As part of a united Europe, interoperability of the vehicles for different rail networks must be ensured. The vehicles must therefore satisfy the respective national rules and regulations concerning noise protection.
Internal and external noises as well as the speech intelligibility in the train are essential criteria for the design and construction of new rail vehicles. Müller-BBM brings know-how to every stage of development. At the design stage, we support the manufacturers of rail vehicles by defining acoustic objectives and clearly presenting them in the tender and detailed specifications. With the help of simulation calculations, the data from the various disciplines are evaluated and updated during the course of acoustic management. Extensive metrological studies on rail vehicles provide us with a wealth of experience, which enables us to implement ongoing tests for the plausibility of the findings obtained during the design phase. Systematic transfer path analyses enable us to gain deeper insights into the dynamic and acoustic behaviour of the structure.
Müller-BBM offers you services in the following fields:
Müller-BBM made its mark by accompanying rail vehicle development with so-called acoustics management. This starts as early as the tendering phase, in which the achievable acoustic target values are ascertained for the rail vehicle being developed using initial simulation calculations. The vehicle layout is evaluated with respect to the client's requirements, so that the critical operating conditions and areas in the vehicle can be identified. As part of the development of the rail vehicle, the individual specifications for acoustics are drawn up in the initial project phases, in order to specify the necessary acoustic standards governing noise-emitting parts and components. The acoustic forecasting models are continually detailed in line with project progress, thus enabling continual review the extent to which the acoustic objectives are achievable, and if necessary allowing the appropriate measures to be taken at an early stage in case of deviation from these objectives.
The tool used for acoustic management is the forecasting methods developed by Müller-BBM for interior and exterior noise. A hybrid approach was used to combine various acoustic methods, such as spatial acoustics, statistical energy analysis, finite element method, and ray tracing.
Müller-BBM continually implements experimental analyses and acoustic tests on materials, discrete components, components that emit noise, and entire vehicles. We are able to draw on our wealth of experience, which provides the necessary basis for a solid forecast.
Consulting during the development phase
In the development phase of a rail vehicle, the acoustic concept must be adapted to a multitude of specific requirements. Müller-BBM can help you with you with consultancy on low noise construction as well as with assessment of special acoustic solutions or of the general concept. Doing so, we always take into account the complete system from noise sources over the relevant transmission mechanisms up to the acoustic receiver.
Air and structure-borne noise tests
Due to the complexity of modern rail vehicles, the solutions to acoustic and vibration problems are sometimes not evident, hence the need for experimental analyses. Together with you, we develop the necessary steps for working out acoustic solutions in the most effective, fast and cost-effective way. We carry out acoustic tests in our test areas, in your test benches or even directly on the vehicle as part of running trials.
Müller-BBM has state-of-the-art measuring equipment at its disposal. We determine all relevant acoustic and vibratory measurement levels in multi-channel and synchronous mode in conjunction with the most significant vehicle parameters, such as velocity or starting torque, and GPS vehicle location. In conjunction with experimental methods of acoustics and vibration technology, such as operational transfer path analysis (OTPA), modal analysis (MA), operational vibration analysis (OVA) or panel contribution analysis (PCA) and the high-performance PAK® measurement and analysis software of our sister company Müller-BBM VibroAkustik Systeme, we have all tools at our disposal for getting to the root causes of noise and vibration phenomena and noise-emitting components.
Structural dynamics and material fatigue
The topic “fatigue” increasingly gains in importance by the lightweight construction of rail vehicles. Müller-BBM conducts multichannel measurements of sound, acceleration, rotation, displacement and temperature – also telemetrically, if necessary. So, strain and vibration of the vehicle and/or selected components can be recorded during operation.
These examinations are supported by numerical simulations such as calculation of deflection shapes and natural frequencies carried out by means of FEM. Evaluating all these results by means of a rainflow-analysis combined with common hypotheses of cumulative damage, we can support you in considering the operating lifespan of your rolling stock.
Müller-BBM has developed an automatic train monitoring system based on its acoustic and structural-dynamic competence. Significant vibration of relevant components are therefore continually recorded and evaluated. This makes it possible to obtain and evaluate a complete overview of the strains that occur.