Exact stiffness matrix of multi-step columns and its application in non-uniform crane structure stability analysis

2021 ◽  
Vol 43 (7) ◽  
Author(s):  
Hongsheng Zhang ◽  
Liang Du ◽  
Nianli Lu
Keyword(s):  
Stability Analysis ◽  
Stiffness Matrix ◽  
Structure Stability ◽  
Exact Stiffness Matrix

Stiffness of Cable-based Parallel Manipulators With Application to Stability Analysis

2005 ◽  
Vol 128 (1) ◽  
pp. 303-310 ◽  
Author(s):  
Saeed Behzadipour ◽  
Amir Khajepour
Keyword(s):  
Stability Analysis ◽  
Trajectory Planning ◽  
Stiffness Matrix ◽  
Sufficient Conditions ◽  
Parallel Manipulators ◽  
Rotational Stiffness ◽  
New Approach ◽  
Cable Forces

The stiffness of cable-based robots is studied in this paper. Since antagonistic forces are essential for the operation of cable-based manipulators, their effects on the stiffness should be considered in the design, control, and trajectory planning of these manipulators. This paper studies this issue and derives the conditions under which a cable-based manipulator may become unstable because of the antagonistic forces. For this purpose, a new approach is introduced to calculate the total stiffness matrix. This approach shows that, for a cable-based manipulator with all cables in tension, the root of instability is a rotational stiffness caused by the internal cable forces. A set of sufficient conditions are derived to ensure the manipulator is stabilizable meaning that it never becomes unstable upon increasing the antagonistic forces. Stabilizability of a planar cable-based manipulator is studied as an example to illustrate this approach.

An Exact Three-Dimensional Beam Element With Nonuniform Cross Section

2010 ◽  
Vol 77 (6) ◽  
Author(s):  
M. Jafari ◽  
M. J. Mahjoob
Keyword(s):  
Cross Section ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Direct Method ◽  
Three Dimensional ◽  
Curved Beams ◽  
Element Analysis ◽  
Shear Loads ◽  
Line Passing ◽  
Exact Stiffness Matrix

In this paper, the exact stiffness matrix of curved beams with nonuniform cross section is derived using direct method. The considered element has two nodes and 12 degrees of freedom, with three forces and three moments applied at each node. The noncoincidence effect of shear center and center of area is also considered in this element. The deformations of the beam are due to bending, torsion, tensile, and shear loads. The line passing through center of area is a general three-dimensional curve and the cross section properties may change arbitrarily along it. The method is extended to deal with distributed loads on the curved beams. The stiffness matrix of some selected types of beams is determined by this method. The results are compared (where possible) with previously published results, simple beam finite element analysis and analytic solution. It is shown that the determined stiffness matrix is exact and that any type of beam can be analyzed by this method.

Performance Study of Evolutionary Algorithms for Structure Stability Analysis of Aln (n = 2–22)

2016 ◽  
Vol 5 (3) ◽  
pp. 322-329 ◽  
Author(s):  
Yadunath Pathak ◽  
Kavita Sharma ◽  
Khushboo Singh ◽  
Prashant Singh Rana
Keyword(s):  
Stability Analysis ◽  
Evolutionary Algorithms ◽  
Structure Stability ◽  
Performance Study

BUCKLING OF COLUMNS WITH INTERNAL SLIDE RELEASE

2002 ◽  
Vol 02 (04) ◽  
pp. 593-598 ◽  
Author(s):  
M. EISENBERGER ◽  
H. AMBARSUMIAN
Keyword(s):  
Stiffness Matrix ◽  
Buckling Load ◽  
Buckling Loads ◽  
Simply Supported ◽  
Axial Forces ◽  
Exact Stiffness Matrix

The exact buckling loads of columns with internal slide release are found using the exact stiffness matrix of the column including the effect of the axial forces. Two types of columns are considered: clamped–clamped and clamped-simply supported with internal slide release at variable locations along the member. It is found that for both the clamped–clamped and the clamped-simply supported columns the buckling load is constant and does not depend on the location of the slide discontinuity.

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