Discussion: Thin-Walled Curved Beams. I: Formulation of Nonlinear Equations

1996 ◽  
Vol 122 (5) ◽  
pp. 482-484 ◽  
Author(s):  
Yeong-Bin Yang ◽  
Shyh-Rong Kuo
Keyword(s):  
Nonlinear Equations ◽  
Curved Beams ◽  
Thin Walled

Pretwisted Curved Beams of Thin-Walled Open Section

1972 ◽  
Vol 39 (3) ◽  
pp. 779-785 ◽  
Author(s):  
A. I. Soler
Keyword(s):  
Numerical Technique ◽  
Equations Of Motion ◽  
Highway Bridges ◽  
Major Effect ◽  
Curved Beams ◽  
Open Section ◽  
Straight Beam ◽  
Thin Walled ◽  
Bending Modes ◽  
Axes Of Symmetry

Equations of motion are derived for coupled extension, flexure, and torsion of pretwisted curved bars of thin-walled, open section. The derivation is based on energy principles and includes inertia terms. The major effect of initial pretwist is to allow coupling of all possible beam deformation modes; however, if the bar is straight and has two axes of symmetry, pretwist causes coupling only between the two bending modes, and between extension and torsion. The governing equations are presented in first-order form, and a numerical technique is suggested for the case of space varying pretwist. It is suggested that these equations may form the basis for a simplified study of the effect of superelevation on the static and dynamic response of curved highway bridges. Finally, a simple straight beam with uniform pretwist is studied to compare effects of pretwist and restrained torsion in a thin-walled beam of open section.

Hinges and Curved Lamina Emergent Torsional Joints in Cylindrical Developable Mechanisms

2020 ◽  
Author(s):  
Kendall Seymour ◽  
Pietro Bilancia ◽  
Spencer Magleby ◽  
Larry Howell
Keyword(s):  
Cylindrical Surface ◽  
Small Scale ◽  
Membrane Thickness ◽  
Cylinder Wall ◽  
Small Length ◽  
Curved Beams ◽  
Modeling Assumption ◽  
Thin Walled

Abstract Cylindrical developable mechanisms are devices that conform to and emerge from a cylindrical surface. These mechanisms can be formed or cut from the cylinder wall itself. This paper presents a study on adapting traditional hinge options to achieve revolute motion in these mechanisms. A brief overview of options is given, including classical pin hinges, small-length flexural pivots, initially curved beams, and an adaptation of the membrane thickness-accommodation technique. Curved Lamina Emergent Torsional (LET) joints are then evaluated in detail, and a thin-walled modeling assumption is checked analytically and empirically. A small-scale cylindrical developable mechanism is then evaluated with Nitinol curved LET joints.

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