Radial Fatigue Testing Machine

Introduction

The Radial Fatigue Testing (RFT) machine allows the simulation of an endurance fatigue test on car/light truck/bus wheels subjecting them to radial fatigue stress and holding the test conditions constant throughout the test duration. This is the type of stress a wheel experiences when travelling on straight road. The machine is of dual-spindle type allowing to test two wheels at the same time thereby reducing the overall test time.

How it works

The Creative Dynamics Engineering’s radial fatigue test machine uses a cantilevered “C” frame carriage which are supported and guided by two roundways. The roundways are mounted horizontally and are parallel to each other in the vertical plane of the machine. The carriages are interfaced to the roundways by ball bushings mounted in the carriage. The test machine is configured to independently test two tires individually or simultaneously. The two-position machine contains two load control and one speed control servo loops. Tire loading is controlled at +/- 1% of set point within stated load range.

The operation and performance of the machine conforms to or exceeds the following international standards:

1. ISO-3006 Road vehicles – Passenger car wheels for road use – Test methods
2. ISO-3894 Road vehicles – Wheels/rims for commercial vehicles – Test methods
3. SAE-J328a Wheels – Passenger Car and Light Truck Performance Requirements and Test Procedures
4. SAE-J267a Wheels/Rims – Trucks Test Procedures and Performance Requirements

A ballscrew jack is attached to the machine end frame, so that the axial center line of the cylinder extends through the center of the tire spindle as well as the centerline of the road wheel in the vertical plane of the machine. The radial force exerted on the tire is measured through a load cell. The roadwheel is of a fabricated steel construction and 1707.6 mm diameter; rim face widths of 16 to 36 inches are available. One rotation of the roadwheel is equal to 1/300 mile (5.364 m). The roadwheel is supported by two heavy duty bearing housings. The bearing assemblies are adjustable allowing the roadwheel to be aligned parallel to the spindle. An adjustable motor base is used to allow for proper tensioning of the drive belt. The motor can be adjusted in relation to the motor base in both planes allowing for belt tracking. The drive belt connecting the motor to the roadwheel is a heavy-duty timing belt, insuring a positive non slip drive.

The machine is controlled (load, speed and test time) by Siemens S7-300 programmable logic controller (PLC). All machine controls (start/stop of drive motor, load/unload of test stations) are performed using a touch screen operator interface panel located on the front of the control panel. The desired test parameters (load, speed and test time) are entered from a keypad located on the operator display unit. The machine will control to the values (load, speed) entered by the machine operator until new values are entered, the tire fails, the test time is reached or the test is stopped by the operator. During the test the current test parameters are displayed on the display unit (load, speed, current time, elapsed test time, elapsed test distance). The PLC will automatically control the machine (load, speed and step duration). At the completion of the last step the machine will automatically unload the tire and stop the roadwheel.  

Machine Specifications

Loading Method

Ballscrew Jack

RimDiameterRange

12 – 22 inch

Roadwheel Diameter

1,707 mm

Roadwheel Width

460 mm

Drive Motor

75 HP

Roadwheel Speed

Upto 485 km/hr

Roadwheel Speed Accuracy

< 0.5 %

Speed Accuracy

< ± 1 km/hr

Load Range

upto 50,000 N

Load Accuracy

< ± 1 %

Programmable Logic Controller

Siemens S7-300

Touch screen HM

12 Inch

Force measurement

1 Load cell per spindle

Over travel measurement

Limit switches

Electrical Power supply

3 ∅, 380/220V, 50Hz, 60.0 kW

Video