Thermomechanical Fractional Derivative Model of Viscoelastic Isolators

2014 ◽  
Vol 952 ◽  
pp. 219-222
Author(s):  
Zhen Li Zhang ◽  
Chao Shang ◽  
Wei Hua Shi
Keyword(s):  
Fractional Derivative ◽  
Engineering Application ◽  
Coupling Model ◽  
Measured Data ◽  
Thermomechanical Coupling ◽  
Damping Characteristics ◽  
Fractional Derivative Model ◽  
Proposed Model ◽  
Vibration Process ◽  
Difference Form

In vibration process, viscoelastic isolators’ temperature will rise due to energy dissipation, especially when the isolators have high damping characteristics. First, for the arbitrary loadings, the thermomechanical coupling model and the corresponding difference form are established based on the five-parameter fractional derivative model. Then, for the steady-state harmonic inputs, which is very common in engineering application, the derived model is significantly simplified by Fourier transformation. Finally, the proposed model is verified by experiments and shows a reasonable agreement with measured data.

Prediction of Beyond Design and Residual Performances of Viscoelastic Dampers by a Simplified Fractional Derivative Model

2021 ◽  
pp. 2150081
Author(s):  
Shiang-Jung Wang ◽  
Qun-Ying Zhang ◽  
Chung-Han Yu
Keyword(s):  
Energy Dissipation ◽  
Fractional Derivative ◽  
Main Shock ◽  
Full Scale ◽  
The Other ◽  
Ambient Temperatures ◽  
Viscoelastic Dampers ◽  
Fractional Derivative Model ◽  
Proposed Model ◽  
Residual Performance

When subjected to excessive shear deformation, viscoelastic (VE) dampers may inevitably suffer from damages, due to their VE material layers with limited thickness. Under the circumstance, their stiffness and energy dissipation capabilities may deteriorate but not totally vanish. To estimate the seismic performances of viscoelastically damped structures, the beyond design and residual performances of damaged VE dampers are crucial to protect structures from severe failure during the following main shock or aftershocks. On the other hand, for new viscoelastically damped structures under the normal design earthquakes, neglecting the residual performance of damaged VE dampers may result in nonconservative design. Thus, this study aims to provide approaches to analytically characterize the beyond design and residual performances of damaged full-scale VE dampers. Based on the simplified fractional derivative model, the analytical predictions have been compared with the experimental results. The proposed model works well for the design performance of the intact full-scale VE dampers. Particularly, it can also reproduce the beyond design and residual performances of damaged full-scale VE dampers, if due consideration is taken of the effects of excitation frequencies, ambient temperatures, temperature rises, softening, and hardening.

A variable-order time-fractional derivative model for chloride ions sub-diffusion in concrete structures

2013 ◽  
Vol 16 (1) ◽  
Author(s):  
Wen Chen ◽  
Jianjun Zhang ◽  
Jinyang Zhang
Keyword(s):  
Fractional Derivative ◽  
Measurement Data ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Influence Coefficient ◽  
Variable Order ◽  
Binding Behavior ◽  
Fractional Derivative Model ◽  
Proposed Model ◽  
Variable Function

AbstractThis study proposes a new variable-order fractional diffusion equation model to describe the coupled chloride diffusion-binding processes in reinforced concrete, in which the order of fractional derivative term is a variable function instead of a constant in the standard fractional model. The concentration influence coefficient k is introduced to capture the effect of concentration dependency on chloride transport due to the chloride binding behavior. The two parameters in the proposed model can be determined directly by a statistical analysis of measurement data. Four test cases illustrate that the proposed variable-order fractional derivative model agrees significantly better with experimental data than the most commonly used traditional model governed by the classical Fick’s second law, especially when a large concentration coefficient k is involved. That proposed model is also verified by accurately predicting chloride concentration profiles in a period of 200 days.

scholarly journals Modeling ramp-hold indentation measurements based on Kelvin–Voigt fractional derivative model

2018 ◽  
Vol 29 (3) ◽  
pp. 035701 ◽  
Author(s):  
Hongmei Zhang ◽  
Qing zhe Zhang ◽  
Litao Ruan ◽  
Junbo Duan ◽  
Mingxi Wan ◽  
...  
Keyword(s):  
Fractional Derivative ◽  
Fractional Derivative Model

Can a Time Fractional-Derivative Model Capture Scale-Dependent Dispersion in Saturated Soils?

Ground Water ◽  
2017 ◽  
Vol 55 (6) ◽  
pp. 857-870 ◽  
Author(s):  
Rhiannon M. Garrard ◽  
Yong Zhang ◽  
Song Wei ◽  
HongGuang Sun ◽  
Jiazhong Qian
Keyword(s):  
Fractional Derivative ◽  
Saturated Soils ◽  
Fractional Derivative Model ◽  
Time Fractional Derivative

Kelvin-Voigt versus fractional derivative model as constitutive relations for viscoelastic materials

AIAA Journal ◽  
1995 ◽  
Vol 33 (3) ◽  
pp. 547-550 ◽  
Author(s):  
Lloyd B. Eldred ◽  
William P. Baker ◽  
Anthony N. Palazotto
Keyword(s):  
Fractional Derivative ◽  
Constitutive Relations ◽  
Viscoelastic Materials ◽  
Fractional Derivative Model

A Fault-Tolerant Offset Algorithm for Measured Data with Defects

2014 ◽  
Vol 902 ◽  
pp. 344-350
Author(s):  
Xiang Jia Li ◽  
Ning Dai ◽  
Wen He Liao ◽  
Yu Chun Sun ◽  
Yong Bo Wang
Keyword(s):  
High Efficiency ◽  
Fault Tolerant ◽  
Engineering Application ◽  
Measured Data ◽  
Sphere Model ◽  
High Quality ◽  
Fitting Method ◽  
Enveloping Surface ◽  
Practical Engineering ◽  
Offset Surface

Offsetting of measured data, as a basic geometric operation, has already been widely used in many areas, like reverse engineering, rapid prototyping and NC machining. However, measured data always carry typical defects like caves and singular points. A fault-tolerant offset method is proposed to create the high quality offset surface of measured data with such defects. Firstly, we generated an expansion sphere model of measured data with the radius equivalent to the offset length. Secondly, using the computational geometry application of convex hull, we acquire the data of outermost enveloping surface of this expansion sphere model. Finally, we use local MLS projection fitting method to wipe out existing defects, and generate the high-quality triangular mesh surface of the offset model. The offset surface generated by this method is suitable for practical engineering application due to its high efficiency and accuracy.

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