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

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

PO-112 The exploration of constitutively expressed myokines utilizing tissue-engineered skeletal muscle

Objective Recent evidence has identified skeletal muscle as a secretory organ. Many myokines, which are bioactive substances secreted from skeletal muscle, have been identified in plane muscle culture cells. Compared to the plane muscle culture cells, the tissue-engineered muscle is an excellent model as culture system mimicked native skeletal muscle. However, constitutively expressed genes and secreted compounds from tissue-engineered muscle have not been analyzed sufficiently. The purposes of this study were 1) to clarify kinetics of constitutively secreted compounds, and 2) to explore constitutively expressed genes in the tissue-engineered muscle. Methods C2C12 cells embedded within collagen gel solution were placed between two tendons made up of elastase-treated acelluar porcine blood vessel. The constructs were cultured in growth media for 2 days and cultured in differentiation media for 6 days. To compare with plane culture cells, C2C12 cells were cultured in plane under the same condition as the construct. The culture media were obtained, and analyzed by MALDI-TOF Mass Spectrometry. Furthermore, constitutively up-regulated genes in tissue-engineered skeletal muscle were explored based on microarray analysis and confirmed by RT-PCR. Results MALDI-TOF Mass Spectrometry revealed that the number of detected peaks in tissue-engineered muscle was abundant compared to that of plane muscle culture cells, especially at range of low molecular weight. Furthermore, the detected peaks were substantially different among these culture media and specific peaks were identified in tissue-engineered muscle. Based on microarray analysis, the transcription of cholecystokinin identified, and confirmed the up-regulation in tissue-engineered skeletal muscle by RT-PCR. Conclusions These results suggested that the tissue-engineered muscle constitutively secreted many compounds compared to plane culture cells, especially at range of low molecular weight. Furthermore, the transcription of cholecystokinin was up-regulated in tissue-engineered skeletal muscle. Besides of the plane muscle culture cells, it is possible to expect to obtain novel myokines utilizing tissue-engineered muscle

Newly developed wear testing machine having sufficient reproducibility useful for investigating roller chains

Roller chains are commonly used to transmit mechanical power in many kinds of machineries for wide industrial fields. Roller chain manufactures are doing a lot of efforts to improve the wear resistance through conventional real chain type wear testing with huge amount of time and cost. In this study, a new wear testing machine is developed to evaluate wear amounts more efficiently without using main chain components such as inner plate, outer plate and roller. The results show that the nearly same amounts of wear rate and wear status can be obtained between the newly developed wear testing machine and the conventional machine. It may be concluded that the newly developed wear testing has sufficient reproducibility and can be used more conveniently for investing roller chains compared to the conventional wear testing machine

So2 solubility in low molecular weight polyethylene glycoldimethyl ether and correlation using cubic equation of state

The solubility of sulfur dioxide (SO2) was measured in polyethelene glycol dimethyl ether (PEGDME) by use of a static type apparatus in the pressure range from 15.2 to 231.2 kPa at 308.18 K. The stated average molecular weight of PEGDME was Mw = 240 g·mol−1 and the molecular structure of the repeating unit is similar to that of dimethyl ether (DME). The bubble point pressure showed a negative deviation from Raoult law. The behavior was expected from consideration of the vapor–liquid equilibrium data of DME + SO2, reported by Noles and Zollweg (Fluid Phase Equilib 66:275–289, 1991). The ‘bridge-like structure’ will be microscopically formed between the DME unit and SO2, because the two unshared electron pairs of the oxygen atom in DME unit act as an electron donner for some molecules. The Peng–Robinson equation of state was used to correlate the experimental data. Two types of mixing rules were employed. One was a conventional model, and the other was of the excess Gibbs energy type. The latter, Wong–Sandler model combined with Flory–Huggins equation, showed a good reproducibility for the experimental data

Development of a clinically-precise mouse model of rectal cancer.

Currently-used rodent tumor models, including transgenic tumor models, or subcutaneously growing tumors in mice, do not sufficiently represent clinical cancer. We report here development of methods to obtain a highly clinically-accurate rectal cancer model. This model was established by intrarectal transplantation of mouse rectal cancer cells, stably expressing green fluorescent protein (GFP), followed by disrupting the epithelial cell layer of the rectal mucosa by instilling an acetic acid solution. Early-stage tumor was detected in the rectal mucosa by 6 days after transplantation. The tumor then became invasive into the submucosal tissue. The tumor incidence was 100% and mean volume (±SD) was 1232.4 ± 994.7 mm(3) at 4 weeks after transplantation detected by fluorescence imaging. Spontaneous lymph node metastasis and lung metastasis were also found approximately 4 weeks after transplantation in over 90% of mice. This rectal tumor model precisely mimics the natural history of rectal cancer and can be used to study early tumor development, metastasis, and discovery and evaluation of novel therapeutics for this treatment-resistant disease