scholarly journals Durability of steel rail bridges as a part of environmental protection

2016 ◽  
Vol 15 (1) ◽  
pp. 061-070
Author(s):  
Petro Savchuk ◽  
Olesya Maksymovych ◽  
Vitaliy Knysh
Keyword(s):  
Stress Intensity ◽  
Adverse Effects ◽  
Experimental Research ◽  
Fatigue Cracks ◽  
Steel Structures ◽  
Intensity Factors ◽  
Steel Rail ◽  
Method Of Calculation ◽  
A Value ◽  
Existing Bridges

Condition of bridges with defects can lead to destruction and at the same time adverse effects on the environment, causing discomfort to society. Therefore, it is necessary to predict the durability of existing bridges, including resistance to increasing number of fatigue cracks, which can lead to the destruction of the steel elements. The article presents the results of theoretical and experimental research, which can be used to assess the durability of steel structures. The method of calculation of fatigue cracks growth in anisotropic elements, occurring at different angles to the stiffeners, was presented in the paper. Developed calculation allows estimating time of growth of cracks to some (safe) sizes and determining a value of stress intensity factors, based on which major repairs of the damaged areas can be planned.

Monitoring Fatigue Cracks and Stress Intensity Factors Based on the Distributed Dislocation Technique

2012 ◽  
Vol 525-526 ◽  
pp. 189-192
Author(s):  
Ramdane Boukellif ◽  
Andreas Ricoeur
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Detection ◽  
Dimensional Space ◽  
Fatigue Cracks ◽  
Particle Swarm Algorithm ◽  
Problem Solution ◽  
Intensity Factors ◽  
Unknown Parameters ◽  
Factor Measurement

We present a method for crack detection and stress intensity factor measurement in plate structures by using strain gauges and applying the dislocation method. The presented approach is based on the strain measured at different locations on the surface of the structure. This allows both the identification of crack position parameters, such as length, location and angles with respect to a reference coordinate system and the calculation of stress intensity factors (SIF). The method solving the direct problem is based on the idea of representing the crack by a line of point dislocations. The latter are formed by applying a constant displacement between adjacent points located at either side of the crack. Thus, the approach is based on the weighted superposition of elastic Greens functions representing the strain field due to the presence of a crack, where the weights are being identified by inverse problem solution. Since the strain fields are controlled by both external loads and the crack growth the unknown parameters are crack length, position and inclination as well as loading quantities. The particle swarm algorithm (PSO) came out to be most suitable for parameter identification in a high dimensional space.

Frequency Transfer Function From Fluid Temperature Fluctuations to Stress Intensity Factors

2003 ◽  
Author(s):  
Naoto Kasahara ◽  
Masanori Ando ◽  
Ihciro Furuhashi ◽  
Chen Fuquan ◽  
Hideki Takasho
Keyword(s):  
Stress Intensity ◽  
Transfer Function ◽  
Stress Intensity Factors ◽  
Temperature Fluctuation ◽  
Fatigue Cracks ◽  
Temperature Fluctuations ◽  
Fluid Temperature ◽  
Intensity Factors ◽  
Rational Analysis ◽  
Frequency Transfer

Temperature fluctuation from incomplete fluid mixing can induce fatigue cracks on structures of nuclear components, which should be prevented. For rational analysis of this phenomenon, the authors have developed a frequency transfer function that translates fluid temperature fluctuation to stress intensity factors. This function is formulated by a product of the effective heat transfer and the stress intensity factor functions, and enables us to quickly calculate stresses intensity factors induced by fluid temperature fluctuations. Furthermore, it can evaluate sensitivities of stress intensity factors to frequencies of temperature fluctuation, Biot number and constraint conditions of structures. Applicability of this function was verified through comparison with stress intensity factors calculated by the finite element method.

Propagation of Fatigue Cracks Emanating from Sharp Notches under Different Loading Direction

2007 ◽  
Vol 348-349 ◽  
pp. 461-464
Author(s):  
Matteo Benedetti ◽  
M. Beghini ◽  
L. Bertini ◽  
V. Fontanari
Keyword(s):  
Stress Intensity ◽  
Applied Load ◽  
Fatigue Cracks ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Notched Specimens ◽  
Loading Direction ◽  
Al 7075 ◽  
Elastic Fracture ◽  
Edge Cracks

The present paper is aimed at investigating the behaviour of fatigue cracks emanating from sharp V-shaped notches. To this purpose, several tests has been conducted on Al-7075-T651 notched specimens using a servohydraulic machine by changing the directions and levels of the applied load. The crack growth have been interpreted on the basis of a linear elastic fracture mechanics approach by adopting a weight function derived by the authors for the calculation of the stress intensity factors (SIFs) of inclined edge-cracks emanating from V-shaped notches.

Mode I and Mode II Stress Intensity Factors Based on Crack Opening and Sliding Displacements

2011 ◽  
Vol 179-180 ◽  
pp. 1417-1422
Author(s):  
You Li Ma
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Stress Ratio ◽  
Fatigue Cracks ◽  
Crack Opening ◽  
Intensity Factors ◽  
Slant Angle ◽  
Measured Stress ◽  
Discontinuous Displacement ◽  
Made In

It is necessary to study crack opening and sliding discontinuous displacement behavior under mixed-mode conditions because parts or structures of a machine with a crack maybe subject to stress from various directions. In this study ,therefore, using the cracks with different slant angle, which are made in circle stress of modeⅠwith stress ratio of R=0, the opening and sliding discontinuous displacements are measured ,so that modeⅠand mode Ⅱ stress intensity factors (KⅠ)mes and (KⅡ)mes at the crack tip are calculated. As a result, the measured stress intensity factors value of (KⅠ)mes from the fatigue crack with the slant angle β=60 deg. is smaller than the theoretical one (KⅠ). But for mode Ⅱ,(KⅡ)mes is about the same with (KⅡ). On the other hand, for the fatigue cracks with smaller slant angle β=45 deg.,(KⅡ)mes declined because of the crack-surface contact while (KⅠ)mes reduced.

Estimation of Stress Intensity Factors for Embedded Irregular Cracks Subjected to Arbitrary Normal Stress Fields

1980 ◽  
Vol 102 (2) ◽  
pp. 202-211 ◽  
Author(s):  
M. Oore ◽  
D. J. Burns
Keyword(s):  
Stress Intensity ◽  
Normal Stress ◽  
Fatigue Cracks ◽  
Three Dimensional ◽  
Stress Fields ◽  
Intensity Factors ◽  
Opening Mode ◽  
Mode Stress ◽  
Planar Crack ◽  
Integral Procedure

An integral is developed for calculating opening mode stress intensity factor at any point on the front of an irregular planar crack embedded in an infinite solid and subjected to an arbitrary normal stress field. No other solutions are available for irregular cracks, therefore the integral is first used to analyze three-dimensional regular cracks for which there are solutions. An embedded square crack is used to illustrate the integral procedure for an irregular shape. The integral is also used to explain qualitatively how irregular fatigue cracks will grow.

Calculation of Stress Intensity Factors and Crack Opening Displacements for Cracks Subjected to Complex Stress Fields

2003 ◽  
Vol 125 (3) ◽  
pp. 260-266 ◽  
Author(s):  
A. Kiciak ◽  
G. Glinka ◽  
D. J. Burns
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Fatigue Cracks ◽  
Crack Opening ◽  
Complex Stress ◽  
Pressure Vessels ◽  
Stress Fields ◽  
Function Technique ◽  
Weight Functions ◽  
Intensity Factors

Fatigue cracks in shot peened and case hardened notched machine components and high-pressure vessels are subjected to the stress fields induced by the external load and the residual stress resulting from the surface treatment or autofrettage. Both stress fields are usually nonuniform and available handbook stress intensity factor solutions are in most cases unavailable for such configurations, especially in the case of two-dimensional surface breaking cracks such as semi-elliptical and quarter-elliptical cracks at notches. The method presented in the paper makes it possible to calculate stress intensity factors for such cracks and complex stress fields by using the generalized weight function technique. It is also shown that the generalized weight functions make it possible to calculate the crack opening displacement field often used in the determination of the critical load or the critical crack size.

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