Fatigue crack nucleation and growth in filled natural rubber

Abstract

Rubber components subjected to fluctuating loads often fail due to nucleation and the growth of defects or cracks. The prevention of such failures depends upon an understanding of the mechanics underlying the failure process. This investigation explores the nucleation and growth of cracks in filled natural rubber. Both fatigue macro‐crack nucleation as well as fatigue crack growth experiments were conducted using simple tension and planar tension specimens, respectively. Crack nucleation as well as crack growth life prediction analysis approaches were used to correlate the experimental data. Several aspects of the fatigue process, such as failure mode and the effects of R ratio (minimum strain) on fatigue life, are also discussed. It is shown that a small positive R ratio can have a significant beneficial effect on fatigue life and crack growth rate, particularly at low strain range.

Techniques for predicting the lifetimes of wave-swept macroalgae: a primer on fracture mechanics and crack growth

“…In spite of such complexities in material behavior, range of energy release rate, ⌬T, has been used successfully to correlate crack growth rate under zero-to-tension repeated loading in rubber (Lake, 1995;Seldén, 1995;Mars and Fatemi, 2003;Schubel et al, 2004;Busfield et al, 2005), much as ⌬K has been used successfully in linear elastic analyses. Since the value of T at the maximum point of a load cycle is ⌬T when the minimum point is zero (no extension), T will be used here without ⌬.…”

Fatigue of swollen elastomers

“…Mars and his co-workers utilized the crack nucleation approach in their works (Mars, 2001;Mars andFatemi, 2003, 2006) to investigate and to predict the appearance of a 1 mm fatigue crack length at the surface of rubber. It was explained that fatigue crack nucleation life can be interpreted as the growth period of pre-existing micro-cracks (smaller than 0.1 mm in size) (Mars and Fatemi, 2003). Later, Le Cam et al (2008 affirmed this finding through a detailed description in their research on the mechanism of crack growth from microscopic flaws, which subsequently led to the appearance of macroscopic crack initiation under uniaxial and multiaxial fatigue loading conditions.…”

“…Indeed, the chosen quantity for plotting the Wohler curves has already been widely used (Andriyana et al, 2010;Mars and Fatemi, 2003;Abraham et al, 2005). The maximum stretch was plotted as a function of number of cycles for the appearance of a 1 mm crack and complete rupture as shown in Figure 6 and Figure 7 respectively.…”

Overview of Experimental Studies on Strength Problem of Rubber Material

“…Abraham [5] through the filling of ethylene propylene rubber and styrene butadiene rubber and non filled EPR and SBR under single axial load characteristics, analyzed the minimum stress and stress amplitude on fatigue life influence of non-strain crystalline rubber. Mars [6] used uniaxial tension specimen stud-ied crack nucleation life of rubber, indicate the effect of minimum strain on crack nucleation life is relatively large.…”

“…Yamashita [14] by using strain energy density as fatigue damage parameters studied fatigue life of the shock absorber. Mars [6] summa-rized the relationship between crack propagation life and strain energy function under uniaxial load. Abraham et al [5] based on the effect of minimum stress and stress amplitude on fatigue life of non strain crystalline rubber, proposed strain energy density can be used as the equivalent parameters of fatigue life.…”