The global performance of any road vehicle is affected substantially by the performance of its tyres, which transmit all the tyre contact patch inputs to the rim and chassis. However, tyre behaviour is also affected by wheel motion, which is controlled by the vehicle chassis. It is therefore imperative to draw on all available tyre-characterisation processes when studying how best to integrate the tyres with the vehicle chassis.
Using a vehicle
Applus+ IDIADA offers a wide range of characterisation services that permit the subjective and objective analysis of the tyres’ contribution to overall vehicle performance.
Subjective tyre evaluations include the evaluation of those aspects of vehicle performance that are influenced by the tyres (comfort, noise, steering, longitudinal behaviour and response); winter, wet-track and dry-track condition testing; project management (evaluation of different sets of tyres); and joint tests if required.
In contrast, objective tyre evaluations comprise braking tests; aquaplaning tests while accelerating and turning; dynamic tests; NVH tests; and running-resistance and fuel-consumption tests.
Building tyre models
Advanced parametric tyre models (such as FTire and MF-Tyre) permit Applus+ IDIADA chassis engineers to consider tyre performance while the vehicle is being designed without the need for FEM tyre models. Consequently, this methodology enables the proper integration of the tyre in the chassis during the vehicle-development process.
Applus+ IDIADA offers the generation of two parametric tyre models that are widely used to simulate tyre performance.
- MF-Tyre: the Magic Formula tyre model is a “semi-empirical” tyre model that is able to predict handling performance. The MF-Tyre model is generated by means of force and moment tests such as pure concerning, pure braking and combined tests, which are performed with IDIADA’s skid trailer.
- FTire: FTire is a short-wavelength, intermediate-frequency tyre model. Applus+ IDIADA has developed its own measurement procedure based on research conducted in its laboratory and proving ground in order to collect precise and representative data on tyre behaviour.
Independent tyre characterization
Applus+ IDIADA provides the full tyre-characterisation service required to generate MF-Tyre and FTire models.
The processes available include measuring the tyre contact patch, the wheel-centre forces under a punctual input application while the tyre is rolling in proving-ground conditions, static tyre stiffness, the basic tyre properties and the tyre’s handling response in proving-ground conditions.
The basic rigs used to characterise the tyres during Applus+ IDIADA’s modelling phase are:
- Applus+ IDIADA’s skid trailer, which permits tyre dynamics characterisation by controlling tyre
attitude over the ground. All the motions and forces are being registered at the wheel centre when the wheel is free rolling or braking. Lateral slip, longitudinal slip tests, combined slip test or cleat tests are performed on a real proving ground
- Applus+ IDIADA’s K&C rig (Kinematics and Compliance test rig) permits tyre static-stiffness characterisation. Tyre attitude is controlled over the ground while all the motions and forces are being registered. The tyre contact patch is placed on a platform that can be controlled with five degrees of freedom.
- Applus+ IDIADA’s indoor tyre laboratory permits the measurement of rolling resistance under defined conditions.