A “Tee” section test assembly was made using three 300mm lengths of galvanised size 7 standard tube held together by a three socket tee fitting (Type 25-7). The vertical leg of the test assembly was supported in a standard railing flange (Type 62-7). The completed assembly was then rigidly attached to the vibration table.
The test assembly was initially assembled using standard set screws and tested in this configuration. The standard set screws were then replaced with the self-locking screws and the tests repeated.
The test was conducted on a Ling 667Kg Electromagnetic Vibration Table. The table was programmed to perform a resonance search between 25 and 350Hz and resonant frequencies were recorded and shown in the table below.
|Resonance Frequencies||Q Factor||RunningTime|
During the resonance search, amplification factors (Q) were measured at each resonant frequency, the point of reference being the end of one horizontal tube. The table was then held at one of the resonant frequencies, set in motion with a controlled acceleration level of 4g, and ran for a period of six hours. This was repeated for three more resonant frequencies in descending order of Q factor.
Furthermore, during the twenty-four hours of vibration at the four resonant frequencies above, no signs of loosening with either type of attachment screw occurred.