Assistance in the design and validation of beams for supporting train-mounted sensors
When renovating rolling stock or fitting new train-borne equipment (automatic control systems, etc.), manufacturers or operators have occasion to attach sensors or ground-to-train communications under rail vehicles. To do this, it is often necessary to fit beams on the vehicle bogies.
Beam design and interfaces with suspended components are factors vital to railway safety (mechanical behaviour of beam and sensors) and the solution proposed must also be suitably adapted to the environment in which it has to operate from a vibration perspective in order to ensure the robustness of the train-borne systems.
To help the designers of such systems in the validation process, the Test and Measurement Laboratory (LEM) can draw on a wealth of feedback from its work in designing and validating sensor support beams.
The challenges are enormous because, apart from the risks to the safety of people and equipment, unsatisfactory design can also be seriously detrimental to the reliability of train-borne systems and their life cycles.
Bespoke dynamic tests for your projects
Using its test facilities and its knowledge of railway loads and forces, the LEM is able to offer its support in designing beams with suitable fatigue characteristics or in choosing vibration-resistant securing devices for the parts to be suspended.
- Experimental modal analysis to ascertain the frequencies specific to the structure as a whole with a view to FEM model recalibration,
- Dynamic stress measurement at the welded joints or the "hot" points revealed by FEM analysis in order to study the mechanical behaviour of the different parts,
- Measurements of acceleration at the various points of attachment (bogie, beam, sensors) to gauge the efficiency of the suspension developed.
Dynamic measurements can, of course, be supplemented by capturing other parameters such as train speed, movement of parts in relation to each other, forces in fastening screws, etc. and by means of video recordings produced using mini-cameras or high-speed cameras able to capture phenomena up to 500 Hz.
Sophisticated post-processing for thorough analysis of the test data and validation of your product design
The parameters logged under real rolling stock operating conditions will be used to:
- study the fatigue behaviour (mechanical and vibratory) of the beam and the suspended parts,
- characterise tbehaviour modes and vibratory stresses according to NF EN 61373,
- qualify the efficiency of the vibration-resistant suspensions,
- check or recalibrate a FEM model.
On these bases, the LEM is also able to help designers with any changes they may need to make to their design or the materials selected for the beam, its securing devices or even in the choice of anti-vibration mountings, etc.
In addition, at an earlier stage of the project, the LEM can help in finalising personalised text specifications for your train-borne systems in relation to their true operating environments (vibrations and impact) not only to ensure the most accurate possible design but also to enable validation using vibration generators.