Mechanical Evaluation of Spectacles at Contact Area around Ear

When the relationship between the dimensions of face form and those of spectacle frames is poor, it may cause problems such as slipping frames and sore areas on the nose and behind the ears. In this study, mechanical characteristics in face-spectacles interface are discussed. CAD models of face form and spectacle frames were constructed from the three dimensional measurements of the human face that wore spectacles. The finite element method (FEM) model of the face was constructed by using CT images of the scalp organization. Next, the FEM model of spectacles constructed with the 3 D measurements was synthesized to the face model. Then, mechanical behavior in the interface between the face and spectacles was investigated by FEM analysis. In the result of the frame which was adjusted to the face, contact area between tip and skin is so wide that the effect of holding spectacles stably was recognized with the end of tip hold head. At the frame which was not adjusted, contact area is so small that enough pressure was not generated to hold spectacles stably.