The explanation of rheological properties of paper and pulp sheets in terms of their structure has hitherto been considered to be very difficult, seeing that they are composed of a lot of macroscopic elements or fibers, though it seems rather easier than those of other materials composed of microscopic elements or molecules. Therefore, rheological studies in this field have not been very actively made in spite of practical importance of these materials. In this article, the rheological studies by the author, especially those on non-destructive elastic and viscoelastic properties, have been reviewed along with the related studies by other investigators. There are two distinct lines in the theories relating the rheological and other physical properties of paper to its structure. Nissan's works are typical of the first of the two. He assumes that the strain of paper under stress is derived from the extension of hydrogen bonds. The author and several others, assuming that paper consists of randomly arranged three-dimensional array of fibers, have put forward theories for elastic and other properties, assuming also that the deformation of paper arises from the bending, stretching and shearing of the fiber segments between the bond sites. The latter theories can presuppose many important facts, some of which have been known experimentally or empirically, though imperfectly yet. Paper is a typically orthotropic material, and its Young's modulus and tensile strength in an arbitrary direction are well represented by the Horio-Onogi equations (8) and (9), which describe a peculiar elastic property of paper, as was pointed out by Campbell and Craver and Tayler. The correlation between the density and modulus of elasticity, the effects of humidity and several manufacturing variables such as beating, wet press, screening and drying on rheological properties of papers and pulp sheets are also discussed. The viscoelastic data reported by the author reveal that paper has essentially the same viscoelastic properties as cellulosic fibers such as viscose and Bemberg rayons if, and only if, they are corrected for the density. This indicates that the junctions between the constituent fibers are very strong and similar to those between the cellulose molecules as was assumed in the above theories, while the macroscopic structural factor should also be taken into account.
The Rockwell superficial hardness tester is generally used to measure the hardness of thin metal sheets. The measurement of such metal sheets as those which have comparatively low hardness (HV<200) is practiced with ball indenter and spot anvil as a rule. In this case, as the plastically deformed region would often reach the reverse surface of the specimen, the peculiar phenomenon well known as anvil effect lowers the reliability of hardness values. It is expected, moreover, that the difference of roughness of either the anvil surface or the reverse surface of the specimen will affect the hardness values. In our study, we investigated experimentally how the roughnesses of either the anvil surface or the reverse surface of the specimen would affect the Rockwell superficial hardness readings of thin metal sheets. From these results, we have found an empirical formula which defines the interrelationships of variations in hardness, in the roughness of the surface, in the thickness of the specimen and in the depth of indentation, in order to obtain reliable hardness value. By using this formula, we shall be enabled to devise rational methods for preparing specimens and measuring their hardness.
A report is presented in this paper of the investigation made of the behavior of carbon steel (S10C, S20C, S30C and S40C) in plastic range by ultrasonic attenuation. The relation of attenuation to plastic deformation and annealing temperatures was observed. The interpretation of the results is based on the assumption that the change in attenuation is caused by the motion of the movable dislocation line, that the internal stress is related to the changes in the magnetomechanical losses, and that these are associated with the micro-eddy current induced by the vibration of the magnetic domain walls. The conclusions reached from the results are as follows: (1) The internal stress reaches its maximum at 3∼4% plastic deformation. (2) In strain aging, the dislocation is perfectly stabilized by annealing nearly at 300°C. (3) It seems that plastically deformed materials are perfectly recovered by annealing nearly at 600°C.
In this paper, an experimental stress analysis is reported on flat plates with rivet holes of zigzag arrangement. The birefringent coating method was used in combination with the electrical analogy method to measure the principal strain ε3 normal to the plate surface. The material used was heat-treated 13% Cr steel with thickness of 3mm, and epoxy resin plate of 2mm thickness was pasted on one surface of the specimen. Nine specimens were tested, the pitch of the rivet hole p and the distance from the hole center to the plate edge e being changed in three ways, respectively. The tensile loads of seven steps were applied to all these specimens, and the isochromatic fringe orders were measured at the boundaries and in the vicinities of circular holes as well as along the main cross sections. For the stress analysis in the plastic range, the Mises' yield criterion and the Prandtl-Reu β incremental strain law were adopted. The principal strain increment dε3 measured from the electrical analogy method combined with the fringe order increment dN obtained photoelastically allows the separation of each principal strain increment (dε1 and dε2), and in consequence, the principal stress increments dσ1 and dσ2 may be calculated. The principal stress σ2 acting in the minimum cross section through the hole was much smaller than the principal stress σ1. The variation of stress concentration factors at the circumference of each hole due to the increase in applied load was examined, and the evolution of plastic ranges in each load step was also investigated. Through this experiment, the spread of plastic regions was fastest in the diagonal direction between the zigzagwise located holes.
Spiral steel wires wound over adequate length near the end or the butted part of the members will produce gripping force, especially when they are under tension. The joint of the members where the spiral wire is thus applied is called“wire grip”. This has been used gradually for joining wire ropes or steel bars, but the transmission mechanism of its stress and gripping force has not been mechanically made clear. In this report the theoretical analysis is made of how the tension acting on the member is transmitted to the wire grip under consideration of the contact pressure and the friction force between the members and the wire. The following results have been obtained by comparing its theoretical studies and experimental investigations. (1) Under tension the wire grip is distributed among the three regions which show different mechanical behaviors. The theoretical results coincide with the experimental results on mechanical properties in each region. Hence this analytical method seems to be valid for resolving the transmission mechanism of the stress in the wire grip. (2) The resistance load of the grip PS for the sliding on the surface of the member depends sensitively on the coefficient of friction μ. In this experiment μ is 0.27 and generally it is considered to be μ=0.2∼0.3. (3) The resistance load of the grip PS increases rapidly with the larger length of the grip and beyond a certain length the member is broken before the sliding of grip on the surface of the member. The minimum requisite length of the grip LS, in case which PS equals to the breaking load of the member, can be theoretically calculated. (4) The resistance load of the grip PS becomes larger with the increase of the initial gripping rate φ. (5) The optimum wire grip can be designed by this analytical method in connection with the pitch angle of spiral wire β, the diameter of wire d and the length of the grip L.
In this paper the characteristics of the moving friction of a plate on dry soil are investigated; the differences of the moving friction of steel and rubber plates on sandy soil mixed with gravel, and on silty soil respectively, are found out in several confining conditions of the soil particles, and the antifrictional effects with a vibrating plate are exemplified. When a plate is tracted on dry soil, the void ratio of the soil under the plate approaches the critical void ratio, independently of the initial degree of compaction. In this case the confining soil particles drop to the minimum of degree. But when the soil particles are confined in a sample box used in this friction test, the confining soil particles increase in degree generally with decrease in the thickness of soil samples, and when they are confined in the densest state, the rotation of soil particles are inhibited, and the moving frictional resistance does not decrease by the rolling friction. In this case, the confining soil particles reach their maximum degree. When a vibrated plate is tracted on dry soil, the rolling friction of soil samples decreases remarkably by the kinetic energy given by the plate to each soil particle, even if the void ratio is constant. In this case, the moving frictional resistance decreases, and especially there is considerable decrease of optimum frequency. For these phenomena it is assumed that the degree of confining of the soil particles is represented by the void ratio, and that the coefficient of the mutual rolling friction between the soil particles is proportional to the number of contact points with the adjacent soil particles and so is variable with the kinetic energy of the vibrated soil particles. It may therefore be theoretically concluded that the coefficient of the moving friction is expressed by the function of the void ratio.
Water soluble phenolic resin and oil soluble xylenic resin were used as the surface treatment agent for wood (Beech, The shape of wood blocks will be rectangular parallelopiped being planed smoothly with two quater-swan surfaces. size: 10×25×90mm). The wood Specimen treated with the agent decreased in dimensional change less than control wood samples, when immersed in water and then dried. Pretreatment of the surface of the metal was as follows: aluminum plates were immersed in hot solution which consists of conc. H2SO4, sodium dichromate and water in 10min. at 70-75°C, linsed with running water at room temperature for 24hrs. and then dried in the oven. The steel plates were also immersed in 10% HCI solution at room temperature for 24hrs., ground with sand paper and then linsed with acetone. The size of the metal plates was 0.6×25×90mm, respectively. The surface of the control wood (no treatment) and treated wood with synthetic resin was bonded with aluminum or steel plates using neoprene system adhesive. In the normal condition, the mean adhesive strength of the control sample (the combination of untreated wood and aluminum plate) was shown as greater than that of others, and some of aluminum plates were broken by tensile load in the operation. In decreasing order was the combination of the control wood and steel plate, the treated wood and aluminum plate and the treated wood and steel plate. After about a half of them was immersed in water, their adhesive strength was measured in wet condition. The wood and metal plate treated with phenolic resin was shown as stronger than that of control samples. This shows that the surface treated wood fixed with metal plate has the improving quality to prevent water aggression within the outer and inner surface of wood. The phenolic resin content penetrated in wood was assumed about 2 times compared with that of outer layer of the wood specimen from the result of the colorimetry measurement using iodine as an indicator by Ukena colorimeter and Beckmann photo-electric colorimeter and the tracer method using I131 and scintillation counter. Its distribution showed high concentration in the cross section and its adjacent part and low concentration in the middle section and its adjacent part of the wood specimen.