Extending the bandwidth of validity of FEM models used in vibroacoustic design is a generic objective of model generation processes at PSA Peugeot Citroën. Increasing this bandwidth implies a critical review of
test/analysis correlation, focusing on both experimental errors and parameters having a visible influence on the vibration characteristics.

Detection of test inconsistencies

Using the case study of an engine cradle, tools used to detect modal test inconsistencies have been developed. They allow to locate problematic sensors and to discard them from the experimental data


Model parameter selection and updating

Connections are usually major sources of uncertainties in models. In this engine craddle model, SDT was used to refine the models of weld spots and weld beads  An energy based indicator was used to select which connections needed updating.

Another important parameter is the variable thickness of the engine craddle due to stamping. A remeshing strategy was adopted to take that factor into account.

The contact areads between the welded parts were shown to have a large influence on the dynamic response.

Usual junction simplifications have also been shown to play a major role particularly at higher frequencies where more localized modeshapes occur.


More details in the conference paper presented at ISMA 2016.



Train/track interaction model

The aging of the various components of the train track is a major concern for maintenance. Experience with high speed trains indicates that train/track interactions need to be taken into account to study these effects properly.

SNCF (French Rail Road Company) needed a simplified coupled model (track and vehicule) to answer questions such as

  • When is it important to take into account track dynamics for the evolution of geometrical defects?
  • What is the impact of each layer component on the global track behaviour?
  • What is the influence of non linearities?
  • What is the influence of layers variability?

The Dynavoie software is designed to allow rapid iterations on the on relation between track components and dynamic response in the low frequency range. Publications are

Graphical user interface and parameters handling with Excel

Periodic sub-structuring of the train track

For more information on these extensions contact


Simulation and Active Control of Hydroacoustics in Flexible Piping Systems

Institute of Applied and Experimental Mechanics, University of Stuttgart
Robert Bosch GmbH, Stuttgart

In 2005, a new transfer unit TFB 51 funded by the German Research Society (DFG) is launched at the Institute of Applied and Experimental Mechanics. Following the Collaborative Research Center SFB 412, the transfer unit entitled “Simulation and Active Control of Hydroacoustics in Flexible Piping Systems” continues research goals related to pipe acoustics. The project is realized in cooperation with Robert Bosch GmbH, Stuttgart, for a period of three years.

New efficient simulation methods for the numerical analysis of sound propagation in fluid-filled piping systems, which were developed at the institute and at Robert Bosch GmbH, are employed for passive and active noise and vibration reduction (ANC, AVC) of car components. In breaking systems, common rail and hydraulic devices of modern cars, periodic pump noise and valve actuation leads to the generation of hydrosound propagating along flexible pipes. The coupling with attached structural components, as for example with the car body, affects vibrations of these components entailing undesired sound radiation or even malfunctions.

By means of innovative 3D simulation tools including acoustic fluid-structure interaction, it is intended to design and to apply passive noise control for automotive prototypes. This includes fluid pulsation dampers, resonators and structural dampers as well as the optimization of bearings and supports in order to decouple pipe vibrations from the dynamics of the attached structural components. Active noise control to be developed at the institute includes combinations of ANC and AVC. Active concepts are evaluated in cooperation with Robert Bosch GmbH.

FEMLink is used to import ANSYS models and SDT to perform model reduction of the coupled fluid/structure model.

SDT image

Sample mode of the coupled fluid/structure model.


Control design and validation of the HYDRA platform for ESTEC

The European Space Agency, ESTEC, The Netherlands uses SDT to build state space models from very large (2 million DOF, 8 GB modal base) NASTRAN results. These are then used in SIMULINK for control design and validation of the HYDRA platform.

SDT image
FE model of the HYDRA platform


A design tool for railway brake squeal

AcouFren was a collaborative project sponsored by ADEME (the french agency for energy and environment) and steered by the SNCF (the french railway agency) to improve the understanding of squeal occurrences as function of braking pad designs. The brake pad market is a multi-million EUR yearly market for the TGV only, in which noise performance specifications are tightening for environmental reasons. The squeal noise can indeed attain 120 dB in the bogie vicinity. The project involved several main actors in the domain from industry and academia, SNCF, Faiveley Transport, Alstom, Bombardier, IFSTTAR, ECL-LTDS, ENPC, Vibratec, and SDTools.

The main outcomes were a large experimental database and a software package developed by SDTools (see presentation of AcouFren software ). The software provides a complete simulation process from model generation to acoustic post-treatment, including

  • parametric meshing of simplified brake pad finite element models
  • assembly of the full brake model with advanced pad/disc interface remeshing (interface mesh compatibility handling) (the targets are TGV and AGC models with 1 to 1.5 million DOF)
  • non-linear static computations
  • complex mode computation with a control on convergence based on the residue iteration method
  • transient simulation of squeal instability (up to 0.5s simulated) based on reduced model developed by SDTools
  • post-processing providing cutting edge information at several levels : shape of the pressure fields through acoustic BEM coupling, potential instabilities, limit cycle amplitudes, noisy shape/frequency identification, component wise energy distribution, and opens the door to refined parametric analysis of the underlying mechanical behavior of squeal with realistic models

Railway brake

Stability prediction and transient simulation

Each step was interfaced through a Graphical User Interface (GUI), offering post-processing capabilities and automatic reporting.

The use of the latest SDT functionalities regarding data handling (advanced use of HDF5 and other out-of-core features), unsymmetric system resolution (interfacing of the latest PARDISO libraries from INTEL), Java GUI strategies, and formatted image caption strategies were exploited along with the latest SDT extensions on

  • nonlinear transient simulation
  • remeshing through GMSH and TetGen calls and mesh morphing within SDT
  • model reduction

The final software was packaged for industrial deployment using the MATLAB Compiler. A pre-computed database for the TGV and AGC brake models was built to allow optimized studies of brake pads effect on squeal.

Communications on the project

SDT Extensions

SDTools seeks to support industrial partners in solving test and analysis related problems. Our base libraries SDT and FEMLink are meant as of the shelf solutions for standard problems in vibration, but we also develop custom software solutions for use in industrial design processes. This document describes our licensing policies. 

Solutions available for direct industrial licensing are

  • Viscoelastic vibration tools. Parameterization of complex modulus constitutive law from material testing results. Computation of transfer functions for large order frequency dependent models. Parametric design tools.
  • SDT Runtime lets you use the MATLAB compiler to generate stand-alone executables that use SDT and FEMLink capabilities. The Runtime answers the need to allow large scale deployment of solutions developed with SDT. It was for example used by SNCF to deploy OSCAR. Contact us for more information on licensing.
  • SDT Rotor. Vibration analysis of rotating machinery. Fast generation of Campbell diagrams trough advanced disk model reduction, mistuning, multi-disk reduction, …
  • ctc_utils contact utilities for the support of contact in SDT (brake squeal, joint damping, …)
  • fe_shapeoptim mesh morphing tools that can be used for shape optimization studies

Solutions that are not documented well enough for direct licensing, but can be deployed as part of consulting projects

  • Distributed Structural Modification. These tools were originally developed for EDF for use in on-site vibration problem solving.
  • ProSpadd an integrated application layer for ARTEC SPADD damping devices. It allows initial evaluation of the damping potential, where the viscoelastic vibration tools are meant for detailed study.
  • Modal analysis and test analysis correlation with rotation sensors. These tools were originally developed for Siemens for use in machine tool diagnostics.

For more information on these services please contact

Viscoelastic Vibration Toolbox

These extensions to the SDT combine all the tools needed for the study of structural vibration and acoustics for structures with frequency and temperature dependent materials. The main areas covered are

  • material description. Standardized representation of material behavior. Non parametric representations as a function of parameters (frequency, temperature, pre-stress, …). Master curve extraction and identification tools to build parametric models, …
  • Meshing tools generating shell/volume/shell models from shell only meshes and for importing model matrices (from NASTRAN, ANSYS, …) for use of MATLAB/SDT solvers.
  • Acoustics tools allowing the generation of fluid/structure coupling conditions for incompatible fluid/structure interfaces, fluid FEM models in pressure formulation, model reduction strategies for resolution of the coupled problem.
  • Specialized solvers. Full order computation of transfer functions for parametric ranges (frequency, temperature, …) using innovative iterative methods. Implementation of Modal Strain Energy (MSE) method for reference.
  • Post-processing tools. Damping estimation from computed FRFs. Modal filter based mode tracking. Construction of superelements for substructuring analyses, …
Automotive floor panel :
optimization and design of viscoelastic layers
Fluid/structure interaction for an automotive body (structural model with 1e6 DOFs)

While this toolbox does not have the maturity of other SDTools products (imperfect documentation, lack of robustness, … ) we have proposed specific licensing to industrial users in the automotive, aerospace and energy industries. For more information about such licensing get in touch with

You will find the current PDF documentation here (again please understand that this is still work in progress).

System requirements are current licenses of MATLAB, SDT, FEMLink are also needed for most practical applications where the toolbox is used to design structures.

Sample application Viscoelastic materials are often used to damp vibrations in automotive and aerospace applications. The SDT allows easy manipulations of the models which enable parametric studies for various viscoelastic materials, temperatures, …

Response of a metal/viso/metal press formed part for a range of frequencies and temperatures

OSCAR Pantograph/catenary interaction

The ageing of the various components of the catenary is a major concern for maintenance. Being able to simulate the pantograph/catenary interactions provides useful information to analyze perturbed situations in the catenary : defects, singularities, extreme climatic conditions. It also helps to optimize existing catenaries and to design the future ones.

The OSCAR software, developed in collaboration with SNCF, is a portable multi-platform simulation package that is certified against TSI and can be used for pantograph/catenary interaction studies. For publications see here. The main features are

  • 3D geometry modeling with full generality (allows detailed modeling of defects, …).
  • Unilateral contact between catenary and possibly non-linear spring/mass models of the pantograph. Extension for cosimulation with MSC-ADAMS.
  • Test verified for many catenaries in Europe.
  • Automated generation of design studies with distribution of computations and merging of results.
  • Typical run times in minutes.

French high speed line, TGV

OSCAR has been used extensively for design and consulting activities by SNCF. For a possible distribution to other partners, please contact SDTools.

Results : Finite Element Model and measured/computed contact force

OSCAR is an extension of SDT which is used to run the application. The SDT Runtime feature was used to generate a deployable application that runs independently from MATLAB.

OSCAR is property of SNCF and you should contact them for licensing. For more information on SDT and related consulting contact


Reduced order brake models to study the effect of squeal of pad redesign
Vermot des Roches, Guillaume, Balmes, Etienne, Chiello, Olivier, Lorang, Xavier,
Eurobrake 2013   Download PDF

From transient simulation to extended complex mode analysis. Squeal simulation of an industrial automotive brake
Vermot des Roches, Guillaume, Balmes, Etienne, Lemaire, Remi,
Eurobrake 2012   Download PDF

Benchmarking Signorini and exponential contact laws for an industrial train brake squeal application
G. Vermot des Roches, O. Chiello, E. Balmes, X. Lorang
ISMA, Leuven, 2012  Download PDF


SDTools is an independent and privately owned software development company that provides off the shelf scientific libraries called from the MATLAB environment and consulting services to implement custom applications using these libraries.

SDTools was formed in 2001 by Etienne Balmes to transform the original academic Structural Dynamics Toolbox, sold by Scientific Software Group (now The MathWorks, France) since 1995, to a fully professional product. From 2001 to 2008 SDTools collaborated with the MSSMat Laboratory of Ecole Centrale Paris, where Etienne Balmes headed the Vibration research group. Starting september 2008, SDTools is now hosted by the PIMM laboratory at ENSAM Paris. Current PhD theses are funded by PSA, SAFRAN and SNCF.

In 2002 SDTools partnered with INRIA to combine efforts in the development of a general purpose multi-physics finite element library OpenFEM. This joint effort greatly augments the number of people involved in developing FEM capabilities distributed with SDTools products.

To get in touch with us

44 Rue Vergniaud
75013 Paris (France)
Phone: (33) +1 44 24 63 71