This toolbox have been developed during a project called:
Novel Rail Pads for Improved Noise Reduction and Reduced Track Maintenance.
This project was founded by the Swiss Federal Office for the ENvironment FOEN and carried out by a consortium of scientific laboratories form Switzerland. This consortium was a collaboration between the following entities:
- Swiss Institute of Technology of Lausanne (EPFL),
- Swiss Federal Railways (SBB),
- School of Engineering and Management of Yverdon (HEIG-vd),
- Swiss Federal Laboratories for Materials Science and Technology (EMPA).
For the last phase of the project, a company has joined the consortium to develop prototype railpad:
- Semperit Group from Austria
The project aims to reduce the noise emission of rail tracks and increase track maintenance intervals by the development of a new rail pad. The selected approach was the development of an experimental set-up combine with a digital tween (i.e. The Three Sleepers Model presented later). Other models have been developed and experimentally validated to achieve our goals.
As said previously, the toolbox have been develops to design new rail pads, and thus can be used in the same way.
Furthermore, models has been created using open source tools and can be easily modified and/or incremented with new functionalities.
Therefore this toolbox is the first step in the creation of a open source and collaborative platform for the rail way experts.
Anyone interested and working in this field can use and/or developed the existing models or add new ones.
This toolbox is composed of four finite element models and one semi-analytical model:
- The PadStiffness Model
- The Semi-Analytical Model
- The Three Sleepers Model
- The Impulse Model
- The Multi-Sleepers Model
Each model can be found separately in the src directory. Alternatively the full toolbox can be downloaded as a Virtual Machine container and run on any Linux distribution.
A overview of each model is presented in the following paragraphs, please refer to the specific chapter in the documentation for more information on the models.
The Pad Stiffness Model aim to estimate the static and dynamic stiffness of the input pad design. It is a digital twin of an experimental compression system. After validation in static and low dynamic (10 and 20 Hz) compression with the experimental results, the model have been extended to provide the stiffness in various directions and with an extended frequency range.
The Semi-Analytical Track Model is aimed at simulating the dynamic response in terms of point mobility and track decay rate (TDR) of a nearly infinite track as well evaluate the radiate noise. This model uses as input the frequency dependent stiffness and damping of the pads as evaluated by the PadStiffness model.
The Three-sleeper model is a Digital Twin of an existing test setup consisting of three sleepers with two 1.8m rails installed in our lab. It carries out an harmonic simulation of the system over a user defined frequency range (multiple bands on multiple CPUs) and is able to compute the frequency response of the setup as well as the radiated noise using a monopole superposition method. This model and experimental setup form together an efficient method to validate the modeling assumptions such as for example the frequency dependant complex moduli of the railpad material(s) or the effective properties of the prestressed concrete in the sleepers. This model allows to optionnally include undersleeper pads as well.
The Impulse model is a variation of the three sleepers model, operating in the time and not the frequency domain. The rail pad materials are modelled as a generalized Maxwell model described by a Prony series. It aims to reproduce a pass-by of a bogie on a sleeper. Therefore a M shaped impulse is imposed to both rails above the middle sleeper. The model output can be used to evaluate the rail pad deformation / stresses, the clamping system deformation, the ballast deflection and the mean stress acting on the ballast. These results cab thus be used to evaluate fatigue of fastening component, rail pad visco elastic recovery time as well as ballas settlement.
The multi-sleeper FE model is a large scale 3D structural model of a railtrack (with an arbitrary number of sleepers) using frequency dependent dynamic substructuring to evaluate quickly but in great details the vibration response of the rail and sleepers as well as compute the radiated noise level. This model allows to optionnally include undersleeper pads as well.
To facilitate the use of the toolbox, a custom version of CAELinux 2020 is provided as a ISO image which can be used to install a physical or virtual machine with all software preconfigured. To use the toolbox in another Linux operating system. including Windows WSL2, a Singularity container image is also provided.
Download link to the virtual machine image/ container: see readme.md in ToolboxVM folder.
The code was developed to run in a CAELinux 2020 Lite (http://www.caelinux.com) but can be adapted to run on other similar distributions (Ubuntu 18.04 for example).
The toolbox requires the following software installed on the system to run:
- Code_Aster with MFront support (tested version 14.6)
- Salome-Meca 2019
- Python 2.7 with PyQT5, pyperclip and numpy libraries
This repository contain three folders: Documentation, src and Toolbox-VM.
The first folder contain the documentation of the toolbox: description of the models, how to use the interface and so on. The second folder, src, contain the individual models. The last folder, Toolbox-VM, contain a ISO image of a customized CAELinux/Ubuntu 18.04 environment with the whole toolbox ready to be used.
The easiest way to start using the toolbox is to download and use the ISO image in Toolbox-VM. This image can be used to create a bootable USB disk (using Ventoy https://www.ventoy.net is recommended) in order to boot and install the OS + toolbox on a physical PC. Or even simpler, the ISO image can be used directly to install a Virtual Machine, on any OS, for example in VMware player https://www.vmware.com/fr/products/workstation-player.html.
Once booted from the ISO image, the (virtual) machine can be installed by running.
sudo ubiquity gtk_ui
Please note the default username / password is :
username: caelinux
password: caelinux
If you decide to install "from scratch", you will need to have first a working installation of all the prerequisites (see src/INSTALL, src/dependencies.txt and src/installDependencies.sh) and then run the setup.sh script in the root of the toolbox:
cd PathToToolBox
./setup.sh
Once installed, the best way to start using the model is to use the GUI provided for each model. Part of the documentation describes the steps to follow in order to run a simulation with the selected model.
The FE models included in this toolbox require at least a 4 core CPU with 16Gb of RAM to run. However, to run simulations in parallel and with detailed 3D mesh, a 8 to 16 core CPU with at 64Gb of RAM is optimal. Most of the simulations that we have carried out have been running on AMD Threadripper 24 core 128Gb or 16core 64Gb workstations. To make use of the available computer resources, please edit the ".export" files in the "working_directory" folders of the models. See Code-Aster documentation for the details of the .export files.
If you want to learn more about Code_Aster you can visit their official web site
If you want to learn more about Salome, a multi-platform open source scientific computing environment, you can visit their official web site
This code is published under Gnu Public Licence v3 / GPL v3
This toolbox was developed in the framework of the "Novel Railpad Project" funded by the Swiss Federal Office of Environment and developed in collaboration with EPFL, HEIG-VD, EMPA and SBB.
The finite element models of the toolbox have been developed at COMATEC institute / HEIG-VD by Maurice Ammann, Raphael Nardin and Joël Cugnoni.
The semi-analytical track model was developed in the laboratory of acoustics at EMPA by Benjamin Morin and Bart Van Damme.