scholarly journals THE INVESTIGATION AND PECULIARITIES OF CALCULATION OF TRANSPORT MACHINE ELEMENTS MADE OF AUSTEMPERED DUCTILE IRON

Transport ◽  
2003 ◽  
Vol 18 (4) ◽  
pp. 162-167 ◽  
Author(s):  
Mindaugas Leonavičius ◽  
Algimantas Krenevičius ◽  
Marijonas Šukšta ◽  
Jukka Posa
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Ductile Iron ◽  
Fatigue Crack Initiation ◽  
Austempered Ductile Iron ◽  
Compact Specimen ◽  
Complete Evaluation ◽  
Growth Ratio

In this article the statical and cyclical strength investigations of austempered ductile cast iron (ADI) are presented. ADI material becomes more and more popular. Ductile iron is lighter than steel and its mechanical properties are better. ADI has good resistance to fatigue, high tensile strength, toughness and ductility. The fatigue crack initiation generally occurs in the graphite matrix. In the work the kinetic fatigue diagrams, longevity distributions laws and the mathematical model of crack growth ratio are described. The blanks of material were cut from a tooth of gear. Structure of the material consists of bainite and spherical graphite. The mechanical properties of ADI were obtained with assessment of chemical composition. The detennined statical mechanical properties of two different ADI materials are presented. The compact specimen was produced in order to detennine a threshold stress intensity factor. According to the investigations the stress intensity factor (threshold) is ΔK th = 9,8 MPa√m for the ADI 6.2.02 and ΔK th = 8,6 MPa√m for the ADI 9.4.02. The carried out investigations are insufficient for the complete evaluation of austempered ductile iron for the production of transport equipment elements.

General Method for Optimizing Composite Patch Repairs

2015 ◽  
Vol 1120-1121 ◽  
pp. 670-674
Author(s):  
Abdelmadjid Ait Yala ◽  
Abderrahmanne Akkouche
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Optimization Problem ◽  
Composite Patch ◽  
Matlab Program ◽  
Patch Repairs ◽  
Selection Of ◽  
General Method

The aim of this work is to define a general method for the optimization of composite patch repairing. Fracture mechanics theory shows that the stress intensity factor tends towards an asymptotic limit K∞.This limit is given by Rose’s formula and is a function of the thicknesses and mechanical properties of the cracked plate, the composite patch and the adhesive. The proposed approach consists in considering this limit as an objective function that needs to be minimized. In deed lowering this asymptote will reduce the values of the stress intensity factor hence optimize the repair. However to be effective this robust design must satisfy the stiffness ratio criteria. The resolution of this double objective optimization problem with Matlab program allowed us determine the appropriate geometric and mechanical properties that allow the optimum design; that is the selection of the adhesive, the patch and their respective thicknesses.

Nondestructive detection of fatigue cracks in PM 304 stainless steel by internal friction and elasticity

1993 ◽  
Vol 8 (9) ◽  
pp. 2216-2223 ◽  
Author(s):  
S.M. McGuire ◽  
M.E. Fine ◽  
O. Buck ◽  
J.D. Achenbach
Keyword(s):  
Stress Intensity Factor ◽  
Stainless Steel ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Internal Friction ◽  
Crack Growth ◽  
Fatigue Cracks ◽  
Mechanical Vibration ◽  
Fatigue Crack Initiation ◽  
304 Stainless Steel

A resonant frequency mechanical vibration method was used to nondestructively detect fatigue crack initiation in notched 304 stainless steel samples prepared by powder metallurgy. This method allowed the determination of an effective elastic modulus and the direct measurement of internal friction. Changes in the modulus and internal friction were found to correlate well with the presence of 50 μm long fatigue cracks. The length of the through cracks initiated at the notch was measured using surface replicas, which were examined in a scanning electron microscope. Small crack growth rate data were also obtained and plotted versus the stress intensity factor. The crack growth rates were compared with long crack data performed on compact tension samples of this material. The short cracks grew at intensity factors below the long crack threshold stress intensity factor.

scholarly journals Investigation on the Effect of Crack Length on Mechanical Properties of Functionally Graded Materials

2010 ◽  
Vol 44-47 ◽  
pp. 2244-2248
Author(s):  
Gang Chen ◽  
Xi Yu Zhao ◽  
Peng Cheng Zhai
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Pure Metal ◽  
Functionally Graded ◽  
Crack Tip Field ◽  
Graded Materials ◽  
Barrier Coating

In this article, the thermo-mechanical responses of ceramic/metal functionally graded thermal barrier coating(TBC) in work environment are analyzed by a finite element method. Both the crack-tip field and the stress intensity factor of functionally graded TBC are analyzed and calculated. It is discussed that the effect of crack length on mechanical properties of functionally graded TBC in the condition creep and no creep of pure metal. The numerical results indicate that the effect of crack length(a/t) is negligible to temperature distributions and the maximum displacements of whole model but remarkable to the 1st principal stress and stress intensity factor of crack region. Moreover, creep phenomenon of pure metal can relax the value of displacement, stress and stress intensity factor but do not alter their distribution.

scholarly journals NUMERICAL EVALUTION OF STRESS INTENSITY FACTOR AND STRESS BIAXIALITY FOR COMPACT SPECIMEN BASED ON GRAPH MODEL OF ELASTIC SOLID

2020 ◽  
pp. 58-61
Author(s):  
A. Tyrymov
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Graph Model ◽  
Elastic Solid ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Compact Specimen ◽  
Tension Specimen ◽  
Singular Element

The paper presents the results of numerical calculation of the stress intensity factor and the biaxiality factor for a compact tension specimen. A singular element of the graph model of an elastic solid is used to analyze the stress state near a crack.

Estimation of Fatigue Limit in Interior Inclusion Induced Fracture Mode for Bearing Steel in Rotating Bending

2015 ◽  
Vol 664 ◽  
pp. 188-198
Author(s):  
Noriyasu Oguma ◽  
Naoya Sekisugi ◽  
Yasuhiro Odake ◽  
Tatsuo Sakai
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fatigue Limit ◽  
Fracture Mode ◽  
Hydrogen Charge ◽  
Stress Intensity Factor Range ◽  
Growth Ratio ◽  
Rotating Bending

The fatigue life forming fine granular area (FGA) is expected to occupy a large fraction of the total fatigue life. In order to examine the commencing time of the FGA forming and estimate the fatigue limit in the interior inclusion induced fracture mode, rotating bending fatigue tests were carried out by using SUJ2 specimens with and without the hydrogen charge. Especially, the hydrogen charge time was set in the wide variety of the cyclic loadings to confirm the FGA forming process supposing the effect of the hydrogen charge on the fatigue crack propagation behavior. From experimental and analytical results, it is concluded that the FGA formation is already started at early stage as 5 % of the fatigue life. Another finding is that we have a clear correlation between the stress intensity factor range and the FGA growth ratio. Based on this aspect, the critical value of the stress intensity factor range in which the FGA is not formed around the inclusion was given as 2.65 MPa.

Effect of the Size of the Reinforcement Phased on the Properties of Silica-Filled Composites

2007 ◽  
Vol 544-545 ◽  
pp. 267-270 ◽  
Author(s):  
Hyung Jin Kim ◽  
Sung Wi Koh ◽  
Jae Dong Kim ◽  
Byung Tak Kim
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Particle Size ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Flexural Strength ◽  
Critical Stress ◽  
Particle Diameter ◽  
Critical Stress Intensity Factor ◽  
Average Particle

In this study, the mechanical properties of silica-filled epoxy resin composites with average silica particle diameter of 6-33m were investigated at ambient temperature and pin-ondisc friction test was conducted for this. Experimental results demonstrated that mechanical properties such as flexural strength, flexural modulus and critical stress intensity factor depend on average particle diameter. The flexural strength decrease with increase of particle size whereas the critical stress intensity factor increases with increases of particle size. Wear rates of silica-filled composites are below a half those of unfilled epoxy. Fracture surface analysis was discussed based on SEM examination.

Numerical analysis of cracked aluminum plate repaired with multi-scale reinforcement composite patches

2020 ◽  
Vol 54 (28) ◽  
pp. 4341-4357
Author(s):  
A Yousefi ◽  
M Mosavi Mashhadi ◽  
M Safarabadi
Keyword(s):  
Mechanical Properties ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Cohesive Zone Model ◽  
Volume Fraction ◽  
Aluminum Plate ◽  
Zone Model ◽  
Composite Patch ◽  
Different Thickness

In this study, numerical modeling is used to investigate the performance of a single-sided composite patch with different scale fillers, as reinforcement of a cracked aluminum plate under static tension. The main concerns of previous studies are about the geometry of patches, composite layups, and failure of adhesive. In this research, the effect of patch properties such as size and fiber volume fraction, the thickness of patch, and thickness of adhesive on the overall performance of the cracked aluminum plate are investigated numerically. Indeed, first, a 3 D representative volume element (RVE) is adopted to calculate the mechanical properties of carbon nanotube (CNT)/epoxy and carbon fiber (CF)/epoxy composite patch at each specified volume fraction for investigating the effect of patch properties on the performance of a single-sided patch for crack repairing. In this regard, the cohesive zone model is adopted to analyze the debonding between the epoxy matrix and reinforcement to characterize the mechanical properties of composite patches. Finally, a linear 3 D finite element analysis is performed to calculate the stress intensity factor (SIF) for cracked aluminum plate repaired by a single-sided composite patch at each specified reinforcement volume fraction for different thickness of patch and different thickness of adhesive. The results demonstrated that the stress intensity factor highly depends on the patch properties (patch stiffness) in addition to patch thickness and adhesive thickness.

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