Damage Detection in Rods Using Wave Propagation and Regression Analysis

1999 ◽  
Author(s):  
K. T. Feroz ◽  
S. O. Oyadiji
Keyword(s):  
Wave Propagation ◽  
Regression Analysis ◽  
Damage Detection ◽  
Numerical Study ◽  
Time History ◽  
Ball Impact ◽  
Spherical Ball ◽  
Time Histories ◽  
Measured Strain ◽  
Force Time

Abstract The phenomena of wave propagation in rods was studied both numerically and experimentally. The finite element (FE) code ABAQUS was used for the numerical study while PZT (lead zirconium titanate) sensors and a 50 MHz transient recorder were used experimentally to monitor and to capture the propagation of stress pulses. For the study of damage detection in the rods the analyses and the experiments were repeated by introducing slots in a fixed axial location of the rod. A longitudinal wave was induced in the rod via collinear impact which was modelled in the FE analyses using the force-time history computed from the classical Hertz contact theory. In the experimental measurements this was achieved by a spherical ball impact at one plane end of the rods. It is shown that the predicted and measured strain-time histories for the defect-free rod and for the rods with defect correlate quite well. These results also show that defects can be located using the wave propagation phenomena. A regression analysis technique of the predicted and measured strain histories of the defect free rod and of the rod with defect was also performed. The results show that this technique is more efficient for smaller defects. In particular, it is shown that the area enclosed by the regression curve increases as the defect size increases.

scholarly journals Development of a Novel Damage Detection Framework for Truss Railway Bridges Using Operational Acceleration and Strain Response

Vibration ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 422-445
Author(s):  
Md Riasat Azim ◽  
Mustafa Gül
Keyword(s):  
Damage Detection ◽  
Damage Identification ◽  
Numerical Study ◽  
Damage Index ◽  
Strain Analysis ◽  
Time History ◽  
Principal Component ◽  
Element Model ◽  
Railway Bridges ◽  
Truss Bridge

Railway bridges are an integral part of any railway communication network. As more and more railway bridges are showing signs of deterioration due to various natural and artificial causes, it is becoming increasingly imperative to develop effective health monitoring strategies specifically tailored to railway bridges. This paper presents a new damage detection framework for element level damage identification, for railway truss bridges, that combines the analysis of acceleration and strain responses. For this research, operational acceleration and strain time-history responses are obtained in response to the passage of trains. The acceleration response is analyzed through a sensor-clustering-based time-series analysis method and damage features are investigated in terms of structural nodes from the truss bridge. The strain data is analyzed through principal component analysis and provides information on damage from instrumented truss elements. A new damage index is developed by formulating a strategy to combine the damage features obtained individually from both acceleration and strain analysis. The proposed method is validated through a numerical study by utilizing a finite element model of a railway truss bridge. It is shown that while both methods individually can provide information on damage location, and severity, the new framework helps to provide substantially improved damage localization and can overcome the limitations of individual analysis.

Dynamic Load Factor for Surge Load on Pipe Using the Stress Wave Propagation Methodology

2017 ◽  
Author(s):  
Abu Seena
Keyword(s):  
Wave Propagation ◽  
Dynamic Load ◽  
Time History ◽  
Stress Wave Propagation ◽  
Load Factor ◽  
Full Time ◽  
Maximum Value ◽  
Force Time ◽  
Full Force ◽  
Dynamic Load Factor

The full time history method for calculating the pipe stresses and restraint loads due to transient flow event requires high computing memory and long simulation time. Alternately, the static equivalent method has been extensively used in power and process industry where a dynamic load factor is used to account for the dynamic amplification response of suddenly applied surge/hammering loads on pipe. In practice, the DLF is multiplied on the maximum value of dynamic force depending on the time rise of load. Due to the complexity of calculating DLF, the engineers adopt maximum value of DLF = 2.0 irrespective of the load variation. The present paper discusses the uncertainty and inaccuracy involved in performing approximate analysis or static equivalent analysis and shows the significance and need of performing full force time history analysis. A new methodology has been derived for the estimation of approximate DLF from the full force time history profiles. Using the stress wave propagation methodology, the DLF can be estimated for the pipe with axial restraints and guides. The axial line stoppers are precondition to apply present method, which can be easily included during design phase of the pipe routes. The DLF’s are computed for sample force curve with various other parameters and are compared with the FEA results. It has also been shown that the load amplification does not scale with the displacement amplification. With proposed methodology the DLF for can be calculated for each pipe. Then it is recommended to perform the static analysis with the estimated DLF’s based on full time history profiles.

EFFECT OF THE FLUID ON THE IMPACT FORCE OF THE WET MISSILE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Duc-Kien Thai ◽  
Seung-Eock Kim
Keyword(s):  
Impact Force ◽  
Force Plate ◽  
Time History ◽  
Research Centre ◽  
Element Analysis ◽  
Time Histories ◽  
Target Wall ◽  
Force Time ◽  
Missile Test ◽  
The Impact

In this paper, the force-time histories of soft missiles, with and without filled water, impacting the target wall were investigated using finite element analysis. The force plate tests, with a dry missile (test FP8) and a wet missile (test FP16) carried out by Technical Research Centre of Finland (VTT), were used. The numerical analysis results were verified by comparing with those of experiments. A parametric analysis with different missile velocities was also performed to investigate the force-time history and impulse of the missile impact on target plate. Based on a comparison with the Riera approach, the coefficients were proposed to modify the Riera function. The analysis results show that, the Riera function accurately predicted the impact force time history in the case of the dry missile. However, in the case of the wet missile, the coefficients α from 1.24 to 1.45 are recommended to be added to the second term of the Riera function in the case in which the impact velocity is in the range of 70 m/s to 200 m/s.

scholarly journals Dynamic effects induced by the impact of debris flows on protection barriers

2018 ◽  
Vol 10 (1) ◽  
pp. 116-131 ◽  
Author(s):  
Maddalena Marchelli ◽  
Valerio De Biagi
Keyword(s):  
Impact Force ◽  
Time History ◽  
Element Model ◽  
Interaction Force ◽  
Accurate Analysis ◽  
Vibration Period ◽  
Time Histories ◽  
Mode Vibration ◽  
Force Time ◽  
The Impact

Debris flow is a transient phenomenon that causes large disasters. Retaining systems, whose design is still nowadays a crucial issue, can mitigate this risk. Multiple surges can arise during this phenomenon; thus, an accurate analysis might consider the impact force time histories rather than only its maxima. The aim of this work is to analyze the effects of the interaction between the debris and the barrier during one surging phenomenon. A discrete element model models the granular motion and the interaction between the debris and a rigid open barrier set at the end of the channel. The estimated interaction force time history is then used as input impact force for the dynamic structural analyses of the piles. A total of 12 different structural sections are adopted and the internal forces at the base are critically compared. It results that the first mode vibration period is the parameter that largely affects the behavior of the piles.

Impact factor method for design of bridge foundations under ship collisions

2016 ◽  
Vol 20 (4) ◽  
pp. 534-548 ◽  
Author(s):  
Junjie Wang ◽  
Yanchen Song ◽  
Zhiran Yu
Keyword(s):  
Impact Factor ◽  
Impact Force ◽  
Time History ◽  
Rigid Wall ◽  
Static Method ◽  
Factor Method ◽  
Empirical Function ◽  
Time Histories ◽  
Dynamic Amplification ◽  
Force Time

Due to the complexity involved and limited study on the topic, the equivalent static method, adopted in the current codes for structural design of bridges under ship collisions, does not take into account the dynamic amplification effect correctly. In this article, impact factor method is proposed to estimate the response of bridge’s piers and foundations, as a better alternative of the equivalent static method. Through refined numerical simulations of ship-rigid wall collisions for nine typical ships under various impact velocities, 81 impact force time-histories are obtained. The period-dependent impact factor is defined, and empirical function of it is proposed and parameters in the empirical function are determined by the 81 sample impact force time-histories. Finally, both impact factor method and dynamic time-history method are used to estimate the responses of piers and foundations of two example bridges, and the precision of impact factor method is discussed.

scholarly journals Phase manipulation and the harmonic components of ringing forces on a surface-piercing column

2014 ◽  
Vol 470 (2168) ◽  
pp. 20130847 ◽  
Author(s):  
C. J. Fitzgerald ◽  
P. H. Taylor ◽  
R. Eatock Taylor ◽  
J. Grice ◽  
J. Zang
Keyword(s):  
Water Waves ◽  
Fourier Transforms ◽  
Time History ◽  
Wave Force ◽  
Separation Method ◽  
Coastal Protection ◽  
Time Histories ◽  
Local Wave ◽  
Harmonic Components ◽  
Force Time

A general phase-based harmonic separation method for the hydrodynamic loading on a fixed structure in water waves of moderate steepness is proposed. An existing method demonstrated in the experimental study described by Zang et al. (Zang et al. 2010 In Proc. Third Int. Conf. on Appl. of Phys. Modelling to Port and Coastal Protection. pp. 1–7.) achieves the separation of a total diffraction force into odd and even harmonics by controlling the phase of incident focused waves. Underlying this method is the assumption that the hydrodynamic force in focused waves possesses a Stokes-like structure. Under the same assumption, it is shown here how the harmonic separation method can be generalized, so that the first four sum harmonics can be separated by phase control and linear combinations of the resultant time-histories. The effectiveness of the method is demonstrated by comparisons of the Fourier transforms of the combined time-histories containing the harmonics of interest. The local wave elevations around the focus time are also visualized for the first three harmonics in order to reveal the local dynamics driving components within the wave force time-history.

Soft Computing Based Force Recovery Technique for Hypersonic Shock Tunnel Tests

2018 ◽  
Vol 18 (05) ◽  
pp. 1871004 ◽  
Author(s):  
Ramesh Babu Pallekonda ◽  
Soumya Ranjan Nanda ◽  
Santosha K. Dwivedy ◽  
Vinayak Kulkarni ◽  
Viren Menezes
Keyword(s):  
Fuzzy Inference ◽  
Time History ◽  
Shock Tunnel ◽  
Force Balance ◽  
Inference System ◽  
Time Histories ◽  
Recovery Technique ◽  
Hypersonic Shock ◽  
Force Recovery ◽  
Force Time

A hemispherical model equipped with a three component accelerometer force balance has been tested in a shock tunnel at Mach 8.0 freestream conditions. A novel technique has been devised using the Artificial Neuro-Fuzzy Inference System (ANFIS) for recovering the forces experienced by the model during the experiments. Implementation of this methodology in calibration of the force balance showed encouraging agreement with the impulse forces recovered from the calibration tests. The same recovery procedure is then adopted to obtain the time history of the forces for 0[Formula: see text] and 15[Formula: see text] angle of attack experiments. The drag recovered in steady state is found to agree well with the conventional methods with minor discrimination for the lift and pitching moment. In light of the limitation of the accelerometer force balance theory due to the unaccountability of model dynamics, the force recovery technique proposed herein is found simple to implement and can be opted as a tool for prediction of the aerodynamic coefficients and force time histories.

Physical Modelling of Hydrodynamic Loads on Piggyback Pipelines in Combined Wave and Current Conditions

2010 ◽  
Author(s):  
Masˇa Brankovic´ ◽  
Hammam Zeitoun ◽  
James Sutherland ◽  
Andrew Pearce ◽  
Vagner Jacobsen ◽  
...  
Keyword(s):  
Time History ◽  
Physical Modelling ◽  
Model Tests ◽  
Test Method ◽  
Hydrodynamic Loads ◽  
Time Histories ◽  
Flow Mechanisms ◽  
Force Time ◽  
The Stability ◽  
Pipeline Design

One of the aspects of pipeline design is ensuring pipeline stability on the seabed under the action of environmental loads. During the 1980s, significant efforts were made to improve the understanding of hydrodynamic loads on single pipeline configurations on the seabed (Reference 1). The stability of piggyback (bundled) pipeline configurations is less well understood, with little quantitative data readily available to the design engineer for practical application in engineering problems (References 2–6). This paper describes an extensive set of physical model tests performed for piggyback on-seabed and piggyback-raised-from seabed (spanning or lifting pipeline) configurations to determine hydrodynamic forces in combined wave and current conditions. The piggyback is nominally in the 12 o’clock position. The well-established carriage technique was used, in order to obtain data for use in full-scale stability modelling. The model tests are benchmarked against existing test data, to confirm the validity of the test method. Key findings are presented in terms of non-dimensional coefficients, and force time histories for the vertical and horizontal forces. A brief interpretation of the hydrodynamic load behaviour of the Piggyback System is provided by considering the physical flow mechanisms causing the force time history variation; furthermore the influence of the seabed separation on the piggyback loads is also discussed.

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