CCES Unicamp

UNICAMP engineers are designing models to simulate how ground vibrations affect Sirius

Computational models may help increase the effectiveness of the source of synchrotron light

A team led by researchers Euclides Mesquita and Josué Labaki, of the Faculty of Mechanical Engineering at the University of Campinas (UNICAMP), is getting closer to solving a problem that is still open in engineering: computer simulating the effects of microscopic vibration on the foundations of large-scale buildings.

The motive for solving this issue is the construction of Sirius, one of the most advanced sources of synchrotron light laboratories in the world, which will be concluded by the end of 2018. The lab functioning will be extremely sensitive to mechanical vibrations. The researchers expect their model calculations obtained from simulations generated by supercomputers of CEPID CCES-eScience, at UNICAMP, could help increase Sirius’ effectiveness.

Sirius is a circular building, located at the Brazilian National Research Center of Energy and Materials (CNPEM), in Campinas, São Paulo. Its interior will shelter powerful particle accelerators. Beams of electrons going around the circular accelerators circuit millions of times per second will produce light with intense shine, the so called synchrotron radiation. Researchers from different areas, from medicine to nanotechnology, will use this light to analyze materials and chemical reactions at a molecular or atomic level, generating images and videos that could lead to new discoveries and inventions.

However, in order for it to work properly, Sirius’ delicate machinery must remain as isolated as possible from mechanical vibrations disseminated through the ground, generated from various sources, such as trucks passing by the building or occasional earthquakes. Although the engineers involved in the construction of the building are doing everything possible to isolate the equipment, it is possible that vibration sources still unknown may cause Sirius problems in the future.

“The light power generated by Sirius is in proportion to how narrow its beam of electrons is”, explains Labaki. “Vibrations as low as 4 micrometers, a tenth of the thickness of a strand of hair, can alter the orbits of the electrons, dispersing the beam.”

The challenge of describing the effects of microscopic vibrations going through an approximately 68 thousand square meters circular building, the equivalent of a soccer stadium, is an issue still open in engineering. “We know how to engineer large structures where small vibrations aren’t a problem”, says Labaki. “We also know how to engineer small foundations sensitive to vibrations. However, there’s still a lot to be studied about the combination of both problems.”

Their work begun in 2010, when Labaki was still one of Mesquita’s PhD students, who is an expert in modeling wave propagation on structures in contact with the ground. First, the researchers modeled the circular plate in contact with the ground, which serves as the foundation to Sirius’ building. Then, they studied how a wave disseminates from the ground to the foundation, and vice-versa. Later, they modeled stakes stuck to the ground, which support the circular plate. “First we modeled a single stake, and now we’re working on models of groups of several stakes”, explains the researcher. “Sirius’ circular plate is sustained by 1,230 stakes.”

Solving these mathematical models demands several complex calculations, which go way beyond the capacity of a regular computer. To solve all the required calculations to simulate the propagation of waves in their models, the researchers have developed parallel computing programs in Graphic Processing Units (GPUs). The techniques and simulations were successfully tested on the GPU cluster of CEPID CCES-eScience.

In case Sirius fails due to the interference of vibrations from unknown sources, Mesquita and Labaki’s models will help understand what caused the problem and suggest strategies to solve it. “This knowledge, which no one has developed yet, may be applied not only in particle accelerators like Sirius, but also in wind power stations and hydroelectric power plants, in nanomechanical laboratories and in concert halls”, clarifies Labaki.

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