When using stress-independent material models (such as Linear Elastic or Mohr Coulomb) the material set window allows for the alternative input of shear or pressure wave velocity (Vs or Vp). Based on the specified (unsaturated) volumetric weight, the poisson ratio and the wave velocity the associated Young’s modulus is back calculated. For this back calculation the mass is required which is derived indirectly from the specified volumetric weight and the gravity.
However when changing the default gravity value or when using non-metric units the mass is incorrectly calculated since the program always uses the value of 9.8 (m/s2). As a result also the back calculated associated Youngs modulus is incorrect.
Since PLAXIS 2D AE.00 and PLAXIS 3D AE.00, the gravity value is a fixed value of 9.8 m/s2 and will be converted correctly to the used units in the PLAXIS 2D 3D project.
For older versions, when changing the gravity value or when using non-metric units do not use the alternative input of shear or pressure wave velocity but hand calculate the resulting Youngs modulus and enter this value directly.