crack growth

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.

In this review of particularly readworthy papers in EFM, I have selected a paper about the tearing of large ductile plates, namely:

”Cohesive zone modeling and calibration for mode I tearing of large ductile plates”  by P.B. Woelke, M.D. Shields, J.W. Hutchinson, Engineering Fracture Mechanics, 147 (2015) 293-305.

http://hdl.handle.net/10993/12316

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.

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.

Call for Papers - deadline 9 December 2011

Submit your abstract here: www.fatiguedamageconference.com 

We welcome poster and abstract submissions on the following topics:

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.

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.

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.