On the assumption that the values of the fatigue limit of machine parts disperse following the law of normal distribution, though the working stress amplitude on those parts is maintained constant, the relation between the allowable stress or the factor of safety of a machine part, subjected to a repeated stress, and the probability of failure of the machine part was investigated. In order to clarify the relation, the data of the fatigue limit of notched specimens of any size collected by a committee in the Japan Society of Mechanical Engineers were utilized. Formulas to get the arithmetic mean of fatigue limit of machine parts were derived. The standard deviations and the coefficients of variance of fatigue limit of machine parts were also calculated. As the results, the factor of safety for any probability of failure was obtained just from the tensile strength of the material and the dimensions of the machine part.

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Free vibration of impellers of rotating hydromachines is analyzed by both the finite element method and experiment. An isoparametric, thick shell element is used in the analysis, which allows arbitrary changes in the shape, the thickness and the curvature. The eigenvalue problem is solved with the subspace iteration method. In the experiment, impellers are excited by the piezo element, and vibration is picked up by the piezo element and the displacement meter of the non-contact type. The holographic technique with the Ne-He gas laser beam is adopted in order to observe the natural modes. The calculated values of the frequency and the natural mode are in good agreement with the experimental ones.

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This paper deals with experimental and theoretical analyses of the excitation mechanism of vibrations induced by an air-and-water two-phase flow in a straight horizontal pipe. The experiment reveals a strong relationship between the first natural frequency of a piping system and the dominant frequency of void-signals -- that is, the frequency ratio being 1/2, 1/1, 3/2, -- when extraordinarily strong vibrations are observed. The equation of motion in a straight horizontal pipe conveying a two-phase fluid is derived by accounting for 1) inertia force, 2) the pipe's elastic restoring force, 3) Coriolis' force, 4) centrifugal force, 5) pressure fluctuations, 6) momentum change due to time-varying density of the two-phase flow and 7) gravity as an external force. The equation is transformed into a Mathieu's with a periodic external term ; instability analysis concludes that parametric excitation and resonance are the main causes of such strong vibrations. Good agreement can be seen between experimental and theoretical results.

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This paper discusses the problem of designing an observer to estimate a vector-valued (multi-) linear function of the state of a linear time-invariant system, for the purpose of implementing a feedback control law. First, the standard form of an observer is obtained by using the Luenberger observable canonical form. Second, the design procedure of a multi-linear functional observer is derived using this standard form. Observers derived using this procedure are generally o flower order than those of Luenberger. Lastly, the procedure presented is illustrated by an example.

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This paper presents a systematic analysis of static and dynamic characteristics of plate heat exchangers having a number of heat transfer plates. There are various flow types in a plate heat exchanger system. The results are numerically compared under the condition that each flow rate of the hot- and cold-side fluids remains constant, respectively in any flow type. The significant results are : 1) In almost every flow type, the temperature effectiveness increases as the number of passages increases. 2) Dynamic responses may greatly depend on the relation between the inlet and outlet passages where each fluid flows in a counter- or a parallel current. 3) Series flow types where the inlet and outlet passage are adjacent and the flow is a countercurrent have the best statics and dynamics among all types when the number of passages is the same.

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An analysis is made of a pulsating laminar liquid flow in a pipe of circular cross-section with through flow. In this case, M, the ratio of the representative velocity of through flow to sound speed is much smaller than unity, so a regular perturbation method with M is available. When the flow of the order to M¹ is considered, owing to the through flow the eigenvalue and the velocity distribution of out-going wave differ from those of in-coming one.

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It is a well known fact that the heat transfer from each part of the engine influences the volumetric efficiency. There have been already shown many papers treating the problems of the heat transfer at the compression and expansion strokes, but few works regarding this problem have been made at the intake process. In this paper, the averaged formulas of heat transfer coefficient at the intake process are obtained with reference to the past studies at the compression and expansion stroke, and the prediction method of the volumetric efficiency including the heat transfer effect is shown. Good agreement between the predictions and experiments on the intake charge show that this prediction method is appropriate to obtain the volumetric efficiency with heat transfer effect.

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Exhaust gas recirculation (EGR) is one of the most available reduction methods of NO concentration in the exhuast gas, and there are generally two ways in EGR: one is external EGR and the other is internal EGR that is mainly controled by the valve timing. In this paper, it is shown that the burned gas amount in the intake air charge, that is the amount internal EGR, depending upon the valve timing, throttle degree, mainfold volume, number of cylinder, and engine speed, can be predicted by the method of predicting the volumetric efficiency already written in the previous paper, 1st report. This method is examined to compare the predicted values with the experimental ones using CO₂ as the tracer gas and confirmed for good agreement of their tendencies. Moreover, the general effects of the valve timing on the internal EGR are shown by this prediction method.

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Up to this day, known piston crank mechanisms used in various reciprocating internal combustion engines are inevitably accompanied with vibration, as the forces and moment caused by the inertia of the reciprocating mass are not balanced. Perfectly balanced rotation-reciprocation mechanisms can obviate or mitigate such disadvantages. This report relates to a gasoline engine utilizing an eccentric geared device of crank-shaft rotary motion system as the mechanism of motive power. Theories and experiments of this engine are described: that is - vibration tests, various performance test of this engine which is designed by the authors and manufactured on trial, are carried out. Moreover results of their numerical computations on the equivalent moment of inertia and load on each portion are shown. As a result, it is proved that the inertia force and moment are perfectly balanced in this engine and that their vibrations are very small in comparison with those of the conventional reciprocating engines. However, it is important to study on the improvement of the performances of this engine hereafter.

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The purpose of this paper is to investigate the influence of forced vibrations on the geometrical accuracy of ground surface. The methods to calculate the grinding stiffness, the contact stiffness and the effect of geometrical interference between grinding wheel and workpiece which are important factors in grinding are shown and discussed. Considering these factors a model of grinding process is proposed to analyse the vibration problem. A summary of the results is : (1) A sufficiently low table speed in surface grinding and a suitable speed of workpiece rotation in cylindrical plunge grinding improve the geometrical accuracy of ground surface. (2) It was found in cylindrical plunge grinding that the forced vibration, whose frequency is within a resonant region of the system, is considerably amplified and it becomes difficult to differentiate forced and self-excited vibrations. A new experiments were performed to verify the theoretical results.

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Deep drawability of clad sheet metals is investigated experimentally by using the model clad sheets in which a commercially pure hard aluminium sheet, annealed one and a brass sheet are stuck to each other by a binding agent. Based on the interaction of each composing sheet during deformation, the conditions of the optimum combination of composing sheets are summarized. In the cases of flat-headed punch the optimum conditions are that in a single-clad sheet a soft sheet is positioned at the outside of a hard one during working and these composing sheets have remarkably different values of the work-hardening exponent n and almost equal strength ratio. In the cases of round-headed punch the combinations which do not lower n are desirable and side positions of the sheet are indifferent.

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In order to collect the fundamental data about the press-forming under half-melting of Al-4.5%Cu alloys and Al-4%Cu alloys containing Mg, investigation has been made on influence of pressure, billet temperature and die temperature on the mechanical properties of the products. The results are as follows. The tensile strength and the tensile elongation of the products pressed under 1030 kg/cm² are remarkably large as compared with those under no pressure. This might be explained by the decrease of intermetallic compound Al₂Cu and the yield of a sub-boundary. As to billet temperature, the tensile strength and the tensile elongation become the highest at midpoint between the liquidus line and the solidus line. It may be caused by a dendritic structure remaining in the product when the temperature is lower than the middle temperature, and by a precipitation of granular Al₂Cu and the decrease of copper solubility in the center of the grain when the temperature is higher.

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