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Mechanical behaviour and fatigue lifetime of natural rubber reinforced by two grades of precipitated silica
Published in Per-Erik Austrell, Leif Kari, Constitutive Models for Rubber IV, 2017
L. Laiarinandrasana, A. Bennani, S. Cantournet, Y. Bomal
Let us introduce the Haigh diagram that displays the stress range versus mean stress. Figure 7 shows such a diagram for the carbon black filled natural rubber (André 1998). The crack initiation definition is the same here as a surface millimetric crack. Several cyclic tests under tension/compression on diabolo specimens have been carried out until crack initiation. For such a loading, the calculation of the maximum and minimum values of the largest principal stress is straightforward. It consists of the uniaxial stress value in the volume element corresponding to the gauge length (10 mm in fig. 1). Knowing these quantities, the diagram consisting of stress range 0.5(σmax − σmin) versus mean stress 0.5(σmax + σmin) can be displayed. Then points with approximately the same number of cycles to crack initiation (Ni) are linked up with solid lines. Rs is the load ratio defined as σmin/σmax.
Mean stress correction and fatigue failure criteria for hyperelastic adhesive joints
Published in The Journal of Adhesion, 2023
Pedro Henrique Evangelista Fernandes, Christof Nagel, Andreas Wulf, Vinicius Carrillo Beber
The Haigh-diagram for both adhesives and both conditions can be found in the fatigue experimental data, i.e. SN-curves, is presented in log-log plots in Figures 9 and 10, which will later be used for the mean stress correction. The Haigh-diagrams are obtained from the SN-curves taking into account iso-lifetime curves (same lifetime at different R-values, e.g. N = 1.000 and N = 1.000.000). With this type of plot, it is possible to observe that for the same lifetime (e.g. blue curve) as the mean stress increases, the bearable stress amplitude is reduced.