A strain distribution of a carbon fiber reinforced plastics (CFRP) laminate plate due to a light load is measured by electronic speckle pattern interferometry (ESPI) for evaluating the stiffness degradation of the CFRP plate. The stiffness of the CFRP plate is decreased by applying the load of 62.5 % for the fracture load using a three-point bending test. Strain distributions due to the load less than 12.5 % for the fracture load using the same bending test are measured by ESPI before and after the damage. Strain distributions less than 2.5 × 10-4 are obtained and indicate strain increasing after the damage. The strain increasing ratio due to the stiffness loss is larger than the stiffness loss ratio obtained from the relationship between the load and the displacement. Additionally, the distribution of strain increasing ratio is evaluated and shows the variation less than 10 % immune to the surface structure of the laminate. Therefore, the evaluation of the stiffness degradation of the CFRP laminate by ESPI is effective, and can realize a non-destructive evaluation.
In order to identify the parameter of AE signal produced by pencil lead breaking with different product, relationship between mechanical property of mechanical pencil lead and AE source parameter was investigated. Dispersion of bending strength of pencil lead was first studied. Bending strength tended to increase with increasing hardness of lead. However, there was dispersion in the value of bending strength in comparison of the same hardness of leads with different products. AE parameters were next measured and identified the relationship between bending strength and AE parameter. There were no relationship between bending strength and rise time of AE sources. Rise time tended to be faster and released force was lower than the value that was conventionally used for AE analysis. Artificial AE signals were next compared by using the lead with different AE source parameters. Maximum amplitude and peak frequency was different by using different pencil lead.
In this study, the fracture processes of carbon fiber reinforced thermoplastic polyimide (CFRPI) were investigated by using Acoustic Emission (AE) method during tensile tests. In the case of unidirectional composites, fracture processes of carbon fiber reinforced thermosetting epoxy (CFREP) and CFRPI were compared to understand the difference of the fracture processes between these composites. The frequency properties of AE waves that were detected during tests were correlated to the fracture types. In the case of cross-ply composites, the fracture processes of [0/90]6s and [90/0]6s were investigated with the distinguish the type of fracture by frequency responses.
In our country which is an aging society, hundreds of thousands of a year become the gonarthrosis. It is thought that the causes are senescence, daily living environment, and walking habit. Early treatment or preventive treatment against gonarthrosis is beneficial. Therefore we suggested a simple evaluation method with a quantity of burden impulse of the knee by stabilometers and (3D) acceleration sensors. Subjects wore the (3D) acceleration sensors on their lateral condyle of both tibiae, and "one-step-walk," the stepping on a loading device, was measured. Burden impulses of both knees were analyzed by mass, times, and acceleration, and the difference of impulse between the knees were regarded as a parameter for evaluating the state of the knee. As a result of experiment, it recognized 5.4% difference between the knees.
Multichannel heart motion sensors using flexible circuits were fabricated for the monitoring the heart motion in the heart diseases. In this study, the PVDF sensors were used as the heart motion sensors. These sensors were modified with the air gap and the protection sheet, and the sensors with the flattest frequency response were selected. These selected modified sensors were preliminary used in a 4-channel sensor array in order to check whether the heart sounds were detected, and they precisely detected the motion of S1 and S2. Furthermore, 80 sensors were used for the multichannel sensor array using the flexible printed circuits. By using this 80-channel sensors array, the vibrations of the chest surface were measured and analyzed. As a result, this multichannel sensor array could measure the heart sound and detected a sound distribution of the chest surface. It was concluded that our developed measurement system could be applied to inspect heart diseases employing a digital database management of the auscultation examination.
A new technique for imaging heart motion to assist in the understanding of heart diseases for both clinical doctors and patients has been developed. The technique is based on the measurement of micro-vibration of the chest surface using 63 sensors as a multiple-auscultator to show global and simultaneous heart motion. The results showed clear and simultaneous image of heart motion; contraction/expansion of atrioventricular and ventricle, and they showed also location of four values. It was also found that heart vibration has four frequency bands including one band that is inaudible sound using auscultation. Using these distinctive frequency bands, the Wavelet analysis was carried out to obtain the group velocity of heat sounds. The location of the tricuspid valve was detected by using group velocity and the location of sensors. It is concluded that the technique could be applied to inspect heart disease in visual and the digital database management of the auscultation examination.
Rheological behavior of interstitial fluid in epidermal tissue, including blood micro-circulation, can vary skin mechanics in micro scale, i.e. visco-elasticity. Therefore, an in vivo quantitative measurement of fluid velocity is necessary to clarify their properties. In this paper, we constructed OCDV (Optical Coherence Doppler Velocigraphy), which is a method of tomographic micro-visualizing interstitial fluid velocity using a high frequency modulated low coherence interferometer. The tomographic detection of modulated Doppler frequency can determine fluid velocity profile within tissue. An optimal signal processing of OCDV was evaluated alternately on short time FFT and Hilbert transform, and validated by measuring the fluid velocity of Intralipid solution (2%) in micro channel. Consequently, Hilbert transform has further advantages in the accuracy even with a rapid scanning system than short time FFT. OCDV was suggested to be effective to diagnose flow velocity profiles in tissue non-invasively and tomographically.