Time-domain elasto-dynamic model of a transversely isotropic, layered road structure system with rigid substratum under a FWD load

2021 ◽  
pp. 1-19
Author(s):  
Junhui Zhang ◽  
Haishan Fan ◽  
Shiping Zhang ◽  
Jie Liu ◽  
Jianlong Zheng
Keyword(s):  
Dynamic Model ◽  
Time Domain ◽  
Transversely Isotropic ◽  
Structure System

scholarly journals Dynamic Analysis of Partially Embedded Structures Considering Soil-Structure Interaction in Time Domain

2011 ◽  
Vol 2011 ◽  
pp. 1-23 ◽  
Author(s):  
Sanaz Mahmoudpour ◽  
Reza Attarnejad ◽  
Cambyse Behnia
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Time Domain ◽  
Soil Structure ◽  
Soil Structure Interaction ◽  
Structure System ◽  
Structure Interaction ◽  
Scaled Boundary Finite Element ◽  
Element Method

Analysis and design of structures subjected to arbitrary dynamic loadings especially earthquakes have been studied during past decades. In practice, the effects of soil-structure interaction on the dynamic response of structures are usually neglected. In this study, the effect of soil-structure interaction on the dynamic response of structures has been examined. The substructure method using dynamic stiffness of soil is used to analyze soil-structure system. A coupled model based on finite element method and scaled boundary finite element method is applied. Finite element method is used to analyze the structure, and scaled boundary finite element method is applied in the analysis of unbounded soil region. Due to analytical solution in the radial direction, the radiation condition is satisfied exactly. The material behavior of soil and structure is assumed to be linear. The soil region is considered as a homogeneous half-space. The analysis is performed in time domain. A computer program is prepared to analyze the soil-structure system. Comparing the results with those in literature shows the exactness and competency of the proposed method.

Swing Reduction of Ropeway Carriers by Means of Two-Ball Rolling Type Damping Equipment: 2nd Report — Way to Implement Desired Damping for Two-Ball System

2007 ◽  
Author(s):  
H. Sato ◽  
M. Chishima
Keyword(s):  
Friction Coefficient ◽  
Frequency Response ◽  
Dynamic Model ◽  
Time Domain ◽  
Damping Coefficient ◽  
Ball Rolling ◽  
Safety And Reliability ◽  
Transport Safety ◽  
Time Domain Response ◽  
Rolling Balls

To enhance transport safety and reliability of ropeway systems, it is essential to reduce the swing of the carriers that results from wind, etc. In the previous report [1], we provided a practical damping equipment using two rolling balls (hereinafter described as “two-ball rolling type damping equipment”) to reduce the swing of ropeway carriers. A linearized dynamic model is proposed. Then, on the basis of relevant parameters, the frequency response and time domain response of the system is studied and discussed. In this report, we will study relationship between theoretical best damping coefficient ratio and friction coefficient of two-ball system. Then we will provide the way to implement the desired damping for the two-ball system. We will then provide the detail on how to estimate the inherent damping within the two-ball system. In addition, we will show and discuss two balls behavior when this equipment works experimentally.

A Dynamic Model of Electrostrictive Unimorph Actuators for Haptic Devices

2016 ◽  
Author(s):  
Tahzib Safwat ◽  
Ryan Tosto ◽  
Michael D. Grissom ◽  
Christopher D. Rahn
Keyword(s):  
Frequency Response ◽  
Dynamic Model ◽  
Time Domain ◽  
Haptic Feedback ◽  
High Strain ◽  
Piezoelectric Materials ◽  
Domain Model ◽  
Electroactive Polymer ◽  
Step Response ◽  
Compliant Actuators

Piezoelectric materials are commonly found in many devices, but their usage is limited by the low strain and high stiffness of the material. This prevents their use in “soft” applications, such as compliant actuators for haptic feedback devices and wearable technology. The actuation dynamics of a ferro-electric relaxor terpolymer, a type of soft and high strain electroactive polymer (EAP), are examined. This paper studies the unimorph actuator via a linearized time-domain model and experiments to validate the model include step response and frequency response of tip displacement.

Chatter stability of the constrained layer damping composite boring bar in cutting process

2019 ◽  
Vol 25 (16) ◽  
pp. 2204-2214 ◽  
Author(s):  
Zhang Yuhuan ◽  
Ren Yongsheng ◽  
Tian jishuang ◽  
Ma jingmin
Keyword(s):  
Dynamic Model ◽  
Time Domain ◽  
Structural Parameters ◽  
Frequency Domain Method ◽  
Constrained Layer Damping ◽  
Chatter Stability ◽  
Analysis Model ◽  
Structural Dynamic ◽  
Boring Bar ◽  
Cutting System

Traditional boring bars are generally made up of isotropic metallic materials and exhibit extremely poor chatter suppression ability. For enhancing the chatter stability, using anisotropic composite materials in the preparation of boring bars proves to be an effective method so as to enhance the boring bar’s natural frequency and damping. Additionally, the addition of constrained layer damping (CLD) technology on the composite boring bar can further improve the damping performance. This study aims to develop a theoretical analysis model for the prediction of the chatter stability of the CLD composite boring bar and explore the effectiveness and practicability of the CLD technology in suppressing the chatter of composite boring bar. Based on Euler–Bernoulli beam theory and the complex stiffness method of CLD, the structural dynamic model of the CLD composite boring bar was derived, and some structural parameters of the bar mainly including the ply angle of the composite material, the thicknesses of both damping layer, and constrained layer were also optimized. By combining the linear model of cutting force with a regenerative delay effect and the established dynamic model, the chatter analysis model of the CLD composite boring bar was constructed and the lobe diagram of the chatter stability of the cutting system was plotted by means of frequency domain method. The effects of the ply angle of the composite boring bar, the thicknesses of damping layer, and constrained layer on the chatter stability were examined. By performing time integral of the delay equation of motion, the time-domain response curves of the cutting system are obtained. The chatter stability prediction results based on the lobe diagram fit well with the prediction results on the basis of dynamic stiffness calculation and time-domain numerical integral results.

Time Domain Study on the Construction Mechanism of Milling Stability Lobe Diagrams With Multiple Modes

2021 ◽  
Author(s):  
Weitao Li ◽  
Liping Wang ◽  
Guang Yu
Keyword(s):  
Dynamic Model ◽  
Time Domain ◽  
Single Mode ◽  
Milling Process ◽  
Time Domain Method ◽  
Multiple Modes ◽  
Milling Stability ◽  
Stability Lobe ◽  
Flexible Mode ◽  
Domain Method

Abstract The stability lobe diagram (SLD) is an important expression way of milling stability prediction result. The SLD obtained by only selecting the most flexible mode fails to predict the chatter if the milling process is dominated by multiple modes. To reveal the relationship between the SLD with multiple modes and the SLDs corresponding to each single mode, this paper studies the construction mechanism of the SLD with multiple modes by using the time domain method. First, the milling dynamic model of the tool with multiple modes is established. Then, the numerical method based on the Newton-Cotes rules is used to solve the milling dynamic model with multiple modes whose solution is in the form of the SLD. It shows that the SLD with multiple modes can be approximated by using the lowest envelope of the SLDs corresponding to each single mode. Finally, two study cases are adopted to verify the construction mechanism of the SLD with multiple modes. To verify the correctness of the SLD with multiple modes, a series of milling tests are carried out. The experimental results agree with the simulation results, which means the proposed time domain method can reveal the construction mechanism of the SLD with multiple modes.

Discontinuous Galerkin modeling of 3D arbitrary anisotropic Q

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. C295-C309 ◽  
Author(s):  
Qiwei Zhan ◽  
Mingwei Zhuang ◽  
Yuan Fang ◽  
Qing Huo Liu
Keyword(s):  
Differential Equations ◽  
Discontinuous Galerkin ◽  
Time Domain ◽  
Numerical Models ◽  
Transversely Isotropic ◽  
Memory Effects ◽  
Global Memory ◽  
Transformation Rule ◽  
Anelastic Attenuation ◽  
Text Model

For wave propagation problems, conventional time-domain anelastic attenuation modeling involves either Caputo fractional time derivatives for an exactly constant-[Formula: see text] model, thus leading to globally temporal memory effects; or auxiliary partial differential equations (PDEs) for a nearly constant-[Formula: see text] model, thus resulting in globally spatial operators. Therefore, memory and time consumptions increase tremendously, compared with the purely elastic counterpart. Moreover, the numerical models are usually limited to isotropic or transversely isotropic attenuation, due to the ambiguity of anisotropic attenuation parameterization. Therefore, it is indispensable to investigate an efficient method, to easily incorporate the general anisotropic attenuation effects in the time domain. To tackle these problems, we have first developed a [Formula: see text]-transformation rule, via the correspondence principle, revealing the validity range for a large enough [Formula: see text] value. Then, we construct a new constitutive equation, by extending the generalized Maxwell body, from the isotropic viscoelastic media to fully anisotropic scenario, i.e., as complex as triclinic attenuation. As a result, global memory effects are effectively localized, with several anelastic functions subject to ordinary differential equations, while preserving the original governing equations. An efficient hp-adaptive discontinuous Galerkin (DG) time-domain algorithm is implemented, where the Riemann problem is exactly solved. Consequently, the extra computation cost to incorporate [Formula: see text] effects is nearly negligible. Furthermore, we derive an analytical solution for the general anisotropic attenuation to verify this DG implementation.

Q-compensated reverse time migration in tilted transversely isotropic media

Geophysics ◽  
2020 ◽  
pp. 1-79
Author(s):  
Ali Fathalian ◽  
Daniel O. Trad ◽  
Kristopher A. Innanen
Keyword(s):  
Time Domain ◽  
Transversely Isotropic ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Modeling And Analysis ◽  
Seismic Amplitude ◽  
Time Migration ◽  
Transversely Isotropic Media ◽  
Isotropic Media ◽  
The Time Domain

Anisotropy and absorption are critical to the modeling and analysis of seismic amplitude,phase, and traveltime data. To neglect any of these phenomena, which are often bothoperating simultaneously, degrades the resolution and interpretability of migrated images.However, a full accounting of anisotropy and anelasticity is computationally complex andexpensive. One strategy for accommodating these aspects of wave propagation, while keepingcost and complexity under control, is to do so within an acoustic approximation. Weset up a procedure for solving the time-domain viscoacoustic wave equation for tilted transverselyisotropic (TTI) media, based on a standard linear solid model and, from this, developa viscoacoustic reverse time migration (Q-RTM) algorithm. In this approach, amplitudecompensation occurs within the migration process through a manipulation of attenuationand phase dispersion terms in the time domain differential equations. Specifically, theback-propagation operator is constructed by reversing the sign only of the amplitude lossoperators, but not the dispersion-related operators, a step made possible by reformulatingthe absorptive TTI equations such that the loss and dispersion operators appear separately.The scheme is tested on synthetic examples to examine the capacity of viscoacoustic RTM to correct for attenuation, and the overall stability of the procedure.

TIME DOMAIN STUDY ON THE CONSTRUCTION MECHANISM OF MILLING STABILITY LOBE DIAGRAMS WITH MULTIPLE MODES

2021 ◽  
pp. 1-9
Author(s):  
Liping Wang ◽  
Weitao Li ◽  
Guang Yu
Keyword(s):  
Dynamic Model ◽  
Time Domain ◽  
Single Mode ◽  
Milling Process ◽  
Time Domain Method ◽  
Multiple Modes ◽  
Milling Stability ◽  
Stability Lobe ◽  
Flexible Mode ◽  
Domain Method

Abstract The stability lobe diagram (SLD) is an important expression way of milling stability prediction result. The SLD obtained by only selecting the most flexible mode fails to predict the chatter if the milling process is dominated by multiple modes. To reveal the relationship between the SLD with multiple modes and the SLDs corresponding to each single mode, this paper studies the construction mechanism of the SLD with multiple modes by using a time domain method. First, the milling dynamic model of the tool with multiple modes is established. Then, the numerical method based on the Newton-Cotes rules is used to solve the milling dynamic model with multiple modes whose solution is in the form of the SLD. It shows that the SLD with multiple modes can be approximated by using the lowest envelope of the SLDs corresponding to each single mode. Finally, two study cases are adopted to verify the construction mechanism of the SLD with multiple modes. To verify the correctness of the SLD with multiple modes, a series of milling tests are carried out. The experimental results agree with the simulation results, which means the proposed time domain method can reveal the construction mechanism of the SLD with multiple modes.

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