Numerical modeling of ground-borne vibrations induced by pile driving with a simple and direct material damping approach

2021 ◽  
Vol 263 (1) ◽  
pp. 5291-5300
Author(s):  
Tales Sofiste ◽  
Luís Godinho ◽  
Delfim Soares ◽  
Pedro Alves Costa
Keyword(s):  
Time Integration ◽  
Element Model ◽  
Pile Driving ◽  
Material Damping ◽  
Post Processing ◽  
Construction Sites ◽  
Construction Operations ◽  
Numerical Application ◽  
Large Cities ◽  
Direct Approximation

Ground-borne vibrations are an increasingly common problem in large cities due to its considerable disturbance in terms of human comfort and health. In this sense, construction operations stand as a significant source of vibrations and may be critical since construction sites are frequently adjacent to existing buildings. In the present work, vibrations induced by pile driving are studied. A time-domain finite element model is developed and a post-processing approach is proposed to simulate the material damping of the soil. This damping formulation stands as a simple and direct approximation of the material damping in the system. In order to do so, the numerical response is computed without material damping, which is introduced as a post-processing procedure. An explicit and highly efficient method is applied for the time integration of the equation of motion, considering an axisymmetric formulation. A numerical application is carried out and the obtained results are compared to previous numerical and in-situ measurements available in the literature, indicating a good agreement with previous studies.

A Simplified Finite Element for Added Mass and Inertial Coupling in Arrays of Cylinders

1985 ◽  
Vol 107 (2) ◽  
pp. 118-125 ◽  
Author(s):  
R. E. Harris ◽  
M. A. Dokainish ◽  
D. S. Weaver
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Element Model ◽  
Added Mass ◽  
Cylindrical Structures ◽  
Beam Elements ◽  
Inertial Coupling ◽  
Fundamental Frequencies ◽  
Tube Bundles ◽  
Primary Advantage

A simplified finite element has been developed for modeling the added mass and inertial coupling arising when clusters of cylinders vibrate in a quiescent fluid. The element, which is based on two-dimensional potential flow theory, directly couples two adjacent beam elements representing portions of the adjacent cylindrical structures. The primary advantage of this approach over existing methods is that it does not require the discretization of the surrounding fluid and, therefore, is computationally much more efficient. The fundamental frequencies of tube bundles of various pitch ratios have been predicted using this method and compared with experimental data. Generally, the agreement is good, especially for the bandwidth of fluid coupled natural frequencies. The transient response of tube bundles is also examined using time integration of the finite element model. The beating phenomenon and time decay characteristics exhibited by the experimental bundles under single-tube excitation are well predicted and valuable insights are gained into the measurement of damping in tube bundles.

Methods for Reducing a Thermal Finite Element Model Including the Advection Network Contribution

2006 ◽  
Author(s):  
Daniele Botto ◽  
Stefano Zucca ◽  
Muzio M. Gola
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Real Time ◽  
Residual Life ◽  
Mathematical Formulation ◽  
Time Integration ◽  
Element Model ◽  
Computational Time ◽  
Fatigue Damage Accumulation ◽  
Secondary Air

The life monitoring concept needs on-line calculation to evaluate stresses and temperatures on aircraft engine components, in order to asses fatigue damage accumulation and residual life. Due to the amount of computational time required it is not possible for a full finite element model to operate in real time using the on-board CPU. Stresses and temperatures are then evaluated by using simplified algorithms. In the present work Guyan reduction and component mode synthesis have been applied to a thermal finite element model, including the cooling stream flow — the so called advection network — in order to reduce the size of the solving equation system. The appropriate mathematical formulation for the advection network reduction has been developed. Two reduction methods have been performed, discussed and subsequently applied to a thermal finite element model of a real low pressure turbine disk. The reduced system includes both the disk and the correlated fluid network model, simulating turbine secondary air system. The finite element model is axi-symmetric, with constant convective coefficients. Results of time integration for the reduced and the complete models have been compared. Results show that the proposed techniques gives models with a reduced number of degrees of freedom and at the same time good accuracy in temperature calculation. The reduced models are then suitable for real time computation.

scholarly journals Mistuning Analysis of a Detuned Bladed-Disk With Geometrical Nonlinearities

2019 ◽  
Author(s):  
Anthony Picou ◽  
Evangéline Capiez-Lernout ◽  
Christian Soize ◽  
Moustapha Mbaye
Keyword(s):  
Probabilistic Approach ◽  
Element Model ◽  
Deterministic Approach ◽  
Complex Dynamic ◽  
Order Model ◽  
Numerical Application ◽  
Reduced Order ◽  
Bladed Disk ◽  
Geometrical Nonlinearities ◽  
Disk Structure

Abstract This work concerns the nonlinear numerical analysis of mistuned blades for a rotating detuned bladed-disk structure with geometrical nonlinearities. The detuning phenomenon is taken into account through a deterministic approach by modifying material properties of some blades. A nonlinear reduced-order model is obtained by setting up a basis using a double projection method. The mistuning uncertainties are implemented through a nonparametric probabilistic approach for which the level of uncertainties is controlled by a hyperparameter. A numerical application is carried out on a bladed-disk structure made up of 24 blades whose finite element model has about 800,000 dofs exhibiting complex dynamic behaviors.

Effects of a Cracked Blade on Mistuned Turbine Engine Rotor Vibration

2007 ◽  
Author(s):  
Akira Saito ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Time Integration ◽  
Element Model ◽  
Forced Response ◽  
System Response ◽  
Turbine Engine ◽  
Reduced Order ◽  
Hybrid Interface ◽  
Engine Rotor

An efficient methodology for predicting the nonlinear forced vibration response of a turbine engine rotor with a cracked blade is presented and used to investigate the effects of the damage on the forced response. The effects of small, random blade-to-blade differences (mistuning) and rotation on the forced response are also considered. Starting with a finite element model, a hybrid-interface method of Component Mode Synthesis (CMS) is employed to generate a reduced-order model (ROM). The crack surfaces are retained as physical degrees of freedom in the ROM so that the forces due to contact interaction in three-dimensional space can be properly calculated. The resulting nonlinear equations of steady-state motion are solved by applying an alternating frequency/time-domain method, which is much more computationally efficient than traditional time integration. Using this reduced-order modeling and analysis framework, the effects of the cracked blade on the system response are investigated for various mistuning levels and rotation speeds. First, the advantages of the selected hybrid-interface CMS method are discussed and demonstrated. Then, the resonant frequency shift associated with the stiffness loss due to the crack, as well as vibration localization about the cracked blade are thoroughly investigated. In addition, the results of the nonlinear ROMs are compared to those obtained with linear ROMs as well as blade-alone ROMs. It is shown that several key system vibration characteristics are not captured by the simpler models, but that some insight into the system response can be gained from the blade-alone response predictions. Furthermore, it is demonstrated that while the effects of the crack often appear similar those of mistuning, differences between the effects of mistuning and damage can be discerned by observing and comparing the response across different families of system modes.

Finite Element Analysis of Dynamic Coupled Thermoelasticity Problems With Relaxation Times

1983 ◽  
Vol 50 (4a) ◽  
pp. 817-822 ◽  
Author(s):  
J. H. Prevost ◽  
D. Tao
Keyword(s):  
Finite Element ◽  
Classical Model ◽  
Relaxation Times ◽  
Time Integration ◽  
Propagation Speed ◽  
Element Model ◽  
Stress Wave Propagation ◽  
Element Analysis ◽  
Transient Phenomena ◽  
Coupled Thermoelasticity Problems

A general finite element model is proposed to analyze transient phenomena in thermoelastic solids. Green and Lindsay’s dynamic thermoelasticity model is selected for that purpose since it allows for “second sound” effects and reduces to the classical model by appropriate choice of the parameters. Time integration of the semidiscrete finite element equations is achieved by using an implicit-explicit scheme proposed by Hughes, et al. The procedure proves to be most effective and versatile in thermal and stress wave propagation analysis. A number of examples are presented which demonstrate the accuracy and versatility of the proposed model, and the importance of finite thermal propagation speed effects.

Interactive Simulation of Crawler Crane’s Lifting Based on OpenGL

2008 ◽  
Author(s):  
Xin Wang ◽  
Honglu Wang ◽  
Di Wu
Keyword(s):  
Three Dimensional ◽  
Interactive Simulation ◽  
Construction Sites ◽  
Construction Operations ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Processing Abilities ◽  
Dimensional Simulation ◽  
Lifting Equipment ◽  
Crawler Crane

Crawler cranes are the most expensive and frequently shared resource on construction sites, industries, etc. It is engaged in offering various combination for booms and large-capacity of mobile cranes to meet the building industry requirements. Computer simulation has proved to be an effective tool for aiding practitioners in modeling complex construction operations, especially three-dimensional simulation that can provide interactive, three-dimensional graphics. As a graphic standard, OpenGL has powerful three-dimensional graphic processing abilities, but is weakness in three-dimensional modeling. Bounding Hierarchical Volumes Tree (BHVT) is very popular structures for objects storage of virtual scenes. Based on BHVT, a method of three-dimensional modeling is proposed. According to its structure and characteristics, the model of the crawler crane is designed. To achieve three-dimensional simulation for a main hoisting crane and an assistant crane (i.e., sliding tail crane) cooperative lifting, several typical mathematical models are established. When simulating the lifting process in the cooperative working mode, the changes of cranes and the lifting equipment, needed for steady lifting, are figured out simultaneously, and then those changes are output to form the relevant curves. The curves are analyzed to decide whether the lifting plan that using a main hoisting crane and a sliding tail crane to lift is safe and reasonable. For the sake of a better interactive simulation, object-oriented framework for three-dimensional graphic creation based on OpenGL is developed, it consists of class BHVTNode, class camera and class renderer, which make data and instructions separated. Combining the class camera and class renderer with the technology BHVT, succeed to simulate the lifting operations of crawler crane, especially achieve the animation of the cooperative lifting, it is visual to observe the whole lifting process, which is good for assisting to design the lifting plan.

A Finite Element Analysis for Unbonded Flexible Risers Under Torsion

2007 ◽  
Author(s):  
A. Bahtui ◽  
H. Bahai ◽  
G. Alfano
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Model ◽  
Finite Element Model ◽  
Time Integration ◽  
Element Model ◽  
Integration Scheme ◽  
Element Analysis ◽  
Benchmark Solutions ◽  
The Finite Element Model

This paper presents a detailed finite element analysis of a five-layer unbonded flexible riser. The numerical results are compared analytical solutions for various load cases. In the finite element model all layers are modelled separately with contact interfaces placed between each layer. The finite element model includes the main features of the riser geometry with very little simplifying assumptions made. The numerical model was solved using a fully explicit time-integration scheme implemented in a parallel environment on a 16-processor cluster. The very good agreement found from numerical and analytical comparisons validates the use of our numerical model to provide benchmark solutions against which further detailed investigation will be made.

Dynamic Characteristics of Fluid-Conveying Pipes with Piecewise Linear Support

2016 ◽  
Vol 16 (06) ◽  
pp. 1550025 ◽  
Author(s):  
Zhan-Ying Li ◽  
Jian-Jun Wang ◽  
Ming-Xing Qiu
Keyword(s):  
Dynamic Characteristics ◽  
Piecewise Linear ◽  
Time Integration ◽  
Measurement Data ◽  
Element Model ◽  
Harmonic Excitation ◽  
Dynamic Responses ◽  
Fluid Structure ◽  
Pipe System ◽  
Fluid Conveying Pipes

For the analysis of dynamic characteristics of fluid-conveying pipes with piecewise linear support, a fluid–structure coupling dynamic model based on the finite element method is proposed. A user-defined pipe element based on Euler–Bernoulli beam is developed for modeling the pipes, considering the dynamic flow conditions. A nonlinear spring element is utilized to model the clamp between the pipe and the base. The dynamic responses of the system are obtained through the direct time integration. The stiffness of the clamp support is investigated by the analytical method and the experimental method, in which it is found that the clamp stiffness is piecewise linear. For different pipe geometries the user-defined element model, analytical model and measurement data are compared. The results show high quality of the element developed in this paper. Finally, the dynamic characteristics of the pipe system with piecewise linear support subjected to base harmonic excitation are calculated and the effects of the system parameters on pipe behaviors have also been studied. As a consequence, the model proposed in this paper can represent the piecewise linear nonlinearity of the clamp support and be used conveniently to investigate the effects of the fluid–structure coupling on the system behaviors.

Effects of a Cracked Blade on Mistuned Turbine Engine Rotor Vibration

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Akira Saito ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Time Integration ◽  
Element Model ◽  
Forced Response ◽  
System Response ◽  
Turbine Engine ◽  
Reduced Order ◽  
Hybrid Interface ◽  
Engine Rotor

An efficient methodology for predicting the nonlinear forced vibration response of a turbine engine rotor with a cracked blade is presented and used to investigate the effects of the damage on the forced response. The influence of small random blade-to-blade differences (mistuning) and rotation on the forced response are also considered. Starting with a finite element model, a hybrid-interface method of component mode synthesis (CMS) is employed to generate a reduced-order model (ROM). The crack surfaces are retained as physical degrees of freedom in the ROM so that the forces due to contact in three-dimensional space can be properly calculated. The resulting nonlinear equations of steady-state motion are solved by applying an alternating frequency/time-domain method, which is much more computationally efficient than traditional time integration. Using this reduced-order modeling and analysis framework, the effects of the cracked blade on the system response of an example rotor are investigated for various mistuning levels and rotation speeds. First, the advantages of the selected hybrid-interface CMS method are discussed and demonstrated. Then, the resonant frequency shift associated with the stiffness loss due to the crack and the vibration localization about the cracked blade are thoroughly investigated. In addition, the results of the nonlinear ROMs are compared with those obtained with linear ROMs, as well as blade-alone ROMs. It is shown that several key system vibration characteristics are not captured by the simpler models, but that some insight into the system response can be gained from the blade-alone response predictions. Furthermore, it is demonstrated that while the effects of the crack often appear similar to those of mistuning, the effects of mistuning and damage can be distinguished by observing and comparing the response across multiple families of system modes.

scholarly journals Approach for Selection of Rayleigh Damping Parameters Used for Time History Analysis

2009 ◽  
Author(s):  
R. E. Spears ◽  
S. R. Jensen
Keyword(s):  
Seismic Analysis ◽  
Time Integration ◽  
Time History ◽  
Element Model ◽  
System Response ◽  
Piping System ◽  
Rayleigh Damping ◽  
Modal Damping ◽  
The Difference ◽  
Selection Of

Nonlinearities, whether geometric or material, need to be addressed in seismic analysis. One good analysis method that can address these nonlinearities is direct time integration with Rayleigh damping. Modal damping is the damping typically specified in seismic analysis Codes and Standards [1, 2]. Modal damping is constant for all frequencies where Rayleigh damping varies with frequency. An approach is proposed here for selection of Rayleigh damping coefficients to be used in seismic analyses that are consistent with given Modal damping. The approach uses the difference between the modal damping response and the Rayleigh damping response along with effective mass properties of the model being evaluated to match overall system response levels. This paper provides a simple example problem to demonstrate the approach. It also provides results for a finite element model representing an existing piping system. Displacement, acceleration, and stress results are compared from model runs using modal damping and model runs using Rayleigh damping with coefficients selected using the proposed method.

Sign in / Sign up

Export Citation Format

Share Document