By optical lithography, a wave shape is formed on a side-wall of a column type resist pattern due to standing wave effect which occurs during exposure process. After the pattern collapse with atomic force microscope (AFM), surface topography of the pattern side-wall can be imaged clearly. Based on standing wave effect, refractive index distribution of the resist pattern can be estimated to be the range from 1.51 to 1.79. It is clarified that refractive index at the pattern bottom is relatively high comparing with that of the pattern top. This tendency reflects the distribution of cohesion strength of the resist pattern resulting from the heat treatment with a hot plate. By this method, optical and cohesion properties of a micro condensed matter can be analyzed quantitatively.

View full abstract

A simple tack-evaluation technique of adhesion properties between soft materials was developed, where two soft materials with uniform thickness adhered on cylindrical glass sticks were placed in a crossed-cylinder geometry and formed a point contact. The notable features of this technique were that the shape of contact surface was circular and that the contact radius of interfacial boundary continuously changed in all processes from press after contact to separation. The adhesion properties between the hydrogels which were consisting of partially neutralized poly (sodium acrylate) and physically cross-linked by Al3+ ions (PSA gels) have been extensively studied with the use of this technique. In this paper, the effects of the degree of neutralization and the addition of hydrophilic fumed silica on adhesion properties of PSA gels are presented. The adhesion force and the separation energy depended on the degree of neutralization or the amount of fumed silica. The results were discussed in terms of the molecular interaction in the surface and the elastic and viscous properties in the bulk network on the basis of the measurements of Fourier transform infrared spectroscopy and dynamic viscoelasticity.

View full abstract

We developed long handling arms which were applied to transfer press machine for car body manufacturing. The arms consisted of aluminum alloy pipes adhered with CFRP plates on their surfaces to reinforce their stiffness and to reduce their vibration. To design these structures, predicting the fatigue life of the adhesive joints is indispensable. However, there wasn't a suitable test method to evaluate such fatigue life using specimens defined in standards. Therefore, we had to use full scale specimens equivalent to actual structure in terms of scale. In this study, we suggest a test method to predict the fatigue life of the actual structures using reduced scale specimens instead of the full scale specimens. At first, fatigue tests using both these full scale specimens and reduced scale specimens were carried out. Next, estimating the dependence of their fatigue lives on the dimension of the specimens, we predicted the fatigue life of the full scale specimens from those of the smaller specimens. As the result, we could establish a new method to predict the fatigue life of full scale specimens by translating those of the smaller ones.

View full abstract