Studies Of Dynamic Crack Propagation And Crack Branching With Peridynamics,
2010
University of Nebraska at Lincoln
Studies Of Dynamic Crack Propagation And Crack Branching With Peridynamics, Youn Doh Ha Ph.D., Florin Bobaru Ph.D.
Department of Engineering Mechanics: Faculty Publications
In this paper we discuss the peridynamic analysis of dynamic crack branching in brittle materials and show results of convergence studies under uniform grid refinement (m-convergence) and under decreasing the peridynamic horizon (δ-convergence). Comparisons with experimentally obtained values are made for the crack-tip propagation speed with three different peridynamic horizons.We also analyze the influence of the particular shape of themicro-modulus function and of different materials (Duran 50 glass and soda-lime glass) on the crack propagation behavior. We show that the peridynamic solution for this problem captures all the main features, observed experimentally, of dynamic crack propagation and branching, as well …
Damage Detection In Wind Turbine Blades Using Time-Frequency Analysis Of Vibration Signals,
2010
Dublin Institute of Technology
Damage Detection In Wind Turbine Blades Using Time-Frequency Analysis Of Vibration Signals, Breiffni Fitzgerald
Breiffni Fitzgerald
The dynamic behaviour of modern multi-Megawatt wind turbines has become an important design consideration. One of the major aspects related to the reliability of operation of the turbines concerns the safe and adequate performance of the blades. The aim of this paper is to develop a time-frequency based algorithm to detect damage in wind turbine blades from blade vibration signals. It is important that damage to blades is detected before they fail or cause the turbine to fail. A wind turbine model was developed for this paper. The parameters considered were the rotational speed of the blades and the stiffness …
Large-Scale Capacitance Sensor For Health Monitoring Of Civil Structures,
2010
Massachusetts Institute of Technology
Large-Scale Capacitance Sensor For Health Monitoring Of Civil Structures, Simon Laflamme, Matthias Kollosche, Jerome J. Connor, Guggi Kofod
Simon Laflamme
In this paper, a new type of sensing technique for damage localization on large civil structures is proposed. Specifically, changes in strain are detected using a capacitance sensor built with a soft-stretchable dielectric polymer with attached stretchable metal film electrodes. This sensor is sensitive to a change in strain that causes a change in its capacitance. Fixed to a structure, small changes in the strain can be monitored directly by measuring the change in the capacitance of the unit. This technology allows for simple yet highly accurate measurements of cracks occurring due to deformation, aging, or other structural failures. The …
Estimating The Characteristic Vertical Response Of A Flexible Footbridge Due To Crowd Loading,
2010
Athlone Institute of Technology
Estimating The Characteristic Vertical Response Of A Flexible Footbridge Due To Crowd Loading, Joe Keogh, Colin C. Caprani, Paul Archbold, Paul Fanning
Conference papers
The issue of excessive vibration of footbridges due to pedestrian loading is now well documented. Bridge vibrations produced from a crowd of pedestrians have been estimated by modifying the effect caused by a single pedestrian by an enhancement factor to take crowd synchronization into account. In this paper this approach is extended to account for the fact that all pedestrians will not have the same pacing frequencies, and the effects of distributions of pacing frequency and other parameters on the enhancement factor are investigated. It is shown that this more faithful representation of pedestrian crowd walking behaviour gives reduced vibration …
A New Congested Traffic Load Model For Highway Bridges,
2010
Technological University Dublin
A New Congested Traffic Load Model For Highway Bridges, Colin C. Caprani, Colm Carey, Bernard Enright
Conference papers
Long span highway bridges are critical components of any nation’s infrastructure. Therefore accurate assessment of highway bridge loading is essential, and it is well known that congested traffic governs load effect for such bridges. Current congestion models use conservative assumptions about traffic and inter-vehicle gaps. This research investigates congested traffic flow through the use of traffic microsimulation which has the ability to reproduce complex traffic phenomena based on driver interactions. A time series model has been developed to produce a speed time-series similar to the results of the microsimulation. The speed time-series from the new model, combined with the established …
Management Strategies For Special Permit Vehicles For Bridge Loading,
2010
Technological University Dublin
Management Strategies For Special Permit Vehicles For Bridge Loading, Bernard Enright, Eugene J. Obrien
Conference papers
An examination of weigh-in-motion data collected recently at sites in five European countries has shown that vehicles with weights well in excess of the normal legal limits are found on a daily basis. These vehicles would be expected to have permits issued by the responsible authorities. It can be seen from the measurements that most of them are travelling at normal speeds. Photographic evidence indicates that, while many are accompanied by an escort vehicle, normal traffic is flowing alongside in other lanes. As European freight volume grows, the frequency of these special vehicles can be expected to increase. Hence, the …
Site Specific Modelling Of Traffic Loading On Highway Bridges,
2010
Technological University Dublin
Site Specific Modelling Of Traffic Loading On Highway Bridges, Bernard Enright, Eugene J. Obrien
Conference papers
Accurate traffic loading models based on measured weigh-in-motion (WIM) data are essential for the accurate assessment of existing bridges. Much work has been published on the Monte Carlo simulation of single lanes of heavy vehicle traffic, and this can easily be extended to model the loading on bridges with two streams of traffic in opposing directions. However, a typical highway bridge will have multiple lanes in the same direction, and various types of correlation are evident in measured traffic, such as groups of very heavy vehicles travelling together and heavy vehicles being overtaken by lighter ones. These traffic patterns affect …
The Influence Of Correlation On The Extreme Traffic Loading Of Bridges,
2010
University College Dublin
The Influence Of Correlation On The Extreme Traffic Loading Of Bridges, Eugene J. Obrien, Bernard Enright, A. T. Dempsey
Conference papers
Accurate traffic loading models based on measured data are essential for the accurate assessment of existing bridges. There are well-established methods for the Monte Carlo simulation of single lanes of traffic, and this can easily be extended to model the loading on bridges with two independent streams of traffic in opposing directions. However, a typical highway bridge will have multiple lanes in the same direction, and various types of correlation are evident in measured traffic. This paper analyses traffic patterns using multi-lane WIM data collected at two European sites. It describes an approach to the Monte Carlo simulation of this …
Optimal Design Of Trusses With Geometric Imperfections,
2010
Cleveland State University
Optimal Design Of Trusses With Geometric Imperfections, Mehdi Jalalpour, Takeru Igusa, James K. Guest
Civil and Environmental Engineering Faculty Publications
The present paper focuses on optimization of trusses that have randomness in geometry that may arise from fabrication errors. The analysis herein is a generalization of a perturbation approach to topology optimization under geometric uncertainties. The main novelty in the present paper is in the consideration of potential buckling due to misaligned structural members. The paper begins with a brief review of the aforementioned perturbation approach, then proceeds with the analysis of the nonlinear effects of geometric imperfection. The paper concludes with some numerical examples.
Using Virtual Reality To Enhance Electrical Safety And Design In The Built Environment,
2010
Technological University Dublin
Using Virtual Reality To Enhance Electrical Safety And Design In The Built Environment, Martin Barrett, Jonathan Blackledge, Eugene Coyle
Articles
Electricity and the inherent risks associated with its use in the built environment have long since been a priority for the electrical services industry and also the general public who must live and work in this environment. By its nature virtual reality has the advantage of being safe for both the user and equipment. In addition, it offers the user an opportunity to be exposed to a range of scenarios and conditions that either occur infrequently or are hazardous to replicate. This paper presents a prototype desktop virtual reality model, to enhance electrical safety and design in the built environment. …
Characteristic Dynamic Increment For Extreme Traffic Loading Events On Short And Medium Span Highway Bridges,
2010
University College Dublin
Characteristic Dynamic Increment For Extreme Traffic Loading Events On Short And Medium Span Highway Bridges, Eugene J. Obrien, Daniel Cantero, Bernard Enright, Arturo González
Articles
More accurate assessment of safety can prevent unnecessary repair or replacement of existing bridges which in turn can result in great cost savings at network level. The allowance for dynamics is a significant component of traffic loading in many bridges and is often unnecessarily conservative. Critical traffic loading scenarios are considered in this paper with a model that allows for vehicle-bridge interaction and takes into account the road surface condition. Characteristic dynamic allowance values are presented for the assessment of mid-span bending moment in a wide range of short to medium span bridges for bi-directional traffic.
Importance Of The Tail In Truck Weight Modeling For Bridge Assessment,
2010
University College Dublin
Importance Of The Tail In Truck Weight Modeling For Bridge Assessment, Eugene J. Obrien, Bernard Enright, Abraham Getachew
Articles
To predict characteristic extreme traffic load effects, simulations are sometimes performed of bridge loading events. To generalize the truck weight data, statistical distributions are fitted to histograms of weight measurements. This paper is based on extensive WIM measurements from two European sites and shows the sensitivity of the characteristic traffic load effects to the fitting process. A semi-parametric fitting procedure is proposed: direct use of the measured histogram where there are sufficient data for this to be reliable and parametric fitting to a statistical distribution in the tail region where there are less data. Calculated characteristic load effects are shown …
