Microforce materials tester

A material tester for evaluating the mechanical response of general objects against micro-Newton level impact forces has been proposed. In the tester, an inertial mass is made to collide with the material under test. The impact force acting on the material is measured as the inertial force of the mass. A pneumatic linear bearing is used to realize linear motion with small friction acting on the mass that is the moving part of the bearing. The velocity of the mass is measured highly accurately by means of an optical interferometer. The acceleration, the inertial force, and the position of the mass is numerically calculated from the velocity after the collision measurement. The other force, which is mainly consisted of the friction acting inside the bearing, is determined using the same instrumentations. Using the estimated friction inside the bearing, the measured force is corrected. The force acting on the mass from the material under test of approximately 0.1 mN is measured with the standard uncertainty of approximately 1.4 mu N. (c) 2005 American Institute of Physics.