Computation and Simulation

We use innovative simulation methods to optimize the transmission’s acoustic and vibrational behavior (NVH)

Against the backdrop of growing demands users are making on comfort, vibration dynamics and acoustic behavior of vehicle powertrains play a crucial part in the development process. This is why our development engineers optimize the layout of transmissions in terms of acoustics and dynamics at an early concept and development stage. They do this using numeric computation and simulation processes, such as the finite-element method (FEM) and multi-body simulation (MBS).

Often, pure torsional-vibration analyses are the best method for computing the typical acoustic transmission phenomena of “rattle” and “whine”. We use them for modeling both the dynamic behavior of modern decoupling systems (dual-mass flywheel, centrifugal force pendulum, dual-damper torque converters) as well as the transmission gear stages with their meshing stiffnesses.

To deal with powertrain analysis tasks of a more complex nature, MBS models are generated for simulating the entire 3D multi-body dynamics of transmission components while integrating elastic bodies from FEM computation. This, for example, allows us to analyze the acoustic behavior of rear-axle transmissions (“hum”, “boom”) in chassis subframe mounts.

A complete model based on CAD geometries is generated for analyzing vibration of the entire engine/transmission assembly. We use this model to conduct a mathematical modal analysis for evaluating the structure-borne sound entering the body under engine excitation in the frequency range (at full load, part load).

Our NVH optimization activities further focus on computing noise emitted from transmission casings through engine excitation on the one hand and through direct transmission excitation resulting from gearing orders on the other.

To simulate the longitudinal dynamics of powertrains, we have developed the innovative VeLoDyn (Vehicle Longitudinal Dynamics) simulation tool on the basis of Matlab / Simulink / Stateflow. This simulation tool is used for the following applications:

  • Concept studies
  • Vehicle studies
  • Algorithm development
  • Calibration
  • HiL, MiL and SiL simulation
  • Investigations on engine, transmission and powertrain test benches

A model library holds the fundamental powertrain components in varying degrees of detailing. Depending on purpose, these components provide the basis for configuring the desired overall model using the integrated model management capability. If necessary, VeLoDyn can be connected with appropriate domain simulation tools, such as Dymola, SimulationX or GTPower, for co-simulation.