Fatigue initiation mechanisms in elastomers: a microtomography-based analysis

Abstract

The fatigue properties of filled elastomers are strongly related to the population of inclusionsinduced by their complex recipes and mixing/injection processes. The description and the understanding of the basic damage and dissipation mechanisms involved around these inclusions, the influence of their nature, geometry, size, interface and cohesion properties are especially important to optimize the fatigue design of industrial compounds and parts. The objective of the study is to take advantages of tomography observations to characterize the effects of the 3D inclusions on the fatigue resistance of rubber filled with carbon black. An images processing is necessary to dissociate accurately the inclusions of the matrix. The three dimensional observations provide many information on the inclusion’s morphology (size, shape) and their spatial distribution. Moreover, the proposed images processing allows detecting cracks inside and on the surface of the specimen, which offers a better insight on the early stages of the fatigue damage scenario. Then, a numerical model and thermo-mechanical measurements are used to understand why some inclusions become initiation sites. Finally, one activated site is fully described as example.

Coupling effect of non‐relaxing and high temperature on fatigue properties of carbon‐black filled isoprene rubber

“…Le Cam et al also revealed that the cavitation induced by the decohesion between zinc oxides and rubber matrix is the major fatigue damage 41 . Some studies 42,43 using x‐ray computer micro‐tomography, concluded that in carbon‐black filled NR, the damage mechanisms are the cavitation phenomenon at the two poles of aggregates and the fracture of aggregates. Federico et al 44 analyzed silica‐filled styrene‐butadiene rubber and found that large and non‐elliptical silica aggregates were the source of cavity formation.…”

Influence of Silica Specific Surface Area on the Viscoelastic and Fatigue Behaviors of Silica-Filled SBR Composites

“…Therefore, the shortest distance between the two agglomerates will be more significant compared with C3. It is reported that a decrease in the distance between two agglomerates drastically decreases the strain for the cavitation [ 33 ]. Thus, there could be a delay in losing the structural stability of the compound, hence improving fatigue end of life.…”

“…In many studies, the fatigue behavior of these compounds has been investigated by means of structural characterization techniques, including SEM [ 32 ], micro-computed X-ray tomography (µCT) [ 33 , 34 , 35 ], and small-angle X-ray scattering [ 36 ]. Huneau et al [ 2 ] investigated the fatigue crack initiation on CB-filled natural rubber and revealed that the predominant crack initiation sites were around CB agglomerates.…”

Research Progress on Fatigue Life of Rubber Materials

“…Pérocheau et al [ 106 ] used stretching and electron beams to break the cross-linking between macromolecules and found that the debonding between the filler and matrix caused the cavity at the crack tip. Glanowski et al [ 107 ] observed the fatigue of carbon-filled natural rubber by X-ray computer micro-tomography and obtained two damage mechanisms: one is the cavitation phenomenon at the two poles of aggregates, and the other is the fracture of aggregates; Lesaux et al [ 108 ] reached the same conclusion. Federico et al [ 109 ] analyzed styrene–butadiene rubber filled with silica by microcomputer X-ray tomography and observed that the size of silica aggregates ranged from 6 microns to 140 microns, and the sphericity ranged from 0.35–1.…”