scholarly journals Large Deflection of Clamped Curved Beam Under Finite Clamping and Different Combinations of Bending-Stretching

2020 ◽  
pp. 121-134
Author(s):  
Sushanta Ghuku ◽  
Kashinath Saha
Keyword(s):  
Theoretical Model ◽  
Large Deflection ◽  
Experimental System ◽  
Local Deformation ◽  
Curved Beam ◽  
Engineering Structures ◽  
Energy Principle ◽  
Geometric Nonlinearities ◽  
Experimental Specimen ◽  
Torque Values

The paper experimentally and theoretically analyses large deflection behaviour of clamped curved beam subjected to finite clamping and combined bending-stretching loads. The experimental specimen is clamped around central location under vertically concave and convex orientations. For each specimen settings, clamping is done by two different torque values. Application of vertical end loads on the clamped concave and convex systems produces two different combinations of bending and in-plane loadings. Large deflection behaviour of the experimental system is modelled theoretically considering geometric nonlinearities coming from combined bending-stretching, non-uniform curvature and asymmetric geometry. Effect of finite clamping is incorporated in the theoretical model through equivalent additional end loads. Due to the involved geometric nonlinearities, analysis is carried out through variational energy principle based incremental Lagrangian approach in curvilinear system and transformed into global frame. The semi-analytical model is successfully validated by comparing with the experimental results. The combined theoretical-experimental study addresses practical complication associated with local deformation at boundaries. In addition, the physically plausible theoretical model may be of interest for simulation of many real world structures with complicating system parameters. Moreover, observations on combined effects of curvature, loading combinations and finite clamping may provide reference for design optimization of equivalent engineering structures.

Parametric Deflection Approximations for Initially Curved, Large-Deflection Beams in Compliant Mechanisms

1996 ◽  
Author(s):  
Larry L. Howell ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Curved Beam ◽  
Analysis And Design ◽  
Body Model ◽  
Rigid Body Model ◽  
Fundamental Type ◽  
Applied Forces ◽  
Flexible Member

Abstract The analysis of systems containing highly flexible members is made difficult by the nonlineararities caused by large deflections of the flexible members. The analysis and design of many such systems may be simplified by using pseudo-rigid-body approximations in modeling the flexible members. The pseudo-rigid-body model represents flexible members as rigid links, joined at pin joints with torsional springs. Appropriate values for link lengths and torsional spring stiffnesses are determined such that the deflection path and force-deflection relationships are modeled accurately. Pseudo-rigid-body approximations have been developed for initially straight beams with externally applied forces at the beam end. This work develops approximations for another fundamental type of flexible member, the initially curved beam with applied force at the beam end. This type of flexible member is commonly used in compliant mechanisms. An example of the use of the resulting pseudo-rigid-body approximations in compliant mechanisms is included.

scholarly journals Photovoltaic effect in Light Emitting Diodes

2016 ◽  
Vol 1 (1) ◽  
pp. 30-36
Author(s):  
K. Remidi ◽  
A. Cheknane ◽  
M. Haddadi
Keyword(s):  
Theoretical Model ◽  
Experimental Work ◽  
Photovoltaic Effect ◽  
Research Work ◽  
Electrical Characterization ◽  
Experimental System ◽  
Photoelectric Effect ◽  
Electrical Characteristics ◽  
Light Emitting

This paper describes an experimental work on the electrical characterization of commercial LED of different colors and their photoelectric effect. A research work has been carried out to develop the experimental measurement in order to show the presence of a photovoltaic effect on LEDs. For this purpose, we measured the electrical characteristics of individual LED and studied their light intensities using a pyranometer EPLEY. This work focused mainly on red, green and yellowLEDs. Moreover, we have implemented an experimental system for the measurement of sensitivity of different LEDs depending on the power of light from a light source. A comparison was made between theoretical model and experimental results.

The transient behaviour of alloys solidified from below prior to the formation of chimneys

1994 ◽  
Vol 269 ◽  
pp. 23-44 ◽  
Author(s):  
M. Grae Worster ◽  
Ross C. Kerr
Keyword(s):  
Theoretical Model ◽  
Rayleigh Number ◽  
Ammonium Chloride ◽  
Copper Sulphate ◽  
Experimental System ◽  
Mushy Layer ◽  
Onset Of Convection ◽  
Transient Behaviour ◽  
Experimental Findings ◽  
Compositional Convection

We investigate interactions between interfacial disequilibrium and compositional convection during the freezing of an alloy from below to form a mushy layer. A theoretical model is developed in which a stagnant mushy layer underlies a melt that is convecting vigorously, driven by compositional gradients associated with undercooling at the mush-liquid interface. In a series of laboratory experiments, we measure the interfacial undercooling in aqueous solutions of ammonium chloride contaminated to varying degrees by copper sulphate. It has recently been found (Huppert & Hallworth 1993) that a small amount of copper sulphate added to a solution of ammonium chloride significantly inhibits the formation of chimneys in the mushy layer that forms when the solution is cooled below its liquidus. It is our thesis that this phenomenon can be explained in large part by the consequences of the interactions between compositional convection and interfacial undercooling that are investigated herein. The measured undercooling is a function of the rate of advance of the interface and is found to be a very strong, increasing function of the concentration of copper sulphate in solution. The theoretical model is evaluated using parameter values appropriate to the experimental system and it is found that the transient development of the mushy layer depends significantly on the level of interfacial disequilibrium. In particular, it is predicted that the time taken for the Rayleigh number associated with the mushy layer to reach any particular value increases enormously as the level of interfacial disequilibrium increases and that the Rayleigh number can have an upper bound that is less than the critical value needed for the onset of convection within the mushy layer. This suggests that the formation of chimneys in the mushy layer can be similarly delayed or prohibited, in agreement with the experimental findings of Huppert & Hallworth (1993). Additionally, the model predicts that under certain conditions the solid fraction can increase away from the cooled boundary leading to trapping of the interstitial liquid. The model also describes a mechanism for macrosegregation of alloys cooled and solidified from below.

Dynamic response of pre-stressed orthotropic circular membrane under impact load

2017 ◽  
Vol 24 (17) ◽  
pp. 4010-4022 ◽  
Author(s):  
Dong Li ◽  
Zhou-Lian Zheng ◽  
Cao He ◽  
Cao-Yu Liu
Keyword(s):  
Theoretical Model ◽  
Dynamic Response ◽  
Impact Load ◽  
Equations Of Motion ◽  
Experimental System ◽  
Polar Coordinates ◽  
Circular Membrane ◽  
Virtual Displacement ◽  
System A ◽  
Displacement Speed

In this paper, the governing equations of motion of pre-stressed orthotropic circular membrane under impact load are derived in polar coordinates based on the principle of virtual displacement and solved by the Krylov–Bogoliubov–Mitropolsky perturbation method. The analytical solutions of the displacement, speed, acceleration and frequency of circular membrane with fixed edges are obtained. Then the dynamic response of membrane is experimentally studied by using a new pneumatic experimental system. A comparison between the experimental and theoretical results validates the theoretical model and the vibration principles of membrane under different conditions. The results also indicate the relationship between dynamic response of membrane and various parameters related to radius, elastic modulus, pretention force, and load. This study provides a theoretical model to calculate the dynamic response of pre-stressed orthotropic circular membrane under impact load. In addition, a new pneumatic experimental system to study the dynamic response of pre-stressed membrane is developed as well.

The Effect of Chucking Methods on Roundness Error in the Boring Process

1976 ◽  
Vol 98 (1) ◽  
pp. 233-238 ◽  
Author(s):  
C. H. Kahng ◽  
H. W. Lord ◽  
T. L. Davis
Keyword(s):  
Theoretical Model ◽  
Beam Theory ◽  
Geometric Parameters ◽  
Curved Beam ◽  
Roundness Error ◽  
Cylindrical Workpiece ◽  
Analytical Expressions ◽  
Good Agreement

Curved-beam theory is used to obtain a theoretical model to describe deformations in a cylindrical workpiece during boring processes. Analytical expressions are obtained for roundness error due to two-, three-, and four-jaw chucks. Experiments are carried out and theory is compared with measured values of roundness errors for several combinations of material and geometric parameters, showing good agreement.

scholarly journals A novel analytical curved beam model for predicting elastic properties of 3D eight-harness satin weave composites

2018 ◽  
Vol 25 (4) ◽  
pp. 689-706 ◽  
Author(s):  
Faqi Liu ◽  
Zhidong Guan ◽  
Tianya Bian ◽  
Wei Sun ◽  
Riming Tan
Keyword(s):  
Finite Element ◽  
Elastic Properties ◽  
Three Dimensional ◽  
Element Model ◽  
Close Correlation ◽  
Sensitivity Study ◽  
Curved Beam ◽  
Beam Model ◽  
Energy Principle ◽  
Representative Unit Cell

AbstractAn offset representative unit cell (ORUC) is introduced to predict elastic properties of three-dimensional (3D) eight-harness satin weave composites both analytically and numerically. A curved beam model is presented based on minimum complementary energy principle, which establishes an analytical solution for elastic modulus and Poisson’s ratio calculation. Finite element method is developed to predict engineering constants of composites. Modified periodic boundary conditions and load method for ORUC are also presented. Experiments of simulated material are performed under tensile test. Close correlation is obtained between experimental data and predictions. Sensitivity study is conducted and manifests that within a large variation of constitutive material properties, the curved beam model derives close predictions comparing to finite element model, which indicates the stability of the curved beam model. Parametric study is also conducted to discuss the effect of weave type and geometric dimensions on elastic properties. It is argued that the curved beam model could manifest fine predictions accurately and stably, and is recommended for the prediction of elastic properties of satin weave composite.

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