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MEFISSTO (English)


Environmental vibrations propagation and ground-structure interaction

MEFISSTO
is a numerical solution for calculating the propagation of vibrations in the ground and structures. It is based on two complementary numerical methods: finite element (FEM) and boundary elements (BEM). It can be used to size vibration reduction systems for buildings or to carry out impact studies regarding the risk of structure-borne noise in buildings close to railway tracks, both underground or on the ground.

PROS

  • Simultaneous use of FEM and BEM, which allows to take full advantage of both methods: well-described infinite domains with BEM, ease of calculation in thin structures with FEM
  • Available 2.5D calculation (2D geometry and 3D excitation), which yields realistic results but with a limited computation time and a simplified input of geometrical data
  • Accurate description of complex ground propagation effects (multilayer ground, tunnel structures)
  • Estimate of structure-borne noise in building rooms using an innovative hybrid method 2.5D/3D (2D3/4 approach)


Simplified data input

The end-user defines a set of materials and domains. The geometry is defined easily by straight segments or simple objects (polygons, circles), representing domain boundaries. Criteria for minimum mesh density per wavelength and minimum number of elements are then applied at each frequency to generate the mesh. Besides, input of a complex geometrical object (such as a tunnel) can be achieved by defining the point coordinates of closed contour from an image file.

Optimization of computation time

BEM and FEM meshes are generated automatically at each frequency. FEM domains are condensed on nodes coupled with BEM domains and FEM meshes are organized to reduce height of matrices columns.

Method modularity depending on domains

The user can choose which domains are modelled sing FEM or BEM. Infinite and homogeneous domains such as ground layers can easily be taken into account thanks to BEM. On the other hand, complex domains with multiple heterogeneities (such as track rails and slabs, or building foundations) are modelled more easily using FEM.

2.5 calculation

2D calculation is available but is not recommended, except as a preliminary step and in order to compare situations.

2.5D calculation is on the other hand well-adapted to many situations, especially train vibration problems. Indeed, this type of calculation assumes that the geometry remains the same in one direction, which approximates well a railway track on the ground or in a tunnel underground. 2.5D formalism is implemented both for BEM and FEM methods. At each frequency, 2.5D approach is based on a set of calculations for different wavenumbers.

Possibility to model multilayer ground and tunnels

Complex stratifications profiles are defined with straight segments with are automatically extended at each frequency. Tunnels are defined using their inside and outside contours and they can intersect a boundary between two layers (MEFISSTO can handle multiple tractions at a junction).

Module for estimation of structure-borne noise in building rooms using a hybrid approach

Apart from 2.5D calculation, which is used to predict vibration levels in the ground and in structures, MEFISSTO offers the possibility to define 3D volumes in which the acoustic radiation of walls is used to predict structure-borne noise inside the rooms. This approach has been validated against full 3D calculations.

MEFISSTO therefore provides a complete simulation kit to deal with structure-borne noise, from the vibrations induced by the pass-by of a nearby train to the acoustic emission from building walls and floors.

Did you know ?

MEFISSTO outputs have been validated against in situ measurement of tunnel mobility as part of preliminary studies of Grand Paris lines. It is also the reference tool for all vibration impact studies for the whole project.

Minimum required configuration:

• Processor : 4 cores, 2 GHz

• RAM : 4 GB

Supported operating systems

• Windows XP and higher, 64 bits


MEFISSTO is available in French.

CSTB TRAINING SESSION

Training session MEF1: Mefissto - Getting Started with the Software

Training program:

  • FEM and BEM calculations
  • Conditions of application
  • Data entry with the help of the MEFISSTO manual
  • Application examples
  • Simulation on a workstation under environment

Duration: 2 days

This training is available in intra.
For inter-company dates: 
contact us

PACK MEFISSTO - TRAINING

Do you want to acquire MEFISSTO and train your teams for an efficient use? Choose the pack MEFISSTO+TRAINING.

CSTB experts help you with getting used to MEFISSTO and acquire the basic knowledge for an optimal use.

You get a 10% discount when buying a pack MEFISSTO+TRAINING.

If you are interested by this PACK, please contact us

For more information about MEFISSTO and an offer, please contact us