Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Sept 2011

Mechanics of Bend-Over-Sheave (Shoeshine) Fatigue Testing of Cord-Rubber Laminates

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Page Range: 168 – 192
DOI: 10.2346/1.3637742
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Abstract

The Bend-Over-Sheave test is used for screening reinforcement cords used in tires, especially on fatigue interply delamination as well as rubber-fabric and rubber-cord adhesion degradation. The typical cyclic load of tension-tension of the sidewalls or tension-compression of the belt can be achieved by the proper definition of two-ply laminates bent over a sheave. The objective of this paper is to define relevant fatigue test conditions that can predict the performance of new materials. A finite element model of the Bend-Over-Sheave test configuration is presented and shows that, for the test arrangements studied in this paper, flanged wheels should be used to prevent lateral buckling in the compressed cords. Besides, a simplified model enables us to determine the different factors that have significant effect on the strain levels in the cords. The material of the cords, the rubber hardness (“Shore”), and the sample manufacturing process are shown to have an influence on the specimen strain levels. The test conditions, i.e., the sheave radius, the traction force, and the contact angle between the sheave and the sample, also affect the behavior specimen strain levels. On the other hand, if the sample length is higher than a certain value, it is shown not to have a significant effect on the results.

Keywords: finite element analysis; Abaqus; bend-over-sheave; composite fatigue test; shoeshine; cord; tension; compression; delamination; rubber adhesion
Copyright: The Tire Society
FIG. 2
FIG. 2

Compression of the rubber matrix with Abaqus model without flanges.

FIG. 3
FIG. 3

Macrobuckling of the bottom ply with Abaqus model without flanges.

FIG. 4
FIG. 4

Side waviness of the composite sample flexed around the pulley.

FIG. 5
FIG. 5

No buckling of the bottom ply with Abaqus model with flanges.

FIG. 6
FIG. 6

No compression of the rubber matrix with Abaqus model with flanges.

FIG. 7
FIG. 7

Forces on each element in the ”dual shear” model.

FIG. 8
FIG. 8

Strains in cords and shear stresses in rubber according to distance (nylon fabric reinforcement).

FIG. 9
FIG. 9

Comparison of planar, “dual shear,” and FEA model (aramid on top and steel on bottom).

FIG. 10
FIG. 10

Comparison of planar, “dual shear,” and FEA model (aramid on top and bottom).

FIG. 19
FIG. 19

Strains in the middle of the cords according to the tensile force (“dual shear” model).

FIG. 11
FIG. 11

Microbuckling of a cord in the bottom ply with Abaqus model.

FIG. 12
FIG. 12

Strain in cords according to distance for different rubber “Shore” hardness (“dual shear” model).

FIG. 13
FIG. 13

Strains in cords according to distance for different height of bottom rubber layer and constant curvature (“dual shear” model).

FIG. 14
FIG. 14

Strains in cords according to distance for different interply distances (“dual shear” model).

FIG. 15
FIG. 15

Strains in cords according to distance for different belt length (“dual shear” model).

FIG. 16
FIG. 16

Strains in the middle of the cords according to the belt length (“dual shear” model).

FIG. 17
FIG. 17

Strains at the end of the cords according to the belt length (“dual shear” model).

FIG. 18
FIG. 18

Strains in cords according to distance for different tensile forces (“dual shear” model).

FIG. 20
FIG. 20

Strains at the end of the cords according to the tensile force (“dual shear” model).

FIG. 21
FIG. 21

Strains in cords according to distance for different angles of contact (“dual shear” model).

FIG. 22
FIG. 22

Strains in cords according to distance for different sheave radii (“dual shear” model).

FIG. 1
FIG. 1

Bend-Over-Sheave test.

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