Belt failure tooth root cracking

Test results from experimental studies on belt life suggest the following as the major belt failure modes tooth root cracking, wear, cord failure and fabric separation [14,15,16, 17, 18], and this classification has support from field data [19, 20]. Figure 12.2 shows examples of tooth root cracking, cord delamination and fabric separation failures. 

Tooth root cracking is the prevalent failure mode for belts and the literature suggests two mechanisms for its generation. The most commonly reported mechanism is fatigue and eventual failure of the facing fabric in the tooth root, followed by rapid crack propagation through the tooth rubber compound, usually across the rubber compound/... 

Figure 12.2 Synchronous belt failure modes, a) tooth root cracking, b) cord delamination, c) fabric separation...

Fabric separation failure occurs when the belt teeth and fabric land become detached from the belt cords [17] and is essentially seen as purely an adhesion failure, although there may be links between this failure mode and the tooth root cracking failures observed by lizuka [18], originating from cracks developed in the cord itself through internal delamination. Wear causes belt failure through changing the tooth profile to such an extent that the belt teeth can no longer support the required load [25]. 

In attempting to identify parameters which allow the belt life to be predicted within the adhesion related failure modes identified above, the most common approach has been to use measures of belt distortion. Dalgarno [17] examined belt life data from belt failures within the tooth root cracking, fabric delamination and cord separation failure modes. 

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