The fatigue limit of force-fitted specimens can be raised by induction hardening.
In order to investigate the season of this improvement, the authors carried out the fatigue test on specimens, of which the shafts were respectively as induction hardened; tempered at 40°C, or at 600°C after induction hardening; as electric furnace quenched; tempred at 600°C after electric furuace quenching or normalized; and the hardness of bosses was varied H_s 26.40 or 60.
The results show that:
i) The fatigue limit of force-fitted specimens scarcely influeuces the hardness, after different heat treatments of shafts.
ii) The residual compressive stresses and micro-structure of these shafts are more effective in improving their fatigue limits than the difference of hardness between the shaft and the boss.
iii) The fatigue limit of force-fitted specimens must be improved by induction hardening for same reason as the case of notched specimens.

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The authors had carried out the static and the fatigue tests of high grade cast iron pipe materials to study the causes of the accidents of water supply and distribution pipes of high grade cast iron, to find out remedies for them, and to get some data for fatigue design of pipes. The test pieces used were taken out from the actual pipe bodies of three kinds in axial direction, that is from the pieces of the ruptured pipe and the unused ones manufactured in 1935 and 1954 respectively. The tests performed were divided into the following two groups:
(I) Concerning with the unused pipes manufactured in 1935 and 1954, the static tests and the fatigue ones under the pulsating stress +1kg/mm²∼σ_max were carried out with the test pieces taken from the pipe body near the socket, the middle and the spigot part.
(II) Concerning with the unused pipes manuactured in 1935 and 1954, and with the ruptured pipe, the static tests and the fatigue ones under the repeating stresses taken as +1kg/mm²∼+ σ_max, +6kg/mm²∼+σ_max and-σ_max∼+σ_max were carried out with test pieces taken from the pipe body near the socket.
Main results obtained are summarized as follows:
(1) The fatigue strength σ_2000000 of the test pieces taken out from the socket were higher about 11.5∼38.5% than that of the one from the spigot.
(2) Comparing with the others, the strengths of the ruptured pipe specimens used in these experimental researches showed a little falling. But, we can not suppose that the ruptured accident may occurs due to such falling.
(3) Static strength of ruptured pipe showed 84.2% of that of unused pipe manufactured in the same year, and, the pulsating fatigue strength at n=2×10⁶ showed 83.3%.
(4) According to the classification of ASTM, all sereies belong to type A of graphite flake type chart, while the ruptured pipe and the unused one manufactured in 1935 belong to size 4 and the pipe in 1954 belong to size 5 of graphite flake size chart, respectively.
(5) The graphite flake size of the ruptured pipe was too coarse in comparison with the other pipes to emphasize the notch effect. This fact seems to behave as a cause of the lower fatigue resistance of the ruptured pipe.
(6) The authors obtained the time strength diagram for fatigue design of high grade cast iron pipes to be used for water works.

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The parallel-shaft type of adjustable cone pulley consists of two parallel shafts on which are mounted a pair of adjustable cone pulleys, with a belt as the connecting medium. Provision is made for adjusting the spacing between the faces of the cones by a movement of one or both halves of the pulley in such a manner that, when the spacing of the pulley opening on one shaft is being increased, the spacing of the pulley opening on the opposite shaft is being decresed. Thus when the effective diameter of the pulley on the first shaft is being decreased, that of the opposing pulley is increased, and the length of belt necessary to encompass the two pulleys is substantially the same. In this sort of variable speed control mechanism, acccording to the speed changing ratio, the tension of the belt and the contact condition between the belt and the pulleys change very little and we can not get a constant transmissive torque regardless of the changing speed ratio. However if we maintain a constant tension in the belt and a constant condition of contact between the belt and the pulley regardless of the changing speed ratio, a constant transmissive torque is produced. As a means of maintaining these condition, one possible idea would be to turn the cone faces of the pulley into certain special surfaces of revolution. This paper deals with this subject theoretically.

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The high grade cast iron has generally been used in the structure which needs the strength according to the improvement of the cast iron, which was used comparatively widely for the high tension cast iron and in the easy manufacturing process, has been studied considerably well as to the mechanical and the physical property and so on. But it seems that the data on the fatigue strength of the high tension cast iron is not yet searched fully enough and that cast iron seems to have been used increasingly under repeated stress. So, we make experiments of the fatigue test under repeated torsion for the pearlite cast iron, and propose in this paper some considerations on the endurance limit.
Generally, the fatigue test is pursued under the basis of the stress like the experiment under a constant torsional moment, and it seems that this method is suitable to ascertain the strength of material as it is clear the weak material tends to be abused. But in fact there are many occasions on which the oscillation is under a constant torsional angle, and in this case the endurance limit does not always agree with the limit found by measuring it under a constant torsional moment and it some cases a weak material has a good endurance limit than a strong one. So the fatigue test based upon the torsional angle has some significance. We pursue the experiment with above mentioned point of view.
The Shenk type repeated torsion and bending tester is used. The results are summarized as foolows:
(1) The endurance limit under completely reversed torsion is about 15' as for the shearing angle and about 11kg/mm² as for the torsional stress.
(2) There is a close connection between the endurance limit curve and the damping capacity curve in the pearlite cast iron, and the endurance limit may be discussed by measuring the damping capacity.
(3) And it seems that the endurance limit is intimately associated with the magnetic hysteresis loss.

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The term“Fatigue Damage”is very ambiguous and has been used as different meanings. In some cases, fatigue damage is represented by the degree of changes in physical or mechanical properties of materials due to stress reversals, such as changes of shock resistance, damping cofficient, and others. But the author believe teat these changes do not represent the true fatigue damage, because they do not always mean the decrease of fatigue life of materials. On the contrary, in some cases, they mean even the incresse of it. In such cases, these changes are training rather than damage.
In some cases, fatigue damage has been represented with the decrease of the endurance limit of materials. But the author cannot agree with this representation, because it seems to contain the following unreasonableness. The term “Fatigue Damage” is used when we consider the fatigue life of materials at the stress levels over the endurance limit. If we attempt to keep working stresses always less than endurance limit, the conception of fatigue damage is needless, because fatigue failure does not occure at the stress levels below endurance limit. Fatigue damage is the matter concerning with fatigue life and not with endurance limit. So fatigue damage should not be represented with the decrease of endurance limit.
Then the author believe that it is most reasonable to represent fatigue damage as the rate of diminution of fatigue life in future. This representation has been already adopted by many researchers. (Refer to the Notes (2), (3) at the end of the paper.) If we adopt the representation, fatigue damage cannot be decided only by the stress history in past, but must be influenced by the stress which will be applied in future. It is self-evident that the life in future depends on the stress in future. This is the so-called future effect on fatigue damage.
In this paper the future effect on fatigue damage was obtained by experiments in some cases.

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In this paper, the results of determination of the air content in fresh concrete by AE-55 indicator are described.
First of all, laboratory tests of the accuracy of this apparatus were made. The air contents of large number of concrete mixtures prepared in our laboratory were determined by using this indicator, and the results were compared with those obtained by the gravimetric and pressure methods, JIS method A 1116-1952 and A 1117-1952, respectively. Moreover, tests were made on 143 mixed concretes, in order to determine the accuracy and usability of this apparatus in the field.
These results are summarized as follows:
1) Each value of air content determined by AE-55 indicator method was 2.1% higher than that determined by the pressure method. This difference can be corrected with the contrrction of total volume occring in the mixing of alcohol and water contained in mortar.
2) Each value reported for the AE-55 indicator method is an average of two tests always made by two operators, whose values generally agreed within 0.5% of air content.
3) In the field's test, the total average of air content determined by the AE-55 indicator methad agreed within 0.3% of error.

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Experimental studies on the neutralization of concrete specimens and the rusting of reinforcement embeded have been conducted throught 20 years.
Kinds of cement used in this test were normal portland cement, blust furnace slag cement and portland pozzolan cement. The proportions of concrete of each kind of cements were as follows:
Proportion Slump(cm) W/C(%) Compacted by
1:2:4 {0 41-42 vibration
5 50-51 rodding
20 61-63 _??_
1:3:6 {0 48-50 vibration
5 68-69 rodding
20 89-90 _??_
Standard specimens of φ15cm×30cm with φ16mm steel bars, embedded were made in July, 1937, cured in moisture for 28 days, and then stored outdoors until the tests were mrde.
The neutralization depth was measured by the use of phenol-phtalene alcohol solution on the splitted section of each specimen at the ages of 6 month, 1, 3, 5, 10 and 20 years, and at the same time, the rusting conditions of embedded steel bars were observed.
The results of tests are summarized as follows:
1) When concrete has not defects and the water cement ratio is smaller than 70%, the neutralization depth is less than 10mm and the neutralization scarcely pregresses further after it has advanced to certain depth. There results are same irrespective of kinds of cement.
But, if concrete has some defects such as air voids, cracks and water film under aggregates, the neutralization develops mostly through the defects. Particularly when the water cement ratio is larger than 70%, for instance 89%, the neutralization progresses gradnally as the develops with age increases, and the neutralziation depth reaches 3-5 times as deep as that found in the concrete of smaller water cement ratio. In this case, the degree of neutralization varies depending upon the kind of cement; that is to say, concrete made with blended cement is neutralized much faster than concrete with portland cement.
2) It is considered that the rusting of reinforcing steel occurs not by neutralization of concrete. Almost of the rusting of embedded steel bar develops due to the defects of the concrete, and movement of air or water through the defects.

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In order to investigate the influence of calcium chloride on portland and portland blastfurnace cement, the author tested the various properties of the paste, mortar and concrete made with normal portland cement, portland blastfurnace cement and other pozzolanic cements, with the addition of the various amount of calcium chloride (CaCl₂·2H₂O).
The results are summarized as follows:
1. Portland and portland blastfurnace cement, containing insufficient amount of gypsum, which showed flash set or abnormal slow set show the nearly normal set, by the addition of the suitable amount of calcium chloride.
2. By the addition of calcium chloride in amount of 1-3 percent by weight of cement, the mortar and concrete made with portland blastfurnace cement, show higher strength at early ages than those of normal portland cement without this salt, and yet thereafter show similar strength at later ages to the portland blastfurnace cement without this salt.
3. By the addition of calcium chloride, portland blastfurnace cement shows the beneficial property in promoting early higher strength than other pozzolanic cements.
4. Portland blastfurnace cement requirer larger amount of calcium chloride for the occurence of flash set than normal portland cement.
5. The addition of calcium chloride increases progressively an entrained air content in mortar and concrete, mortar flow and concrete slump.
6. The premature stiffened paste, mortar and concrete, made with aerated fake setting cement, resume its plasticity slightly, by the addition of the suitable amount of calcium chloride.

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