Influence of Friction On the Fatigue Crack Growth of Components Under High Compression

One of the main uses of elastomers is in laminated bearings and flexible joints as load bearing members providing flexibility to structures and components under high compression loading. In these cases, elastomers are subjected to fatigue loading conditions under high mean compression loads. In such loading conditions, the rate of failure is governed by the rate of fatigue crack growth and the assessment of this is an important aspect of the design analysis of these structures. It has been found theoretically and in practice that friction can have a significant influence on the fatigue crack growth of the elastomeric components under high compressive loads.  The influence of friction on the predicted fatigue crack growth of the elastomeric components has been investigated in this work and the results have been validated by comparison with the experimental data.

Fatigue crack growth on compression specimens with high aspect ratio have been modelled using finite element techniques. The influence of friction on the calculated tearing energy as a function of crack growth has been evaluated.  The capabilities of commercial finite element codes in modelling cracks under high levels of compression and their capabilities of accounting for friction, in particular, has been investigated.   

Experiments have been carried out on pre-cracked compression specimens with lubricated crack faces to measure the fatigue crack growth under low friction conditions. Experimentally measured fatigue crack growth results are compared with the analysis predictions to validate the approach. The Analysis approach is then used to predict the influence of high friction between the crack faces.  The results indicate that friction will reduce tearing energy levels and significantly and hence significantly reduce the rate of failure.