Cloud Applications Performance in Crack Growth Simulations of Pre-Hydrogenated Structure Components

2016 ◽  
Vol 844 ◽  
pp. 97-102
Author(s):  
Daniel L. Kishlakov ◽  
Pavel V. Tarakanov ◽  
Georgy V. Shashurin ◽  
Yury V. Berchun
Keyword(s):  
Crack Growth ◽  
Batch Processing ◽  
Growth Time ◽  
Efficiency Criterion ◽  
Durability Analysis ◽  
Fracture Crack ◽  
Efficiency Estimation ◽  
Type Calculation ◽  
Loaded Structure ◽  
Computational Resources

The design of durable structure components requires durability analysis in CAE systems and cloud computations use is favorable for batch processing of multiple same-type calculation routines. To develop CAE durability modules analytical approach to different batch processing systems efficiency estimation is necessary. Such modules are intended for durability analysis of pre-hydrogenated and statically loaded structure components with initial defects. Durability estimate is defined as crack growth time elapsed from initial defect state to structure component fracture. Crack kinetics model had been used to simulate a fracture process, required for safe operation of a structure; crack length curves had been obtained and analyzed. The results were verified with the published experimental data on the subject at hand.The authors’ efficiency criterion was applied for performance analysis of the developed cloud application to find a subset of one modelling parameter in which the application is efficient being constrained in number of computational resources available and in the desirable level of performance.

PWSCC Crack Growth Modeling Approaches

2011 ◽  
Author(s):  
F. W. Brust ◽  
D.-J. Shim ◽  
G. Wilkowski ◽  
D. Rudland
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Stress Intensity ◽  
Residual Stresses ◽  
Crack Growth ◽  
Corrosion Cracking ◽  
Growth Time ◽  
Pressurized Water ◽  
Primary Water ◽  
Water Reactors

Flaw indications have been found in some dissimilar metal (DM) nozzle to stainless steel piping welds and reactor pressure vessel heads (RPVH) in pressurized water reactors (PWR) throughout the world. The nozzle welds usually involve welding ferritic (often A508) nozzles to 304/316 stainless steel pipe) using Alloy 182/82 weld metal. The welds may become susceptible to a form of corrosion cracking referred to as primary water stress corrosion cracking (PWSCC). It can occur if the temperature is high enough (usually >300C) and the water chemistry in the PWR is typical of operating plants. The weld residual stresses (WRS) induced by the welds are a main driver of PWSCC. Several mechanical mitigation methods to control PWSCC have been developed for use on a nozzle welds in nuclear PWR plants. These methods consist of applying a weld overlay repair (WOR), using a method called mechanical stress improvement process (MSIP), and applying an inlay to the nozzle ID. The purpose of a mitigation method is to reduce the probability that PWSCC will occur in the nozzle joint. The key to assessing the effectiveness of mitigation is to determine the crack growth time to leak with and without the mitigation. Indeed, for WOR and MSIP, the weld residual stresses are often reduced after application while for inlay they are actually increased. However, all approaches reduce crack growth rates if applied properly. Procedures for modeling PWSCC growth tend to vary between organizations performing the analyses. Currently, the prediction of PWSCC crack growth is based on the stress intensity factors at the crack tips. Several methods for evaluating the stress intensity factor for modeling the crack growth through these WRS fields are possible, including using analytical, natural crack growth using finite element methods, and using the finite element alternating method. This paper will summarize the methods used, critique the procedures, and provide some examples for crack growth with and without mitigation. Suggestions for modeling such growth will be provided.

scholarly journals Computing the Growth of Small Cracks in the Assist Round Robin Helicopter Challenge

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 944 ◽  
Author(s):  
Rhys Jones ◽  
Daren Peng ◽  
R.K. Singh Raman ◽  
Pu Huang
Keyword(s):  
Crack Growth ◽  
Computational Study ◽  
Fatigue Tests ◽  
Economic Life ◽  
Growth Equation ◽  
Load Spectrum ◽  
Load Spectra ◽  
Helicopter Flight ◽  
Durability Analysis ◽  
Small Cracks

Sustainment issues associated with military helicopters have drawn attention to the growth of small cracks under a helicopter flight load spectrum. One particular issue is how to simplify (reduce) a measured spectrum to reduce the time and complexity of full-scale helicopter fatigue tests. Given the costs and the time scales associated with performing tests, a means of computationally assessing the effect of a reduced spectrum is desirable. Unfortunately, whilst there have been a number of studies into how to perform a damage tolerant assessment of helicopter structural parts there is currently no equivalent study into how to perform the durability analysis needed to determine the economic life of a helicopter component. To this end, the present paper describes a computational study into small crack growth in AA7075-T7351 under several (reduced) helicopter flight load spectra. This study reveals that the Hartman-Schijve (HS) variant of the NASGRO crack growth equation can reasonably accurately compute the growth of small naturally occurring cracks in AA7075-T7351 under several simplified variants of a measured Black Hawk flight load spectra.

CRACK GROWTH IN SOLID WITH MANY INITIAL DEFECTS

Fractals ◽  
1995 ◽  
Vol 03 (01) ◽  
pp. 79-90 ◽  
Author(s):  
SABUROU NISHIUMA ◽  
SASUKE MIYAZIMA
Keyword(s):  
Crack Growth ◽  
Cluster Size ◽  
Fractal Structure ◽  
Square Lattice ◽  
Dynamic Scaling ◽  
Matrix Interface ◽  
Delayed Fracture ◽  
Fracture Crack ◽  
External Forces ◽  
Inclusion Matrix

Hydrogen-induced fracture of steel is characterized by the formation of internal voids caused by hydrogen precipitation at an inclusion-matrix interface, followed by the formation of microcrack array under the superposed action of internal hydrogen pressure and external forces. The propagation of the hydrogen-induced fracture is considerably random and the fracture develops by stepwise linking of the microcracks. We present a new fracture model describing the patterns of crack growth by hydrogen embrittlement to find a generic feature of delayed fracture. Crack growth in solid with many initial defects is studied by Monte Carlo simulation on a square lattice. By analyzing time-dependent cluster size distribution of crack and its dynamic scaling, it is found that the crack growth process has a fractal structure. “Percolation of cracks” which corresponds to macroscopic breakdown of materials is also investigated.

scholarly journals Review of Requirements for the Durability and Damage Tolerance Certification of Additively Manufactured Aircraft Structural Parts and AM Repairs

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1341 ◽  
Author(s):  
Sudip Kundu ◽  
Rhys Jones ◽  
Daren Peng ◽  
Neil Matthews ◽  
Alankar Alankar ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Residual Stresses ◽  
Crack Growth ◽  
Rough Surface ◽  
Cold Spray ◽  
Damage Tolerance ◽  
Growth Equation ◽  
Durability Analysis ◽  
Structural Parts ◽  
The Individual

The USAF requirements for the durability and damage tolerance certification for additively manufactured (AM) aircraft structural parts, which are detailed in Structures Bulletin EZ-19-01, raise a number of new and, as yet, unanswered questions. The present paper attempts to address three questions: How to perform a fracture mechanics-based analysis of crack growth in an AM part so as to account for the residual stresses, how to perform a fracture mechanics-based durability analysis of a cold spray repair so as to account for both the induced residual stresses and the presence of multiple co-located cracks, and how to perform a fracture mechanics-based durability analysis of an AM part so as to account for the presence of multiple collocated surface braking cracks. In this context, the present paper reveals the potential of the Hartman–Schijve variant of the NASGRO crack growth equation to accurately predict the growth of each of the individual (collocated) cracks that arose in a cold spray-repaired specimen and in a specimen from a crack that nucleated and grew from a rough surface.

scholarly journals Residual life assessment of welded joints in the girth weld root

2020 ◽  
Vol 315 ◽  
pp. 12001
Author(s):  
Leonid Shron ◽  
Vladimir Bogutsky ◽  
Elmar Yagyaev ◽  
Illa Tabolin
Keyword(s):  
Crack Growth ◽  
Welded Joints ◽  
Residual Life ◽  
Critical Length ◽  
Initial Crack ◽  
Calculation Model ◽  
Life Assessment ◽  
Internal Crack ◽  
Growth Time ◽  
Weld Root

The article analyzes the influence of the structural crack-like defect in the girth weld root welding the bottom to the collector body on the crack growth resistance. A mathematical model has been developed to estimate the residual life resource of welded joints with an internal crack-like defect in the root of the weld under creep. Results of metallographic studies of bench tests results for the welded joints long-term strength formed the basis of the calculation model. In all tested models the cracks start at the top of the narrow structural gap in the weld root and develop along almost the entire weld axis, perpendicular to the wall of the pipe and have a discrete growth pattern. As a result, discrete rupture of material occurs on a length of rc, and the initial crack is incremented by this length. After that, a “plastic core” of rc length is formed in the newly formed crack tip, additional damage is accumulated, and the crack development process continues until the stress level in the section weakened by the crack reaches a critical value. The obtained dependence characterizes the crack growth time from the initial crack-like defect to its critical length.

scholarly journals Methodology for distributing information protection tasks between computer devices of automated systems based on the branch and border method

2020 ◽  
Vol 28 (3) ◽  
pp. 24-34
Author(s):  
Maxim S. Gnutov ◽  
Alexander B. Sizonenko
Keyword(s):  
Branch And Bound ◽  
Automated System ◽  
Multiprocessor System ◽  
Distributed Programming ◽  
Branch And Bound Method ◽  
Information Protection ◽  
Software Protection ◽  
Efficiency Criterion ◽  
Computational Resources ◽  
Generalized Indicator

The influence of software protection on various information systems is analyzed. Using set theory, the use of computational resources for the joint solution of direct tasks and information protection tasks in an automated system is described. A hybrid implementation of computing in a CPU + GPU system is proposed. The relevance of using the branch and bound method to compile a minimum schedule of information security tasks in a hybrid multiprocessor system is considered. The features of processing data structures by various types of calculators are indicated. The computational strategies of the branch and bound method with the greatest possibility of acceleration with limited resources are analyzed. The efficiency criterion is selected, the performance indicators are considered when applying the frontal and one-sided branching strategies depending on the complexity of the calculations and the amount of occupied memory. The generalized indicator of efficiency is defined. The prospects of applying the considered method in distributed systems through distributed programming are emphasized.

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