Mechanical tests of a module box prototype

A realistic mechanical prototype for the outer tracker module boxes has been built and tested in a combined
effort of the Heidelberg and Krakow group. The module has a length of 3m and is made of two aluminium coated
sandwich panels with Rohacel as core material. The sidewalls are formed by 0.4 mm thick, aluminium coated (15µm)
carbon fibre tissue epoxy. To ensure the gas tightness of the module a 50µm thick layer of Kapton is added to the module box.
The test method is to check the gas tightness of the box before and after loading, bending and handling of the module.
Damages of the gluing joints and eventual microcracks between the sidewalls and the panels can be detected by an increase of
leak rate. The following pictures give an idea of the treatment of the module.

The module under test:
First a gas tightness test at 3 mbar is performed. No pressure drop within 15 min has been observed.

Cross section of the module

A detail of the module: New ideas for make the electrical connection of the aluminium foil have been teseted. The picture shows the solder point of the fan-out from the sidewalls to the fan-out of the ground foils from the panels. The soldering is done by ultrasonic soldering.

The gas pressure is increased to 5 mbar and later to 8mbar. Again no pressure drop is observed within 30 min. The maximum allowed overpressure during operation in the LHCb gas system is 2 mbar.

For the next step, the module is transported to another lab. No special care has been taken for the transport of the module.

The deflection of the module with and without additional load has been measured.

Set-up for deflection measurement

Results from deflection measurement

Long panel down

deflection without load: 6.0 mm

additional load additional deflection

150 g 0.99 mm

300 g 2.00 mm

510 g 3.40 mm

Long panel up

deflection without load: 5.0 mm

additional load additional deflection

150 g 0.86 mm

300 g 2.05 mm

510 g 3.60 mm

The module was transported back to the other lab, where the gas tightness of the module was verified again at an overpressure of 8mbar.
After that, the module was brought back for a second loading test with a higher weight.

Loading test with one kilogram

A final gas leak test shows that the module did not suffer from the loading, bending and handling performed during the tests!

Last updated: march 27th, 2002 by sb .

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