Mechanical joints play a significant role in vibration
transfer and damping in structures, and therefore in
noise radiation. However, the development of the joining
technologies welding, riveting, bolting, bonding, etc.
has been always influenced by manufacturing and
structural integrity issues: as a consequence, these
technologies are not optimised for an efficient
The present day knowledge on vibration properties of
joints is largely insufficient to understand the behavior
of joints in mid frequency range (100 500 Hz) which is
the most important part of audible zone (highest ear
sensitivity) when typical mechanical structures like cars
or machines are concerned. Poor knowledge of transmission
and damping properties of joints forces industry to carry
out costly experimental work for optimising the shape,
location and volume of noise damping layers.
The project targets four industrial sectors: glass
industry, car manufacturers, domestic appliances and
engine driven machinery. Industrial objectives of the
To cut down by 20% noise transmission by existing
joints through optimisation of their implementation.
To increase the distributed damping produced by the
joints in complex structures, and consequently to reduce
by at least 20% the quantity of added damping materials
necessary for achieving given performance.
To reduce the spreading of noise emission of mass
To reduce prototype development time and cost, by
creating realistic computation and experimental models.
To develop dissipative smart joints for increased
This project is innovative at four levels:
1. New measurement and characterisation of joints alone
and embedded in structures:
Characterisation of single joints will be done by
using inverse and intensity techniques.
2 Coherent modelling techniques: Introduction of the
vibroacoustic characteristics of joints into
mathematical models will allow coherent modelling of
complex systems including joints.
3 Noise reduction efficient implementation of joints:
Influence of the implementation of joints on
vibration structural noise transmission and damping
effect will be extensively studied. Best
practice guidelines will be elaborated.
4 New smart joints: A particular innovative technology
using "smart joints" will upgrade the approach
to joint design in that the smart joints will provide a
dual role: structural integrity plus optimised
energy dissipation for noise and vibration
The technological approach is based upon 6 main steps:
1. Setting industrial priorities by identifying joints
where a significative improvement can be expected.
2 Use of two specialised test rigs will allow fast
appraisal of performance of joints incorporated
into spacious thin wall structures
3. Simple smart joints will be optimised, and rules for
the design of such joints will be produced.
4. Test procedures will be developed for characterising
individual joints in industrial environment.
5. A set of rules for FE modelling of vibro acoustic
properties of traditional and smart joints will be
6. Industrial case studies will be performed for
experimental validation of the modelling
techniques assessment and evaluation of vibroacoustic
performance of joints. All results of the project
will be synthesised into industrial guidelines.
Funding SchemeCSC - Cost-sharing contracts
10043 Orbassano Torino
20009 San Sebastian
BS37 5NG Bristol
105 45 Stockholm
100 44 Stockholm