A Proposition of Eulerian Displacement Meter and Its Application to Materials Testing

Ordinary displacement meter tracks the motion of specific points in a solid to give Lagrangian description of displacement. This paper proposes Eulerian type displacement meter which gives Eulerian description of displacement and shows that PC mouse, which is now an indispensable computer input device, is on its own an excellent Eulerian displacement meter. While in computer environments, mouse moves on the fixed pad and it measures its own movement, in this study, the movement of the object is measured by the mouse fixed in space. It is shown that the true strain is obtained by dividing the difference of the readings of two Eulerian meters by their separation distance. It can also give Lagrangian description if it tracks the target strip attached to the gauge point. Uniaxial tensile tests of rubber and membrane materials have been conducted and their elongation has been measured successfully by the present method.