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The goal of this research was to improve thermal efficiency under conditions of stoichiometric air-fuel ratio and 91 RON (Research Octane Number) gasoline fuel. Increasing compression ratio and dilution are effective means to increase the thermal efficiency of gasoline engines. Increased compression ratio is associated with issues such as slow combustion, increased cooling loss, and engine knocking. Against these challenges, a higher stroke-bore ratio (S/B ratio) and a lower effective compression ratio were tried as countermeasures. With respect to increased dilution, combustion of a high-EGR (Exhaust Gas Recirculation) was tried. High-energy ignition and optimized combustion chamber shape with high tumble port were tried as countermeasures against slow combustion and reduced ignitability due to a higher EGR rate.

In this paper, the advanced damage analysis of composite materials and structures made of continuous fibers embedded in a polymer matrix is addressed. The solution is based on the LMS Samtech Samcef finite element code, from Siemens PLM Software, which is now available in the Siemens NX CAE environment, with the specific focus of solving non-linear analysis problems for composites. Globally speaking, LMS Samtech Samcef is an implicit non-linear solver able to solve quasi-static and dynamic problems, with a comprehensive library of structural elements and kinematic joints. First, the sizing strategy based on the building block approach (pyramid of physical and virtual tests) is recalled. Applied for years in the aerospace industry, it is here extended to the automotive context. In this approach, the knowledge on the composite material and structure is built step by step from the coupon level up to the final full scale structure.

Using a 1D simulation that transforms the 3D shape of intake-exhaust systems into one dimension and calculates the thermodynamics and fluid gas dynamics of internal combustion engines, a prediction technology of the output power and intake-exhaust noise for small- displacement single-cylinder motorcycles was established. Output power can be calculated accurately for various engines with different displacements and cooling systems by adjusting the boundary conditions in the calculation model. The intake-exhaust noise can be calculated accurately by clarifying some important points for accuracy when transforming the 3D shapes of the intake-exhaust system into the 1D model and by reflecting them in the calculation model. As for mufflers that have complicated internal structures, the calculation of exhaust-noise cannot be made with sufficient accuracy because 1D simulation does not calculate spatial flow behavior. But, improvement of accuracy is expected using a 1D-3D coupled simulation.

This report describes the mechanical properties, formability, weldability, and collision deformation performance of the new 980 MPa-grade steel sheet used in the front side frame of an automobile’s body framework. In order to determine the material properties of the 980 MPa-grade steel sheet needed for use in the front side frame, the study used special bending tests to find the threshold values at which cracking occurred during collision deformation. It was found that these special bending characteristics correspond closely to hole-expansion properties and it is necessary to increase hole-expansion properties of the new 980 MPa-grade steel sheet. The new 980 MPa-grade steel sheet with high hole-expansion properties has an enhanced forming limit curve compared to conventional 980 MPa-grade steel sheet, and can be formed to the shape of the front side frame. In collapse tests simulating collision deformation, the steel sheets demonstrated the necessary performance without cracking.

Pulley thrust control, changes in the trajectory of the belt as it winds around the pulleys, and the amount of friction transmission were focused on in order to reduce transmission loss and increase the transmission efficiency of CVT. In the case of pulley thrust control, making use of the linear relationship between the rotary speed fluctuation transfer characteristic and the torque transmission capacity between the pulleys and the belt, it was possible to reduce the excess safety factor of the torque transmission volume. Due to pulley tilt, the trajectory of the belt displays deviations with the theoretical geometrical winding radius. The structure of the pulleys was modified in order to reduce this deviation and increase transmission efficiency. Optimization of the additives in the CVT fluid increased the coefficient of friction, decreasing pulley thrust and increasing transmission efficiency.

In motorcycle engines with aluminum crankcases, fatigue fractures at the roots of the internal threads of the fastening bolts used for the cylinder head and crankshaft main bearing often occurs during the durability tests at the prototype stage. A technology that evaluates the fatigue strength of the entire crankcase including the roots of internal threads using a large-scale and nonlinear finite element method (FEM) analysis is established by this research. Parallel process computation by a cluster server enables the evaluation of the fatigue strength of the crankcase in a short time suitable for the development process even when using a model that faithfully reproduces the shape, the contact property, and the elasto-plastic material characteristic of the threads. This technology enables the efficient design of crankcases that are light and durable.

The SAE Fuel Cell Vehicle (FCV) Safety Working Group has been addressing FCV safety for over 11 years. In the past couple of years, significant attention has been directed toward a revision to the standard for vehicular hydrogen systems, SAE J2579(1). In addition to streamlining test methodologies for verification of Compressed Hydrogen Storage Systems (CHSSs) as discussed last year,(2) the working group has been considering the effect of vehicle fires, with the major focus on a small or localized fire that could damage the container in the CHSS and allow a burst before the Pressure Relief Device (PRD) can activate and safely vent the compressed hydrogen stored from the container.

The world's first Variable Cylinder Management (VCM) system for large motorcycles, which will achieve both high power and low fuel consumption, has been developed. The system uses a mass production in-line four-cylinder engine which has a displacement of 1137 cm₃ as the base engine. The VCM system is capable of increasing and decreasing the number of working cylinders between 2-cylinder, 3-cylinder and 4-cylinder operations by modifying some parts of the base engine. Utilizing throttle valves installed on each cylinder, the throttle valves for continuously operating the regularly working cylinders and the on-demand working cylinders are controlled by three motors, which divide them into three independent lines. In order to improve fuel consumption by reducing the pumping loss of the non-working cylinders, the engine is equipped with hydraulically operated intake and exhaust valve deactivating mechanisms.

In order to develop large-scale (100 mm in diameter) Mg-Zn-Y alloys with high strength beyond that of 4032-T6 alloy, we considered a novel casting process to produce large ingots with homogeneous microstructure, and investigated the mechanical properties of the extruded alloys. First, ingots (335 mm in diameter and 850 mm in height) were produced by a novel stir casting process in the ingot case. Then large-scale extruded alloys (100 mm in diameter) were prepared with an extrusion ratio of 10. The Mg-Zn-Y alloys exhibited higher yield and fatigue strengths than those of 4032-T6 aluminum alloy. The yield strengths of the aluminum alloy decreased drastically above 473 K, whereas those of the Mg-Zn-Y alloys did not. It is noteworthy that the yield strength (274 MPa) and fatigue strength (100 MPa) of the Mg-Zn-Y alloys at 473 K were about 1.3 and 1.2 times respectively as high as those of aluminum alloys.

As an index to control the heat release of auto-ignition combustion, our previous paper introduced a concept of ΔT. It was the difference between the adiabatic flame temperature and the initial in-cylinder gas temperature before the heat release, i.e., ΔT physically represents the heat capacity of the in-cylinder gases relative to the calorific value supplied in a cycle. Firing tests of a four-stroke auto-ignition gasoline engine revealed that the heat release process could be successfully controlled when ΔT was maintained at a proper level. This paper evolved the ΔT theory into the every possible gas exchanging state in the four-stroke engines and found out a chain of the low-temperature combustion cycle (LTC), which continuously varied from the spark-ignition (SI) to auto-ignition (AI). By using a hydraulic-electromagnetic fully-free valve actuator system, the LTC was examined in our 650 cm₃ single-cylinder experimental-engine.