Stress Intensity Factors and Paths for Cracks in Photoelastic Motor Grain Models Under Internal Pressure

2001 ◽  
Author(s):  
C. W. Smith ◽  
D. M. Constantinescu ◽  
C. T. Liu
Keyword(s):  
Stress Intensity Factor ◽  
Experimental Investigation ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Computational Analysis ◽  
Tensile Tests ◽  
Small Radius ◽  
Two Dimensional ◽  
Intensity Factors ◽  
Tip Radius

Abstract Computational analysis and two-dimensional tensile tests on single motor grain fins suggest that cracks in fin tips are most likely to originate at the coalescence of a fin end tip radius, with a small radius from the side of the fin. Some manufacturers have also noticed defects formed during casting at the fin tip on the fin axis. The following is an experimental investigation utilizing frozen stress photoelastic models of an existing motor grain geometry in order to clarify stress intensity factor (SIF) values and crack growth paths for cracks emanating from the two above-noted potential critical loci. Comparisons between results from cracks grown from the two loci will be made, suggesting interesting conclusions.

Stress Intensity Factors and Crack Paths for Cracks in Photoelastic Motor Grain Models

2002 ◽  
Author(s):  
C. W. Smith ◽  
D. M. Constantinescu ◽  
C. T. Liu
Keyword(s):  
Stress Intensity ◽  
Computational Analysis ◽  
Tensile Tests ◽  
Small Radius ◽  
Two Dimensional ◽  
Intensity Factors ◽  
Photoelastic Method ◽  
Shear Modes ◽  
Tip Radius ◽  
Crack Paths

Computational analysis and two dimensional tensile tests on single motor grain fins suggest that cracks in fin tips are most likely to originate at the coalescence of the fin end tip radius with a small radius emanating from the side of the fin. Prior studies have indicated that under internal pressure, cracks on the fin axis are subject to similar stress peaks and may grow more readily than the former types due to an absence of shear modes. The present study focuses upon two types of cracks emanating from the former location called “off-axis” cracks and attempts to differentiate from the two types by their paths and SIF values, determined by the frozen stress photoelastic method.

An Experimental Investigation of the Crack Tip Stress Intensity Factors in Plates Under Cylindrical Bending

1962 ◽  
Vol 84 (4) ◽  
pp. 542-546 ◽  
Author(s):  
Fazil Erdogan ◽  
Ozcan Tuncel ◽  
Paul C. Paris
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Crack Tip ◽  
Tensile Tests ◽  
Critical Value ◽  
Intensity Factors ◽  
Cylindrical Bending ◽  
Crack Tip Stress

This experimental study was undertaken to investigate the validity of the theory based on the crack tip stress intensity factors to explain the fracture of thin cracked plates subjected to static bending moments. Plexiglas sheets were used as specimens and the loading was pure cylindrical bending. The results indicate that there is in fact a critical value of the stress intensity factor at which the crack starts growing. It was found that, while in static tensile tests the crack growth was unstable, in the case of bending, the external load (here, the bending moment) which starts the crack growing is not sufficient for the complete fracture of the plate if it is maintained constant. That is, when the critical value of the stress intensity factor is reached, the crack starts growing on the tensile side of the plate whereupon the crack tip takes a triangular shape and the system again becomes stable. In order to make the crack grow further, a considerable increase in the load is required.

Stress intensity factor solutions for kinked surface cracks

1990 ◽  
Vol 25 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Li Yingzhi ◽  
D A Hills
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Field ◽  
Two Dimensional ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Bulk Stress ◽  
Straight Segments ◽  
General Method

A general method is described of determining the stress intensity factors for two-dimensional cracks composed of straight segments but with one or more angular discontinuities. The bulk stress field used is for illustrative purposes only, and the only requirement is that the crack remains open throughout its length.

Dimensionless Stress Intensity Factors of an Annular Notched Shaft

2011 ◽  
Vol 488-489 ◽  
pp. 174-177
Author(s):  
Bo Chen ◽  
You Tang Li
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Field ◽  
Displacement Field ◽  
Stress Concentrator ◽  
Intensity Factors ◽  
Blunt Crack ◽  
Dimensionless Stress ◽  
Tip Radius

The tip radius ρ, depth t and field angle α of notch and the geometrical sizes a and b of shaft are looked as descriptive parameters in the annular notched shaft. Taken the crack, blunt crack and notch as breach, the stress field and displacement field near the tip of breach which serve dimensionless factor fα(a/b) as descriptive parameter are obtained. The effects of parameters ρ, t and α to fα(a/b) are analyzed. The connections between stress intensity factor of crack and stress concentrator factor of notch, between sharp V-notch and crack, between V-notch and U-notch have been founded.

Stress Intensity Factors for Unequal Longitudinal-Radial Cracks in Thick-Walled Cylinders

1991 ◽  
Vol 113 (1) ◽  
pp. 22-27 ◽  
Author(s):  
J. L. Desjardins ◽  
D. J. Burns ◽  
R. Bell ◽  
J. C. Thompson
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Finite Elements ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Two Dimensional ◽  
Intensity Factors ◽  
Radial Cracks ◽  
Good Agreement

Finite elements and two-dimensional photoelasticity have been used to analyze thick-walled cylinders which contain arrays of straight-fronted, longitudinal-radial cracks of unequal depth. The stress intensity factor K1 has been computed for the dominant crack and for some of the surrounding cracks. Cylinders with 2, 4, 6, 8, 16, 36 and 40 cracks have been considered. Good agreement has been obtained between the experimental and the numerical results and, for cylinders with 2 or 4 cracks, with previously published predictions. The results for all of the foregoing cases are used to develop simple, approximate techniques for estimating K1 for the dominant crack, when the total number of cracks is different from those that have been considered herein. Estimates of K1 obtained by these techniques agree well with corresponding finite element results.

Stress intensity factor solutions for two-dimensional elastostatic problems by the hypersingular boundary integral equation

2009 ◽  
Vol 44 (4) ◽  
pp. 235-247 ◽  
Author(s):  
A Sahli ◽  
O Rahmani
Keyword(s):  
Stress Intensity Factor ◽  
Integral Equation ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Boundary Integral Equation ◽  
Stress Intensity Factors ◽  
Boundary Integral ◽  
Two Dimensional ◽  
Intensity Factors ◽  
Hypersingular Boundary Integral Equation

The boundary element method is a numerical method that can be advantageously used for a wide range of engineering problems, including the stress concentration problems encountered in fracture mechanics. In linear elastic fracture mechanics (LEFM), the stress intensity factor is an important parameter. Cracks, if present in the region experiencing the modes of deformation, increase the stress amplitude significantly and this high stress may lead to premature failure of the engineering components. If the value of the SIF is known, it is possible to predict whether the crack will propagate or not. As the conventional boundary integral equation (CBIE) degenerates when a mathematical crack is modelled, a previously developed dual boundary integral equation approach has been adopted in the current work. It utilizes the hypersingular boundary integral equation (HBIE) along with the CBIE. A weakly singular form of HBIE is utilized in the current work to eliminate the hypersingularity analytically. Stress intensity factors are evaluated using the crack opening displacement (COD), displacement extrapolation (DE), and the J-integral approaches. A stand-alone code has been developed for calculating the stress intensity factors of general two-dimensional domains with cracks. The code has been validated by evaluating the stress intensity factors for the standard components, for which the stress intensity factor values are available in the literature. Accurate and well-converged results are obtained proving the robustness of the code. A linear combination of the CBIE and HBIE was applied at the crack and a significant (87–97 per cent) reduction in the condition numbers for the system of equations was observed for the examples studied. Again, the results obtained are accurate and well converged.

Computational analysis for stress intensity factor (KI) measuring in metal-ceramic interface

2019 ◽  
pp. 15-18
Author(s):  
Elza M.M. Fonseca ◽  
Joana F. Piloto ◽  
Maria G. Fernandes ◽  
R.M. Natal Jorge
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Computational Analysis ◽  
Metal Ceramic
Sign in / Sign up

Export Citation Format

Share Document