A variable-kinematic model for variable stiffness plates: Vibration and buckling analysis

2016 ◽  
Vol 142 ◽  
pp. 15-26 ◽  
Author(s):  
Riccardo Vescovini ◽  
Lorenzo Dozio
Keyword(s):  
Kinematic Model ◽  
Variable Stiffness ◽  
Buckling Analysis

Development and analysis of a bio-inspired wire-driven variable stiffness double spring based tapered multi-section flexible robot

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alok Ranjan Sahoo ◽  
Pavan Chakraborty
Keyword(s):  
Inverse Kinematics ◽  
Kinematic Model ◽  
Variable Stiffness ◽  
Radius Of Curvature ◽  
Flexible Robot ◽  
Content Type ◽  
Cluttered Environments ◽  
Collapsed Buildings ◽  
Practical Implications ◽  
Robot Body

Purpose The purpose of this paper is to develop a tendon actuated variable stiffness double spring based continuously tapered multi-section flexible robot and study its capability to achieve the desired bending and compression for inspection in cluttered environments. Design/methodology/approach Spring-based continuum manipulators get compressed while actuated for bending. This property can be used for the advantage in cluttered environments if one is able to control both bending and compression. Here, this paper uses a mechanics based model to achieve the desired bending and compression. Moreover, this study tries to incorporate the tapered design to help in independent actuation of the distal sections with minimal effects on proximal sections. This study is also trying to incorporate the double spring based design to minimize the number of spacers in the robot body. Findings The model was able to produce desired curvature at the tip section with less than 4.62% error. The positioning error of the manipulator is nearly 3.5% which is at par with the state-of-the-art manipulators for search and rescue operations. It was also found that the use of double spring can effectively reduce the number of spacers required. It can be helpful in smooth robot to outer world interaction without any kink. From the experiments, it has been found that the error of the kinematic model decreases as one moves from high radius of curvature to low radius of curvature. Error is maximum when the radius of curvature is infinity. Practical implications The proposed manipulator can be used for search operations in cluttered environments such as collapsed buildings and maintenance of heavy machineries in industries. Originality/value The novelty of this paper lies in the design and the proposed kinematics inverse kinematics for a spring-based continuously tapered multi-section manipulator.

Efficient post-buckling analysis of variable-stiffness plates using a perturbation approach

2019 ◽  
Vol 143 ◽  
pp. 106211 ◽  
Author(s):  
R. Vescovini ◽  
E. Spigarolo ◽  
E.L. Jansen ◽  
L. Dozio
Keyword(s):  
Variable Stiffness ◽  
Buckling Analysis ◽  
Perturbation Approach ◽  
Post Buckling

Isogeometric buckling analysis of composite variable-stiffness panels

2017 ◽  
Vol 165 ◽  
pp. 192-208 ◽  
Author(s):  
Peng Hao ◽  
Xiaojie Yuan ◽  
Hongliang Liu ◽  
Bo Wang ◽  
Chen Liu ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Buckling Analysis ◽  
Composite Variable

scholarly journals Design and Modelling of a Cable-Driven Parallel-Series Hybrid Variable Stiffness Joint Mechanism for Robotics

2017 ◽  
Vol 8 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Cihat Bora Yigit ◽  
Pinar Boyraz
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Kinematic Model ◽  
Variable Stiffness ◽  
Research Field ◽  
Universal Joint ◽  
Element Analysis ◽  
Translational Movement ◽  
Profile Characteristics ◽  
Parallel Series

Abstract. The robotics, particularly the humanoid research field, needs new mechanisms to meet the criteria enforced by compliance, workspace requirements, motion profile characteristics and variable stiffness using lightweight but robust designs. The mechanism proposed herein is a solution to this problem by a parallel-series hybrid mechanism. The parallel term comes from two cable-driven plates supported by a compression spring in between. Furthermore, there is a two-part concentric shaft, passing through both plates connected by a universal joint. Because of the kinematic constraints of the universal joint, the mechanism can be considered as a serial chain. The mechanism has 4 degrees of freedom (DOF) which are pitch, roll, yaw motions and translational movement in z axis for stiffness adjustment. The kinematic model is obtained to define the workspace. The helical spring is analysed by using Castigliano's Theorem and the behaviour of bending and compression characteristics are presented which are validated by using finite element analysis (FEA). Hence, the dynamic model of the mechanism is derived depending on the spring reaction forces and moments. The motion experiments are performed to validate both kinematic and dynamic models. As a result, the proposed mechanism has a potential use in robotics especially in humanoid robot joints, considering the requirements of this robotic field.

scholarly journals Foam core composite sandwich plates and shells with variable stiffness: Effect of the curvilinear fiber path on the modal response

2017 ◽  
Vol 21 (1) ◽  
pp. 320-365 ◽  
Author(s):  
Francesco Tornabene ◽  
Nicholas Fantuzzi ◽  
Michele Bacciocchi
Keyword(s):  
Kinematic Model ◽  
Free Vibration Analysis ◽  
Variable Stiffness ◽  
Sandwich Plates ◽  
Composite Sandwich ◽  
Doubly Curved Shells ◽  
Present Solution ◽  
Reinforcing Fibers ◽  
Doubly Curved ◽  
Composite Sandwich Plates

This paper presents the free vibration analysis of composite sandwich plates and doubly curved shells with variable stiffness. The reinforcing fibers are located in the external skins of the sandwich structures according to curved paths. These curvilinear paths are described by a general expression that combines power-law, sinusoidal, exponential, Gaussian and ellipse-shaped functions. As a consequence, the reinforcing fibers are placed in these orthotropic layers in an arbitrary manner, in order to achieve the desired mechanical properties. The effect of this variable fiber orientation on the natural frequencies is investigated by means of several parametric studies. As far as the structural theory is concerned, an equivalent single layer approach based on the well-known Carrera Unified Formulation is employed. The Murakami’s function is added to the kinematic model to capture the zig-zag effect, when the soft-core effect is significant. Thus, several higher order shear deformation theories are taken into account in a unified manner. The differential geometry is employed to describe the reference surface of doubly curved shells and panels, which are characterized by variable radii of curvature. The numerical solution is obtained using the generalized differential quadrature method, due to its accuracy and stability features. The present solution is compared with the results available in the literature or obtained by finite element commercial codes.

Pre-buckling and Buckling Analysis of Variable-Stiffness, Curvilinearly Stiffened Panels

2019 ◽  
Vol 99 (1) ◽  
pp. 43-52 ◽  
Author(s):  
R. Vescovini ◽  
V. Oliveri ◽  
D. Pizzi ◽  
L. Dozio ◽  
P. M. Weaver
Keyword(s):  
Variable Stiffness ◽  
Buckling Analysis ◽  
Stiffened Panels

scholarly journals Buckling analysis of stiffened composite panels with variable stiffness

2019 ◽  
Vol 504 ◽  
pp. 012059
Author(s):  
W Wu ◽  
R X Bai ◽  
Z K Lei ◽  
C H Geng ◽  
X Z Zhang ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Buckling Analysis ◽  
Composite Panels ◽  
Stiffened Composite Panels

Buckling Analysis of Variable Stiffness Composite Cylindrical Shells Based on Hermite Curves

2019 ◽  
Vol 805 ◽  
pp. 191-197
Author(s):  
Chun Bo Nian ◽  
Xiao Ping Wang ◽  
Jing Yu Pei
Keyword(s):  
Cylindrical Shell ◽  
Cylindrical Shells ◽  
Initial Point ◽  
Variable Stiffness ◽  
Tangential Direction ◽  
Buckling Analysis ◽  
Buckling Load ◽  
Practical Significance ◽  
Composite Cylindrical Shell ◽  
End Point

Based on the Hermite curve, the buckling behavior of a variable stiffness composite cylindrical shell is investigated. Firstly, the cylindrical shell is unfolded into a plane, and the Hermite curve is taken as the basic reference path on the plane and the variation of the fiber orientation is obtained. Then, the finite element analysis pre-processing program of the variable stiffness composite cylindrical shell is written by Python to develop ABAQUS interactive interface. Finally, the GUI plug-in is developed successfully, the buckling analysis of the constant stiffness and variable stiffness cylindrical shells is carried out and the effect of buckling load on the initial tangential direction q1, the initial point tangential magnitude L1, the end point tangential direction q2, the end point tangential magnitude L2 is preliminarily explored. It is found that the buckling load of the variable stiffness cylindrical shell is improved greatly. The secondary development of ABAQUS by Python is used to realize the automatic modeling and calculation analysis of the variable stiffness cylindrical shell parts, which provides research ideas and processes for practical engineering research, and has certain practical significance.

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