Welcome!
CONTACT
INFORMATION
Prof. Mårten Olsson
Dept. of Solid Mechanics
Royal Institute of Technology
(KTH)
SE - 100 44 Stockholm
Sweden
Visiting address: Osquars backe
1, Room no. 362
Phone: +46 8 790 75 41
Fax: +46 8 411 24 18
E-mail: mart@kth.se
PRESENTATION
M.Sc. in Engineering Physics (F) 89 from KTH (spec. in Applied Mechanics),
Ph.D 94, Post Doc (Sw: Fo.ass.) 94-97, Assoc. Prof.
97-06, Habilitation (Sw: Docent) 99,
Prof. 06-, holder of the Sverker Sjöström
chair of Reliable Structures
Director of graduate studies (Sw: Studierektor-FoFu):
May 96-Oct 99,
Director of undergraduate studies (Sw: Studierektor-Gru):
Oct 99-Jan 05,
Director of the specialisaton in Solid Mechanics: Oct
99-
Director of the track in Solid Mechanics of the Master´s program Engineering Mechanics: Aug
10-
TEACHING
● Lectures for several programs at KTH over the
years (B, F, I, K, M, P and T), mostly for T (Vehicle Engineering) followed by
M (Mechanical Engineering).
● In the fall of 2010 I gave the basic course in
solid mechanics for student of Mechanical Engineering (M) and Materials Science
(BD). Very nice.
● For many years, I have given an annular course
called "Dynamic problems in Solid Mechanics". Starting this year, my colleague
Artem Kulachenko will give this
course.
● Another advanced course, "Solid Mechanics
Modeling for Design”, has also been given annually. Link to Solid Mechanics Modelling for Design. This course will be reworked, developed, to another
course called “Fatigue, Reliability and Design”. It will be given the first
time in the fall of 2011. It will includes
lectures (also guest lecturers from industry and academia), FE-based design
labs and project work. There are oral and written presentations.
● Examiner and advisor for M.Sc. thesis projects
(a list).
● Has given courses for Scania, such as
"Dynamics for the mechanical analyst", “Fatigue and reliability”.
TRACK IN
SOLID MECHANICS, in the Master´s programme in ENGINEERING MECHANICS
This KTH-programme is open to students with an
appropriate B.Sc.-degree. Most students come from KTH but also from abroad.
The programme three tracks: Solid Mechanics, Fluid
Mechanics and Sound and Vibration.
KTH-students from programmes BD, F, M, P and T are
welcome! Other students from Sweden, and indeed from the world; you are also welcome!
The curriculum is ready - for more information, follow this link.
I work to assure that the track is continuously developed and that the
education we offer is of high quality and is both scientifically and
industrially relevant. I also help our students in direct, practical matters;
ideas on which courses to take, thesis work, international openings, etc.
Currently, I do not have a link to a brochure, or
similar. However, if you are a student
and interested in our track, you are more than welcome to contact me! I will
then provide material.
I am chairman of the KTH Solid Mechanics Society (Sw.
abbreviation: KTH-HTK, link).
It is an KTH alumni society, currently with 226 members. The society offers a
protected website, presentations and social gatherings like After Works. The
photo is taken from an evening with the society at Stockholm Chamber of
Commerce.
Eng-Swe translation:
Solid Mechanics
track = Spår Hållfasthetsteknik,
Master programme in
Engineering Mechanics = Masterprogram Teknisk Mekanik.
RESEARCH
Why?
The key motivation for me is utility in design.
How?
Projects: Short industrial cooperations (can be in the
form of a M.Sc.-thesis). Most research projects are PhD-projects and last for
about five years.
Methods: Analytical, numerical and experimental.
Funding: Industry or research agencies (like Swedish
Research Council, VR, or Vinnova).
Partners: Industry and academia. The main industrial
partner by far is Scania, other important are SKF ERC, Siemens, Volvo Aero,
ABB, Atlas Copco, Sandvik.
What?
Industrial needs in solid mechanics define our
projects. We develop models, methods and methodologies. Our expertise lays in
the development of solid mechanics based “tools” for design against X, where
“X” can represent many phenomena. Our emphasis is X = fatigue.
In fatigue design we work on fatigue and design. We also study the
variability of fatigue in order to design structures that are reliable. The
fatigue failure then has a certain probability. On the other hand, structures
should not be too reliable.
● Fatigue
- key words and concepts: critical plane approaches, weakest link methods,
probability of fatigue failure.
● Design
- key words and concepts: Robustness, Taguchi, optimal concepts and
geometries (and feasibility), material, heat- and surface treatment, etc. The
solution is the “product specification” – a document that specify how the ideas
are realized. Also, re-designs are of importance.
●
Fatigue design - key words and concepts: In industrial product development, creativity is first focused on
synthesis. This creativity shifts to analysis at latter stages. In-between, a synthesis-analysis is needed and we
develop methods for this activity.
Synthesis-analysis is a systematic exploration of the
design space. We may optimize the product (say reduce weight, or cost to a
minimum) still fulfilling fatigue life requirements using stochastic simulation
or RBDO (Reliability Based Design Optimization).
Some
PRESENTATIONS
At the UTMIS-meeting at Atlas Copco in Örebro 2005,
three presentations were given on contact fatigue (link), fatigue
crack growth during non-sequential mixed mode loading (link) and
fatigue design (link).
UTMIS is the Fatigue Network of Sweden.
At the UTMIS-meeting at Volvo CE in Braås
At a Scania meeting in
At SMD, June 15-17 2009 (Swedish Mechanics Days) I
held a plenary lecture (link).
RESEARCH
RESULTS - current and previous
References to papers are not given here, instead see
the department´s list
of publications.
In the area of RBDO (Reliability Based Design
Optimization) and RBRO (Reliability Based Risk Optimization (and it includes Design,
too)) I work with M.Sc. Rami Mansour. A numerical tool is developed, capable of working
with ANSYS for the solution of RBDO and RBRO problems. So far, we have studied
truss problems.
Criteria for High Cycle Fatigue (HCF) for accurate
predictions are crucial for successful design work of advanced products. In
turbine design, I work with M.Sc. Salar Sadek and M.Sc. Daniel Sandberg in order to study the fatigue behavior of metals and
develop such criteria. We study different ways to find the probability of
failure for a specified geometry loaded by a specified load history. When such criteria
exist, they can be used in an optimization of the geometry of the product with
respect to weight under the constraint that the probability of failure is at
(or below) a given value. Other optimization goals can also be achieved. The
possibility opens to employ computationally driven development work. However,
an accurate HCF-criterion is the key element needed for such an
synthesis-analysis to give meaningful results.
The project is a joint effort with partners at other
departments at KTH as well as at Siemens Industrial Turbomachinery and Volvo
Aero Corporation. Funding is given through the Swedish research center TURBO POWER.
In the area of stochastic simulation I work with Tekn.Lic. Tomas Dersjö, from Scania. The research is focused on how variation
in the “input” of a product affects the “output”. Input variation may be in
loading, material, etc. The output is probability of fatigue failure.
We have developed synthesis-analysis methods for RBDO
with optimisation of the cost. In each iteration a new design is chosen based
on the changes of fatigue life in different directions in “design space”. Research
has also been performed on how to reduce the requried number of computations in
order to find the best direction in design space. Currently, problems with many
constraints are studied. Methods of finding a single point in design space
where all the constraints can be approximated are developed.
We have also augmented the concept of “design space”
to include the full specification of the product, including heat- and surface
treatments. Please note that the best geometric design against fatigue will
change if we change the surface treatment and/or introduce shot-peening and/or
exchange to another material.
In the department I work with Tekn.Lic. Kristoffer Karlén
on reliable fatigue design based on stastistical methods. Currently our
research is devoted to the inherent scatter of the fatigue process using a new
experimental set-up. We investigate details of the “volume effect”.
Prof. Gunnar
Härkegård from NTNU in Trondheim, Norway, visited us during
2008. In a joint effort, we studied the fatigue behaviour of a welding steel
that contain defects with a distribution that have local maxima at two
different sizes.
A notorious problem in much engineering work is to
determine the loading on products when they are used “in the field”.
On the frame of a truck components are mounted. They
are loaded by their own weight as the frame move during use. Finally, there
will be a fatigue failure. To find the loading on the components is very
demanding due to the friction of the bolted joints used for 
fastening. There is micro sliding with friction in the contact. This
leads to damping.
In this field I work with Dr. Henrik Wentzel at Scania. He presented a PhD-thesis in
December 2008 that include non-linear FE-analysis of the dynamic behavior of
the joints as well as the whole structure. A sub-structuring technique was
developed that replace the joint, and a small part of the surrounding material,
with a cylindrically shaped super-element with few DOFs. This allows for the
dynamic modeling of frictional joints with is not feasible in full FE-analysis.
In addition, the thesis present analyses of a method
to purposely control the dissipation of frictional joints with perforated
inserts in the clamped contact. Extra dissipation is due to plastic dissipation
at the perforation edges. The method is patented.
Research has been carried
out on fatigue crack growth during sequential loading in mixed Mode I and II
with Dr. Peter Dahlin. We developed
a criterion for the growth of such a fatigue crack - how much and in what
direction it grows.
The
project included testing, computations and modeling of the specific mechanisms
that appear in non-proportional loading of cracks. The direction of a
non-proportionally loaded crack may be different in the beginning of its growth
and after a while.
In the
figure, the result of a single Mode II load on the crack propagation rate of
Mode I loading. RD = Recovery Distance is the crack growth needed until the
original Mode I CG-rate is retained.
In the
area of fatigue avoidance I worked with Tekn.Lic.
Sven Norberg, then at Scania. We developed a computer-based tool with good
accuracy that can be used to pre-determine if a component will sustain many
load cycles, i.e. design against the fatigue limit.
The
program is called FAST = Fatigue Analysis Tool.
In the area of contact fatigue, Dr. Bo Alfredsson and myself at KTH Solid Mechanics and M.Sc. Christer Olsson at Scania has
developed a testing method, with results shown in the figure. It is a contact mark
(dark region), where a spherical indenter has been pressed against the surface
millions of times (diameter
The
test method is SCF = Standing Contact Fatigue. With SCF, you can create
different cracks, both at and beneath the surface. We have also subjected the
indenter to inclined loading, in order to get friction effects. The result is a
surface crack that grows around the contact mark in an elliptical shape.
The SCF
tests is a “spin-off” from a project on contact fatigue of gears, cams and
followers. SCF can be used to rank materials in such applications.
In an effort to combine gear
technology and robust design, I and Dr.
Magnus MackAldener, Scania, identified and analyzed a new type of fatigue
failure of gears: Tooth Interior Fatigue Fracture = TIFF. This fracture is
initiated in the interior of the tooth.
The
failure is becoming increasingly important due to the fact that thinner teeth
are being used (because they are quieter). The picture show a TIFF in an idler
gear. The initiation is in the interior central region of the tooth. The crack
has kinked at growth into the case hardening layer.
After
we first presented TIFF in 2000, more than 10 companies that manufacture
transmissions and gears have contacted us and said they have this problem too.
They want to know how to design against it.
We
studied involute gear teeth, but TIFF can be found in other types of teeth as
well. One problem in testing gearboxes is that after the fracture it can be very
difficult to determine what has happened since the damage caused to fracture
surfaces may be extensive. In some cases this is not the case, and the details
of TIFF has been fractographically examined.