Evaluating device of flexural property of material, and evaluation method using thereof

A method of evaluating flexural property of a bent specimen using a device for evaluating flexural property comprising:

• a holder,
• a body disposed on the holder and capable of being moved along with a length direction of the holder,
• a clamp coupled to the body and capable of being rotated on the body and fixing a first side of a specimen to be evaluated, and
• a pressing part disposed on the clamp and pressing a second side of the specimen opposite to the first side and disposed upper than the first side of the specimen to bend the specimen,
• the method comprising:
• evaluating at least one of a strain L of the bent specimen, a folding stress σf applied to the bent specimen, a folding modulus Mf applied to the bent specimen, by using:
• a thickness h of the bent specimen,
• a length L″ of a first arc connecting a first point and a second point which are different from each other and applied with a principal stress corresponding to a half of a maximum principal stress applied to the bent specimen,
• a length L′ of a first straight line connecting a shortest distance between the first point and the second point,
• a curvature radius p of a virtual circle when the first arc is extended to set the virtual circle, and
• a bending angle θ between the clamp and the lower surface of the pressing part.