We will be teaching a short course on residual stress on June 12, 2022 at the SEM Experimental Mechanics conference in Pittsburgh.

See below and https://sem.org/annual (under PROGRAMS/COURSES) for details.

Residual stress short courses don't happen too often. The course should be appropriate for students, industrialists, and researchers. Hope you can make it. The proceeds all benefit SEM.

Residual Stress 101

Description:
This course aims to cover a broad, practical introduction to residual stresses for students, researchers, and industrialists with an interest in the subject. We cover the most practically important aspects of residual stress, things that are fairly simple but often counterintuitive, poorly understood, or just not widely known. Most of this material is not covered by coursework for engineers or material scientists. We will answer the most important questions: What are residual stresses and where do they come from? What effects do they have? How are the stress components throughout a body interrelated? How can you measure residual stresses? How can you use residual stress knowledge in models to predict failures or other issues? How can you use superposition to simplify many calculations? Along the way we will point out pitfalls to avoid and mistakes that appear in the literature.

Instructors:
Michael Prime–Los Alamos National Laboratory;
Michael Hill–University of California, Davis;
Adrian DeWald–Hill Engineering;
Iuliana Cernatescu–Pratt & Whitney;
Jeff Bunn–Oak Ridge National Laboratory;
Gary Schajer–University of British Colombia

Outline:
1. Introduction of instructors and students
2. Introduction and why do we care

• a. What are residual stresses?
• b. How do they arise?
• c. What do they do and why do we care?
• d. Fatigue, fracture, distortion, the effect on property measurements

3. Practical Mechanics of Residual Stress

• a. Stress, strain, elastic strain as applied to residual stress
• b. What makes an admissible residual stress field and why does that matter?
• c. Global equilibrium
• d. Boundary Conditions
• e. Local equilibrium: stress components are not independent
• f. Superposition and calculating deformations and changes in residual stress as, for example, a crack grows

4. Residual Stress Measurement

• a. Introduction
• b. Relaxation methods
• c. Optical methods (Holography, DIC, etc.)
• d. Neutron Diffraction
• e. X-ray Diffraction

5. Residual Stress Applications.
6. Accounting for residual stress in fatigue analysis
7. Engineered residual stress

Date/Time: Sunday, June 12, 2022, 9:00 a.m. – 5:00 p.m.
Cost: $500/$250 student

The day before the SEM Conference this June in Reno, Nevada, USA, we will be teaching a short course entitled Residual Stress 101: https://sem.org/annualprogram. See below for a description of the course. We will cover lots of practical material on residual stresses, much of which is not covered in standard engineering curricula. This is great material for any interested researcher who never got a comprehensive background in residual stress. It will also be great for graduate students or advanced undergrads, and students pay half price. Please also forward to colleagues who might be interested for themselves or for students.

Regards,
Mike, Mike, Adrian, Antonio, Cev

Description

This course aims to cover a broad, practical introduction to residual stresses for students, researchers and industrialists with an interest in the subject. We cover the most practically important aspects of residual stress, things that are fairly simple but often counterintuitive, poorly understood, or just not widely known. Most of this material is not covered by coursework for engineers or material scientists. We will answer the most important questions: What are residual stresses and where do they come from? What effects do they have? How are the stress components throughout a body interrelated? How can you measure residual stresses? How can you use residual stress knowledge in models to predict failures or other issues? How can you use superposition to simplify many calculations? Along the way we will point out pitfalls to avoid and mistakes that appear in the literature.

Instructors
Michael Prime, Los Alamos National Laboratory
Michael Hill, University of California, Davis
Adrian DeWald, Hill Engineering
Antonio Baldi, Università degli Studi di Cagliari
Cev Noyan, Columbia University

Tentative Outline:

Introduction and why do we care.

• What are residual stresses?
• How do they arise?
• What do they do and why do we care?
• Fatigue, fracture, distortion, the effect on property measurements

Practical Mechanics of Residual Stress.

• Stress, strain, elastic strain as applied to residual stress
• What makes an admissible residual stress field and why does that matter?
• Global equilibrium
• Boundary Conditions
• Local equilibrium: stress components are not independent
• Superposition and calculating deformations and changes in residual stress as, for example, a crack grows

Residual Stress Measurement

• Relaxation methods
• Penetrating diffraction
• Laboratory X-ray
• Combining multiple methods
• What full field (Holography, DIC, etc.) buys you and what it does not

Residual Stress Applications.

• Accounting for residual stress in fatigue analysis

.
.

In this work, we were able to improve existing residual stress measurement capabilities so that we could measure smaller length scales. We were able to measure residual stresses that oscillated from build layer to build layer (0.5 mm thick) in an additively manufactured part. The oscillations persisted over nearly 30 layers!

The paper is free until April 20, 2019 at https://authors.elsevier.com/c/1YekJ4r9SUFESl

A few of you might find this interesting. We indented a disk of aluminum in order to make a specimen with residual stress. The loading was axisymmetric. The aluminum had plastic anisotropy of about 10%. Because of that mild anisotropy, the residual stresses were anisotropic by about 40% and the residual strains were anisotropic by 100%.

The paper is free until July 31 at https://authors.elsevier.com/a/1VCA54kE0BEFT

This was an interesting little study to show how constraints caused this amplification in the anisotropy.

We also showed that simple Hookean elasticity showed why the residual strain anisotropy should be the square of the stress anisotropy for Poisson's ratio of 1/3, which matches the observation (2 ~ 1.4^2).

I’ll present this below without the answer, in case you want to enjoy a little brain teaser. It is a solid and experimental mechanics problem that, while not terribly practical, I found very interesting:

A part fractures cleanly in two by brittle fracture (no plasticity) under the action of residual and applied stresses. You only have the broken part in front of you, no prior information.

What were the original residual stresses on the fracture plane?

Should this problem be solvable? The original stresses were of course relaxed by the fracture. There are no longer stresses to measure.

I won’t spoil the answer for you in case you want to think about it yourself. The solution is available at http://www.lanl.gov/contour/fracture.html, which proves the method on a fractured aluminum forging, with the results validated by neutron diffraction measurements. Just published in EFM.

The 2013 Residual Stress Summit will take place October 8 - 10,
2013 at the Hilton Garden Inn Idaho Falls, in Idaho Falls, Idaho, USA. You can get more information at http://www.rssummit.org

Conisdering recommending this event to your industrial colleagues.

The Summit is designed to bring together residual stress
users and developers in a format that provides "take home" information
for the entire audience. Our program has only specially selected invited talks that include industrial
specialists and residual stress developers presenting their experiences. This time, we have exciting sessions on

• Practical measurment methods
  
• Failure case studies and forensics
• Industrial speaker talks from aerospace, nuclear power, metal fabrication, shipbuilding and more
• Advances in diffraction techniques, residual stresses in codes and standards, and more

The Summit will again include a combined poster and demonstration
session, where residual stress related equipment, materials and
contributed posters will be displayed. The format of the meetings will
provide substantial time for interaction at the poster/demo session. If
you are interested in contributing and presenting a poster or bringing
equipment for a demonstration during this session, please see http://www.rssummit.org/demos-posters.html

The RS Summit is a non-profit event, and the registration fee is very moderate and covers
the 3 days of focused talks, a welcoming reception and all meals
(breakfasts, lunches, dinners and coffee breaks).

Hope to see you there,

Mike Prime on behalf of the organizing committee.

The 2013 Residual Stress Summit will take place October 8 - 10, 2013 at the Hilton Garden Inn Idaho Falls, in Idaho Falls, Idaho, USA. The meeting follows the successful format of the four previous RS Summits held in Los Alamos in 2003, Vancouver in 2005, Oak Ridge in 2007, and Lake Tahoe in 2010. You can get more information at http://www.rssummit.org

The 2013 RS Summit is designed to bring together residual stress users and developers in a format that provides "take home" information for the entire audience. As in the past, all the sessions will be specifically targeted, with invited talks that include industrial specialists and residual stress developers presenting their experiences regarding the formation, mitigation and effects of residual stresses. We will soon begin scheduling speakers, and would be interested to hear from you with additional themes for the Summit or ideas for specific talks. Please realize that in order to have a cohesive set of talks we will not be able to utilize all suggested topics or talks.

The Summit will again include a combined poster and demonstration session, where residual stress related equipment, materials and contributed posters will be displayed. The format of the meetings will provide substantial time for interaction at the poster/demo session. If you are interested in contributing and presenting a poster or bringing equipment for a demonstration during this session, please see http://www.rssummit.org/demos-posters.html

The RS Summit is a non-profit event, and the aim is to keep the registration fee at a moderate level. The registration fee will cover the 2 1/2 days of focused talks, a welcoming reception and all meals (breakfasts, lunches, dinners and coffee breaks). More details will be posted soon.

Save the date, and we look forward to meeting you in Idaho in the Fall.

Mike Prime, prime@lanl.gov

Mike Hill, mrhill@ucdavis.edu

Gary Schajer, schajer@mech.ubc.ca

Mike Steinzig, steinzig@lanl.gov

Cev Noyan, icn2@columbia.edu

John Jackson, john.jackson@inl.gov

I am hoping someone has some historical knowledge of some
interesting mechanics, or just an interest to discuss it. A superposition principle is widely used to solve crack problems, with illustrations like these:

http://ars.sciencedirect.com/content/image/1-s2.0-S0142112308002211-gr1.jpg

http://ars.els-cdn.com/content/image/1-s2.0-S0142112399000778-gr2.gif

Bueckner proved this principle in 1958 [1] but never published a figure
similar to those we see. He did explain it in text, such as “….. Any [elastic]
crack or notch problem can be reduced to one where the external load appears in
the form of tractions distributed over the faces of the crack.[2]” The first drawing similar to
the modern ones that I could find that was attributed to Bueckner was by
Barenblatt in 1962 [3]. Paul Paris’ landmark 1961 paper
on fatigue crack growth [node/7705]
shows a similar figure that he credits to some report he wrote at Boeing in
1957 [4]

Anybody have any more history of this principle? I would not
be surprised if it was used well before Bueckner proved it. Any earlier
published figures that show the principle? Does anyone have Paris’ 1957 report?

[1] Bueckner, H., 1958, "The propagation of cracks and the energy of elastic
deformation," Transactions of the American Society of Mechanical
Engineers, 80, pp. 1225-1230.

[2] Bueckner, H. F., 1973, "Field singularities and related integral
representations," Mechanics of Fracture G. C. Sih, ed., pp. 239-314.

[3] Barenblatt, G. I., 1962, "The Mathematical Theory of Equilibrium Cracks in
Brittle Fracture," Advances in Applied Mechanics, H. L. Dryden, T. v.
Kármán, G. Kuerti, F. H. v. d. Dungen, and L. Howarth, eds., Elsevier, pp.
55-129.

[4] P. C. Paris,
"The Mechanics of Fracture Propagation and Solutions to Fracture
Arrestor Problems," Document No. D2- 2195, Boeing Co., 1957.

Iain Finnie passed away in December. At the time he was the James Fife Professor Emeritus U.C. Berkeley Dept. of Mechanical Engineering.

Iain had an amazing number of contributions spanning diverse area of mechanics. To the best of my recollection:

He published some great early work on the shear angle in metal cutting in 1953.
He published the first book on creep in 1959 with William Heller.
He published a (the?) pioneering paper on erosion in 1960.
He published some great work on fracture and the directional stability of cracks in the 70’s
He invented the crack compliance method for measuring residual stress in 1986.

Some bio info:
B.Sc. U. Glasgow 1949
“Galloping conductors,” (M.S.) Massachusetts Institute of Technology. Dept. of Mechanical Engineering, 1950. Supervised by J. P. Den Hartog.
“The shear and friction processes in the cutting of metals” Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1953, Supervised by Milton C. Shaw.
Guggenheim Fellow 1967
National Academy of Engineering 1979
Contributions in high temperature design, erosion, and brittle fracture of materials.
ASME Nadai Medal 1982
ASME Honorary Member 1983
Berkeley Medal 1993