scholarly journals STRESS-STRAINED STATE OF BABBIT LAYERS WITH CRACKS

2017 ◽  
Vol 2017 (1) ◽  
pp. 102-111 ◽  
Author(s):  
Михаил Зернин ◽  
Mikhail Zernin
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Crack Resistance ◽  
Stress Intensity Factors ◽  
Crack Tip ◽  
Cyclic Crack Resistance ◽  
Strained State ◽  
Intensity Factors ◽  
Adjusted Analysis ◽  
Finite Element Procedure

A finite element procedure for calculated inves-tigations of SSS at a crack tip in a babbit layer is created. The procedure is adjusted for bimetal cylin-drical sample loaded according to a circuit of bending with rotation. The dependences for stress intensity factors are obtained and it is shown that accuracy of such modeling is higher than in procedure options used ear-lier. A set of computations for samples with some cracks in a layer is carried out. The criteria of crack separation into independent and interacted are revealed. The results of the work will be used for the further adjusted analysis of experiments and for the formation of dependences in a cyclic crack resistance of babbit layers. The procedure shown and results can be useful for other objects with layers applied on a more solid basis.

scholarly journals CRACK RESISTANCE OF BABBIT B83

2017 ◽  
Vol 2017 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Михаил Зернин ◽  
Mikhail Zernin
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Crack Resistance ◽  
Stress Intensity Factors ◽  
Cyclic Crack Resistance ◽  
Intensity Factors ◽  
Finite Element Procedure ◽  
Crack Resistance Test ◽  
Definition Of ◽  
Fracture Viscosity

Babbit 83 crack resistance test in accordance with SSR 25-506-85 was carried out. By finite element method there were defined values of stress intensity factors in flat samples with a grown crack. The fracture viscosity characteristics of babbit are obtained. On the basis of a macro-fractographic analysis of wear fractures of a babbit sample and a finite element procedure for the definition of values of stress intensity factors the cha-racteristics of cyclic crack resistance are obtained. It is shown that a final fracture is realized at 3 МПа , and a transition from an elastic stage to the stage elastoplastic development of a crack is realized at 2,0…2,8 МПа .

scholarly journals Stiffness Derivative Finite Element Technique to Determine Nodal Weight Functions With Singularity Elements

1983 ◽  
Author(s):  
George T. Sha
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Tip ◽  
Weight Functions ◽  
Two Dimensional ◽  
Intensity Factors ◽  
Crack Face ◽  
Crack Geometry ◽  
Crack Problems

The use of the stiffness derivative technique coupled with “quarter-point” singular crack-tip elements permits very efficient finite element determination of both stress intensity factors and nodal weight functions. Two-dimensional results are presented in this paper to demonstrate that accurate stress intensity factors and nodal weight functions can be obtained from relatively coarse mesh models by coupling the stiffness derivative technique with singular elements. The principle of linear superposition implies that the calculation of stress intensity factors and nodal weight functions with crack-face loading, σ(rs), is equivalent to loading the cracked body with remote loads, which produces σ(rs) on the prospective crack face in the absence of crack. The verification of this equivalency is made numerically, using the virtual crack extension technique. Load independent nodal weight functions for two-dimensional crack geometry is demonstrated on various remote and crack-face loading conditions. The efficient calculation of stress intensity factors with the use of the “uncracked” stress field and the crack-face nodal weight functions is also illustrated. In order to facilitate the utilization of the discretized crack-face nodal weight functions, an approach was developed for two-dimensional crack problems. Approximations of the crack-face nodal weight functions as a function of distance, (rs), from crack-tip has been successfully demonstrated by the following equation: h a , r s = A a √ r s + B a + C a √ r s + D a r s Coefficients A(a), B(a), C(a) and D(a), which are functions of crack length (a), can be obtained by least-squares fitting procedures. The crack-face nodal weight functions for a new crack geometry can be approximated using cubic spline interpolation of the coefficients A, B, C and D of varying crack lengths. This approach, demonstrated on the calculation of stress intensity factors for single edge crack geometry, resulted in a total loss of accuracy of less than 1%.

Applications of a Local Multigrid Approach to the Finite Element Analysis of a Crack-Microcrack Problem

1998 ◽  
Author(s):  
G. E. Cardew ◽  
G. M. Seed ◽  
W. K. Koh
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Domain Decomposition ◽  
Stress Intensity Factors ◽  
Main Crack ◽  
Crack Tip ◽  
Intensity Factors ◽  
Fine Grid ◽  
Finite Element Grid ◽  
Restricted Form

Abstract An established group of methods allows fine grid patches to overset their coarser surroundings by an arbitrary amount. These are the Domain Decomposition methods which offer a flexibility, in that finite element models may contain local refinements in the vicinity of significant features such as crack tips. The present application is based on a restricted form of Domain Decomposition using a Multigrid algorithm applied to a composite grid consisting of local refinement patches embedded within selected zones of an underlying finite element grid. Constructing a finite element grid with disjoint, overset refinement patches is significantly simpler than the conventional approach of designing a single, complex grid of strong connectivity, with increased refinements within crack tip regions. Furthermore, the overall size of a problem can be dramatically reduced by using the patch approach, resulting in lower computational effort. Stress intensity factors are presented for the two-dimensional problem of a main crack with multiple, arbitrarily located and oriented microcracks in the vicinity of the main crack tip. The crack-microcrack interactions are further investigated with respect to crack tip shielding and amplification. Predictions of the stress intensity factors, based on the J conservation integral within the local patches, are shown to be in excellent agreement with stress intensity factors obtained on conventional grids and with known solutions.

Finite element analysis of cracked bodies to determine stress intensity factors

1976 ◽  
Vol 11 (1) ◽  
pp. 18-25 ◽  
Author(s):  
C L Chow ◽  
K J Lau
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Tip ◽  
Stress Conditions ◽  
Intensity Factors ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Crack Tip Stress

A method for the computation of the stress intensity and associated geometrical correction factors by use of the finite element analysis is presented. The lack of ability to represent crack tip stress conditions has been the shortcoming of the conventinal techniques in finite-element solutions of problems of cracked bodies. The proposed method provides the representation of crack tip stress conditions with elliptic displacement functions which lead to the direct computation of stress intensity factors. The method is applied to several crack configurations with relatively coarse finite-element networks and the accuracy is found to be satisfactory when compared with results of previous workers.

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