stage 6 triennial report 1 July 2009–30 June 2012 ... - CHARMEC

Materials and maintenance – Material och underhåll (MU) – Werkstoff und Unterhalt – Matériaux et entretien
MU25. ThERMODYNAMICALLY COUPLED CONTACT BETWEEN
WhEEL AND RAIL
Termomekaniskt kopplad kontakt mellan hjul och räl
Thermomechanisch gekoppelter Kontakt zwischen Rad und Schiene
Couplage thermodynamique du contact entre roue et rail
Project leader Docent Anders Ekberg
and supervisor Applied Mechanics/
Division of Dynamics
Assistant supervisors Docent Fredrik Larsson and
Professor Kenneth Runesson,
Applied Mechanics
Doctoral candidate Mr Andreas Draganis
66
(from 2009-06-29;
Lic Eng December 2011)
Period 2009-01-01 – 2012-06-30
(–2014-06-30)
Chalmers budget Stage 5: –
(excluding university Stage 6: ksek 2400
basic resources) Stage 7: ksek 2000
Industrial interests Stage 5: –
in-kind budget Stage 6: –
Stage 7: –
The project has been partially financed by The Swedish Research
Council, VR (through CHARMEC’s budget)
Project mu25 investigates and develops efficient methods
for modelling and computation of the thermomechanically
coupled problem when two deformable bodies are in
high-speed sliding contact. A typical example is a braked
(and locked) railway wheel that moves along the rail. A
major challenge here is to formulate a computationally
efficient description of the motion of the two bodies. In
particular, such a description should account for the high
accuracy needed in the moving contact patch. A significant
motivation for the current study is the possibility to allow
for refined predictions of different forms of rolling contact
damage to wheels and rails.
To achieve these aims, the ale (Arbitrary Lagrangian-
Eulerian) kinematical description is employed. This is a
generalization of the traditional Lagrangian and Eulerian
descriptions. The Lagrangian description follows when the
initial configuration of the bodies is taken as the reference
configuration. This means that a computational finite
element (fe) mesh will be fixed to material points during
deformation. This description naturally allows easy tracking
of boundaries and easy treatment of history-dependent
material parameters, but can lead to severe degradation of
the element mesh at large displacements. In the Eulerian
description, the current configuration is instead chosen
as the reference. This implies that a computational mesh
will be fixed in space. In this description, keeping track of
boundaries and history-dependent material parameters
Spatial (current) configuration B x (t), material configuration B X (t)
and absolute (fixed) configuration B ξ for each of two bodies
w(heel) and r(ail). From the application to VR
may be very difficult, while large displacements/distortions
of the continuum are easily handled.
With the given choice of intermediate configurations (see
figure) pertinent to the ale model as basis, the equations of
motion of the mechanical system have been established and
finite element (fe) formulations derived. The theoretical and
numerical framework for rolling contact simulation setting
out from the ale kinematical model has been finalized and
validated for mechanical two-dimensional (2d) contact. Implemented
features include 2d cylinder–plate contact, transient
dynamics, non-reflecting boundary conditions and customizable
surface profiles, allowing for the implementation
of non-smooth surface profiles. Additional features include a
penalty-type formulation of thermal contact and a numerical
stabilization scheme. Studies of frictional contact, wheel–rail
heat partitioning and temperature distributions for different
operational cases are currently being carried out.
Andreas Draganis presented his licentiate thesis (see
below) at a seminar on 21 December 2011 with Professor
Mathias Wallin of the Division of Solid Mechanics in the
Faculty of Engineering at Lund University (Sweden) introducing
the discussion at the seminar. The research plan
(from the approved first application to vr for three years)
is dated 2008-04-15. An application for continued financing
from vr was rejected. For the joint reference group, see
under project mu18.