SIMIDEA R&D is a Technology-Based Innovative Company that was born promoted by the Laboratory of Material Characterization for Submarine Acoustics of the Universidad Politécnica de Cartagena, by the initiative of Prof. Luis Sánchez Ricart.

Background knowledge has been development at SIMIDEA R&D for a technology that allows the design of tailored materials with extreme acoustic capacities.

The drawback of this technology is its complexity since the rheological model can have up to 11 independent constants. However, this complexity is also the advantage of the present technology, since these constants can be modified in the laboratory, and obtain custom designed materials for each specific application. This technology allows modifying the 4 elastic constants of the aggregate, the static stability or instability of the aggregate, the contact surface between the solid skeleton and the fluid, as well as permeability and tortuosity, the apparent densities of the solid skeleton, of the fluids that saturate them, as well as the apparent density of the dynamic coupling.

This technology has some similarities to metamaterials, however there are other properties that make it radically different. It is not feasible to obtain great acoustic performance at medium and low frequencies with metamaterials, there are even serious difficulties to have great performance at high frequencies, since, when lowering the frequencies, structures with large geometries are needed to produce resonances at low and medium frequencies. In addition, with metamaterials it is not possible to have materials that work well in the entire frequency range, being materials with very selective responses in the frequency domain, and therefore easily detectable.

However, with the technology developed at SIMIDEA R&D, it is possible to obtain very high performance at low, medium, and high frequencies. To our knowledge, it is the only technology capable of producing very high acoustic performance at very low frequencies.

Among the similarities with metamaterials, we can say that this type of materials, like metamaterials, are generated artificially, are made up of periodic structures, and have structures at different scales. As in the case of metamaterials, macroscopic acoustic properties are generated from microscopic structures.

However, there are several differences with metamaterials that make the two technologies radically different. In metamaterials, geometric structures are played with and there is little intervention in dissipation throughout the entire frequency range. This makes metamaterials efficient in some frequency ranges, having a very selective response, being perfectly detectable at some specific frequencies. Besides, intermolecular forces and instabilities play a key role at low frequencies in this technology, that together with extreme dissipation capacity, produce a multiplicative effect for acoustic isolation or acoustic absorption.