Recording wheel loads during durability tests on the track, the road and off-road

Why record loads at the wheel

Durability testing is part of the design and validation of a vehicle and of its components. It estimates how long the parts will last and shows where the design should change. Its input is the load the road puts into the vehicle, and that load enters at the wheels.

Test tracks give repeatable conditions. Public roads are used as well, because they give results from the real environment.

Short events in rough conditions

The events that matter for durability are short and severe. A pothole strike is over in less than half a second. The transducer has to follow the load through the event and survive it, on vehicles from small all-terrain vehicles to heavy trucks.

The wheel is also exposed. The Michigan Tech off-road team described below tests in freezing temperatures, snow and ice.

A transducer sized for the vehicle, on adapters made for it

Michigan Scientific wheel force transducers measure the three forces and three moments at the wheel on vehicles from motorcycles and ATVs to Class 8 trucks, construction and agricultural equipment. The setup is the same in each case.

1. 01

   Choose the transducer for the vehicle

   The model is chosen for the size and load of the vehicle. The LW9.5, for example, is the model for ATVs and small vehicles.

   LW series wheel force transducers
2. 02

   Have the adapters made

   The customer gives the dimensions of the hub and the rim. Michigan Scientific makes the custom adapters that fit the transducer to the vehicle.

3. 03

   Drive the test

   The vehicle is driven over the usual obstacles, tracks or roads. Forces, moments, acceleration, wheel speed and wheel position are recorded together.

4. 04

   Or rent the set

   For a single campaign, a wheel force transducer set can be rented.

   Rental

A pothole at 40 km/h

In this test, the right front wheel of an SUV hits a pothole on a public road at 40 km/h (25 mph). At the start, the radial force is just under 6.7 kN (1 500 lb), which is the load carried by the wheel. The vertical force drops when the wheel enters the hole and falls freely. When the wheel touches the bottom, the force returns to about its starting value.

The largest peak comes on the way out, when the wheel strikes the far edge of the pothole. The force then oscillates while the suspension responds, and settles back to the static load. The whole event lasts less than 0.5 s.

An electric SUV

Bollinger Motors used Michigan Scientific wheel force transducers and instrumentation for the durability testing of the B1, a fully electric SUV. The trials put the vehicle in severe conditions to find the limits of the design. The analysis of the recorded loads feeds back into design and construction changes.

A student off-road car

The Michigan Tech Blizzard Baja team builds single-seat off-road cars for student competitions. The team sent the dimensions of its hub and rims and received custom adapters for an LW9.5. The students drove the obstacles they normally test on and recorded eight channels at once. They plan to use the force and moment data to lighten overbuilt parts, and to work on drivetrain efficiency, clutch tuning, suspension geometry and gearbox configuration.

Frequent questions