A similarity rule of the draped figures for sheets had been investigated by using a model of the F.R.L. drape test. An assumption has been made that the relation between own-weight (Pw) and the resistant forces could be expressed by the following formula:
Pw = P₁ + P₂ + P₃
where, P₁: resistant force against the bending,
P₂: resistant force against the compression,
P₃: resistant force against the torsion and the other.
In this paper, an investigation has been made of the other resistant force containing in P₃ by using the π-number of the similarity rule. Results obtained were as follows:
1) By using the line-joint model replaced the empty part with a variant sheet, the resistant forces have been found of the 3-dimensional bending and the elasticity in the P₃ in addition to the torsional resistance. The π-number (π₁) of the 3-dimensional bending could be equal to π₁, π₂ and π₃ corresponding to P₁, P₂ and P₃ respectively and expressed b the same formula:
π=π₁=π₂=π₃=π₄=L/³√EI/w
where, L: representative length,
EI: bending rigidity,
w: weight per unit area.
In additon, the π-number (π₅) of the elasticity could be expressed by the following formula:
π₅ = L/ (E/ρ)
where, E: Young's modulus,
ρ: density.
2) The F.R.L. drape test carried out with the π by the fixed value has revealed that the F.R.L. draped figures could be classified according to the value of the π₅.

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