Optimization Based Identification of the Dynamic Properties of Linearly Viscoelastic Materials Using Vibrating Beam Technique

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Zhiyong Ren ◽  
Noureddine Atalla ◽  
Sebastian Ghinet
Keyword(s):  
Dynamic Properties ◽  
Steel Specimen ◽  
Direct Result ◽  
Superposition Method ◽  
Optimization Approach ◽  
Viscoelastic Materials ◽  
Master Curves ◽  
Mode Superposition Method ◽  
Viscoelastic Core ◽  
Beam Technique

Sandwich structures with viscoelastic core and metal face sheets are increasingly used in automotive industry to significantly reduce the amplitude of vibration and noise radiation. Several experimental methods such as dynamic mechanical analysis (DMA) and vibrating beam technique (VBT) are used to characterize the dynamic properties of viscoelastic materials as a function of frequency and temperature. This paper investigates the use of a free-free beam setup, as an alternative solution to the classical clamped-free VBT, for a better control of the effect of boundary conditions on the laminated steel specimen. The new setup is developed in combination with a frequency response function based optimization method, to automatically derive the dynamic properties of viscoelastic core materials and generate their master curves. A solver based on the normal mode superposition method, considering the added mass effect of the impedance head, is used in the cost function of the optimization approach. The sandwich model is based on the Ross–Kerwin–Ungar equation, and the four-parameter fractional derivative model is used in conjunction with the Williams–Landel–Ferry equation to describe the frequency and temperature dependent behavior of the viscoelastic material. The master curves are a direct result of the optimization process. Several applications are described to assess the performance of the present method. In particular, a systematic comparison with both the classical VBT and DMA (when available) is presented.

Research on Dynamic Properties of Concrete Steel Tubular Arch Bridge Based on ANSYS

2011 ◽  
Vol 71-78 ◽  
pp. 3233-3236 ◽  
Author(s):  
Rong He ◽  
Wei He ◽  
Guo Hua Geng
Keyword(s):  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Superposition Method ◽  
Vibration Frequencies ◽  
Fem Model ◽  
Arch Bridge ◽  
Mode Superposition Method ◽  
Definition Of

Based on ANSYS for modal analysis of bridges, the basic steps includes: building up the FEM model, applying the load and solving the model, expanding the mode, observing the results and so on. Taking the Friendship Avenue Arch Bridge as an example, the building procedures of FEM model were described from the definition of member section, element selection, and the determination of relevant attributes. At last, the dynamic characteristics of the bridge were analyzed based on ANSYS. The results showed that the first 10th order vibration frequencies of the Friendship Avenue Arch Bridge ranged from 1.3Hz to 3.1Hz, and the more order modes should be considered when calculated the dynamic response based on the mode superposition method.

The Seismic Response Study of Light Steel Storey Adding Structure Considering the Effects of Damping

2014 ◽  
Vol 1030-1032 ◽  
pp. 948-951
Author(s):  
Xue Qing Tang ◽  
Pei Cheng Wu ◽  
Shou Cai Ma
Keyword(s):  
Dynamic Properties ◽  
Response Spectrum ◽  
Earthquake Response ◽  
Superposition Method ◽  
Correction Formula ◽  
Mode Superposition Method ◽  
Development Direction ◽  
Damping Theory ◽  
Complex Damping ◽  
Research Situation

This paper summarized the current research situation and development direction of the storey adding structure all over the country. On the basis of the situation, combined characteristics of light steel storey adding structure, the article analyzed adding structure's damping distribution regularity. Based on the complex damping theory, through the mode-superposition method, there was established the correction formula of the earthquake response spectrum of light steel storey adding structure considered the effects of damping. All above, the article provides the basis for the study on the dynamic properties of light steel storey adding structure.

scholarly journals Transient Response of Bridge Piers to Structure Separation under Near-Fault Vertical Earthquake

2021 ◽  
Vol 11 (9) ◽  
pp. 4068
Author(s):  
Wenjun An ◽  
Guquan Song
Keyword(s):  
Large Scale ◽  
Bending Moment ◽  
Relative Displacement ◽  
Superposition Method ◽  
Longitudinal Displacement ◽  
Transient Wave ◽  
Vibration Period ◽  
Vertical Excitation ◽  
Mode Superposition Method ◽  
Main Girder

Given the possible separation problem caused by the double-span continuous beam bridge under the action of the vertical earthquake, considering the wave effect, the transient wave characteristic function method and the indirect mode superposition method are used to solve the response theory of the bridge structure during the earthquake. Through the example analysis, the pier bending moment changes under different vertical excitation periods and excitation amplitudes are calculated. Calculations prove that: (1) When the seismic excitation period is close to the vertical natural vibration period of the bridge, the main girder and the bridge pier may be separated; (2) When the pier has a high height, the separation has a more significant impact on the longitudinal displacement of the bridge, but the maximum relative displacement caused by the separation is random; (3) Large-scale vertical excitation will increase the number of partitions of the structure, and at the same time increase the vertical collision force between the main girder and the pier, but the effect on the longitudinal displacement of the form is uncertain; (4) When V/H exceeds a specific value, the pier will not only be damaged by bending, but will also be damaged by axial compression.

scholarly journals Identification of Acoustic-Vibratory System by Acoustic Measurement

1996 ◽  
Vol 3 (1) ◽  
pp. 27-37
Author(s):  
Takuzo Iwatsubo ◽  
Shozo Kawamura ◽  
Masahito Kamada
Keyword(s):  
Inverse Analysis ◽  
Coefficient Matrix ◽  
Superposition Method ◽  
Vibration Modes ◽  
Identification Problems ◽  
Mathematical Property ◽  
Vibratory System ◽  
Stochastic Error ◽  
Mode Superposition Method ◽  
Ill Conditioning

A new method for reducing ill-conditioning in a class of identification problems is proposed. The key point of the method is that the identified vibration of the sound source is expressed as a superposition of vibration modes. The mathematical property of the coefficient matrix, the practical error expanding ratio, and the stochastic error expanding ratio are investigated in a numerical example. The mode-superposition method is shown to be an effective tool for acoustic-vibratory inverse analysis.

scholarly journals Dynamic Impact Factor Determination of an Existing Pre-stressed Concrete I-Girder Bridge Using Vehicle-Bridge Interaction Modelling

2021 ◽  
Vol 10 (3) ◽  
pp. 163-176
Author(s):  
Shuvrodeb Adhikary ◽  
Shohel Rana ◽  
Jerin Tasnim ◽  
Nazrul Islam
Keyword(s):  
Impact Factor ◽  
Dynamic Model ◽  
Superposition Method ◽  
Dynamic Impact ◽  
Mode Superposition Method ◽  
Road Roughness ◽  
Girder Bridge ◽  
Dynamic Impact Factor ◽  
Interaction Problem

The dynamic Impact Factor (IM) of a bridge is influenced by many factors, including Vehicle-Bridge Interaction (VBI), vehicle speed and road roughness. This paper represents the dynamic effects of moving vehicles and the determination of IM of an existing Pre-stressed concrete I-girder bridge utilizing VBI modeling. Evaluation of the IM is expected to provide valuable information for condition assessment and management of the existing bridge. The interaction problem between the vehicle and the bridge includes a dynamic model for the bridge structure subsystem, a dynamic model for the vehicle subsystem, interaction constraints, road roughness modelling and numerical solution techniques for the dynamic systems. The Half-car model is utilized for modelling of the vehicle dynamics and the bridge dynamic model is idealized according to Finite Element Method (FEM). Then FEM along with the mode superposition method are utilized for determining the Equation of Motion (EOM) for the bridge subsystem. D’Alembert’s principle is used for developing EOM for the vehicle subsystem. The interaction between vehicle vibration and bridge vibration is established through the contact forces between the wheels and the bridge by employing the compatibility relationship between the contact points and by applying the static equilibrium condition. Lastly, Newmark’s-β method is used for solving the coupled mathematical model of the vehicle and bridge interaction problem to determine the responses of the two sub-systems. The whole procedure is then performed for different vehicle speeds and various bridge deck surface roughness conditions to determine the dynamic impact on the existing I-girder bridge named Teesta Bridge located in Bangladesh.

Modeling and Experimental Characterization of Viscoelastic 3D Printed Spring/Damper Systems

2017 ◽  
Author(s):  
Heather L. Lai ◽  
Cuiyu Kuang ◽  
Jared Nelson
Keyword(s):  
Dynamic Behavior ◽  
Material Properties ◽  
Dynamic Properties ◽  
Viscoelastic Materials ◽  
Vibration Isolators ◽  
Damping Behavior ◽  
Wide Range ◽  
3D Printed ◽  
Printed Materials

The development of flexible, viscoelastic materials for consumer 3D printers has provided the opportunity for a wide range of devices with damping behavior such as tuned vibration isolators to be innovatively developed and inexpensively manufactured. However, there is currently little information available about the dynamic behavior of these 3D printed materials necessary for modeling of dynamic behavior prior to print. In order to fully utilize these promising materials, a deeper understanding of the material properties, and the subsequent dynamic behavior is critical. This study evaluates the use of three different types of models: transient response, frequency response and hysteretic response to predict the dynamic behavior of viscoelastic 3D printed materials based on static and dynamic material properties. Models of viscoelastic materials are presented and verified experimentally using two 3D printable materials and two traditional viscoelastic materials. The experimental response of each of the materials shows agreement with the modeled behavior, and underscores the need for improved characterization of the dynamic properties of viscoelastic 3D printable materials.

Investigation into the linear velocity response of cantilever beam embedded with impact damper

2019 ◽  
Vol 25 (7) ◽  
pp. 1365-1378 ◽  
Author(s):  
Yiqing Yang ◽  
Xi Wang
Keyword(s):  
Cantilever Beam ◽  
Continuous System ◽  
Linear Velocity ◽  
Superposition Method ◽  
Momentum Exchange ◽  
Impact Damper ◽  
Mode Superposition Method ◽  
Velocity Response ◽  
The Impact ◽  
Nonlinear Velocity

The impact damper causes momentum exchange between the primary structure and impact mass, and achieves vibration attenuation through repeated collisions. A cantilever beam embedded with the impact damper is modeled in the form of a continuous system, and the equations of motion are formulated based on the mode superposition method. The mechanism of the impact damper is investigated, and linear velocity response is achieved by a proper selection of a mass ratio of 8.4%, clearance within 0.30 mm, and excitation force ranged from 3.2 N to 5.5 N. The reverse collision has higher damping than co-directional collision, based on which a new criterion of response regimes is proposed for the design of the impact damper. The velocity responses of the damped cantilever beam under sinusoidal and impulse excitation are simulated and verified via the sinusoidal sweep experiments. The velocity amplitudes of the damped cantilever beam are linearly decreased when the clearance is increased within 0.30 mm. Finally, linear and nonlinear velocity responses of the damped cantilever beam are discussed. It is found that the nonlinear velocity response reaches larger damping, but that a strongly modulated response exists.

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