Nowadays, crankshafts are required to use materials with higher fatigue strength to increase the output and efficiency of marine engines in an attempt to reduce of greenhouse gas emissions. Surface treatment is one of the means to fulfill this requirement. However, instead of giving rise to compressive residual stresses on treated parts, surface treatment causes tensile residual stresses to be produced around boundary positions between treated and non-treated parts. This report presents the distribution of residual stress when induction hardening is performed on a specimen. It also highlights ways to measure X-ray stress using the cosα method that is applicable to crankshafts. Moreover, it shows the axial and torsional fatigue test results of specimens with different sizes of artificial defects using compressive and tensile mean axial stress as a substitute for residual stress. The end of the report introduces the fatigue strength assessment of specimens treated by induction hardening using the Murakami’s equation with a modified coefficient, concluding that the defect in the tensile residual stress region of the specimen could be a starting point of failure.
Closed loop combustion control (CLCC) has established itself in a new generation of large engines such that the capability of using of different fuels, with very high engine efficiency, is now possible. The cylinder pressure sensors required for this application are subjected to high loads from pressure, temperature, and mechanical shock. A simulation led by sensor development approach is indispensable for achieving the best possible trade-off between measurement accuracy and service life. Patented designs such as diaphragm and ceramic feedthrough, paired with PiezoStar® Crystal technology, presented in this paper, form a reliable sensor unit that can satisfy and exceed the market requirements. Additionally, new approaches for transmission of electrical charge have been developed. This has enabled a significant increase in the robustness of signal transmission.
The trend towards higher mean effective pressures (MEP) on large engines means that the sensors must have a higher resilience to these pressure levels. In the testing and validation of service life, a specifically designed endurance test system has been developed for a validation of a service life greater than 109 cycles. The endurance test system enables testing of sensors at an early stage.
Collaboration with engine manufacturers is essential for determining the environmental conditions, which define the requirements and boundary conditions for simulations and testing. Mounting location of the pressure sensor can affect the sensor service life due to environmental factors e.g. temperature and vibration. Collaboration with engine manufacturers allows for creation of robust installations and optimisation of interfaces. Field tests on appropriate target engines are still necessary as the final acceptance test, since the complete engine environment cannot always be fully replicated during the development stages.
Japan is a country prone to many natural disasters. There has been a further demand for Japan to improve the reliability of power supply than before the Great East Japan Earthquake. Given the topography of the country, the authors think that the Earthquake taught us how effective ship-to-shore power supply systems are in improving the reliability. This study is to estimate how much power can be supplied from coastal cargo ships moored at Tokyo Port. For calculation purpose, the authors used ship specification data listed in the annual "Register of Ships" published by the Japan Shipping Exchange, Inc. and port mooring facility specification data on the Tokyo Port Facilities List. The result of the calculation showed that 230 moored ships at the port can provide up to 197,000kW, which accounts for 23% of the total amount of power that can be supplied from 2,314 registered coastal cargo ships in Japan.
Research is widely conducted on air-diluted and EGR-diluted combustion of natural gas that contains no sulfur and less carbon. This study focused on a relationship between the laminar burning speed of methane-diluted mixtures and their heat release rate. In order to analyze the laminar burning speed with high accuracy, we measured the temperature of in-cylinder gas using an infrared absorption method. Using the data obtained, the pressure, temperature, and dilution ratio, we constructed a formula to predict the laminar burning speed with high accuracy. It has been experimentally shown that mixtures with nearly laminar burning speed of equivalence ratio and EGR ratio combination and the same ignition timing have the similar heat release rate.