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Fatigue

Mike Ciavarella's picture

Stress-life vs strain life approaches in efatigue.com ?

dear collegue

 have you ever tried to compare the stress-life approach with the strain-life?

 I was experimenting with some students using the website https://www.efatigue.com/with normal notches and normal materials included in the web site database.

Mechanical Testing- Aerospace Materials & Products

In the aerospace industry, testing is critical in successful product development and implementation. Mechanical testing of materials and products used in aerospace applications is governed by strict standards and often require accreditation. The type of testing performed includes tensile, compressive, flexural, fatigue testing, and more.

Mike Ciavarella's picture

Questions to experts in Variable Amplitude Loading in Fatigue of metals

As a newcomer in this field, I try to pose some questions to the experts in Variable Amplitude Loading fatigue. The questions are probably trivial, but I don't find any reply in the literature, particularly on the arbitrary choice of frequency cutoff in the spectrum loading, and on the distinction  between cracked and uncracked structures. See attach and please respond if you can, even directly on email at mciava@poliba.it

Mike Ciavarella's picture

fatigue: overstressing and understressing

 

While teaching some students from old textbooks, I found reference to "understressing and overstressing" as producing effects into fatigue limits.    Looking at classical papers like  W SCHUTZ, A HISTORY OF FATIGUE Engineering Fracture Mechanics Vol. 54, No. 2, pp. 263-300, 1996, he says that the theory of understressing was largely a mistake due to statistically poor testing.  However, I see some chinese papers still talk of understressing, see below.

 

Shuman_Xia's picture

Abstract Deadline Extended: SEM Fracture and Fatigue Call for Papers

Dear Colleagues,

 

The SEM 2019 annual conference abstract deadline has been extended to October 24, 2018. Please see the Call for Abstracts below and consider submitting an abstract.

 

Postdoctoral vacancy (2.5 years) on multi-axial fatigue modelling and testing for 3D printed metal parts

The use of 3D printed metal structures is taking a very fast ramp-up in industry. General Electric has demonstrated the possibility of printing titanium fuel injectors for their LEAP engine, EADS has printed a nacelle hinge bracket for the Airbus A320, Boeing is printing plastic inlet ducts for high-altitude aircrafts, hip implants and other prosthetics are exploiting the design freedom of additive manufacturing (AM),...

jsegurado's picture

PhD position in Multiscale mechanical modeling of metals , IMDEA-Materials Institute

IMDEA Materials Institute is non-profit research organization located in Madrid, Spain, to carry out research activities in Materials Science and Engineering. More information can be found 

pragtic's picture

Invitation to WCFA2018 - FKM Guideline Training

Dear iMechanicians,

I would like to invite you to the prepared 8th volume of the Workshop on Computational Fatigue Analysis series. The 2018 volume is dedicated to the FKM-Guideline on Strength Assessment, which covers both static and fatigue analysis of common industrial components. The key lecturer this time is Dr Roland Rennert from IMA Dresden, one of the co-authors of its last 6th revised version released in 2012.

jingguo2011's picture

Reminder: 2018 Midwest Mechanics Workshop registration

Dear Colleagues,

This is a gentle reminder that the 2018 Midwest Mechanics Workshop will take place at IIT, Chicago on Thursday, August 9.  The deadline for registration is July 26, so we will have time to figure out the logistics. Note that registration is free for this one-day workshop. Please see:

https://sites.google.com/iit.edu/midmechmat-2018/home

PhD Positions Available (up to 2) on Fatigue Resistance of Bone

Bones not only support and protect the various organs of our body but provide structure and enable mobility making them the most important structural materials in the human body. While aging, diet and health are known to significantly affect the structural integrity and fracture resistance of bone, fatigue, a significantly more important loading condition, is rarely studied.

PhD vacancy (4 years) on fatigue testing of composites with advanced instrumentation

Composites are used more and more as structural components in aerospace industry, automotive sector, wind energy applications,… As a consequence, the loads on those composite components are much higher than for secondary components, and can lead to fatigue damage in the composite part. Moreover, the fatigue behaviour of fibre-reinforced composites is much more complex than that of metals, because of the many different fibre/polymer combinations, the heterogeneous nature of the composite, the anisotropic behaviour of the composite and the multitude of damage mechanisms.

Ruobing Bai's picture

Fatigue Fracture of Self-Recovery Hydrogels

Dear Colleagues,

Here is our recent paper “Fatigue Fracture of Self-Recovery Hydrogels”. To the hydrogel community, this paper distinguishes the fatigue fracture and the self-recovery of a hydrogel. To the mechanics community, we show that, for the first time in hydrogels, the fatigue threshold depends only on the covalent network, but not on the noncovalent interactions that provide dissipation.

Mike Ciavarella's picture

Certification for Damage Tolerance

Choose a channel featured in the header of iMechanica: 

I wonder if anyone in Imechanica follows or deals with Damage Tolerance of Aircraft Structures.  Not having to deal with everyday certification nor having direct experience, I know only what is reported in academic books, but I am confused about what is the standard in industry and certification, assuming there is one!

 

SUMMARIES OF AIRCRAFT LIFING CONCEPTS

 

Safe-Life design

Frequency effect on fatigue life of metal-composite

Choose a channel featured in the header of iMechanica: 

Hi 

I have few questions:

1- why most the experimental fatigue studies on metal or metal-composites in the literature were adopted a frequency less than 35Hz (the majority of these test have conducted using 20Hz).

I ran into some articles mentioned that the frequency (0-100Hz) has a marginal effect on the fatigue life of metal. is that the only answer

 

pragtic's picture

WCFA workshop on Design and Fatigue of Weldments

This is the second announcement about the upcoming Workshop on Computational Fatigue Analysis 2017, this year dedicated to Design and Fatigue of Weldments (WCFA2017-DFW - http://www.pragtic.com/DFW.php). The workshop is held in Prague, Czech Republic in November 13-16, 2017. The key lecturer, who guides the audience through various issues of the fatigue analysis in welds, is Dr Zuheir Barsoum from KTH - Royal Institute of Technology in Sweden.

pragtic's picture

WCFA workshop on Design and Fatigue of Weldments

Choose a channel featured in the header of iMechanica: 

This is the second announcement about the upcoming Workshop on Computational Fatigue Analysis 2017, this year dedicated to Design and Fatigue of Weldments (WCFA2017-DFW - http://www.pragtic.com/DFW.php). The workshop is held in Prague, Czech Republic in November 13-16, 2017. The key lecturer, who guides the audience through various issues of the fatigue analysis in welds, is Dr Zuheir Barsoum from KTH - Royal Institute of Technology in Sweden.

Ruobing Bai's picture

Fatigue fracture of tough hydrogels

Dear colleagues,

Attached please find our new paper "Fatigue fracture of tough hydrogels" published on Extreme Mechanics Letters.

 

Fatigue fracture of tough hydrogels

Ruobing Bai, Quansan Yang, Jingda Tang, Xavier P. Morelle, Joost Vlassak, Zhigang Suo

cemalbasaran's picture

Scientists report solving one of the oldest problems in mechanics

Being able to accurately predict the life span of physical bodies, both living and non-living, has been one of humankind’s eternal endeavors.  Over the last 150 years, many attempts were made to unify the field of Newtonian mechanics  and thermodynamics,  in order to create a generalized and consistent theory of evolution of life-span.

 

Mike Ciavarella's picture

Susmel-Papuga sharp controversy about multiaxial fatigue criteria

I recently came across this sharp controversy between Papuga and Susmel on multiaxial fatigue criteria.  Papuga accuses Susmel of "picking up" data that he likes from the literature, disregarding other data... And of having some constants in the criteria that are set a posteriori as fitting parameters.   Do you know how this ended up?  Anyone else partecipated to the debate? 

 Comments on “A survey on evaluating the fatigue limit under multiaxial loading” by Jan...

In Memoriam: Dr Louis Cloutier (1936-2017)

My friend and former colleague, Dr. Louis Cloutier, passed away on February 26. A long time Hydro-Quebec engineer, among other achievements, he will be remembered for his major contribution to the solution of electric power transmission mechanical problems, most notably to Aeolian vibration control, and related conductor fatigue.

Mike Ciavarella's picture

A simple finding on variable amplitude (Gassner) fatigue SN curves obtained using Miner’s rule for unnotched or notched specimen

We provide a very simple result for a problem which has been often neglected (variable amplitude loading) in academia, but which is of paramount importance in real engineering situations, where fatigue is almost never "constant amplitude".

We found few cases where we could check this extremely simple result, but it worked very well.  We would welcome further verifications.

The paper is in press here.

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