Fatigue Strength Analysis and Fatigue Damage Evaluation of Roller Chain

This paper deals with the roller chain commonly used for transmission of mechanical power on many kinds of industrial machinery, including conveyors, cars, motorcycles, bicycles, and so forth. It consists of a series of four components called a pin, a bush, a plate, and a roller, which are driven by a sprocket. To clarify the fatigue damage, in this paper, the finite element method (FEM) is applied to those components under three different types of states, that is, the press-fitting state, the static tensile state, and the sprocket-engaging state. By comparing those states, the stress amplitude and the average stress of each component are calculated and plotted on the fatigue limit diagram. The effect of the plastic zone on the fatigue strength is also discussed. The results show that the fatigue crack initiation may start around the middle inner surface of the bush. As am example, the FEM results show that the fatigue crack of the inner plate may start from a certain point at the hole edge. The results agree with the actual fractured position in roller chains used in industry

Constraining temperature at depth of the Kakkonda geothermal field, Japan, using Bayesian rock-physics modelling of resistivity: Implications to the deep hydrothermal system

Temperature-at-depth estimation is important for assessing supercritical geothermal resources. Bayesian rock-physics modelling of electrical resistivity is effective for estimating temperatures at depth. In this study, we improved a previously proposed Bayesian framework and demonstrated its effectiveness by estimating subsurface temperatures in the Kakkonda geothermal field, Japan. The proposed framework allows the estimation of either effective porosities or salinities in addition to temperatures; further, we were able to constrain the possible states of the crustal fluid at depth based on the estimates. The estimated 3D temperature structure was consistent with available deep temperature logs. Furthermore, the estimated results suggest the existence of a magmatic-hydrothermal system at depth in the field

Effects of sex and joint action on voluntary activation

The current study tested the hypothesis that voluntary activation during maximal voluntary contraction (MVC) conditionally depends on sex and joint action. Twenty-eight healthy adults (14 of each sex) performed knee extensor MVC and plantar flexor MVC at extended and flexed knee positions. Voluntary activation during MVC was assessed using a twitch interpolation technique. The voluntary activation during plantar flexor MVC at the extended knee position was significantly lower (P = 0.020, 95% confidence interval 1.4 to 14.6, Cohen’s d for between-subject design = 0.94) in women (88.3% ± 10.0%) than in men (96.2% ± 6.6%). In contrast, no significant sex differences were shown in the voluntary activation during knee extensor MVC (93.7% ± 5.9% (women) vs. 95.0%  ± 3.9% (men)) and during plantar flexor MVC at the flexed knee position (90.4% ± 12.2% (women) vs. 96.8% ± 5.6% (men)). The voluntary activation during knee extensor MVC was significantly higher (P = 0.001, 95% confidence interval 2.1 to 8.8, Cohen’s d for within-subject design = 0.69) than that during plantar flexor MVC at the extended knee position in women, whereas the corresponding difference was not observed in men. The results revealed that the existence of sex difference in the voluntary activation during MVC depends on joint action and joint angle

Growth of Functional FeTi Clusters Covered with Carbon Layer

FeTi clusters with a diameter of less than 10 nm and covered with a graphitic layer have been preferentially produced in an H2 gas atmosphere at pressures of 10 and 26.6 kPa by the simultaneous evaporation of Fe and Ti wires from a concave carbon boat. To compare this result with cluster formation in an inert gas atmosphere, the result for an Ar gas pressure of 10 kPa is also discussed. The formation of disordered FeNi clusters predominately took place in an H2 gas atmosphere

Fatigue strength improvement of roller chain by press fitting between pin and plate

To improve the fatigue strength of the roller chain, the fatigue test is conducted by varying the press-fitting ratio between the pin and the holed plate. To model what occurs in a chain under load, a single plate specimen is prepared by press-fitting two pins into two holes at the ends of the plate. The FEM analysis is performed to obtain the stress amplitude and the average stress. The results, in both cases demonstrate that the fatigue strength is improved by the press-fit between the pin and the hole. The fatigue improvement mechanism is discussed based on the stress analysis