Structural shocks and vibrations can become a serious issue in terms of both the operation of high precision medical equipment and patient exposure. Vibration limits are often defined by standards defining velocity-frequency plots from organisations including ASHRAE, ISO and BS. In a clinical context it is often necessary to employ an approach based on patient perception to vibrations. Xi’s engineers have extensive experience in the diagnosis, removal and prevention of structural shock and vibration issues to meet standards and specific clinical situations.
A rigorous solution begins with a visual inspection of the structure to determine problem areas, followed by a campaign of vibration measurement and analysis. Xi make use of highly sensitive equipment including accelerometers, laser vibrometers and crack sensors to perform detailed measurements. Accurate characterisation of the structure and vibrations may require several days of measurement depending on the scale and source of the problem. Xi will determine excitation sources, problematic structural resonances and physical pathways through data analysis.
Depending on the project requirements a detailed computational model can be developed. Structural mechanics can be simulated to evaluate dynamic behaviour and determine its response to isolation or damping strategies. Physical couplings to fluid dynamic and acoustic domains are also possible to evaluate, for example, wind excitation and acoustic noise generation. The development of an accurate model enables a fast and cost-effective design solution, preventing a trial and error approach.
Based on the results of measurement and modelling a means of eliminating or managing the vibrations will be established. Xi have developed a range of solutions which include tuned mass dampers for large floor spans, seismic trenches and other bespoke isolation solutions. Our medical experiences include shock isolation of neonatal trolleys for ambulances and evaluation of ground vibrations for the construction of a pathology department microscope facility.