This paper deals with mechanical response of material against small impact force using levitation mass method (LMM). Material properties observed by evaluate deformation of material and force acting on the material. In LMM, the force acting on the material is generated by collision of a levitated mass which has very small friction. The impact Force and deformation of material which cause of the collision is accurately measured by optical interferometer. A dynamic impact force, less than 10 N are applied to the three types of material. The mechanical response of material is indicated by time of collision, Whv and ratio of loss energy. It shows stiffness properties and elasticity level of material, respectively.

A method for evaluating the dynamic characteristics of force transducers against small and short-duration impact forces is developed. In this method, a small mass collides with a force transducer and the impact force is measured with high accuracy as the inertial force of the mass. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. Small and short-duration impact forces with a maximum impact force of approximately 5 N and minimum half-value width of approximately 1 ms are applied to a force transducer and the impulse responses are evaluated.

The dynamic mechanical characteristics against small impact force of konjak were measured in this study. Konjak is one of the popular and healthy Japanese foods and is the Gunma prefectural specialty. There are many studies discussing the sensory characteristics of food materials, however few of them measure the characteristics quantitatively and accurately. If it has been done, the detail of sensory properties will be able to be discussed. We have done the experience and shown the characteristics. Konjak is flexible and slimy food material. We thought konjak is like rubbers and it can be measured the response against small impact force. To measure the precise dynamic mechanical force, the levitation mass method (LMM) is used. In LMM, a pneumatic linear bearing is used to reduce friction to almost zero, and an optical interferometer is used. The acceleration, velocity, position, and inertial force of the mass are calculated from the measured time-varying frequency due to Doppler Effect, which can be calculated by using the zero-crossing fitting method (ZFM). LMM had been used to only measure the dynamic forces acting on the mass before, but we utilized it to test the mechanical characteristics of food materials. Konjak has the characteristics of viscoelasticity. We have revealed the quantitative and logical characteristics of konjak.

Impact response of contact lenses is measured using the Levitation Mass Method (LMM). In the LMM, a small mass collides with contact lenses and the impact force is measured with high accuracy as the inertial force of the moving part. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the moving part. Hysteresis loop and consumed energy as mechanical characteristics of contact lenses are also calculated.

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