Originally, the SILENTWOOD project was divided into two prime objectives:
Develop the sound-insulating sandwich or multilayered structure, containing new noise reduction materials and designing an innovative attenuating internal geometry;
Design, test, validate and certify the door full system (door or panel, frame and fixing elements), firstly using computer models for optimization and rapid prototyping purposes, and secondly carrying out standardised tests.

After 3 years of research and development, SILENTWOOD has achieved the following results:

I. Sound-insulating sandwich/multilayered door, containing new noise reduction materials and design of an innovative attenuating internal geometry
The combination of the use of a novel engineered wood with an innovative multi-layered structure has been successfully tested with prototypes (2 panels and 4 doors). The solutions, using material combination of Fiber Composite fibre panels, absorbent materials and high density sheets and an optimized multi-layered structure, complies with the sector requirements (mechanic/thermal/fire-resistant), weighing less than 90 kg, having a thickness of 45mm, and with a sound reduction above the initial requirement of 30 dB (reaching above 37-39 dB).
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II. Innovative multilayered structure
Various structures were evaluated (e.g. honeycomb, spikes, omega shape). The structure with the best performance and manufacturing possibilities was selected, improved and adapted to manufacturing/assembly conditions. Different prototypes, using variants of design and materials preliminary assessed and evaluated, were manufactured and tested.

III. Composition of the novel engineered wood
Materials have been evaluated in laboratory tests and modeling procedures, based on the properties and characteristics of a large number of plastics, natural fibers, inorganic fillers. From experimental data and simulations, the best performing material combinations were selected to be processed into door structures (according to acoustic, mechanical, fire testing, and industrial consideration [material price, quality, industrial processes]).

IV. CAE module to simulate noise transmission through multistructured panels and door integral systems and to enable a future rapid prototyping software
A customized Computer Aided Engineering (CAE) module has been developed to simulate noise transmission through multistructured panels and so evaluate the panels’ acoustic performances, along with its mechanical properties. The simulation module has allowed the Consortium to reduce drastically the trials performed in laboratory, the module showing high accuracy compared with reality (i.e. validation through comparison with actual data and the results of the trials with the prototypes).
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