Papers by Keyword: Directionality

Abstract: We have previously shown that microparts can be fed along an asymmetric microfabricated surface using simple planar symmetric vibrations. Microparts move forward because they adhere to the microfabricated surface asymmetrically. We have also described the effects of sawtoothed surfaces on the movement of submillimeter-sized microparts; for example, 0603 (size, 0.6 x 0.6 x 0.3 mm; weight, 0.3 mg) and 0402 (size, 0.4 x 0.2 x 0.2 mm; weight, 0.1 mg) capacitors. In the present work, we studied the effects of feeder materials on the feeding of single layer chip capacitors (size, 0.25 x 0.25 x 0.35 mm ; weight, 0.06 mg). We found that the motion of submillimeter microparts was affected not only by inertia but also by adhesion due to electrostatic, van der Waal's, and intermolecular forces, and to surface tension. These effects are dependent on the two materials that are in contact with each other. The four materials selected for feeder surfaces were microfabricated so that periodic sawtooth structures were present on their surfaces. We assessed micropart feeding using these surfaces, as well as the relationship between feeding velocity and vibration frequency. By comparing the feeding velocity on each feeder surface, we assessed the effects of feeder surface materials on the feeding of microparts.

Abstract: The instrumented indentation technique (IIT) is a powerful method for evaluating mechanical properties of materials such as elastic modulus, tensile strength, fracture toughness and residual stress. Especially, IIT is a promising alternative to conventional methods of residual stress measurement such as hole drilling, saw cutting, X-ray/neutron diffraction, and ultrasonic methods because of its various advantages of nondestructive specimen preparation, easy process, characterization of material properties on local scales and measurement of in-service structures. Evaluation of residual stress using IIT is based on the key concepts that the deviatoric-stress part of the residual stress affects the indentation load-depth curve and that the quantitative residual stress in a target region can be evaluated by analyzing the difference between the residual stress-induced indentation curve and residual stress-free curve. To verify the applicability of the suggested technique, indentation tests were performed on the welded zone.