Analysis of the Relationship Between Rail Seat Load Distribution and Rail Seat Deterioration in Concrete Crossties

2014 ◽  
Author(s):  
Matthew Greve ◽  
Marcus S. Dersch ◽  
J. Riley Edwards ◽  
Christopher P. L. Barkan ◽  
Jose Mediavilla ◽  
...  
Keyword(s):  
Load Distribution ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Past Research ◽  
Concrete Surface ◽  
Hydraulic Pressure ◽  
Valuable Insight ◽  
Increased Risk ◽  
Abrasive Erosion ◽  
Field Experimentation

One of the most common failure modes of concrete crossties in North America is the degradation of the concrete surface at the crosstie rail seat, also known as rail seat deterioration (RSD). Loss of material beneath the rail can lead to wide gauge, rail cant deficiency, and an increased risk of rail rollover. Previous research conducted at the University of Illinois at Urbana-Champaign (UIUC) has identified five primary failure mechanisms: abrasion, crushing, freeze-thaw damage, hydro-abrasive erosion, and hydraulic pressure cracking. The magnitude and distribution of load applied to the rail seat affects four of these five mechanisms; therefore, it is important to understand the characteristics of the rail seat load distribution to effectively address RSD. As part of a larger study funded by the Federal Railroad Administration (FRA) aimed at improving concrete crossties and fastening systems, researchers at UIUC are attempting to characterize the loading environment at the rail seat using matrix-based tactile surface sensors (MBTSS). This instrumentation technology has been implemented in both laboratory and field experimentation, and has provided valuable insight into the distribution of a single load over consecutive crossties. A review of past research into RSD characteristics and failure mechanisms has been conducted to integrate data from field experimentation with existing knowledge, to further explore the role of the rail seat load distribution on RSD. The knowledge gained from this experimentation will be integrated with associated research conducted at UIUC to form the framework for a mechanistic design approach for concrete crossties and fastening systems.

Evaluation of Laboratory and Field Experimentation Characterizing Concrete Crosstie Rail Seat Load Distributions

2015 ◽  
Author(s):  
Matthew J. Greve ◽  
Marcus S. Dersch ◽  
J. Riley Edwards ◽  
Christopher P. L. Barkan
Keyword(s):  
Load Distribution ◽  
Concrete Surface ◽  
Primary Concern ◽  
University Of Illinois ◽  
Factors Affecting ◽  
Load Distributions ◽  
Increased Risk ◽  
Heavy Haul ◽  
Field Experimentation ◽  
The University

As higher demands are placed on North American railroad infrastructure by heavy haul traffic, it is increasingly important to understand the factors affecting the magnitude and distribution of load imparted to concrete crosstie rail seats. The rail seat load distribution is critical to the analysis of failure mechanisms associated with rail seat deterioration (RSD), the degradation of the concrete surface at the crosstie rail seat. RSD can lead to wide gauge, cant deficiency, and an increased risk of rail rollover, and is therefore of primary concern to Class I Freight Railroads in North America. Researchers at the University of Illinois at Urbana-Champaign (UIUC) have successfully characterized the loading environment at the rail seat using matrix-based tactile surface sensors (MBTSS). Previous research has proven the feasibility of using MBTSS in both laboratory and field applications, and recent field experimentation has yielded several hypotheses concerning the effect of fastening system wear on the rail seat load distribution. This paper will focus on the analysis of data gathered from laboratory experimentation with MBTSS to evaluate these hypotheses, and will propose a metric for crosstie and fastening system design which considers the uniformity of the load distribution. The knowledge gained from this experimentation will be integrated with associated research conducted at UIUC to form the framework for a mechanistic design approach for concrete crossties and fastening systems.

Methodology for Analysis of Schottky Diode Failures

2010 ◽  
Author(s):  
Bhanu P. Sood ◽  
Michael Pecht ◽  
John Miker ◽  
Tom Wanek
Keyword(s):  
Failure Mode ◽  
Schottky Diode ◽  
Failure Modes ◽  
Schottky Diodes ◽  
Failure Mechanisms ◽  
Forward Voltage ◽  
Fast Switching ◽  
Voltage Drops ◽  
The Common

Abstract Schottky diodes are semiconductor switching devices with low forward voltage drops and very fast switching speeds. This paper provides an overview of the common failure modes in Schottky diodes and corresponding failure mechanisms associated with each failure mode. Results of material level evaluation on diodes and packages as well as manufacturing and assembly processes are analyzed to identify a set of possible failure sites with associated failure modes, mechanisms, and causes. A case study is then presented to illustrate the application of a systematic FMMEA methodology to the analysis of a specific failure in a Schottky diode package.

scholarly journals Physical modelling of failure in composites

2016 ◽  
Vol 374 (2071) ◽  
pp. 20150280 ◽  
Author(s):  
Ramesh Talreja
Keyword(s):  
Composite Materials ◽  
Failure Modes ◽  
Structural Integrity ◽  
Failure Mechanisms ◽  
Local Stress ◽  
Physical Modelling ◽  
Stress Fields ◽  
Systematic Analysis ◽  
Composite Failure ◽  
Failure Theories

Structural integrity of composite materials is governed by failure mechanisms that initiate at the scale of the microstructure. The local stress fields evolve with the progression of the failure mechanisms. Within the full span from initiation to criticality of the failure mechanisms, the governing length scales in a fibre-reinforced composite change from the fibre size to the characteristic fibre-architecture sizes, and eventually to a structural size, depending on the composite configuration and structural geometry as well as the imposed loading environment. Thus, a physical modelling of failure in composites must necessarily be of multi-scale nature, although not always with the same hierarchy for each failure mode. With this background, the paper examines the currently available main composite failure theories to assess their ability to capture the essential features of failure. A case is made for an alternative in the form of physical modelling and its skeleton is constructed based on physical observations and systematic analysis of the basic failure modes and associated stress fields and energy balances. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

Stiction Failure Mechanisms of the Micromachined Electrostatic Comb-Drive Structures

2011 ◽  
Vol 80-81 ◽  
pp. 850-854
Author(s):  
Yi Shen Xu ◽  
Ji Hua Gu ◽  
Zhi Tao
Keyword(s):  
Failure Modes ◽  
Failure Mechanisms ◽  
Mems Devices ◽  
Comb Drive ◽  
Interfacial Forces ◽  
Restoring Forces ◽  
Critical Investigation

Stiction is one of the most important and almost unavoidable problems in MEMS, which usually occurs when the restoring forces of the microstructures are unable to overcome the interfacial forces. Stiction could compromise the performance and reliability of the MEMS devices or may even make them malfunction. One of the pivotal process of advancing the performance and reliability of MEMS is to comprehend the failure modes and failure mechanisms of these microdevices. This article provides a critical investigation on the stiction failure mechanisms of the micromachined electrostatic comb-drive structures, which is significant to improve the reliability of microdevices, especially for microfilters, microgrippers, microaccelerometers, microgyroscopes, microrelays, and so on.

Materials Failure Logic Models—A Procedure for Systematic Identification of Material Failure Modes in Mechanical Components

1982 ◽  
Vol 104 (3) ◽  
pp. 626-634 ◽  
Author(s):  
D. L. Marriott ◽  
N. R. Miller
Keyword(s):  
Failure Modes ◽  
Planning Process ◽  
Service Failure ◽  
Failure Mechanisms ◽  
Material Failure ◽  
Cad System ◽  
Logic Models ◽  
Identification Technique ◽  
Mechanical Components ◽  
Systematic Identification

This paper addresses the problem of improvement of mechanical component reliability by the systematic identification of material failure mechanisms. Experience shows that, in many cases of service failure, failure was caused by a known mechanism which was overlooked, either by design, or elsewhere in the planning process. This paper describes one approach to designing mechanical components against failure by material deterioration, but may have application to other fields. It is based on a finding from the examination of case studies which shows that material failures follow logic structures which can be described by Boolean algebra expressions. These structures are defined as Material Failure Logic Models (MFLM’s), and can be used as a means of systematically identifying potential failure mechanisms in a complex process. The identification technique is based on the observation that MFLM’s are insensitive to the precise causes of the individual events. The paper deals primarily with problems of defining MFLM’s. Some examples of MFLM’s are given. A brief discussion is presented of a CAD system under development at the University of Illinois at Urbana-Champaign.

scholarly journals Childhood maltreatment and inflammation among pregnant women with gestational diabetes mellitus: A pilot study

2017 ◽  
Vol 10 (3) ◽  
pp. 120-124 ◽  
Author(s):  
Margaret Bublitz ◽  
Suzanne De La Monte ◽  
Susan Martin ◽  
Lucia Larson ◽  
Ghada Bourjeily
Keyword(s):  
Diabetes Mellitus ◽  
Pilot Study ◽  
Gestational Diabetes ◽  
Gestational Diabetes Mellitus ◽  
Pregnant Women ◽  
Birth Outcomes ◽  
Childhood Maltreatment ◽  
Secondary Data ◽  
Past Research ◽  
Increased Risk

Background Women with childhood maltreatment histories are at increased risk for adverse birth outcomes. Mechanisms explaining this link are poorly understood. Past research is limited by sampling pregnant women at low risk for adverse maternal and neonatal outcomes. Methods This pilot study was a secondary data analysis of 24 women with gestational diabetes mellitus; 17% of the sample also reported a maltreatment history. Women provided a blood sample to measure inflammatory cytokines and insulin resistance, and saliva samples to measure diurnal cortisol. Birth outcomes for past and current pregnancies were recorded. Results Histories of maltreatment were associated with elevated interleukin-15 and a marginally greater incidence of preterm delivery in current and past pregnancies. Conclusions This pilot study was the first to demonstrate an association between childhood maltreatment history and inflammatory cytokine levels in pregnant women diagnosed with gestational diabetes mellitus.

Failure modes and failure mechanisms of single-layer reticulated domes subjected to interior blasts

2018 ◽  
Vol 132 ◽  
pp. 208-216 ◽  
Author(s):  
Jialu Ma ◽  
Feng Fan ◽  
Lingxin Zhang ◽  
Chengqing Wu ◽  
Xudong Zhi
Keyword(s):  
Failure Modes ◽  
Failure Mechanisms ◽  
Single Layer ◽  
Reticulated Domes

Global load determination in linear guides based on the fusion of local rolling element loads determined from strain sensitive sensor groups

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
David Krampert ◽  
Sebastian Unsleber ◽  
Leonhard Reindl ◽  
Stefan J. Rupitsch
Keyword(s):  
Load Distribution ◽  
Mechanical Load ◽  
Sensor System ◽  
Distribution Model ◽  
Valuable Insight ◽  
Estimation Errors ◽  
Rolling Element ◽  
Rolling Elements ◽  
Load Mode ◽  
Measurement Principle

Abstract Measuring the mechanical load on linear guides provides many possibilities regarding predictive maintenance and process monitoring. In this contribution, we provide an in depth evaluation of a Diamond Like Carbon (DLC) based sensor system integrated into the runner block’s raceway that is capable of directly measuring the load on individual rolling elements. An efficient algorithm based on an Extended Kalman Filter (EKF) for local sensor fusion and load estimation is presented and proven to reliably retrieve the load regardless of the rolling element’s position. Afterwards, we compare locally measured loads to results from a theoretical load distribution model, providing valuable insight into modeling parameters and a verification of the sensor measurement principle. In a final step, an algorithm to invert the load distribution model is derived and used for an evaluation of the sensor system, achieving Root-Mean-Square (RMS) estimation errors of equivalently 1.4 kN in the preload range and 2.75 kN overall for one dimensional loads. Load mode distinction was equally successful with a suppression RMS error of 0.7 kN in the preload range and 2.87 kN in total.

Modelling and Experimental Investgations of Tooling Issues for Thixoforming of Steel

2019 ◽  
Vol 285 ◽  
pp. 347-353
Author(s):  
Ahmed Rassili
Keyword(s):  
Finite Elements ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Surface Treatments ◽  
Hot Working ◽  
Tool Steels ◽  
Tool Materials ◽  
Tool Coating ◽  
Experimental Trials

Since the early 90’s, and from the very early investigations of steel thixoforming, tool materials as well as different kinds of coatings, including different tool steels and fully ceramic systems have been evaluated. The failure mechanisms have been carefully investigated by experiments and simulations and are nearly fully understood. Analysis of the reported literature on this topic shows that there is still a lot to do in this field and no excellent solution exists now a days for steel thixoforming. The aim of this work is to evaluate the thermal and mechanical loadings applied to the tools during steel thixoforming process in order to determine appropriate tool materials and solutions. This evaluation was realized thanks to experimental trials and to the finite elements simulations. The effect of these loadings on the tool’s failure modes are highlighted and compared to the ones observed in classical forming processes. Beyond this, the failure modes of different tool materials and solutions are presented. The tested materials are hot-working tool steels. Other possibilities and tool coating or surface treatments are discussed as well.

Finite Element Analysis of X-Cor Sandwich's Compressive Strength

2011 ◽  
Vol 306-307 ◽  
pp. 733-737
Author(s):  
Xu Dan Dang ◽  
Xin Li Wang ◽  
Hong Song Zhang ◽  
Jun Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compressive Strength ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Element Model ◽  
Failure Criteria ◽  
Stiffness Degradation ◽  
Element Analysis ◽  
Finite Element Software

In this article the finite element software was used to analyse the values for compressive strength of X-cor sandwich. During the analysis, the failure criteria and materials stiffness degradation rules of failure mechanisms were proposed. The failure processes and failure modes were also clarified. In the finite element model we used the distributions of failure elements to simulate the failure processes. Meanwhile the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates that the resin regions of Z-pin tips fail firstly and the Z-pins fail secondly. The dominant failure mode is the Z-pin elastic buckling and the propagation paths of failure elements are dispersive. Through contrast the finite element values and test results are consistent well and the error range is -7.6%~9.5%. Therefore the failure criteria and stiffness degradation rules are reasonable and the model can be used to predict the compressive strength of X-cor sandwich.

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