| 1. |
- Ahlin, Kjell, et al.
(author)
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Comparing Road Profiles with Vehicle Perceived Roughness
- 2004
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In: International Journal of Vehicle Design. - Geneva, Switzerland : Inderscience Enterprises. - 0143-3369 .- 1741-5314. ; 36:2-3, s. 270-286
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Journal article (peer-reviewed)abstract
- Accurate road profiles are useful in vehicle design, such as for simulation of durability and ride quality. Laser/inertial profilometers typically record I mm wide profiles. The question is how well such a profile matches perceived vehicle wheel roughness. The objective here was to create a more representative wheel track longitudinal profile. Simulated and measured wheel vibration was compared on a 6km long road. Simulations were made for several definitions of the profile. Results for single laser sensor profiles showed reasonable likeness to truck perceived roughness. By far the best likeness (14.5% better) was achieved when the profile was based on triangular 25%-50%-25% weighted data from three sensors in the wheel track. Clearly, vehicle engineers can benefit from using multiple laser profile sensors, instead of a single sensor. This will improve test accuracy, thus reducing vehicle design project lead times and costs.
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| 2. |
- Englund, Thomas, et al.
(author)
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Dynamic characteristics of a combined bellows and liner flexible joint
- 2004
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In: Journal of Automobile Engineering. - : Professional Engineering Publishing. - 0954-4070. ; 218:5, s. 485-493
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Journal article (peer-reviewed)abstract
- A bellows combined with an inside liner and an outside braid is commonly used as a flexible joint in automobile exhaust systems to reduce transmission of engine movements to the exhaust system. It greatly influences the dynamics of the complete system. Understanding of its dynamic characteristics and a modelling method that facilitates systems simulation are therefore desired. This has been obtained in earlier works for the bellows itself. In this work an approach to the modelling of the combined bellows and liner joint is suggested and experimentally verified. Simulations and measurements show that the liner adds significant non-linearity and makes the characteristics of the joint complex. Results are presented for the axial and the bending load cases. In torsion, influence of the liner is negligible. Peak responses are significantly reduced when the excitation level approximately corresponds to the friction limit of the liner. The complexity of the combined bellows and liner joint is important to know of and consider in exhaust system design and proves the necessity of including a model of the liner in the theoretical joint model when this type of liner is present in the real joint to be simulated.
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| 3. |
- Wall, Johan, et al.
(author)
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Influence of a bellows-type flexible joint on exhaust system dynamics
- 2004
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In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering. - : Professional Engineering Publishing. - 0954-4070 .- 2041-2991. ; 218:12, s. 1473-1478
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Journal article (peer-reviewed)abstract
- Most modern cars have a bellows-type flexible joint between the manifold and the catalytic converter to allow for thermal expansion and to decouple large engine movements and vibrations from the rest of the exhaust system. To obtain better understanding of the influence of this joint, the dynamic response of a typical exhaust system is studied when excited via different joint configurations. Measurements show the great order of reduction of vibration transmission to the exhaust system that a bellows joint, with and without an inside liner, gives in comparison with a stiff joint. For the combined bellows and liner joint vibration transmission is however higher than for the bellows alone. Together with some other aspects this makes the choice of including a liner in the exhaust system application complex. For a system in general the possibility of tuning the friction limit of the liner, to minimise overall vibrations through friction based damping, depends on how close to ideal the excitation source is and its location. Anyhow, the combined bellows and liner joint makes the exhaust system behaviour significantly non-linear, whereas the system behaviour proves to be essentially linear when the bellows has no liner, which imply that the liner needs to be included in theoretical models when present in the real system.
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