Tyre Testing with VBOX
There are many different dynamic tests that tyre companies need to perform in their product development cycle. VBOX system solutions help to complete tyre tests in an accurate, flexible, and quick way.
A very useful way of comparing the relative performance of a tyre is to perform a number of brake stops using an ABS equipped vehicle. By using ABS the stopping distances are very repeatable and when a number of stops are performed and averaged, the results can be compared with similar tyres.
Another important factor to be measured during this test is the amount of deviation from the straight line, as this gives a measurement of the stability of the vehicle under braking.
The test is usually carried out between two set speeds. The speeds are chosen so that the car has entered the relatively linear stage of the deceleration process, in order to remove the response time of the whole braking system.
For example, if the brakes are applied at 110 km/h, the brake test could start at 100km/h and finish at 15kmh; this eliminates the first and final part of the brake stop which is less repeatable.
For comparison with other compounds and constructions, the brake stops needs to be measured with a high accuracy, preferably within a few centimetres.
An important characteristic of a tyre is the speed at which it will begin to aquaplane. There are two main tests which are used in order to determine this speed. The first is in a straight line, and the second is around a corner.
Straight Line Aquaplane Test
The car accelerates from a standstill with one side of the car running with the wheels in a shallow channel filled with water. When the aquaplane threshold speed is reached, the driven wheel in the water channel will start to slip, and by comparing the speed of this wheel with the overall vehicle speed obtained by GPS, this speed can be captured. This test is then repeated a number of times in order to obtain an accurate and repeatable result. The challenges in this test are to calibrate the wheel speed inputs and relate these to the GPS vehicle speed. In order to simplify and automate this process, Racelogic can supply dedicated aquaplane software which carries out the calibration and collection of the test results.
Cornering Aquaplane Test
The vehicle drives into a flooded section of track whilst turning on a prescribed radius. This test is carried out at different speeds, until the aquaplane threshold is reached, at which point the vehicle will start to slide upon entering the bath.
By using a GPS based VBOX, the vehicle speed and lateral acceleration can be monitored, and the aquaplane threshold can be measured very accurately. A useful measurement in this test is the steering angle, which can either be obtained from CAN or by using a steering angle sensor connected directly to one of the analogue input channels.
Circuit tests are often used to determine the dynamic performance of the tyre. During these tests oversteer and understeer characteristics of the vehicle are monitored, along with the lateral and longitudinal accelerations generated and overall lap-times.
The VBOX range of high accuracy GPS data loggers are now the standard equipment for almost every automotive manufacturer, tyre manufacturer, and vehicle testing company in the world. This is due to their high accuracy, flexibility, and ease of fitting (they can be moved from vehicle to vehicle in minutes).
Full product details are available on the right. Please contact us with specifics of your testing applications, and we will be pleased to advise you.