**1. Introduction**

Passenger car radial (PCR) tyre is one of the most widely used tyres and is designed to follow the international standard and the regulation in the country where the tyre is being used. The recent regulation mainly concerns with the reduction the source of pollution and safety, such as rolling resistance, rolling noise, and wet grip. This study discusses the finite element simulation of tyre in order to design PCR tyre having low rolling resistance coefficient that lead to a low energy consumption tyre.

The energy consumption of vehicle to some extent is contributed by tyres. According to International Council on Clean Transportation [1], improving tyre energy efficiency will reduce fuel consumption by 3 to 5% which will reduce greenhouse gas emission by more than 100 million metric ton annually. Therefore, a low rolling resistance tyre is highly required to reduce the gas emission produce by vehicles.

Tyre rolling resistance is defined as the energy consumed per unit travel distance when the tyre rolls under load [2]. Therefore, lower energy use of vehicle can be obtained by using low rolling resistance tyre.

Tyre design process includes conceptual design, benchmarking, detail design, and design review and analysis. During design review and analysis phase, a simulation was conducted to estimate the value of rolling resistance coefficient. In this simulation, a finite element model was built by using Abaqus software to simulate the tyre deformation and calculate a complete energy loss absorbed by the deformation of rolling tyre under certain load and speed. The hysteresis energy loss was calculated using a user defined subroutine written in Python and is used as Abaqus plug-in.

### **2. Rolling resistance**

Tyre rolling resistance requirement was outlined in United Nation Economic Commission for Europe (UNECE) regulation No. 117 Revision 2, together with rolling sound emission and adhesion on wet surface (wet grip). The country applying this Regulation may refuse to allow the sale or entry into service of a PCR tyre (C1 Class) which does not meet the stage 1 rolling resistance requirements from 1 November 2014 and the stage 2 rolling resistance requirements from 1 November 2018 [3].

However, different countries have different policies regarding implementation standard, date and rating. European Union implements tyre labeling requirement since 2012, where the label states the rating of Rolling Resistance Coefficient, Rolling Sound Emission, and Wet Grip. Gulf Cooperation Council implement GSO standard tyre labeling starting 2014, mandatory for rolling resistance and wet grip.

#### **2.1 Rolling resistance coefficient**

UNECE Regulation No. 117–2 defines Rolling Resistance *Fr* as loss of energy (or energy consumed) per unit of distance traveled, and Rolling Resistance coefficient *Cr* as ratio of the rolling resistance to the load on the tyre (**Table 1**).

As stated by Tonachel [4], rolling resistance occurs as tyres deform during rotation. The load within the rubber material and rebar that construct the tyre are deformed and the loss of energy during these repeated deformations is then dissipated in the form of heat. The dissipation of energy in radial tyre occurs on crown is estimated about 70%, on sidewall 15%, and bead area 15% [5].


#### **Table 1.**

*Standard RR coefficient based on ECE R117–2.*

*Rolling Resistance Estimation for PCR Tyre Design Using the Finite Element Method DOI: http://dx.doi.org/10.5772/intechopen.94144*

#### **Figure 1.**

*Rolling resistance test method [6].*

Therefore, the research was focused on the crown area. The simulation was done on crown initial radius and the stiffness of tread to study their effect on rolling resistance coefficient *Cr*.

#### **2.2 Rolling resistance measurement**

In this research, the rolling resistance test was conducted according to ISO 28580, i.e. using force measurement method (**Figure 1**). In this method, the tyre and drum wheel assembly is forced toward a drum wheel with the skim load *Fpl*, and the reaction force at the axle of tyre and drum wheel assembly *Ft* is then measured. The rolling resistance *Fr* at the contact of tyre and drum can be calculated using the following equation:

$$F\_r = F\_t \left( \mathbf{1} + (r\_L/\mathcal{R}) \mathbf{-} F\_{pl} \right) \tag{1}$$

where *Fr* Rolling Resistance (N) *Ft* Measured force at the spindle (N) *rL* Tyre radius (m) *R* Drum wheel radius (1.7 m) *Fpl* Skim load (N)

#### **3. Design methodology**

Tyre design consists of several phases, including conceptual design, benchmarking, detail design, design review and analysis. Design review and analysis phase is important to ensure that the final product will be in accordance with the required performance as designed. One of the processes in this phase is doing simulation by using finite element method with the following steps [7]:

1.Define target performance

2.Tyre Simulation using FEA

3.Validation of FEA simulation result

#### **3.1 Target Performance**

The tyre being designed is PCR tyre with size of 175/65 R14, should have maximum Rolling Resistance Coefficient of 8.5 N/kN and good cornering stability.
