50 years of FORAN in continuous reinvention - December 2014 - No. 48 /Technology

The Acoustics and Vibrations group expands its range of services

Acoustic photo of a device with separate internal systems. Red indicates the area generating the most noise.

Acoustic photo of a device with separate internal systems. Red indicates the area generating the most noise.

SENER has been deepening its knowledge on the analysis and evaluation of noise and vibration problems for over 15 years, culminating in the creation of the Acoustics and Vibrations discipline, made up of a team of experts in simulation and experimentation. There have been significant advances in this group’s capabilities thanks to the use of sophisticated prediction tools and the acquisition of testing equipment. Recently, the Acoustics and Vibrations group expanded its portfolio of services with new techniques, particularly:

Near/far field acoustic mapping. SENER uses progressive acoustic measurement techniques, with latest generation sensors that enable on site testing and profiling of the acoustic properties of all kinds of products: vehicles and sub-systems (automobiles, aircraft, trains, etc.), industrial facilities (generators, turbines, transformers, etc.), commercial machines and devices (printers, home appliances, etc.), and even civil engineering works (enclosures, HVAC – Heating, Ventilating and Air Conditioning - facilities, partitions, etc.). The acoustic mapping solution is especially impressive; in minimal time it gives a graphic representation of the acoustic field—an ‘acoustic map’ or ‘acoustic photo’—, which helps considerably to locate the origin of the noise problem that needs solving.

Expansion in structural testing capabilities. Similarly, SENER Acoustics and Vibrations group has also been adding to its experimental analysis equipment through the acquisition of new multi-channel systems and complementary sensors. Particularly worthy of mention is the use of solutions developed by LMS and based on LMS SCADA, a type of multi-channel data collection platform that allows for the use of an extensive range of sensors (accelerometers, microphones, pressure sensors, gauges, etc.), all with minimal instrument installation time. In addition to offering a quick solution for experimental evaluation in any situation with noise and vibration emissions, this tool has successfully been used to carry out structural checks on prototypes, including correlation with finite element predictive numeric models. Recently, this type of evaluation/correlation was applied in the space project JPCAM, where it was used in the high-precision actuator system, based on a hexapod mechanism for the real-time positioning of the panoramic camera installed in the Javalambre Survey Telescope. Static and dynamic loads observed on the prototype’s flexures were evaluated using strain gauges, and SENER’s Acoustics and Vibrations group’s structural testing capabilities were also used to carry out correlation tasks with the finite element predictive model.

Anti-vibration slab, Alpha chamber and reverberation chamber. The high capacity integration and testing facilities at SENER’s new headquarters in Barcelona (Spain) ensures that the Acoustics and Vibrations group has plenty of space to develop new test benches. Specifically, SENER offers tests on a floating slab that isolates the object being measured from external vibrations. The anti-vibration slab weighs more than 50 tons and has a resonant frequency of less than 4 Hz. In addition, the group has developed an Alpha chamber, which enables evaluation of the acoustic transmission properties of any type of material (sandwich structure, composite materials, etc.) thanks to its adaptable samples system. The latest innovation is that it also has the capacity to evaluate acoustic absorption coefficients of any material by way of its reverberation chamber.

Gallery

JPCAM actuator system prototype. Finite element model to evaluate internal loads.

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