The Fatigue of Metals: With Chapters on the Fatigue of Wood and of ConcreteMcGraw-Hill Book Company, Incorporated, 1927 - 326 halaman |
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20 axial alloy alternating stress amorphous metal annealed applied Armco iron axial stress axles beam Brit cent carbon steel compression computed concrete cool in furnace cross-section curve cycles of stress ductile Duralumin effect elastic deformation Elastic Hysteresis endurance limit Engineering London fatigue cracks fatigue failure fatigue strength fatigue tests formula heat treatment hold 1 hr hysteresis loop Illinois Eng increase Inst load localized stress maximum stress maximum unit stress McAdam modulus of elasticity Moore and Jasper non-ferrous metals number of cycles overstress permanent set Proc proportional elastic limit quench in oil R. R. Moore range of stress ratio reduced repeated stresses reversed flexure rotating rotating-beam S-N diagram shown in Fig shows slip bands Smax sorbitic specimen square inch strain stress concentration subjected surface temperatures tensile stress tension Tested as received Testing Materials theory of elasticity tion torsion ultimate strength ultimate tensile strength yield point zero
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Halaman 67 - ... clock,— Just the hour of the Earthquake shock! —What do you think the parson found, When he got up and stared around? The poor old chaise in a heap or mound, As if it had been to the mill and ground! You see, of course, if you're not a dunce, How it went to pieces all at once,— All at once, and nothing first,— Just as bubbles do when they burst.
Halaman 20 - Rosenhain1 observed that when a metal is sufficiently stressed, the crystals of which the metal is composed yield by slipping on certain gliding planes within the crystal. This slipping has the effect of breaking up the polished surface of a grain into elevations and depressions in the nature of steps. Under vertical illumination the steps show as dark lines, which Ewing and Rosenhain called "slip bands.
Halaman 15 - Wrought iron and steel will rupture at a unit stress not only less than the ultimate static strength of the material, but even less than the elastic limit, if the stress is repeated a sufficient number of times.
Halaman 101 - One end of the specimen S is held rigid in the vise V, and the other end, which runs in the bearing B, is rotated in a small circle. Sidewise pressure, which can be adjusted by means of a screw, is brought on the bearing B by a calibrated indicator spring 7.
Halaman 67 - Not infrequently the spreading crack can be detected before it has progressed to failure and a disaster averted. This repeated stress fracture spreads slowly like a minute hack-saw cut, but its rate of progress is accelerated, and just before fracture, it is almost as rapid as is the spread of fracture under a single increasing load. In fact, a typical fatigue failure usually shows two distinct zones: (1) A smooth surface where the crack has spread slowly and the walls of the crack are battered smooth...
Halaman 101 - ... spanning the gage holes GG shown near the ends of the spring. The rotating spring is carried in the cross-head C. Sidewise motion of the bearing B is prevented by placing the bearing in. a slot, and excessive displacement of the bearing, when the specimen breaks, is prevented by the rod R. The cross-head is driven by a shaft H, a pulley P, and a motor not shown in the figure. The number of revolutions of the cross-head is measured by the revolution counter K which is driven by a worm on the drive-shaft...
Halaman 72 - ... of the specimen has passed, unless the applied stress is very high. These specimens were cut from car axles. The whole question of fracture in metals brings up the relation of theoretical cohesion and strength. From a determination of the latent heat of fusion and the latent heat of vaporization, physicists have computed the theoretical cohesion of atoms for many metals, and if cohesion in solids is of the same order of magnitude as cohesion in melting solids and vaporizing liquids, then the...
Halaman 253 - Liata are lacking for determining the endurance limit for cases in which r is positive. (10) For shearing stress the best data available indicate that for the wrought ferrous metals tested the endurance limit for cycles of stress varying from zero to a maximum is nearly twice the endurance limit for cycles of completely reversed stress. In the absence of more complete data it may be noted that equations corresponding to those given in the preceding paragraph give results which are on the safe side...
Halaman 20 - ... bending stresses. When the stress was sufficiently high, slip lines appeared on the crystals. With increase in the number of cycles of stress, additional slip lines appeared, and the original ones showed a tendency to broaden. As the number of cycles increased, the broadening process continued, until parts of the surface became covered by groups of dark markings. At this stage, it was found that an actual crack had opened up along some of the broadened slip lines. Once a crack was formed, it...
Halaman 101 - ... can be adjusted by means of a screw, is brought on the bearing B by a calibrated indicator spring 7. The compression of the spring, and hence the load on the specimen, is measured by means of a strain-gage spanning the gage holes GG shown near the ends of the spring. The rotating spring is carried in the cross-head C. Sidewise motion of the bearing B is prevented by placing the bearing in. a slot, and excessive displacement of the bearing, when the specimen breaks, is prevented by the rod R....