Abstract
The model experiments of plow have no practical values, unless the law of similitude has been established. The correspondence between prototype and model, such as scale, velocity and soil condition can not be determined. In this paper, I have introduced the motion equation of soil (5) at the deformation process in plowing, with using the conception of finite strain and Boussinesq's stress-strain relationship, (2), (4) and with dimensional analysis (9) - (13) the low of similitude of model plow is established. That is, prototype and model plow having geometrically. similar form, have the dynamic similitude when the no dimensional quantities such as named K-number, L-number, μ and m are respectively same values on prototype and model. where, K-number: ρV2/S, L-number: ρgL/S, ρ: density of soil, L: longitudinal dimension, V: velocity, S: pressure or stress, μ: coef. of friction, m: Boussinesq's constant of soil. From the fundamental theory, practically, if the model has 1/n scale, the velocity of model must be 1/√n of prototype. The resistance of plow is, with respect to longitudinal dimension, the sum of L2 and L3, where L2 is dominant.
