Editorial Type:
Article Category: Research Article
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Online Publication Date: 20 Mar 2020

Influence of Waveforms on Fatigue Crack Growth Characteristics of Tire Tread Rubber using Finite Element Analysis

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Page Range: 206 – 223
DOI: 10.2346/tire.20.190215
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ABSTRACT

Rubber products are typically subjected to cyclic fatigue loading in service. During prolonged exposure to cyclic loading, damages initiate at intrinsic defect sites at microscopic levels and subsequently propagate, leading to catastrophic failure. Therefore, the material that offers better resistance to fatigue crack growth (FCG) is suitable for a durable product. FCG characteristics of rubber compounds depend on many factors, such as constituent material (rubber, filler, etc.), environment, and operational conditions (loading amplitude, loading pattern, etc.). To simulate the realistic service condition of a product, the choice of loading pattern is a key factor and has emerged as a very important research topic in recent times. The present work focuses on the effect of loading pattern on FCG characteristics of tire tread rubber compounds.

In the present study, FCG characteristics of a 100% natural rubber (NR) compound were measured on a tear and fatigue analyzer (TFA, Coesfeld, Germany) using double edge notched pure shear specimen. Fatigue loading was applied using sinusoidal and pulse waveforms over a wide range of tearing energy levels. Pulse mode recorded a very high crack growth rate (∼2 times) compared to sine mode at equivalent peak energy levels.

In order to understand the mechanics of the higher crack growth rate in pulse mode, finite element analysis (FEA) of a pure shear specimen was performed wherein FCG experimental conditions were used as boundary conditions. FE analyses were carried out using both linear and nonlinear viscoelastic material models. Nonlinear viscoelastic FEA results revealed that viscous energy dissipation at the crack tip is much lower in the case of pulse mode, which is in support of higher the FCG rate in pulse mode as observed in the experiments.

Keywords: fatigue crack growth; finite element analysis; nonlinear viscoelasticity; strain energy density; viscous energy dissipation
FIG. 1
FIG. 1

Pure shear specimen used for FCG testing.

FIG. 2
FIG. 2

Hyperelastic property evaluation of NR compound.

FIG. 3
FIG. 3

Stress relaxation property of NR compound at multiple strains.

FIG. 4
FIG. 4

Normalized stress relaxation plot of NR compound at multiple strains.

FIG. 5
FIG. 5

Viscoelastic property evaluation of NR compound.

FIG. 6
FIG. 6

PRF model evaluation of NR compound.

FIG. 7
FIG. 7

FCG curves for NR for sine and pulse waveforms.

FIG. 8
FIG. 8

FE mesh of pure shear sample.

FIG. 9
FIG. 9

Sine and pulse inputs.

FIG. 10
FIG. 10

SENER contour plots with linear viscoelasticity.

FIG. 11
FIG. 11

Max. principal stress contour plots with linear viscoelasticity.

FIG. 12
FIG. 12

ALLSE of the whole model with linear viscoelasticity.

FIG. 13
FIG. 13

SENER contour plots with nonlinear viscoelasticity.

FIG. 14
FIG. 14

Max. principal stress contour plots with nonlinear viscoelasticity.

FIG. 15
FIG. 15

SENER at crack tip with nonlinear viscoelasticity.

FIG. 16
FIG. 16

ALLSE of the whole model with nonlinear viscoelasticity.

FIG. 17
FIG. 17

ALLCD of the whole model with nonlinear viscoelasticity.

FIG. 18
FIG. 18

CENER contour plots with nonlinear viscoelasticity.

Contributor Notes

1 Corresponding author. Hari Shankar Singhania Elastomer and Tyre Research Institute, Plot 347, Hebbal Industrial Area, Mysore, Karnataka 570016, India. Email: pghosh@jkmail.com
2 Hari Shankar Singhania Elastomer and Tyre Research Institute, Plot 347, Hebbal Industrial Area, Mysore, Karnataka 570016, India. Email: rm@jkmail.com
3 Indian Institute of Technology Madras, Department of Engineering Design, Chennai, 600036, Tamil Nadu, India. Email: rkkumar@iitm.ac.in
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