comparison of the design concepts against several existing machines was made. Based on this evaluation, the final design is selected for stage 3 of the detail design stage. In this final stage, each component is designed and analyzed in detail. Based on the result of design stage, the testing machine is then manufactured in the Universitys workshop. The evaluation of the machine shows a new design that meets the requirements and objectives. The measurements of critical buckling loads and bending displacements for various strut lengths are in good agreements with analytical calculation. The margins are less than 5 percent.

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40

Qi, Yujun, Lei Xie, Yu Bai, Weiqing Liu, and Hai Fang. "Axial Compression Behaviours of Pultruded GFRP–Wood Composite Columns." Sensors 19, no. 4 (2019): 755. http://dx.doi.org/10.3390/s19040755.

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An innovative pultruded fiber reinforced polymer (FRP)–wood composite (PFWC) column with a lightweight southern pine wood core confined by outer FRP sheets was manufactured using an improved pultrusion process. Axial compression tests with both ends pinned as boundary conditions were employed to investigate the mechanical performance of such PFWC columns under concentric load. Through experimental investigations, the effects of the slenderness ratio on the failure modes and the axial load bearing capacities of the PFWC columns were evaluated. The failure modes showed that the specimens with a slenderness ratio less than 43.2 failed through compressive failure at junctions on FRP sheets, while those with slenderness ratios larger than 57.6 showed global buckling. Strain responses on specimens with different slenderness ratios are consistent with the observed failure modes. Finite element analysis was carried out to validate the experimental results, and satisfactory agreement was found between the failure modes and load–displacement curves. An empirical equation was developed with a new factor taking 0.65 into account to predict the load bearing capacities of the PFWC columns, and good agreement was found.

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41

Zhou, S. J., and Robb Thomson. "Dislocation emission at ledges on cracks." Journal of Materials Research 6, no. 3 (1991): 639–53. http://dx.doi.org/10.1557/jmr.1991.0639.

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In this paper, we propose that, depending on their height, ledges on cracks can be efficient sources of dislocations at loadings well below the critical loading for homogeneous emission. Detailed 3-D elastic calculations are presented supporting this proposition. There are two configurations for emission: one which blunts the crack, and one we call a jogging configuration. By our calculations, the blunting configuration should be the more efficient source; however, jogging dislocations are more frequently observed, experimentally. We find that the ledge is only a finite source of dislocations, in the sense that the ledge height decreases as the dislocations are emitted. The atomic configuration at the ledge is composed of finite lengths of real dislocations, which is the reason why such dislocations can be emitted easier than homogeneously produced dislocations. The stresses at the ledge tip produce a cloud of bound dislocations near the ledge, pinned at the ledge ends, so that the ledge crack configuration becomes delocalized. Delocalization of the pileup dislocations in the jogging direction may explain why the jogging dislocations are more frequently seen. Implications for dislocation free zones and ductile transitions are discussed.

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42

Mirza, Sher Ali. "Comparative strength analyses of structural concrete columns." Canadian Journal of Civil Engineering 33, no. 6 (2006): 735–47. http://dx.doi.org/10.1139/l05-072.

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A comparative study was undertaken of selected computational methods for predicting the strength determined from more than 500 physical tests of rectangular, tied structural concrete columns available in the literature. The study included 354 reinforced concrete and 150 composite steel–concrete columns. The computational methods compared were those of CSA A23.3-94 and Eurocode 2 for reinforced concrete and those of CSA A23.3-94 and Eurocode 4 for composite columns. The physical tests used for comparison were conducted on columns that were braced, pinned at both ends, subjected to short-term loads, and constructed using normal-density concrete with a compressive strength between approximately 17 and 57 MPa. Major variables included the concrete strength, the end eccentricity ratio, the slenderness ratio, the longitudinal reinforcing steel index for reinforced concrete or the structural steel index for composite columns, and the transverse reinforcement (tie/hoop) volumetric ratio. The study provided insights into the reliability of the computational methods examined. Recommendations for improving the CSA A23.3-94 procedure for the design of reinforced concrete and composite steel–concrete columns are also presented.Key words: columns, composite construction, computations, physical tests, reinforced concrete, reliability, strength.

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Vartdal, B. J., S. T. S. Al-Hassani, and S. J. Burley. "A Tube with a Rectangular Cut-Out. Part 2: Subject to Axial Compression." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 220, no. 5 (2006): 645–52. http://dx.doi.org/10.1243/09544062c05604.

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Simply supported steel tubes with rectangular cut-outs of different sizes positioned at their mid-length were subject to axial compression to assess the effect of the cut-outs on the deformation behaviour. Experiments on 1000 mm long, 100 mm diameter, and 2.55 mm wall thickness DIN 2391 ST NBK supported steel tubes are described. The experimental tubes were relatively thick walled, with a thickness-to-diameter ratio typical of structural columns, rather than shell structures. The radial position of the cut-outs was such that the reduced cross-section was symmetric with respect to the direction of rotation of the pinned ends. Several permutations of the axial and circumferential dimensions of the cut-out were tested so that the effect of changing these dimensions could be assessed. Finite-element and semi-empirical analyses were carried out to predict the global load-deformation behaviour of the tubes. Both analyses gave good predictions of the experimental results for the majority of the cut-out parameters investigated. The motivation for the study was to investigate the feasibility of using cut-outs to initiate and control the toppling of offshore jacket structures.

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Anbarasu, M. "Numerical investigation on behaviour and design of cold-formed steel built-up column composed of lipped sigma channels." Advances in Structural Engineering 22, no. 8 (2019): 1817–29. http://dx.doi.org/10.1177/1369433218824499.

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This article aims at investigating the structural response and predicting the ultimate resistance of cold-formed steel built-up columns composed of lipped sigma sections with pinned ends. For this purpose, a numerical model is established by using the finite element code ABAQUS. The finite element models include geometric, material nonlinearity. The effects of initial local and overall geometric imperfections have been taken into consideration in the finite element modelling. The results of the nonlinear finite element analysis were validated with the available experimental results present in the literature. A parametric study was carried out using the developed finite element model to study the effect of member slenderness, height-to-width ratio and depth of trapezoidal stiffener on the ultimate resistance of cold-formed steel closed built-up columns. On the basis of the parametric results, presented herein, appropriateness of the current direct strength method in the North American Specification for cold-formed steel columns is assessed. Based on such comparison, design expression is proposed to provide reliable design strength prediction of cold-formed steel built-up column composed of lipped sigma sections and verified through reliability analysis.

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45

Li, Qian, Wei Liu, Zijun Zhang, and Zhufeng Yue. "Parametric Resonance of Pipes with Soft and Hard Segments Conveying Pulsating Fluids." International Journal of Structural Stability and Dynamics 18, no. 10 (2018): 1850119. http://dx.doi.org/10.1142/s0219455418501195.

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In this paper, the parametric resonance of pipes with soft and hard segments induced by pulsating fluids is investigated. The lowest six natural frequencies and mode shapes of the soft–hard combination pipe simply supported at both ends are obtained by the modified Galerkin's method. The Floquet method is used to numerically determine the parametric resonance regions, including subharmonic resonance regions and combination resonance regions. The parametric resonance results are verified by comparison with published ones, which confirm the validity of the present model establishment and numerical calculation. Compared with a uniform pipe conveying fluid simply supported at both ends, the soft–hard pipe conveying fluid is found to reveal different dynamical behaviors. Decreasing the length of the soft pipe, while increasing the stiffness ratio of the hard pipe compared to the soft one, can effectively improve the stability of the pipe system. The parametric resonance results show that the mean flow velocity and pulsation amplitude of the fluid have a great influence on the width of the parametric resonance regions. It is advisable that the ratio (the soft pipe/the whole pipe) of the length may be designed to be 0.4–0.5 for a flexural rigidity ratio (the hard pipe/the soft pipe) of 2. As the stiffness ratio (the hard pipe/the soft pipe) increases beyond 26, the hard pipe may be regarded as a rigid pipe. The probability of parametric resonance occurrence will be smallest if the soft–hard combination pipe is supported in a clamped–pinned way. For certain application cases, the safety design length of the two pipes with different materials can be determined through numerical calculation.

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BRADFORD, M. A. "IN-PLANE NONLINEAR BEHAVIOUR OF CIRCULAR PINNED ARCHES WITH ELASTIC RESTRAINTS UNDER THERMAL LOADING." International Journal of Structural Stability and Dynamics 06, no. 02 (2006): 163–77. http://dx.doi.org/10.1142/s0219455406001897.

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This paper considers the nonlinear in-plane behaviour of a circular arch subjected to thermal loading only. The arch is pinned at its ends, with the pins being on roller supports attached to longitudinal elastic springs that model an elastic foundation, or the restraint provided by adjacent members in a structural assemblage. By using a nonlinear formulation of the strain-displacement relationship, the principle of virtual work is used to produce the differential equations of in-plane equilibrium, as well as the statical boundary conditions that govern the structural behaviour under thermal loading. These equations are solved to produce the equilibrium equations in closed form. The possibility of thermal buckling of the arch is addressed by considering an adjacent buckled equilibrium configuration, and the differential equilibrium equations for this buckled state are also derived from the principle of virtual work. It is shown that unless the arch is flat, in which case it replicates a straight column, thermal buckling of the arch in the plane of its curvature cannot occur, and the arch deflects transversely without bound in the elastic range as the temperature increases. The nonlinear behaviour of a flat arch (with a small included angle) is similar to that of a column with a small initial geometric imperfection under axial loading, while the nonlinearity and magnitude of the deflections decrease with an increase of the included angle at a given temperature. By using the closed form solutions for the problem, the influence of the stiffness of the elastic spring supports is considered, as is the attainment of temperature-dependent first yielding of a steel arch.

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47

Malikan, Mohammad, and Victor A. Eremeyev. "On Nonlinear Bending Study of a Piezo-Flexomagnetic Nanobeam Based on an Analytical-Numerical Solution." Nanomaterials 10, no. 9 (2020): 1762. http://dx.doi.org/10.3390/nano10091762.

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Among various magneto-elastic phenomena, flexomagnetic (FM) coupling can be defined as a dependence between strain gradient and magnetic polarization and, contrariwise, elastic strain and magnetic field gradient. This feature is a higher-order one than piezomagnetic, which is the magnetic response to strain. At the nanoscale, where large strain gradients are expected, the FM effect is significant and could be even dominant. In this article, we develop a model of a simultaneously coupled piezomagnetic–flexomagnetic nanosized Euler–Bernoulli beam and solve the corresponding problems. In order to evaluate the FM on the nanoscale, the well-known nonlocal model of strain gradient (NSGT) is implemented, by which the nanosize beam can be transferred into a continuum framework. To access the equations of nonlinear bending, we use the variational formulation. Converting the nonlinear system of differential equations into algebraic ones makes the solution simpler. This is performed by the Galerkin weighted residual method (GWRM) for three conditions of ends, that is to say clamp, free, and pinned (simply supported). Then, the system of nonlinear algebraic equations is solved on the basis of the Newton–Raphson iteration technique (NRT) which brings about numerical values of nonlinear deflections. We discovered that the FM effect causes the reduction in deflections in the piezo-flexomagnetic nanobeam.

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García-Guerrero, Juan Manuel, and Juan José Jorquera-Lucerga. "Improving the Structural Behavior of Tied-Arch Bridges by Doubling the Set of Hangers." Applied Sciences 10, no. 23 (2020): 8711. http://dx.doi.org/10.3390/app10238711.

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In tied-arch bridges with a single arch, the deck is usually suspended from the arch by means of a single set of cables, pinned at both ends and anchored to the centerline, using either vertical or Nielsen-type hanger arrangements. When properly designed, this layout can significantly reduce forces and deflections under loads that are symmetrical with respect to the plane of the arch. However, it does not contribute to the support of nonsymmetrical loads, such as eccentric loads distributions or wind loading, and does not reduce the sensibility of the arch to out-of-plane buckling. Thus, this paper studies how a cable arrangement composed of two sets of lateral hangers, attached to both edges of a deck, can be very suitable to address these problems. Firstly, it is demonstrated that the structural behavior under symmetrical loads improves with respect to the bridge with centered hangers. Secondly, it is shown how nonsymmetric loads are partially carried by structural systems (such as the transversal stiffness both of the arch and the deck) that would remain inactive for tied-arch bridges with centered hangers, leading to a general reduction in the forces and the deflections of the bridge and in the critical buckling load of the arch.

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49

Mirza, Sher Ali. "Examination of Strength Modeling Reliability of Physical Tests on Structural Concrete Columns." Advances in Civil Engineering 2011 (2011): 1–16. http://dx.doi.org/10.1155/2011/428367.

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Comparisons and analyses of strengths from selected computational procedures were undertaken of more than 500 physical tests of rectangular, tied, structural concrete columns reported in the published literature. The computational procedures compared with the physical tests and with each other include a commercially available nonlinear finite element modeling software and the Canadian Standards Association (CSA) Standard A23.3-04. The requirements of the American Concrete Institute (ACI) 318-08 are very similar to those of the CSA A23.3-04, and hence, strength comparisons and analyses reported here are also applicable to ACI 318-08. The physical tests used for comparison were conducted on columns that were braced and pinned at both ends and were constructed using normal-density concrete with a compressive strength between approximately 17 and 57 MPa. The columns were subjected to short-term loads producing pure axial force, axial force combined with symmetrical single-curvature bending, or pure bending. Major variables included the concrete strength, the end eccentricity ratio, the slenderness ratio, the longitudinal reinforcing steel index for reinforced concrete or the structural steel index for composite columns, and the transverse reinforcement (tie/hoop) volumetric ratio. The study provides an examination of the reliability of the computational methods examined.

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Campbell, Cary. "Returning ‘learning’ to education: Toward an ecological conception of learning and teaching." Sign Systems Studies 46, no. 4 (2018): 538–68. http://dx.doi.org/10.12697/sss.2018.46.4.07.

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This article describes a notion of learning as adaptive semiotic-growth. In line with the theme of this special issue, learning will be approached on a broad ecological and evolutionary continuum – most generally expressed as a form of adaptation to the environment. Viewing learning through the criterion of signification (semiosis) means that learning is continuous across the entire biological realm. Both the life process and the learning process are expressed through forms of semiotic-engagement and involve continual adaptation and meaning-making. Thus, learning cannot be seen as unique to humans. Learning is more broadly ecological before it is “cultural”. From here we can imagine educational institutions as forms of exaptation, that evolved naturally to channel learning more effectively. Thinking of learning on an ecological continuum means that learning cannot be “located” or pinned down easily in educational research or practice. Rather, learning has a sporadic identity; it is emergent in the specificity of events and must be discerned within the practices that enact it. Realizing learning as something emergently enacted in the educative encounter, and not something that can be determined and implemented, allows us to resist turning learning into an accountability tool that can easily be used towards ideological ends.

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Journal articles on the topic 'Pinned-ends'

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