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crack growth

Mike Ciavarella's picture

Analytical Models for Fatigue Life Prediction of Metals in the Stress-Life Approach -- phd thesis by Pietro D’Antuono

dear collegues

  I'd be very grateful if you could have a look, if not a deep reading, at the phd thesis of my last student, playing on classical results on uniaxial fatigue, but with a view of simple, unified perspective on constant and varying amplitude fatigue.  We made large use of e-fatigue.com web site and the data in there.
 Thanks in advance for any remark.  The final thesis will be submitted in few weeks time.

Antonio Papangelo's picture

On unified crack propagation laws

The anomalous propagation of short cracks shows generally exponential fatigue crack growth but the dependence on stress range at high stress levels is not compatible with Paris’ law with exponent m=2. Indeed, some authors have shown that the standard uncracked SN curve is obtained mostly from short crack propagation, assuming that the crack size a increases with the number of cycles N as da/dN=H\Delta\sigma^h where h is close to the exponent of the Basquin’s power law SN curve.

pragtic's picture

VAL2015 conference on Variable Amplitude Loading - Abstract submission system opened

Dear iMechanician

We are preparing everything necessary to host the 3rd International Conference on Material and Component Performance under Variable Amplitude Loading (VAL 2015) in Prague, Czech Republic in March 23-26, 2015. From now on, you can register your abstracts in the online
submission system
. The system will stay open till July 7, 2014, so do not forget to insert your abstract in time.

Research Associate - Modelling of Crack Growth under Fatigue-Oxidation Conditions

A Research Associate is required to undertake an EPSRC-funded project to model oxidation damage at a crack tip and associated crack growth for nickel alloys.

You will join the vibrant Mechanics of Advanced Materials group at Loughborough (www.lboro.ac.uk/moam) which has gained significant experience in the study of mechanical behaviour of advanced materials.

Crack propagation in ANSYS vs. ABAQUS

Hello dear friends,

 

I am Morteza, PhD student of Materials Eng. I have this course of Computational Modelling with Abaqus this semester. My Professor asked me to compare different approaches of crack growth analysis in Ansys and Abaqus including different formulations, procedures,... . He recommended to check the user's manual in these two softwares.

I would like to appreciate it if anybody could help me with this task as I am absolutely new in this field.

modelling the crack in Abaqus

Hi colleage 

I am working on fracture mechanics recently and i am using Abaqus to do it, i am a new user in this software so i have some problems, in getting results and ... i want to get some variable such as J-integral, S.iF, number of cycles and ... but unfortunatelly i donno how to get it .

i want to ask if anybody can send me a sample of abaqus in this srea, then i can study and practise according to it and after that i can go through my project.

 

this is my email: mahyar.iii@gmail.com

Mathematics of Crack growth

  1.  How to find G (energy release rate) using wnuk's equation? by considering the fracture process zone explaining the assumptions and concept involved??
  2. can anyone explain about : Eshelby's basic assumption for finding the change of displacement after the crack tip has moved a distance x?
  3. How is the general form(equation) for singular parts of the stresses in the plane of the crack  derived (explain the breif fundamentals) ?

    all these question are in reference to the book Micromechanics of defects in solids by toshio mura 

 

 

Fatigue crack growth

Choose a channel featured in the header of iMechanica: 

Hi all,

 

I wanted to simulate fatigue crack growth in ls-dyna, obtain dK, crack tip stress fields. But I wanted to start from a simple model. I can't find any examples online, tutorial...

[SOLVED] 3D crack growth modelling in Abaqus by XFEM

Good day everyone,

I'm new to iMechanica and look forward to getting to know everyone here. Smile

I'm currently doing analysis of interlaminar crack growth in fibre-reinforced composite by Extended Finite Element Method (XFEM) using Abaqus. I'm a new Abaqus user and therefore I have to familiarise myself by constructing random 2D and 3D models with isotropic materials before jumping onto anisotropic.

Reza Mousavi's picture

R C Beams

I am a novice user of abaqus and trying to model crack growth in rc beams with longitudinal reinforcement and stirrups under dynamic loads by try and error method Tongue out

fatigue crack growth

Having glanced at the web site I can see that it might be useful to shed some light on fatigue crack growth and crack closure based concepts.

Seeking candidates for positions in Houston, also positions in Germany

Our agency, Reliability Analysis Associates, Inc., specializes in recruiting Reliability Engineers and related skills.   For a client in the oil business in Houston, TX we are seeking candidates for two positions that require knowlege of finite element analysis, crack growth, reliability, and low cycle fatigue.   The two job descriptions are attached.

 

N. Sukumar's picture

Epi-convergence (max-ent bases), crack growth

In the attached paper, we have used Variational Analysis techniques (in particular, the theory of epi-convergence) to prove the continuity of maximum-entropy basis functions. In general, for non-smooth functionals, moving objectives and/or constraints, the tools of Newton-Leibniz calculus (gradient, point-convergence) prove to be insufficient; notions of set-valued mappings, set-convergence, etc., are required. Epi-convergence bears close affinity to Gamma- or Mosco-convergence (widely used in the mathematical treatment of martensitic phase transformations). The introductory material on convex analysis and epi-convergence had to be omitted in the revised version; hence the material is by no means self-contained. Here are a few more pointers that would prove to be helpful. Our main point of reference is Variational Analysis by RTR and RJBW; the Princeton Classic Convex Analysis by RTR provides the important tools in convex analysis. For convex optimization, the text Convex Optimization by SB and LV (available online) is excellent. The lecture slides provide a very nice (and gentle) introduction to some of the important concepts in convex analysis. The epigraphical landscape is very rich, and many of the applications would resonate with mechanicians.

On a different topic (non-planar crack growth), we have coupled the x-fem to a new fast marching algorithm. Here are couple of animations on growth of an inclined penny crack in tension (unstructured tetrahedral mesh with just over 12K nodes): larger `time' increment and smaller `time' increment. This is joint-work with Chopp, Bechet and Moes (NSF-OISE project). I will update this page as and when more relevant links are available.

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