At least one tire at its saturation limit

Overview of a 3D vehicle model with the brake system highlighted

LapSim calculates with a constant brake force distribution between front and rear wheels. The brake force to the left and right wheels of one axle is always equal.

During braking LapSim calculates for each individual wheel how much braking force can be transferred to the road, while staying within the tire saturation limit.

Topview of the 3D vehicle animation with the brake force visible

The minimum value of the braking force (adjusted for the brake balance) of the 4 wheels, determines the total amount of braking which will occur at that moment in time.

This means that there is always minimal one tire on the saturation limit.

Limiting the brake force on the rear axle

Figures showing the brake force per axle and brake force distribution as a function of the total brake force

In addition to the fixed brake balance, a brake force reduction to the rear wheels can be specified. A device commonly used on street cars.

With light braking the emphasis of the brake bias is more to the rear. With higher braking force, creating more load transfer to the front axle, the emphasis of the brake bias shifts more to the front. The graphs show the relative influence of the settings.

Brake balance optimal to vehicle state

Screenshot of the LapSim GUI showing the button to engage ABS braking

LapSim provides an option to run an “ABS” like system. With this option selected, LapSim varies the brake force distribution between the two axles to the momentary optimum.

This provides a good indication of the maximum potential to be gained under braking. An example can be seen in the figure below.

Screenshot of the LapSim GUI showing simulation results of ABS braking

In the item “Brakes” of the plot menus, one can see what the optimal brake balance would be at each point of the track.

The figure on the right shows an example of a braking sequence with (white lines) or without (black lines).

Estimate for brake temperatures

If you select 'Brakes' in the plot menu, 6 edit boxes will appear where you can edit parameters representing your brake system.

With these parameters a simplified brake temperature simulation is done, based on the brake energy generated by the selected simulation runs.

Apart from the brake energy there is the cooling dependent on the vehicle speed, brake disc size and relative cooling.

The disk size in combination with what is called 'heat capacity' determine the thermal mass of the brakes.

What results is a temperature trace. We like to emphasize that you should use the traces for comparisons, without looking to much on the absolute values.

In the example you see the effect of adding 25 [Hp] to engine power on the brake temperatures.