Fundamental Structure of Tire Design

A tire is not a single material but a multilayer composite. It is not just rubber, but an anisotropic structure incorporating reinforcement materials.

・Multilayer structure of tread, carcass, and bead
・Reinforcement by steel cords
・Hyperelastic behavior specific to rubber
・Time dependency due to viscoelasticity
・Large deformation at contact (geometric nonlinearity)

As a result, simple elastic body models are not sufficient. Material nonlinearity, geometric nonlinearity, and contact problems coexist simultaneously.

Furthermore, with electrification, engine noise disappears and tire noise becomes the dominant issue. Regulations are also concentrating on noise, wear, and CO₂, increasing the number of evaluation items.

Hierarchical Structure of Simulation

Tire analysis is not a single analysis, but is built up in stages.

Fundamental Analysis

・Static analysis under internal pressure and load
・Contact shape (footprint)

This becomes the starting point for everything.

Running State

・Steady-state rolling analysis
・Slip, cornering

Deals with dynamic conditions rather than static states.

Dynamic Phenomena

・Step impact (transient analysis)
・Vibration analysis (FRF, modes)
・Air coupling (cavity resonance)

Peaks in cabin noise arise from coupling with air. They cannot be reproduced by the tire alone.

Degradation and Environment

・Wear (Archard law)
・Interaction with water, snow, and soil

Wear is determined not by stress, but by slip and energy dissipation.

Shift from Design to Optimization

Simulation is no longer just reproduction, but is moving toward design generation.

In tread design, the structure is as follows.

・Noise source = impact of tread blocks
・Disperse pitch sequence
・Search combinations with optimization algorithms

Outputs include
・Vibration response
・Sound pressure level

These are set as objective functions.

Reductions on the order of a few dB are targeted, but under regulatory conditions this difference has meaning.

Computational Structure and Efficiency

If solved directly, tire analysis results in excessive computational load.

Therefore, structural techniques are introduced.

・Axisymmetric model → expansion to 3D
・Steady-state analysis → transition to transient analysis
・High-density mesh only at the contact region
・Dimensional reduction using the waveguide method

The key point here is not accuracy but feasibility. Rather than solving everything strictly, the structure selects approximations that make the problem tractable.

Changes in the Development Process

The design process itself is also changing.

Conventional
・Design → Prototype → Test → Revision

Current
・Design → Simulation → Optimization → Test

With further integration

・Design
・Analysis
・Manufacturing
・Data management

are connected on a single platform.

Here,

・DOE (Design of Experiments)
・Automatic parameter updates
・Reuse of results

become the premise.

Meaning as an Institutional Condition

Tire simulation is closer to an institutional condition than a technology.

The reasons are as follows.

・Regulatory items are multi-axis (noise, wear, fuel efficiency)
・Testing costs are high
・There are phenomena that cannot be reproduced by testing
・Design cycles are shortening

In other words

not “whether to do it,”
but “it cannot be done without it”

that is its position.

Sources and References

・YouTube video
“Advanced Tire Modeling for Better Performance”