You cannot apply gravity loads to individual point masses. To include point masses in a gravity load, apply the load to the whole model. Click the arrow to the right of the Distribution field, if available; and select the option of your choice from the li

You can create a gravity load to define a uniform acceleration in a fixed direction. A gravity load is applied to the whole model. ABAQUS calculates the loading using the acceleration magnitude that you enter in the gravity load definition and the density

I tried to apply gravity load in a dynamic explicit step by means of smooth step, but this introduced much kinematic behavior because of the variable velocity of smooth definition. I recommend to ...