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MAE 537 May 2005 Paul Mayni Composite Effects on Tire Mechanics MAE 537: Mechanics of Composites Paul Mayni May 2005.

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Presentation on theme: "MAE 537 May 2005 Paul Mayni Composite Effects on Tire Mechanics MAE 537: Mechanics of Composites Paul Mayni May 2005."— Presentation transcript:

1 MAE 537 May 2005 Paul Mayni Composite Effects on Tire Mechanics MAE 537: Mechanics of Composites Paul Mayni May 2005

2 MAE 537 May 2005 Paul Mayni Agenda Pneumatic tire evolution Pneumatic tire evolution Effects of carcass and belt angles Effects of carcass and belt angles Ply steer phenomenon Ply steer phenomenon References References

3 MAE 537 May 2005 Paul Mayni Interesting Quotes The complexity of the structure and behavior of the tire are such that no complete and satisfactory theory has been propounded Temple, Mechanics of Pneumatic Tires

4 MAE 537 May 2005 Paul Mayni Interesting Quotes Those of us who are active in research and development as applied to rubber-like materials are well aware of the truly interdisciplinary nature of tire- to-ground traction. Physics, chemistry, metallurgy, dynamics, tribology, thermodynamics, heat transfer elasticity, viscoelasticity, rheology, elastohydrodynamics, … play complex and intertwined roles in determining the magnitude of the frictional coupling that ultimately exists in the contact patch… D.F. Moore 1973 Symposium on The Physics of Tire Traction

5 MAE 537 May 2005 Paul Mayni Pneumatic Tire Evolution First modern tire can be considered a simple ply construction From about bias tires dominated the market An even number of cross plies of approximately +/- 45° were used as shown in the figure

6 MAE 537 May 2005 Paul Mayni Pneumatic Tire Evolution Resisting the radial movement in Europe, the belted bias tire was developed in North America American tire manufactures hoped to avoid the costly transition to radial tires Typical construction consisted of additional belt layers restricted to the tread summit and using the same angles and materials as the carcass plies

7 MAE 537 May 2005 Paul Mayni Agenda Pneumatic tire evolution Pneumatic tire evolution Effects of carcass and belt angles Effects of carcass and belt angles Ply steer phenomenon Ply steer phenomenon References References

8 MAE 537 May 2005 Paul Mayni Bias vs. Bias-belted Unrestricted growth of a bias tire for various cross-ply angles is shown in Figure 5.8 With the addition of belt layers of increased stiffness and cable material the shape of the inflated carcass changed as seen in Figure 5.9

9 MAE 537 May 2005 Paul Mayni The Radial Tire Superior performance gains in comfort, wear, and handling were achieved with the introduction of the radial tire In a radial tire the carcass plies are oriented at 90°, and the steel belt package acts to distribute the tires load more efficiently and maintain a particular summit profile

10 MAE 537 May 2005 Paul Mayni Bias vs. Radial Within the contact patch, a bias tire will undergo extreme lateral deflection as shown in Figure In contrast, the radial tire resists this tendency. This greatly reduces tire wear, heat generation, and provides responsive handling characteristics

11 MAE 537 May 2005 Paul Mayni Bias vs. Radial The shape of the inflated tire is not a simple constant radius. Why is this important? If you can predict the inflated shape you can design the tire mold to have the ideal inflated shape thus reducing residual stress of the inflated tire. This figure shows the effect of changing the bias angle of a belt-less membrane

12 MAE 537 May 2005 Paul Mayni Bias vs. Radial The addition of a belt package to a radial sidewall design adds additional complexity to the problem Two interesting behaviors have been observed: For bias-belted tires there exists a special belt angle that in combination with the carcass angle generates a flat summit For bias-belted tires there exists a special belt angle that in combination with the carcass angle generates a flat summit Radial tires without a belt package are unstable Radial tires without a belt package are unstable Top View

13 MAE 537 May 2005 Paul Mayni Bias vs. Radial An example of the flat angle solution is shown above Regardless of inflation pressure, there will be no tendency for the tire to become round. In other words the equilibrium shape is flat.

14 MAE 537 May 2005 Paul Mayni Bias vs. Radial Consider a pure radial tire Consider a pure radial tire Remove the belts and inflate Remove the belts and inflate Note the characteristic round radial membrane shape Note the characteristic round radial membrane shape Increase the pressure a little

15 MAE 537 May 2005 Paul Mayni Bias vs. Radial

16 MAE 537 May 2005 Paul Mayni Agenda Pneumatic tire evolution Pneumatic tire evolution Effects of carcass and belt angles Effects of carcass and belt angles Ply steer phenomenon Ply steer phenomenon References References

17 MAE 537 May 2005 Paul Mayni Conicity & Ply Steer Conicity is derived from imagining a tire constructed to take the shape of a truncated cone. Based on geometry this configuration would generate a force towards the apex of the cone regardless of the direction of rotation. Ply steer can be determined from lateral force variation measurements. An instrumented spindle records lateral force of a tire. Forward and reverse rotations are used in order to separate ply steer from conicity. Ply steer, generated by a coupling of bending and stretching, is dependent on the tires rotational direction.

18 MAE 537 May 2005 Paul Mayni Ply Steer The effects of stacking sequence of the tires summit plies directly influences the ply steer behavior Example A in the figure graphically depicts the results of an asymmetric stacking sequence Example B has little or no coupling of bending and stretching

19 MAE 537 May 2005 Paul Mayni Ply Steer Typical tire constructions are shown in Figure Resulting conicity and ply steer values are shown in Figure

20 MAE 537 May 2005 Paul Mayni Ply Steer The ABD matrix relates membrane loads and moments to strains and curvature The B16 and B26 terms are dependent on the stacking sequence Table 3.10 shows the effect of stacking sequence on ply steer force

21 MAE 537 May 2005 Paul Mayni Ply Steer For reference, some examples of ABD matrices for bias, belted-bias, and a radial tire are provided

22 MAE 537 May 2005 Paul Mayni References Bogdanovich, A. E., Pastore, C. M., (1996). Mechanics of Textile and Laminated Composites. Chapman & Hall, UK Haney, P., (2003). The Racing and High-Performance Tire. TV Motorsports, Springfield Illinois. Clark, S. K., (1981). Mechanics of Pneumatic Tires. US Department of Transportation, Washington, D. C.


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