Research Tpics
Research of material strength (hardness)
■Developing calibration and measreuement methods of hardness standard
Rockwell, Vickers and Brinell hardness standard machines with high-rigidity are installed in our group. We are researching to clarify the relationship between the uncertainty factors and hardness in various conditions.■Research and development for advancement of hardness measurement
We are researching to enhance the convenience of hardness tests, as well as maintaining and supplying the hardness standard. For example, we investigate to identify the influence of material properties on the hardness measurement, and we develop the automatic hardness measurement that can be applied to various materials.■Research on evaluating mechanical properties in minute area
In these days, the demand of material strength measurement in minute area is increasing. Nanoindentation tests can obtain elastic modulus and hardness values in minute area by load-displacement data during loading-unloading indentation in μm- and nm-order. However, there is a problem of large variation due to the complex evaluation method based on some assumptions and corrections. We are investigating to improve the reliability of mechanical property values obtained from nanoindentation tests.Research of ultrasonic
■Expansion to calibration range of ultrasonic standards
We will expand the upper limit of calibration range for ultrasonic power standard to 200 W until the end of 2022FY. As for the ultrasonic pressure standard, we will expand the lower and upper limits of calibration frequency range to 50 kHz and 100 MHz respectively in the end of 2023FY.■Development of precise measurement technique for instantaneous acoustic pressure of broadband ultrasound
■Development of precise measurement technique for instantaneous acoustic pressure of broadband ultrasound Precise technique for measuring the instantaneous acoustic pressure of pulsed (that is, broadband) ultrasound radiated from the equipment is essential in order to balance the safety of patients in diagnosis and advanced performance of ultrasonic diagnostic equipment. The simplest technique to convert hydrophone output voltage into ultrasonic pressure is to divide the voltage by a hydrophone sensitivity amplitude of center frequency of ultrasound. However, this technique is inaccurate when the instantaneous acoustic pressure of pulsed ultrasound is measured using the hydrophone with large fluctuating frequency response of the sensitivity. Therefore, we have been developing the precise technique for measuring the instantaneous acoustic pressure using the frequency response of amplitude and phase of hydrophone sensitivity (also known as deconvolution technique).■Development of quantitative measurement technique for the amount of generated acoustic cavitation
Acoustic cavitation is widely used for the cleaning such as semiconductors and medical devices, however it can damage the object being cleaned. It is required for measurement and control techniques for the amount of generated acoustic cavitation. Therefore, we have been developing a quantitative measurement technique for the generated acoustic cavitation, using acoustic signal emitted from the cavitation.