Extensive, independently conducted research has affirmed that transverse vibration generates the most severe conditions for self­loosening of a fastener joint. Tests have also shown that some form of transverse vibration is present in most installations.

Fatigue and self loosening are the two most frequent causes of failure in dynamically loaded bolted joints. Recent data has indicated that many so­called fatigue failures occur because a partial loosening of the assembly permitted a reduction of preload, accelerating the "fatigue failure". Thus, vibration loosening may also be a factor even when an obvious fatigue failure occurs, and must be taken into account when testing fastener performance in dynamically loaded joints.

The new vibration test machine gives practical answers to the problem of self­loosening. It generates transverse forces and can measure their effect on the joint; preload; angle of rotation; and locking performance of fasteners. The unit can discriminate between various locking elements, types of self­locking fasteners, locking torque, and other factors which influence the fastener's ability to retain preload in a vibration enviroment.
This machine covers fastener sizes M6 and M8 only. It operates at a constant frequency and constant amplitude.

TECHNICAL DETAILS
Vibration Frequency: 750 c.p.m.
Vibration Amplitude: 0.6 mm
Preload: 0 ­ 50 kN
Power Requirements: Single phase supply 1kw.

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