scholarly journals Dynamics of risers analysed by means of the segment method, with consideration of bending and torsional stiffness

2021 ◽  
Vol 43 (3) ◽  
Author(s):  
Iwona Adamiec-Wójcik ◽  
Lucyna Brzozowska ◽  
Stanisław Wojciech
Keyword(s):  
Natural Frequencies ◽  
Forced Vibrations ◽  
Torsional Stiffness ◽  
New Approach ◽  
Finite Segment ◽  
Free And Forced Vibrations ◽  
Joint Coordinates ◽  
Finite Segment Method ◽  
Sea Currents ◽  
The Mathematical Model

AbstractThe paper presents the application of the finite segment method to the analysis of coupled bending torsional vibrations of risers. The method is formulated by means of joint coordinates using multibody methods for kinematics and dynamics. A new approach to calculating bending and torsion moments is presented. The mathematical model and computer program enable us to analyse both free and forced vibrations of risers caused by the motion of the base (vessel or platform) as well as hydrodynamic forces. The model is validated by comparing frequencies of free and forced vibrations calculated from the authors’ own models with the results presented by other researchers. Natural frequencies are also compared with analytical solutions. The influence of sea currents and of the initial twisting of the riser on its natural and forced vibrations is analysed.

Forced vibration of delaminated Timoshenko beams subjected to a moving load

2012 ◽  
Vol 19 (2) ◽  
pp. 145-157 ◽  
Author(s):  
Mohammad H. Kargarnovin ◽  
Mohammad T. Ahmadian ◽  
Ramazan Ali Jafari-Talookolaeia
Keyword(s):  
Dynamic Response ◽  
Composite Beam ◽  
Natural Frequencies ◽  
Moving Load ◽  
Ritz Method ◽  
Forced Vibrations ◽  
Mode Shapes ◽  
Timoshenko Beams ◽  
Free And Forced Vibrations ◽  
Spanwise Location

AbstractA composite beam with single delamination under the action of moving load has been modeled accounting for the Poisson’s effect, shear deformation, and rotary inertia. The existence of the delamination changes the stiffness of the structure, and this affects the dynamic response of the structure. We have used a constrained mode to simulate the behavior between the delaminated surfaces. Based on this mode, eigensolution technique is used to obtain the natural frequencies and their corresponding mode shapes for the delaminated beam. Then, the Ritz method is adopted to derive the dynamic response of the beam subjected to a moving load. The obtained results for the free and forced vibrations of beams are verified against reported similar results in the literature. Moreover, the maximum dynamic response of such beam is compared with an intact beam. The effects of different parameters such as the size, depth, and spanwise location of the delamination, the load velocity, the different ply configurations, and the Poisson’s effect on the dynamic response of the beam are studied.

scholarly journals A New Approach of Soft Joint Based on a Cable-Driven Parallel Mechanism for Robotic Applications

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1468
Author(s):  
Luis Nagua ◽  
Carlos Relaño ◽  
Concepción A. Monje ◽  
Carlos Balaguer
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Experimental Tests ◽  
Humanoid Robots ◽  
Inverse Kinematic ◽  
Element Analysis ◽  
New Approach ◽  
Flexible Polymer ◽  
The Mathematical Model

A soft joint has been designed and modeled to perform as a robotic joint with 2 Degrees of Freedom (DOF) (inclination and orientation). The joint actuation is based on a Cable-Driven Parallel Mechanism (CDPM). To study its performance in more detail, a test platform has been developed using components that can be manufactured in a 3D printer using a flexible polymer. The mathematical model of the kinematics of the soft joint is developed, which includes a blocking mechanism and the morphology workspace. The model is validated using Finite Element Analysis (FEA) (CAD software). Experimental tests are performed to validate the inverse kinematic model and to show the potential use of the prototype in robotic platforms such as manipulators and humanoid robots.

Nonlinear Free and Forced Vibrations of Symmetric Laminated Panels

2011 ◽  
Vol 471-472 ◽  
pp. 616-621 ◽  
Author(s):  
Alireza Shooshtari ◽  
Soheil Razavi ◽  
Hadi Ghashochi Bargh ◽  
Mohammad Homayoun Sadr-Lahidjani
Keyword(s):  
Perturbation Method ◽  
External Force ◽  
Laminated Composite ◽  
Composite Plates ◽  
Forced Vibrations ◽  
Numerical Results ◽  
Transverse Displacement ◽  
Laminated Composite Plates ◽  
Free And Forced Vibrations ◽  
Laminated Panels

In this paper, free and forced vibrations of symmetric laminated composite plates are studied analytically by using a perturbation method where the analytical results for transverse displacement are compared with the numerical results. The external force is taken to be harmonic in time and having uniform amplitude.

scholarly journals Nonlinear dynamics of rectangular plates: investigation of modal interaction in free and forced vibrations

2013 ◽  
Vol 225 (1) ◽  
pp. 213-232 ◽  
Author(s):  
Michele Ducceschi ◽  
Cyril Touzé ◽  
Stefan Bilbao ◽  
Craig J. Webb
Keyword(s):  
Nonlinear Dynamics ◽  
Forced Vibrations ◽  
Rectangular Plates ◽  
Modal Interaction ◽  
Free And Forced Vibrations
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