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Experimental study of the torsion of reinforced concrete members
Chalioris, Constantin E. Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.6
This paper presents the results of an experimental investigation on the behaviour of 56 reinforced concrete beams subjected to pure torsion. The reported results include the behaviour curves, the failure modes and the values of the pre-cracking torsional stiffness, the cracking and ultimate torsional moments and the corresponding twists. The influence of the volume of stirrups, the height to width ratios and the arrangement of longitudinal bars on the torsional behaviour is discussed. In order to describe the entire torsional behaviour of the tested beams, the combination of two different analytical models is used. The prediction of the elastic till the first cracking part is achieved using a smeared crack analysis for plain concrete in torsion, whereas for the description of the post-cracking response the softened truss model is used. A simple modification to the softened truss model to include the effect of confinement is also attempted. Calculated torsional behaviour of the tested beams and 21 beams available in the literature are compared with the experimental ones and a very good agreement is observed.
The linear elastic stiffness matrix model analysis of pre twisted Euler Bernoulli beam
Ying Huang,Haoran Zou,Chang Hong Chen,Songlin Bai,Yao Yao,Leon M. Keer 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.5
Based on the finite element method of traditional straight Euler-Bernoulli beams and the coupled relations between linear displacement and angular displacement of a pre-twisted Euler-Bernoulli beam, the shape functions and stiffness matrix are deduced. Firstly, the stiffness of pre-twisted Euler-Bernoulli beam is developed based on the traditional straight Euler-Bernoulli beam. Then, a new finite element model is proposed based on the displacement general solution of a pre-twisted Euler-Bernoulli beam. Finally, comparison analyses are made among the proposed Euler-Bernoulli model, the new numerical model based on displacement general solution and the ANSYS solution by Beam188 element based on infinite approach. The results show that developed numerical models are available for the pre-twisted Euler-Bernoulli beam, and which provide more accurate finite element model for the numerical analysis. The effects of pre-twisted angle and flexural stiffness ratio on the mechanical property are investigated.
Developing Stiffness Matrix for Analyzing Spatially Twisted Wires
Hae-Kyu Hur(허해규),Ki-Ju Kang(강기주) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
A new analytical model called spatially twisted wires is proposed in this paper with the objective of predicting three-dimensional stiffness matrix of a uniform space-filling wire-woven truss; wire-woven bulk kagome (WBK) and wire-woven bulk diamond (WBD). The stiffness matrix of order 12 by 12 for a helically wound wire is formulated using Castiglianos theorem. Effects of transverse shear forces and tangential thrust are taken into account. From numerical examples, the accuracy of this developed element is checked and shows that the WBD/WBK sub-unit cell stiffness is considerably dependent on the spatially twisted region.
서정욱(Jeong Wook Seo),최용제(Yong Je Choi) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
As the tasks of robots become more diverse, some complicated tasks have come to require force and position hybrid control. A compliant device can be used to control force and position simultaneously by separating the twist of the robot’s end effector from the twist of compliance and freedom by using stiffness mapping of the compliant device. The development of a fuzzy gain scheduling scheme of control for a robot with a compliant device is described in this paper. Fuzzy rules and reasoning are performed on-line to determine the gain of twists based on wrench error and twist error and twist of compliance and twist of freedom ratio. Simulation results demonstrate that better control performance can be achieved in comparison with constant gain control.
김한성(Han Sung Kim) 한국생산제조학회 2014 한국생산제조학회지 Vol.23 No.5
In this paper, the kinestatic control algorithm using a six-axis compliant device is presented. Unlike the traditional control methods using a force/torque sensor with very limited compliance, this method employs a compliant device to provide sufficient compliance between an industrial robot and a rigid environment. This kinestatic control method is used to simply control the position of an industrial robot with twists of compensation, which can be decomposed into twists of compliance and twists of freedom. A simple design method of a six-axis parallel-type compliant device with a diagonal stiffness matrix is presented. A compliant device prototype and kinestatic control hardware system and programming were developed. The effectiveness of the kinestatic control algorithm was verified through two kinds of kinestatic control experiments.
Nonlinear Modeling and Coupled Characteristic of Composite Structure with Complex Curvature
장준환,김재훈 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.
The paper presents an experimental verification for calculating coupled stiffness matrix in complex curvature composite structure. The results of the analytical procedure using Variational Asymptotic Beam Sectional Analysis also indicate that the calculation of 2-D,beam, cross-sectional properties can then be incorporated into and 1-D beam analysis expressed coupled stiffness matrix. This paper presents the 2-D cross-sectional analysis of active anisotropic beams. Comparison between the analytical and experimental results shows that the proposed analytical procedure can provide an accurate and efficient prediction of the both deflection and flexural stiffness of multilayer composite slender structure. Verified comparison results can be used to efficiently design accurate complex slender structure properties for preliminary design and optimization.