National Maritime Research Institute

Threebond Co., Ltd.

Ichihiko Takahashi

Tomio Onoguchi

Michio Ushijima

Chiori Takahashi

Mitsuhiko Uchida

A method of detecting fatigue crack by which the fatigue crack can be easily detected by visual observation even in a relatively early stage, and a method of restraining propagation thereof. The detection method includes the steps of: (a) preparing a paste in which particles having hardness not less than that of a base material and an oil having viscosity are mixed with each other; (b) applying the paste to a desired portion of the base material; and (c) detecting fatigue crack based on a change in color generated by movement of base material powder to a surface of the paste, and the base material powder is produced when the particles grind the base material due to opening and closing of the fatigue crack in the base material.

Method of suppressing extension of fatigue crack, method of detecting fatigue crack and paste used for the methods

In a coating for the inspection of a crack in a structure wherein a coating layer having dispersed therein microcapsules with a visualizing liquid sealed therein is formed on the surface of the structure and when a crack is developed in the structure and propagated to the coating layer, the microcapsules dispersed in the coating layer are ruptured and the visualizing liquid flows out from the ruptured microcapsules and reaches the surface of the coating layer along the crack in the coating layer, thereby making it possible to detect the occurrence of the crack in the structure: at least one second coating layer not containing the microcapsules is formed over the first coating layer with the microcapsules dispersed therein, the second coating layer being transparent and having an outermost layer flexible enough to be prevented from being cracked even upon cracking in the first coating layer.

Growing community of inventors

Tokyo, Japan

Ichihiko Takahashi