and
Niels Kjølstad Poulsen e-mail: nkp@imm.dtu.dk
Section for Mathematical Physics
Section for Statistics
Abstract: Traditional ultrasound inspections require physical
contact between the piezo-electric sound generator and the product or item
to be investigated. Good contact is achieved by smearing oil onto the item
which provides a good impedance match. In many potential new applications
of ultrasound, physical contact is not desirable between the ultrasound
generator/detector and the item to be inspected. This is the case in inspection
at assembly lines, where the high speed of production do not allow cumbersome
smearing and placement of an ultrasound generator/receiver onto the products
on the line. However, in this project non contact ultrasound inspections
are suggested to be accomplished using lasers. A powerful laser pulse is
directed onto an item which generates a sound wave propagating through
the item and is reflected from possible hidden defects. On return to the
surface the wave is detected by laser beams who's interference patterns
register the movement of the surface. The physical laser system is developed
at Risø and FORCE Institute.
The contribution to this project from IMM concerns mathematical modelling
as an add to design and optimize a non touchable inspection system. This
include modelling the generation of ultra sound through rapid laser heating
from short pulses and wave propagation. Feedback control and steering of
a production line with a non touchable inspection system implemented will
be modelled and theoretically investigated.
Collaborators:
Publications:
The propagation of ultrasound in an austenitic weld.S. Halkjær,
M.P. Sørensen and W. Damgaard Kristensen.
Ultrasonics, Vol. 38(1-8), 2000, pp. 256-261.
Funding:
Erhvervsfremmestyrelsen: 1000 KKr
Start date: July 2000
End date: July 2003