Abstract
In quantitative measurement of strain by brittle coatings, it is very important to know the drying condition of coating. As the measure showing the drying condition, the critical strain is used. In order to know the critical strain, the following method is adopted. When a cantilever coated on the tension side is loaded, the coating cracks first at a certain strain value. This strain is called the critical strain.
It was found by the experiment that the critical strain varies with the variation of strain gradient in the tensile direction, even though the cantilever coated under the constant condition is used. Then the authors investigated the experimental results from the standpoint of weak point of coating.
