Setup for evaluation of fatigue crack growth in rubber: Pure shear sample geometries tested in tension-compression mode

Influence of Experimental Parameters on Fatigue Crack Growth and Heat Build-Up in Rubber

“…It further shows the major strain distributions for the two geometries at equal displacement evaluated with 2D digital image correlation. As is also described in [ 5 ], the strain distribution is uniform for flat PS geometry, whereas it shows enhanced strain in the middle of the sample for FWPS geometry. Thus, the strain is constant along the height of the specimen for PS samples and equals a mean strain value, ε mean .…”

“…Two different sample geometries were investigated: one is a flat pure shear (PS) geometry with a thickness of 4 mm, and the other one is a so-called “faint waist pure shear” (FWPS) geometry with a nominal thickness of 2 mm. In [ 5 ], this investigation has been performed for an engineering material. Now, this investigation is resumed for a model material.…”

“…Yet, the crack growth curves of the two overlap if crack growth rates are plotted against the major strain and if the enhanced strain, ε max , is taken into account for FWPS geometry ( Figure 2 b). The crack is affected by ε max ; however, the tearing energy evaluated from force-displacement curves does not account for this enhanced strain, but is related to the mean strain, ε mean [ 5 ].…”

“…This is undesirable, because an additional evaluation increases the user effort. Crack growth out of the plane of the notch was mainly observed with the engineering blend [ 5 ] and seldom with the SBR blend. The major advantage of the PS geometry is that the tearing energy concept was developed for flat pure shear geometries [ 2 , 5 ].…”

“…Furthermore, a broad crack length range can be investigated, due to the small height-to-length ratio. In [ 5 ], we compared “flat” pure shear sample geometries with “waisted” ones, and experimental advantages and disadvantages were identified for both. In the current study, this comparison is resumed for another rubber blend.…”