Quantification of vertical, lateral, and longitudinal fastener demand in broken spike track: Inputs to mechanistic-empirical design

2021 ◽  
pp. 095440972110307
Author(s):  
Marcus S Dersch ◽  
Matheus Trizotto ◽  
J Riley Edwards ◽  
Arthur de Oliveira
Keyword(s):  
Fatigue Life ◽  
Design Principles ◽  
Lateral Load ◽  
System Component ◽  
Applied Loading ◽  
Component Design ◽  
Stress Reversals ◽  
Fatigue Failures ◽  
Empirical Design

To address a recent challenge related to broken spikes in premium elastic fastening systems that have led to at least ten derailments and require manual walking inspections as well as build upon mechanistic-empirical (M-E) design principles for future fastening system component design, this paper quantifies the vertical, lateral, and longitudinal fastening system loads under revenue service traffic in a curve that has regularly experienced spike fastener fatigue failures. Previous data has indicated that the high rail of Track 3 experienced the most failures at this location. The data from this investigation sheds light into why failures are more predominant at this location than others and how the vertical, lateral, and longitudinal loads cannot be considered independently. Specifically, while the magnitude of the applied loading was the lowest on the high rail of Track 3, the threshold for failure was also the lowest given the operations at this location led to unloading of the high rail, thus indirectly highlighting the importance of friction within a fastening system. The data also show the high rail of Track 3 was subjected to the highest L/V load ratios and was an outlier in the typical lateral load reversals applied likely leading to spike stress reversals and thus a shorter fatigue life. Finally, based upon the data, it is recommended that to mitigate spike failures, as well as similar fastener challenges in other track types (e.g. rail seat deterioration, etc.) railroads should ensure trains operate close to the balance speed and use fastening system that transfer loads through friction. This study also provides novel data for M-E design of fastening systems.

Application on H-Beam with Trapezoidally Corrugated Webs

2011 ◽  
Vol 94-96 ◽  
pp. 342-349
Author(s):  
Wen Long Shi ◽  
Xuan Liu
Keyword(s):  
Carrying Capacity ◽  
Design Principles ◽  
Paper Analysis ◽  
Load Carrying Capacity ◽  
Main Design ◽  
Component Design ◽  
Corrugated Webs ◽  
Load Carrying ◽  
New Type ◽  
H Beam

The H-beam with corrugated webs is a new type of H-beam, whose webs are produced by substituting corrugated webs for flat webs. In this paper, analysis was conducted to study main design principles for H-beam with corrugated webs used in a project, including component design and joints design. Compared with H-beams, the products have superior load-carrying capacity and more favorable economic advantages.

Liquid fluorine feed system component design criteria

1970 ◽  
Author(s):  
D. ENDICOTT ◽  
P. KLEVATT ◽  
F. STECKER
Keyword(s):  
System Component ◽  
Design Criteria ◽  
Feed System ◽  
Component Design

Prediction of Equivalent Radial Loads for Tapered Roller Bearings

1996 ◽  
Vol 118 (3) ◽  
pp. 651-656
Author(s):  
Ted E. Bailey ◽  
Robert W. Frayer
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Roller Bearing ◽  
Contact Fatigue ◽  
Subsequent Development ◽  
Rolling Contact ◽  
Tapered Roller Bearing ◽  
Applied Loading ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Calculating the fatigue life of a tapered roller bearing has become a rather straightforward exercise thanks to the accumulation of rolling contact fatigue data and the subsequent development of formulation relating applied loading to bearing fatigue life. An integral part of the prediction process is to define an equivalent radial load (EQRL) by combining a bearing’s applied radial and thrust loading into a single entity. This paper reviews currently accepted formulation and offers a potentially more accurate alternative method for estimating the EQRL of a tapered roller bearing than does the current AFBMA standard.

Vibration Fatigue Assessment of Additive Manufactured Nickel Alloy With Inherent Damping

2020 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Luke Sheridan ◽  
Brian Runyon ◽  
Tommy George
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Vibration Suppression ◽  
Internal Surface ◽  
Powder Bed ◽  
Vibration Fatigue ◽  
Strain Stress ◽  
Internal Volume ◽  
Fatigue Failures ◽  
Damping Capability

Abstract The fatigue life behavior and internal surface conditions of inherently damped Additive Manufactured (AM) specimens subjected to vibration bending are under investigation. This study supports research that demonstrated 95% vibration suppression due to damping capability of AM components with 1–3% internal volume of unfused powder. The damping demonstrations have been carried out using laser powder bed fusion (LPBF) specimens of various thicknesses, lengths, and unfused internal powder configurations. In addition, damping is shown to be achievable with both nickel-based alloys and stainless steel specimens. Despite the promise of this method, the viability of fatigue performance is unknown. The following effort aims to address this structural integrity issue; specifically, this study explores whether internal pocket roughness or erosion caused by powder particle motion induces a fatigue life debit. These concerns are addressed by comparing the fatigue behaviors of unfused powder pocket and fully-fused nickel based alloy 718 specimens. Microscopy results confirmed a long suspected powder interaction phenomena as well as appearances of erosion. Furthermore, fractography supports that fatigue failures initiate near the surface of maximum strain/stress at porous features consistent with stock (non-optimized) LPBF process parameters.

Fatigue of Metals

2012 ◽  
pp. 147-207
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Stress ◽  
Stress Concentrations ◽  
Final Fracture ◽  
Life Improvement ◽  
Three Stages ◽  
Fatigue Failures ◽  
Strength And Ductility

Abstract This chapter discusses the factors that play a role in fatigue failures and how they affect the service life of metals and structures. It describes the stresses associated with high-cycle and low-cycle fatigue and how they differ from the loading profiles typically used to generate fatigue data. It compares the Gerber, Goodman, and Soderberg methods for predicting the effect of mean stress from bending data, describes the statistical nature of fatigue measurements, and explains how plastic strain causes cyclic hardening and softening. It discusses the work of Wohler, Basquin, and others and how it led to the development of a strain-based approach to fatigue and the use of fatigue strength and ductility coefficients. It reviews the three stages of fatigue, beginning with crack initiation followed by crack growth and final fracture. It explains how fracture mechanics can be applied to crack propagation and how stress concentrations affect fatigue life. It also discusses fatigue life improvement methods and design approaches.

A Study of the Surface Penetration of High Cycle Thermal Loading in Pressure Retaining Components

2015 ◽  
Author(s):  
Michael Jones ◽  
Keith F. Carter
Keyword(s):  
Fatigue Life ◽  
Penetration Depth ◽  
Thermal Loading ◽  
Surface Effect ◽  
Temperature Oscillation ◽  
Fluid Mixing ◽  
Design Decisions ◽  
Life Management ◽  
Component Design ◽  
Sensitivity Studies

This paper presents an overview of sensitivity studies undertaken by Rolls-Royce into the penetration of High Cycle Thermal Loading (HCTL) in Pressurised Water Reactor (PWR) components. HCTL is a surface effect which has the potential to impact the fatigue life of pressure retaining components, typically at fluid mixing tees and other regions of turbulent mixing flows at different temperatures. This effect can significantly reduce the fatigue life of components. Understanding the factors that contribute to the penetration depth of HCTL can lead to possible benefits in analysis carried out to inform design decisions and support through-life management. The sensitivity studies presented herein use governing equations for heat transfer at solid surfaces to assess how component properties and loading conditions such as material type, wall thickness and temperature oscillation frequency affect the penetration depth of HCTL and thus the resultant stresses generated within metal surfaces close to fluid mixing zones. This paper discusses the potential benefits of improved analysis of HCTL effects to inform component design decisions and support through-life management. This is directly applicable to the selection of Start-of-Life (SoL) defect sizes for defect tolerance studies i.e. the assumed initial defect size, the development of Non-Destructive Examination (NDE) techniques, and the safe estimation of In-Service Inspection (ISI) periods at areas of concern.

Thermographic Determination of Fatigue Damage

1978 ◽  
Vol 100 (2) ◽  
pp. 200-203 ◽  
Author(s):  
J. A. Charles ◽  
F. J. Appl ◽  
J. E. Francis
Keyword(s):  
Fatigue Life ◽  
Mild Steel ◽  
Surface Temperature ◽  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Temperature Distributions ◽  
Fatigue Failures

The energy released due to hysteresis effects in cyclically loaded materials can be used to predict where fatigue cracks are likely to initiate and to determine the stage of fatigue life. In the present study, thermography is used to monitor the surface temperature distributions on a series of double-notched, mild steel fatigue specimens cyclically loaded in bending. The results indicate that the fatigue life of the material encompasses three thermal stages, each of which is indicative of the fatigue damage the material has sustained. This information can be used to avoid in-service fatigue failures.

scholarly journals Fatigue life and crack growth behavior of post welded Aluminum 5183 alloy

2018 ◽  
Vol 165 ◽  
pp. 21013 ◽  
Author(s):  
Vidit Gaur ◽  
Manabu Enoki ◽  
Toshiya Okada ◽  
Syohei Yomogida
Keyword(s):  
Grain Size ◽  
Fatigue Life ◽  
Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Mean Stress ◽  
Threshold Values ◽  
R Ratio ◽  
Fatigue Failures ◽  
Mean Stresses

In this study we investigated the fatigue life and crack growth behavior of Al-5183 alloy. Microscopic analysis revealed nearly equi-axed grains and no texture in longitudinal or cross-sectional plane of the welded plates. Gas porosities with an average size of 45 μm, comparable to grain size (55 μm), were present and often initiate fatigue failures. Load-controlled cyclic tests at different stress-ratios (R = -1, -0.5, 0.1, 0.5. 0.7 and 0.8) revealed decrease in fatigue lives with increase in R-ratio. At R > 0.7, no fatigue failure could be observed, suggesting a probable mean-stress saturation effect on fatigue. Mean stress also tends to control the crack initiation sites: surface initiated failures at low mean stresses while sub-surface pores induced failures at higher mean stresses. Fatigue-crack growth tests on CT specimens at different R-ratios (0.1, 0.5 and 0.8) revealed reduction in crack growth rates (and in threshold values) with increasing R-ratio. The ΔK applied for pores responsible for fatigue failures were often lower than or near to the threshold values and also, the size of such pores was of order of magnitude of grain size, thus crack initiated from pores are short cracks and further tests are progress.

EFFECT OF FATIGUE TEST ON SPOT WELDED STRUCTURAL JOINT

2017 ◽  
Vol 79 (5-2) ◽  
Author(s):  
Mohammad Khalid Wahid ◽  
Muhammad Nabil Muhammed Sufian ◽  
Mohamed Saiful Firdaus Hussin
Keyword(s):  
Life Cycle ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Spot Welding ◽  
Fatigue Testing ◽  
Fatigue Stress ◽  
Component Design ◽  
Welded Structure ◽  
Different Thickness ◽  
Spot Welded

Spot welding is mainly used method in joining sheet metals for body structure in automotive industry. The comprehension of the fatigue strength for the spot welds is very critical in automotive component design. Parameter for the resistance spot welding and fatigue machines is constant for each specimen used. The S-N curve is obtained from the fatigue testing for each specimen. This experiment parameters are varies the different thickness and different material combination in spot welding structure to investigate the fatigue life cycle and fatigue stress. For 1050A aluminium joint, fatigue life cycle and fatigue strength will decrease from number of cycle 500 at 16.58 MPa to number of cycle 61 at 6.62 MPa as the thickness increase. The fatigue life cycle and fatigue stress for galvanized iron will increase from number of cycle  46 at 9.25 MPa to number of cycle  1500 at 57.8 MPa when the thickness of joint increase. The finding from the combination of 1050A aluminum and galvanized iron on spot welded structure has shown no improvement in term of fatigue life cycle and fatigue strength because specimens experienced failure at number of cycle 19 with fatigue stress 2.36 MPa.

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