Fatigue Crack Propagation Evaluated by Electric Resistance and Ultrasonics in Copper Film Bonded to Base Metal with Resin

As model specimens of surface film-bonded materials, pure copper films with a thickness of 100μm were bonded to the surface of steel base with epoxy resin, where the tensile residual stress was measured by an X-ray on the surface copper film. The distribution of initial electric resistance was measured on both copper film and base specimen by a direct current potential drop technique. As a result, there was a good agreement between the measured and theoretical values. From the fatigue testing results, it was shown that the measured electric resistance increased with the fatigue crack length on the copper film, which was almost equal to the theoretical value calculated for a central slit in a plate with finite width. This was probably because the fatigue crack was opened due to the tensile residual stress on the film even under unloading condition. In addition, the internal crack length during fatigue was examined by ultrasonic testing for the film-bonded specimen. As a result, there was a difference in the fatigue crack length between the surface copper film and the inner base

Highly Stretchable Stress-Strain Sensor from Elastomer Nanocomposites with Movable Cross-links and Ketjenblack

Practical applications like very thin stress-strain sensors require high strength, stretchability, and conductivity, simultaneously. One of the approaches is improving the toughness of the stress-strain sensing materials. Polymeric materials with movable cross-links in which the polymer chain penetrates the cavity of cyclodextrin (CD) demonstrate enhanced strength and stretchability, simultaneously. We designed two approaches that utilize elastomer nanocomposites with movable cross-links and carbon filler (ketjenblack, KB). One approach is mixing SC (a single movable cross-network material), a linear polymer (poly(ethyl acrylate), PEA), and KB to obtain their composite. The electrical resistance increases proportionally with tensile strain, leading to the application of this composite as a stress- strain sensor. The responses of this material are stable for over 100 loading and unloading cycles. The other approach is a composite made with KB and a movable cross-network elastomer for knitting dissimilar polymers (KP), where movable cross-links connect the CD-modified polystyrene (PSCD) and PEA. The obtained composite acts as a highly sensitive stress-strain sensor that exhibits an exponential increase in resistance with increasing tensile strain due to the polymer dethreading from the CD rings. The designed preparations of highly repeatable or highly responsive stress-strain sensors with good mechanical properties can help broaden their application in electrical devices

Epidemiology of Infectious Hepatitis 1st. Chapter Epidemiologic Observations for Infectious Hepatitis in Akaiwa District (No. 1)

Since August 1951 to Feb. 1953, there was a great epidemic of serious infectious hepatitis over the area including Toyota, Onoda, Kama villages in Akaiwa County, as well as Kumayama village in wake County; observing its state, the following results were obtained. 1. Death toll has amounted to 13, out of 93 patients: its mortality rate, 13.98%; in number of the patients, Kama at the top, next, Toyoda, Onoda and Kumayama village, in literal order. 2. The epidemic took the direction, from the south extending to the north in a slow march, taking a hamlet as unit, showed a lack of specific seasonal occurence. 3. As to age, it has ranged roughly from 10 to 60, amid which 21-30 figured out as top years; below 10, only 4 cases; above 70, 5 cases. As to sex, almost similar in number. 4. As to profession, principally, farming people; as one can suppose from its locality. In making investigations into the cause of disease. certain consideration must be taken on the great responsibility imposed on farmers' wives. 5. The infection for this disease was classified as village infection or familiary infection; among 22 cases (23.4% of total patients) of familary infection, there were 4 families, each yielding even 3 sickened members; 5 families whose two members taken infection; in total, amnunted to 9 families. Among these tribal infection, report has been submitted about 1 family whose infection tract was clearly traced, as well as a family in which, if man did not expose certain inapparent infections, all cases have proved utterly whimsical. 6. The incubation period for this disease may probably be estimated to be about 24-27 days, if it may be supposed from these infectious state, and would be considered perorale infection

Friction stir spot welding of cold-rolled low carbon steel plates using TiC0.5N0.5–Xwt%W (X=70, 72, 75) cermet tool specimens

Friction stir spot welding (FSSW) tests of steel plate cold commercial (SPCC) cold-rolled low-carbon steel plates with a thickness of 1 mm were conducted using TiC0.5N0.5–X wt% W (X = 70, 72, 75) cermet tool specimens with Ti(C, N) core–(Ti, W)(C, N) rim structures and the W–based alloy phase. All of the TiC0.5N0.5–X wt% W cermet tool specimens were prepared by the spark plasma sintering of blended TiC0.5N0.5 and W submicron powders. The SPCC steel plates could be welded more than 2000 times using a TiC0.5N0.5–72 wt% W cermet tool specimen, whereas it has been reported that the steel plates could be welded approximately 1000 times using a commercially available Si3N4 tool specimen. Both the upper and lower steel plates after the 6th, 1006th, 1506th, and 2006th welding using the TiC0.5N0.5–72 wt% W cermet tool specimen were joined together without any voids or cracks. The SPCC steel plate specimens after the 1003rd, 1503rd, and 2003rd welding using the TiC0.5N0.5–72 wt% W tool specimen were considerably bent near the joint during the tensile shear test, indicating that the bonding strengths of the plate specimens were at least as high as the yield stress of the untreated SPCC steel plates