Cornering Fatigue Testing Machine

Introduction

The Conering Fatigue Testing (RFT) machine allows the simulation of an endurance fatigue test on car/light truck/bus wheels subjecting them to cornering fatigue stress and holding the test conditions constant throughout the test duration. This is the type of stress a wheel experiences during turning.

How it works

The Creative Dynamics Engineering’s cornering fatigue test machine performs testing on wheels, under rotating condition, with the bending moment applied at 90 degree to the test wheel.

The test machine is configured to test one wheel at a time. The machine contains load control and speed control servo loops. Applied load is controlled to +/- 1% of set point within stated load range. The servoloop is dynamic in that it will continuously compensate for load changes due to flexing of the wheel.

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

The deflection of the rod under load is also measured at two locations to provide deflection around 360°. The deflection signals the start of a crack at the disc wheel and therefore, is an important criterion for shut down of the test.

The servo loop can work in constant load mode or constant speed mode. In constant load mode the instantaneous bending moment measured is compared with the user supplied set point producing an error signal. This error signal id fed to the unbalance mass rotation drive which modifies the speed so as to bring this error signal within acceptable limits. The speed servo loop works in order to maintain a user supplied speed regardless of the resulting bending moment.

The function of the machine is to apply a rotating bending moment to the wheel; the resulting stresses on the wheel are very similar to the stresses created under cornering by a car or truck on the road. The Rotary fatigue test machine applies a force to the wheel central disc. The wheel failures on the machine will be to the center of the test wheel and or in the area of the wheel mounting holes.

The machine may be controlled in a manual or fully automatic mode (load, speed) by means of controls mounted on the front of the control panel. The following settings can be adjusted:

  • No. of load cycles
  • Bending moment or speed set point
  • Percent value of increase in deflection for shut down criteria
  • Maximum speed for shutdown criteria
  • Maximum bending moment for shutdown criteria
  • Information regarding the wheel under test

The following parameters are displayed on the front of the control panel:

  • Applied Load (force / moment)
  • Speed (moment RPM)
  • Deflection
  • Cycles (Total revolutions of wheel)

Machine Specifications

Loading Method Rotating Bending Moment
Table Height 1,150  mm
Table Width 1340 SQ mm
Work disc diameter 1,200  mm
Disc diameter range 12 – 22 inch
Disc width range 3.5 – 14 inch
Length of bending shaft 725 mm
Nominal bending moment 25 kN.m
Test speed at the control of moment 100 – 500 RPM
Test speed at the control of speed 0 – 800 RPM
Load accuracy < 1 %
Speed accuracy < 0.5 %
Programmable Logic Controller Siemens S7-300
Touch screen HMI 12 inch
Bending moment measurement S-type Loadcell
Bending deflection measurement LVDT
Drive servo motor 5.7 kW
Electrical Power supply 3 ∅, 380/220V, 50Hz, 8.0 kW