mechanics_functions.soil_characteristic_funcs.calc_firmness_factor(gravity, max_deceleration, total_penetration_time, impact_velocity)

Calculate the firmness factor (FF) of the soil.

Parameters:

• gravity (float) – Acceleration due to gravity [m/s^2].

• max_deceleration (float) – Maximum deceleration of the probe [m/s^2].

• total_penetration_time (float) – Total time of penetration [s].

• impact_velocity (float) – Impact velocity of the probe [m/s].

Returns:

Firmness factor (FF).

Return type:

float

Notes

The firmness factor is calculated using the following equation:

\[FF = \frac{a_{max}}{g \cdot t_{p} \cdot v_{i}}\]

where:

• \(FF\) : Firmness factor.

• \(a_{max}\) : Maximum deceleration.

• \(g\) : Acceleration due to gravity.

• \(t_{p}\) : Total penetration time.

• \(v_{i}\) : Impact velocity.

The firmness factor is not a dimensionless parameter.

For more information, refer to the paper: [Springer article](https://link.springer.com/article/10.1007/s11001-011-9116-2).