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This study examined the effects of fuel composition and intake pressure on two-stage high temperature heat release characteristics of a Homogeneous Charge Compression Ignition (HCCI) engine. Light emission and absorption spectroscopic measurement techniques were used to investigate the combustion behavior in detail. Chemical kinetic simulations were also conducted to analyze the reaction mechanisms in detail. Blended fuels of dimethyl ether (DME) and methane were used in the experiments. It was found that the use of such fuel blends together with a suitable intake air flow rate corresponding to the total injected heat value gave rise to two-stage heat release behavior of the hot flame, which had the effect of moderating combustion. The results of the spectroscopic measurements and the chemical kinetic simulations revealed that the main reaction of the first stage of the hot flame heat release was one that produced CO from HCHO.

Fatigue strength of adhesive bonded box beams with longitudinal partition was investigate. From results of the fatigue tests, it was seen that the fatigue strength of bonded beams was higher than that of spot welded beams. Fatigue strength of bonded beams was independent of plate thickness and partition. The flexural rigidity of the box beams in the plane of partition can increase without decrease of torsional rigidity and torsional fatigue strength, if the partition is jointed by adhesive bonding instead of spot welding.

Fatigue strength of steel sheet adhesive joints was investigated. From the results of the fatigue tests, it was obtained that the fatigue strength of the tensile-shear adhesive joints was much higher than that of the T-type tension adhesive joints. Stress distributions on adhesive layer have been analyzed by theoretical analysis method. All of the data obtained by the fatigue tests fell almost on one S/N curve, in spite of the differences of joints type and plate thickness, if the equivalent stress(Mises stress) range of the adhesive layer at the periphery of the end of the jointed part obtained by theoretical analysis was taken as the ordinate of S/N curve.

The stress distribution in each plates and the adhesive layer of weldbonding lap joints under tension was theoretically analyzed by superposition of the solutions of a plane stress problem and a plate bending problem based on the theory of elasticity. Main results were as follows: (1) theoretical results of stress distribution in the plates corresponded well with the experimental results; (2) the stress concentration at the edges of spot welded part of plates was much relieved by weldbonding; and (3) as the adhesive layer softens with heat, the load shearing at the spot welded part increases, and shear stress at the lap ends decreases.