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Vol. 10, No. 2 (1954)

1954-01-20
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CONTENT
ON THE PROBLEM OF AXIAL-SYMMETRIC PLASTIC DEFORMATION
LIN HUNG-SUN
1954, 24 (2): 89-104. doi: 10.7498/aps.10.89
Abstract +
In the usual treatment of plane deformation problems in plasticity, the assumption of static determinacy is frequently made, with the advantage of obtaining stress distributions without reference to stress-strain relations. In the present paper, we consider the problem of axial-symmetric deformation, where this advantage is no longer existing. The material is assumed to be incompressible and entirely in a plastic state. The equations of equilibrium are
ON THE SNAPPING OF A THIN SPHERICAL CAP
HU HAI-CHANG
1954, 24 (2): 105-136. doi: 10.7498/aps.10.105
Abstract +
In this paper, the snapping of a thin spherical cap under edge moment is considered. The snapping of the same cap under line load distributed along a circle as shown in Fig. 1 has been disscussed by Chien Wei-zang in two unpublished papers. His results are briefly summarized in this paper.
COMPOSITE BEAMS JOINTED BY BOLTS
KU CHIU-LIN
1954, 24 (2): 137-152. doi: 10.7498/aps.10.137
Abstract +
In this paper, it is proved that the problem of composite beams jointed by bolts can be solved in terms of certain equivalent continuous beams. The equivalent beam is specified as follows: 1) It consists of supports of the original beam and equivalent supports situated at the points where bolts are used. 2) It is loaded by the given load on the original beam.Then the reactions at the bolts in the original composite beam are equal to a constant C times the reactions at various supports of the equivalent continuous beam. The constant is equal to C=(E′J′-k(EJ+E′J′))/(EJ+E′J′), where EJ and E′J′ are flexaral rigidities of the first and second parts of the composite beam respectively, and k is the distributing ratio of load on the second part.The solution of the problem is then greatly simplified.This method can be generalized for composite beams consisting of more than two parts, on which the given load is not proportionately distributed.
INTERNAL FRICTION PEAK ASSOCIATED WITH THE PRESENCE OF HYDROGEN IN STEEL
KE TING-SUI, YUNG PAO-TSUI
1954, 24 (2): 153-170. doi: 10.7498/aps.10.153
Abstract +
Hair-line cracks or flakes in steel are known to be associated with the presence of hydrogen. A prevailing theory states that the crack formation is due to disruptive hydrogen pressure being built up in defects in steel. However, little was known regarding to the nature of these defects and the detailed mechanism of the hair-line crack formation. An attempt was made in the present research to investigate this problem by means of internal friction measurements. The preliminary experiments show: (1) The presence of hydrogen in certain steels may give rise to the appearance of an internal friction peak when internal friction is plotted against the temperature of measurement; (2) a slight amount of cold-work or soaking at a given temperature has a considerable effect on the optimum temperature of the observed internal friction peak, which indicates that the internal friction peak may be connected with the defects or stress condition in steel; (3) the internal friction peak shows an anomalous amplitude effect, i.e., at a given temperature of measurement an internal friction peak is obtained when the internal friction is plotted against the stress amplitude. Such an anomalous behavior is similar to that previously observed by. one of the authors (Ke) in the case of aluminimum containing 0.5% Cu. It is therefore considered that the internal friction peaks observed may be related to the interaction of hydrogen with the dislocations in steel.