Tire analysis using the finite element method is a widely used approach due to the versatility of the numerical model to represent various rolling conditions and material behaviors, and because it enables efficient parametric analysis and optimization.
A tire is modeled as close as possible to the original geometry, considering all structural components and reinforcing layers. Nonlinear material models represent the complex behavior of the rubber compounds. Advanced material models make it possible to determine energy dissipation and rolling resistance.
Tire analysis begins with a static analysis to simulate mounting the tire onto a rim. The wheel is often assumed to be rigid; however, examples of models with deformable wheels can be found, especially for impact analysis where the deformation of the whole system is important. The same static analysis can also simulate inflation of the tire by applying pressure to the inner face of the tire. The rim-mounting and tire-inflation processes are generally simulated on a 2D axisymmetric tire model; if required, however, both processes can be performed on a 3D model.
Following the static analysis, a footprint analysis occurs on the 3D tire model. An appropriate vehicle load is applied and the contact between the tire and the road is established. The interaction between the tire and the road is described via frictional formulations which can consider the friction coefficient as a function of the contact pressure, sliding velocities, and temperature.
For further simulation, two primary analysis types are possible:
Transient
Enables time-dependent phenomena (such as impact) to be examined. The versatility of transient analysis involves significant of computational resources, however, especially when simulating rolling tires.
Steady-state
Offers an efficient alternative to transient analysis. Loading conditions such as pressure, axial load, and velocity are assumed to be constant during the analysis. Another advantage is the possibility of adaptive refinement in the contact region, leaving a coarser discretization everywhere else. Within this framework, it is possible to analyze typical tire maneuvers (such as acceleration, braking and cornering) at various rolling velocities. For more information, see General Steady-State Rolling Assumptions.