Energy Dissipation of a Bi-stable von-Mises Truss under Harmonic Excitation

2012 ◽  
Author(s):  
Silvestro Barbarino ◽  
Michael Pontecorvo ◽  
Farhan Gandhi
Keyword(s):  
Energy Dissipation ◽  
Harmonic Excitation ◽  
Von Mises

A Load-Bearing Structural Element With Energy Dissipation Capability Under Harmonic Excitation

2013 ◽  
Author(s):  
Michael E. Pontecorvo ◽  
Silvestro Barbarino ◽  
Farhan S. Gandhi ◽  
Scott Bland ◽  
Robert Snyder ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Static Load ◽  
Single Layer ◽  
Harmonic Excitation ◽  
Harmonic Load ◽  
Initial Stiffness ◽  
Structural Element ◽  
Load Bearing ◽  
Load Amplitude ◽  
Good Energy

This paper focuses on the design, fabrication, testing and analysis of a novel load-bearing element with good energy dissipation capability over a decade of variation in frequency and harmonic load amplitude. A single layer of the compact sandwiched-plate-like element is comprised of two von-Mises trusses (VMTs) between an upper and lower plate, connected to two dampers which stroke in the in-plane direction as the VMTs cycle between the two stable equilibrium states. The elements can be assembled in-plane to form a large plate-like structure or stacked with different properties in each layer for improved load-adaptability. Also introduced in the elements are pre-loaded springs (PLSs) that provide very high initial stiffness and allow the element to carry a design static load even when the VMTs lose their load carrying capability under harmonic disturbance input. Simulations of the system behavior using the Simscape environment show good overall correlation with test data. Good energy dissipation capability is observed over a frequency range from 0.1 Hz to 2 Hz. While the VMT parameters of a single layer can be optimized to a particular harmonic load amplitude, having two layers with softer and stiffer VMTs allow the system to show good energy dissipation characteristics at different harmonic load amplitude levels. The test and simulation results show that a two layer prototype can provide good energy dissipation over a decade of variation in harmonic load amplitude, while retaining the ability to carry static load on account of the PLSs. The paper discusses how system design parameter changes affect the static load capability and the hysteresis behavior.

Optimization of Damping Configurations in a Plate Embedded with ABH Array

2021 ◽  
Vol 263 (6) ◽  
pp. 817-828
Author(s):  
Haoming Liang ◽  
Yue Bao ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Tian He
Keyword(s):  
Energy Dissipation ◽  
Noise Control ◽  
Vibration Suppression ◽  
Deformation Characteristic ◽  
Harmonic Excitation ◽  
Thin Plates ◽  
Vehicle Body ◽  
Thin Walled Structures ◽  
Damping Material ◽  
Viscoelastic Damping Material

Owing to its broadband and lightweight features, the Acoustic Black Hole (ABH) effect has attracted increasing interests in the structural dynamics and vibration-acoustic communities in recent years. And damping material is essential to achieve effective ABH phenomena. To explore effective vibration and noise control in thin-walled structures such as vehicle body panel using ABH effect, aiming at the plate embedded with two-dimensional ABH array, this paper investigates the coupling between ABH structure and damping material. First, the energy dissipation mechanism of viscoelastic damping material is analyzed to obtain the deformation characteristic that leads to effective energy dissipation. Next, the bending deflection of a plate with a single ABH under harmonic excitation is investigated, and the damping material configuration is optimized to obtain an optimal vibration suppression. Finally, the above-mentioned configuration is applied to a plate embedded with the ABH array and compared with the conventional damping arranging method. And the advantages of this damping material configuration scheme in vibration and noise control are investigated and summarized. This paper provides a reference for the damping material configuration and optimization of the thin plates embedded with ABHs.

Study on Vibration Response Characteristics of Mistuned Bladed Disk Expressed by Vibratory Stress

2019 ◽  
Author(s):  
Yasutomu Kaneko ◽  
Toshio Watanabe ◽  
Tatsuya Furukawa ◽  
Saiji Washio
Keyword(s):  
Amplification Factor ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Von Mises Stress ◽  
Bladed Disks ◽  
Resonant Amplitude ◽  
Response Characteristics ◽  
Bladed Disk ◽  
Disk Structure ◽  
Von Mises

Abstract Although bladed disks of turbomachinery are nominally designed to be cyclically symmetric (tuned system), the vibration characteristics of individual blades on a disk differ slightly owing to manufacturing tolerance, deviation of material properties, wear during operation, etc. These small variations break cyclic symmetry and split eigenvalue pairs. Actual bladed disks with small variations are called mistuned systems. Many researchers have studied mistuning and the main conclusion is that while mistuning has an undesirable effect on forced response, it has a beneficial effect on blade flutter. Although mistuning phenomena have been studied since the 1980s, studies on forced response are mostly related to increase in the resonant amplitude due to harmonic excitation force. In addition, because few papers have treated the amplification factor expressed in terms of vibratory stress, the mistuning phenomena of bladed disks expressed in terms of vibratory stress are not fully understood. In this study, the mistuning effect expressed in terms of vibratory stress is examined using the reduced-order model SNM (Subset of Nominal Modes) without any assumptions. By comparing the amplification factor expressed in terms of displacement response with that expressed in terms of vibratory stress response, including synthesized stress (von Mises stress and principal stress), the mistuning phenomena expressed in terms of vibratory stress are clarified. The effect of bladed disk structure on amplification factor is examined in detail as well.

A load-bearing structural element with energy dissipation capability under harmonic excitation

2015 ◽  
Vol 2 (3) ◽  
pp. 345-365
Author(s):  
Michael E. Pontecorvo ◽  
Silvestro Barbarino ◽  
Farhan S. Gandhi ◽  
Scott Bland ◽  
Robert Snyder ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Harmonic Excitation ◽  
Structural Element ◽  
Load Bearing

Increasing Practical Safety of Von Mises Truss via Control of Dynamic Escape

2016 ◽  
Vol 849 ◽  
pp. 46-56 ◽  
Author(s):  
Diego Orlando ◽  
Paulo Batista Gonçalves ◽  
Stefano Lenci ◽  
Giuseppe Rega
Keyword(s):  
Nonlinear Dynamics ◽  
Limit Point ◽  
Dynamic Environment ◽  
Practical Interest ◽  
Harmonic Excitation ◽  
Basins Of Attraction ◽  
Point Load ◽  
Nonlinear Phenomena ◽  
Von Mises ◽  
Lattice Shell

This paper investigates the nonlinear dynamics and stability of the shallow von Mises truss, which is a prototype for buckling analysis of several planar and spatial truss systems and shallow lattice shell structures, including the geodesic dome, and which has a theoretical and practical interest in many engineering fields. These structural systems are liable to limit point instability and may fail at load levels well below the theoretical limit point load due to complex nonlinear phenomena that reduce the safety and the dynamic integrity of the structure; this often occurs as a consequence of the erosion of the basins of attraction of the safe pre-buckling solutions. So, it is vital to increase the safety of the structure in a dynamic environment. In this paper a method for controlling the global nonlinear dynamics of mechanical systems is applied to the shallow von Mises truss. The method consists of the (optimal) elimination of homoclinic intersection by properly adding superharmonic terms to a given harmonic excitation. By means of the solution of an appropriate optimization problem, it is possible to select the amplitudes and the phases of the added superharmonics in such a way that the manifolds distance is as large as possible. This methodology is here applied to increase the integrity of the basins of attraction of the system and consequently its practical safety.

scholarly journals Linearized dynamics of two-dimensional bubbly and cavitating flows over slender surfaces

1988 ◽  
Vol 192 ◽  
pp. 485-509 ◽  
Author(s):  
Luca D'Agostino ◽  
Christopher E. Brennen ◽  
Allan J. Acosta
Keyword(s):  
Energy Dissipation ◽  
Bubble Dynamics ◽  
Equations Of Motion ◽  
Bubble Radius ◽  
Closed Form Solution ◽  
Harmonic Excitation ◽  
Form Solution ◽  
Two Dimensional ◽  
Viscous Effects ◽  
Fourier Synthesis

The present work investigates the dynamics of two-dimensional, steady bubbly flows over a surface and inside a symmetric channel with sinusoidal profiles. Bubble dynamics effects are included. The equations of motion for the average flow and the bubble radius are linearized and a closed-form solution is obtained. Energy dissipation due to viscous, thermal and liquid compressibility effects in the dynamics of the bubbles is included, while the relative motion of the two phases and viscous effects at the flow boundaries are neglected. The results are then generalized by means of Fourier synthesis to the case of surfaces with slender profiles of arbitrary shape. The flows display various flow regimes (subsonic, supersonic and super-resonant) with different properties according to the value of the relevant flow parameters. Examples are discussed in order to show the effects of the inclusion of the various energy dissipation mechanisms on the flows subject to harmonic excitation. Finally the results for a flow over a surface with a Gaussian-shaped bump are presented and the most important limitations of the theory are briefly discussed.

scholarly journals Energy dissipation in the presence of sub-harmonic excitation in dynamic atomic force microscopy

2012 ◽  
Vol 99 (5) ◽  
pp. 56002 ◽  
Author(s):  
Matteo Chiesa ◽  
Karim R. Gadelrab ◽  
Albert Verdaguer ◽  
J. J. Segura ◽  
Victor Barcons ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Energy Dissipation ◽  
Harmonic Excitation ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Stick–slip vibration of a friction damper for energy dissipation

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771392 ◽  
Author(s):  
Bingbing He ◽  
Huajiang Ouyang ◽  
Shangwen He ◽  
Xingmin Ren
Keyword(s):  
Energy Dissipation ◽  
Harmonic Excitation ◽  
Contact Forces ◽  
Superposition Method ◽  
Friction Damper ◽  
Stick Slip ◽  
Normal Contact ◽  
Friction Dampers ◽  
Slip Regime ◽  
Horizontal Beam

This article studies energy dissipation of a friction damper (due to stick–slip vibration) in the context of harmonic excitation. There are numerous applications of such friction dampers in engineering. One particular example is a new kind of under-platform dry friction dampers for aero engines. The model consists of a clamped cross-like beam structure and two masses (friction dampers) in contact with the short beam of the cross. The two masses are allowed to slide along two extra short vertical clamped beams. They can exhibit three distinct dynamic regimes: pure slip, pure stick and a mixture of stick–slip relative to the short horizontal beam. The finite element method is used to obtain the numerical modes of the structure. The friction at the contact interface between the short horizontal beam and the friction dampers is assumed to follow the classical discontinuous Coulomb friction law in which the static coefficient of friction is greater than the kinetic coefficient. Modal superposition method is applied to solve the dynamic response of the structure with numerical modes. One major finding of this investigation is that there is an intermediate range of the normal contact forces (in stick–slip regime) that provides the best energy dissipation performance.

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