Nearly all [C5H10O]+˙ isomers with the oxygen on the second carbon are shown to interconvert with each other and lose methyl and ethylene at the threshold for dissociation. The methyls contain the carbons from the 1- and 5-positions with about equal frequency, and C(3) or perhaps C(4) about half as often as either terminal carbon. CH3 CH2 CH2 CO+ is formed by loss of the C(1) methyl and by loss of the C(5) methyl. Hydorgen transfer between C(5) and the oxygen and between the oxygen and C(4) are facile, and 1,2-hydrogen transfers between C(3) and C(4) occur with high frequency. Extensive skeletal rearrangements also take placae by 1,2-shifts between C(2), C(3) and C(4). We attribute the occurrence of teh three-center shifts between C(2), C(3) and C(4) to the presence of considerable charge density on C(2) and C(3) in many of the [C5H10O]+˙ isomers. The isomerizations of [C5H10O]+˙ can be considered a mixture of free radical and carbocation reactions. Strong similarities exist between the isomerizations of metastable [C5H10O]+˙ ions with the oxygen on the second carbon and those of isomers of ionized butanoic acid, methyl butanoate and n-butanal. 相似文献
This paper deals with the photoelastic determination of restrained-shrinkage stresses which may be produced by curing or by thermal effects in models of solid propellant grains bonded to the case. Use is made of the birefringence exhibited in the curing process of a restrained polyurethane rubber. The techniques developed to take advantage of this property are shown in detail. The method can also be applied to the determination of the residual stresses produced in the curing process of a propellant cast around a rigid insert. An example of this application is also given. The extension of the method, using epoxies, to three-dimensional analyses is pointed out. 相似文献
If a wedge-shaped sample of material is immersed in a tank of fluid and a coherent beam of light passed through it, the ensuing wavefront can be made to interfere with a holographically stored wavefront produced with the wedge removed. The interference is measured by the resulting fringes, which can be reduced by varying the fluid mix until the fluid matches the index of refraction of the material. The number of fringes can also be used to determine the difference between the indices of refraction of the fluid and material, and determine the material index from a known fluid index. 相似文献
Stress-concentration factors associated with the large deformations of in-plane loaded plates with elliptic holes are presented in a form with which designers are familiar. An analytic expression to obtain the stress-concentration factor is included. 相似文献
Isopachics obtained by holographic methods are combined with the isochromatics and isoclinics of a conventional photoelastic analysis to obtain a complete two-dimensional stress analysis of a highly critical region of a jet engine. The analysis of the disk/blade dovetail region of the third stage fan of a turbine engine shows a stress-concentration factor of 5.2 in the disk fillet and 4.8 in the blade fillet relative to the average stress in the neck section of the disk. The stress distribution along the edge of the blade fillet and on an interior line in the disk lug is also reported. Preliminary redesign of the disk fillet indicates that a 27-percent reduction in the fillet stress of existing third-stage disks is possible by remachining the relief area between the blade and disk lugs. 相似文献
A circular aluminum plate with a small concentric hole (1/10 the plate thickness) and supported on its outer edge by a ring was subjected to a concentrated load at its center, applied through a rigid ball of radius equal to the plate thickness. Strains were determined using grids, moiré, and electrical strain gages on the top and bottom surfaces of the plate for loads up to and including the one associated with the appearance of the first crack in the plate. The investigation is related to the development of specimens to be used to determine fracture characteristics of materials used in lightweight construction. 相似文献
It is pointed out that when strains are computed from a displacement field, the engineering definition of strain(lf?li)/li has advantages in respect to other definitions used in finite-strain theory. Tensorial transformations can still be used easily by means of Mohr's circle. Illustrations for the case of Eulerian and Lagrangian strains are shown. The comments may be of particular interest to experimental analysts. 相似文献
The value of the maximum stress, and its position, at the corner of long strips bonded on one side and shrunk, has been determined using photoelasticity. The angle of the strip end varies from zero (crack) to 180 deg (no corner). The radius at the corner varies from less than 0.0001 to 0.125 in. The solution obtained is an approximation to a plane-stress solution and will have application in composite-materials problems (coatings, solid-propellant rocket grains, etc.). 相似文献