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
The respective acoustic standards applicable to the vehicle require adapted acoustic concepts, as part of development and evaluation. Müller-BBM can provide you with the appropriate support as part of vehicle development. This includes general consultation on low-noise designs to the development and evaluation of individual measures for acoustics and overall concepts. We always take into account the overall chain of effect, from individual noise-emitting components to the respective reception point.
Air and structure-borne noise tests
Because of 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 fatigue
The high demands placed on rail vehicles in terms of weight and the poor condition of the European rail network in certain areas have lead to the subject of "fatigue" gaining increased interest. Müller-BBM also performs multi-channel, partially telemetric vibration tests using sonic, acceleration, expansion, and path and temperature sensors. This makes it possible to determine the strain and vibrations of the rail vehicle and certain components—even during operation. These studies are flanked by computer simulations, such as the calculation of static and dynamic tension on components, and the vibration modes and natural frequencies by means of the FEM (finite element method). We support you when considering service life with the help of an evaluation of the results using a rainflow analysis in combination with common damage accumulation hypotheses.
Wheel roughness measurement: m|wheel
The unevenness of wheel running surfaces is especially significant for the acoustics of rail vehicles, since the rolling noise is determined by track- and wheel roughness. Müller-BBM has developed the simple-to-use, high-precision m|wheel measuring device for determining the running surfaces of all types of rail vehicles. m|wheel is capable of highly accurately measuring the wheel roughness values that are relevant to comfort and acoustics.
In addition to distributing the system, we happily carry out the measurements you need using m|wheel.
Wheel Monitoring System (WMS)
For continuous monitoring of wheel roughness values and damage, Müller-BBM has developed the Wheel Monitoring System (WMS). WMS automatically provides information about the wheel condition of the entire fleet. Progressive damage is documented in detail. Maintenance can be scheduled early, and is only carried out based on the condition of the wheel, when required by the degree of wheel wear. Discontinuing routine wheel inspections reduces maintenance costs, with "listening posts" for identifying noisy vehicles no longer being necessary. WMS is utilised by public transport operators, such as BVG Berlin or for the ongoing quality control of tram wheels in Gothenburg.
1) Testing location: Vehicles entering are identified by a vehicle detector. Sensors in the track record the signals from the crossing vehicle. 2) The computer performs the measurement data analysis (autonomously). The wheel condition is determined. 3) transfer of the analytical results over the network. 4) The SQL Server-based database stores the parameters determined and enables access to the analytical results from any PC-workstation. 5) Clear representation of vehicle condition, evaluation, and analysis is available on any workstation PCs.
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.