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- Andersson, Patrik, 1974
(författare)
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Contact forces and noise generation during hastily separation of tyre tread blocks from road surfaces
- 2005
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Ingår i: Constitutive Models for Rubber IV — Austrell and Kari (eds). - 0415383463 ; , s. 571-577
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Konferensbidrag (refereegranskat)abstract
- Adhesive bonds in the passenger car tyre/road surface contact have a large influence on the contact dynamics for certain tyre/road combinations. The effect is most pronounced for road surfaces with low roughness, so-called smooth surfaces. An experimental setup was designed to study time records of contact forces and sound pressures as tyre tread samples are hastily separated from road surfaces samples. The general character of the separation process on a macroscopic length scale is described, interpreted, and related to theories on smaller scales. A single value (dynamic) adherence force is determined out of the records and it is related to the initial conditions; magnitude of preload, preload duration, and unloading rate. It was found that the exact contact geometry, on larger scales, yields the details in the contact force record and distribution of sound pressure levels in 1/3-octave bands. A model aiming at describing the observed behaviour must consider a wide range of length scales; a dynamic contact model is proposed that considers the exact contact geometry on larger scales via discretisation and uses statistical properties of the surfaces at lower scales to determine contact criteria at contact points.
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| 7. |
- García Tárrago, Maria-José, et al.
(författare)
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An effective engineering formula for torsion stiffness of rubber bush including amplitude dependence
- 2005
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Ingår i: Constitutive Models for Rubber IV. - 0415383463 - 9780415383462 ; , s. 319-323
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Konferensbidrag (refereegranskat)abstract
- Effective engineering formula for torsion stiffness of a long rubber bush in the frequency domain including amplitude dependence is presented. The classical theory of elasticity is the tool used to find this relation between torque and torsion angle in the frequency domain and by assuming an equivalent amplitude strain for the whole bushing. The complex value of the shear modulus to be inserted into the stiffness formula is calculated by applying a separable elastic, viscoelastic and friction rubber model to that equivalent strain.
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| 8. |
- Gil-Negrete, N., et al.
(författare)
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Dynamic stiffness prediction of filled rubber mounts : Comparison between a fractional derivative viscoelastic-elastoplastic model and a simplified procedure
- 2005
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Ingår i: Constitutive Models for Rubber IV. - 0415383463 - 9780415383462 ; , s. 479-485
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Konferensbidrag (refereegranskat)abstract
- A time domain non-linear model is presented to predict the dynamic stiffness of rubber isolators using a FE code. The problem of simultaneously modelling elastic, viscoelastic and friction contributions is removed by additively splitting them. Viscoelastic response is modelled via a fractional derivative model, while amplitude dependency is considered through Coulomb friction elements. Nevertheless, determination of the dynamic stiffness takes long time and requires large amount of memory, as well as the estimation of the transfer function between applied excitation and resulting forces at different frequency and amplitude values. This is why a frequency domain simplified procedure is also proposed to obtain the dynamic stiffness. The technique is based on providing a generalized Maxwell model with the adequate material data set, once the dynamic strain amplitude, to which the mount is subjected, is estimated from quasi-static strain values. The methodology has proved to be efficient and easy to be applied.
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- Holzapfel, Gerhard A.
(författare)
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Similarities between soft biological tissues and rubberlike materials
- 2005
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Ingår i: Constitutive Models for Rubber IV. - 0415383463 - 9780415383462 ; , s. 607-617
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Konferensbidrag (refereegranskat)abstract
- Several scientists have drawn attention to similarities between soft biological tissues and rubberlike materials. This dates back to Roy (1880) in the context of arterial wall mechanics and Karrer (1933) in respect of muscle mechanics. Both soft tissues and rubberlike materials consist of three-dimensional networks of macromolecules held together by covalent and van der Waals bonds. An underlying concept makes use of the idea of expressing the number of conformations that a chain molecule can assume as an 'entropic effect' (leading to entropic elasticity). As a result, the associated thermomechanical behavior of the macromolecules is significantly different from that of, e.g., metals for which an ordered collection of atoms is held together in a lattice structure by interatomic bonds (leading to energetic elasticity). This proceedings paper aims to highlight similarities in the structure, mechanical characteristics and constitutive modeling of soft biological tissues and rubberlike materials for which many advances in the past have gone hand in hand.
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| 10. |
- Johansson, Håkan, 1979, et al.
(författare)
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Calibration of a nonlinear viscoelasticity model with sensitivity assessment
- 2005
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Ingår i: Constitutive Models for Rubber IV, edited by P.-E. Austrell & L. Kari. - 0415383463 ; , s. 341-347
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Konferensbidrag (refereegranskat)abstract
- The calibration of constitutive models isbased on the solution of an optimization problem, where parameter values are sought such that optimal correspondence between measured and simulated response is achieved. The calibration problem is solved using a recently proposed strategy, which has the advantage that discretization errors induced in the simulated response, leading to errors in the optimal parameter values, isrelatively straightforward to estimate. Furthermore, it ispossible to estimate how sensitive the obtained solution is to uncertainties in the experimental data.
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