W. Z. Shen, S. C. Shen, W. G. Tang, Y. Zhao, A. Z. Li, W. Z. Shen, S. C. Shen, W. G. Tang, Y. Zhao, A. Z. Li; Erratum: ‘‘Optical investigation of quaternary Gal
W. Z. Shen, S. C. Shen, W. G. Tang, Y. Zhao, A. Z. Li, W. Z. Shen, S. C. Shen, W. G. Tang, Y. Zhao, A. Z. Li; Erratum: ‘‘Optical investigation of quaternary Gal
The stresses and torque transmission capabilities of adhesively bonded circular, hexagonal and elliptical lap joints were analyzed by the three-dimensional finite element method and compared with the experimental resu...
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The stresses and torque transmission capabilities of adhesively bonded circular, hexagonal and elliptical lap joints were analyzed by the three-dimensional finite element method and compared with the experimental results. The adherends of the joints were composed of carbon fiber epoxy composite shafts and steel shafts. In calculating the torque transmission capabilities, the linear laminate properties of the composite material and the nonlinear shear properties of the adhesive were used. Using this method, the torque transmission capabilities of the adhesively bonded lap joints could be calculated accurately, except the circular and the hexagonal single lap joints whose adherends were failed by bulging when the composite adherends had small stacking angles from the shaft axis. The experiments revealed that the hexagonal joint had the best torque transmission capability among the single lap joints, and the double lap joint had better torque transmission capability than the single lap joint. The torque transmission capability of the hexagonal single lap joint was found to be comparable to that of the circular double lap joint.
The cocured stepped lap joints for composite structures were manufactured and tested under static and fatigue tensile loads. From the tests, it was found that the joints were shear-failed at the joining interfaces. As...
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The cocured stepped lap joints for composite structures were manufactured and tested under static and fatigue tensile loads. From the tests, it was found that the joints were shear-failed at the joining interfaces. As the length of the stepped lap of the joint increased, the average static tensile strength of the joint increased, while the average static shear strength decreased in proportion to the length of the stepped lap of the joint. The fatigue endurance limit was found to be 30-40% of the static strength. Also, the cocured stepped lap joints were manufactured by curing plies laid-up on the composite plates which had machined stepped laps. The static strength of the joints manufactured by the latter method was found to be 70-80% of the static strength of the joints manufactured without machining and the fatigue endurance limit was found to be about 25% of the static strength.
The harmonic drive, which is composed of a circular spline, a wave generator and a flexspline, is a compact, light-weight, and precise torque transmission mechanism with little backlash. From these components, the fle...
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The harmonic drive, which is composed of a circular spline, a wave generator and a flexspline, is a compact, light-weight, and precise torque transmission mechanism with little backlash. From these components, the flexspline is the key element for motion transmission. It must be flexible in the radial direction but stiff in the tangential direction to accurately transmit rotational motion. In order to satisfy this dual role, the conventional steel flexspline is usually manufactured as a thin cup shape which requires a large amount of machining using special jigs. Because of the thin cup shape, the steel flexspline produces noise and vibration when operated at high speed. Since the dual role cannot be satisfied effectively with conventional isotropic materials, anisotropic composite materials have been considered. In this paper the cup section of the flexspline was manufactured with carbon-fiber epoxy composite material and the tooth section using steel. Then the two components were joined by adhesive bonding. Also, in order to make the manufacture of the steel flexspline easy and reduce the noise and vibration of the harmonic drive, the cup and tooth sections were manufactured separately and adhesively bonded. The static torque transmission capabilities and the vibration characteristics of the composite flexspline with adhesively bonded steel teeth and the steel flexspline with adhesively bonded steel teeth were experimentally tested. From these tests it was found that the flexspline manufactured with adhesive bonding had sufficient torque transmission capabilities and both the composite flexspline and the bonded steel flexspline had better dynamic characteristics than the conventional one-piece steel flexspline.
Films of poly(dipropargylsi1ane derivatives) were easily prepared by solvent casting. The resulting red-black films were relatively flexible and ductile. By doping with electron acceptors, the electrical conductivity ...
Characteristics of both thermoplastic and thermoset composite materials as they pertain to marine vehicle applications are discussed. Comparison of various material selection factors such as strength, damage and moist...
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Characteristics of both thermoplastic and thermoset composite materials as they pertain to marine vehicle applications are discussed. Comparison of various material selection factors such as strength, damage and moisture resistance, and flammability and toxicity as well as cost and availability of thermoset and thermoplastic composite materials are presented. Methods for testing and reducing the flammability and toxicity are discussed. Many commercially available composite systems are reported to provide favorable characteristics for marine applications. Although there seems to be a need for improved production technology for thermoplastics, they present potential advantages in physical properties over thermoset composites.
作者:
CRANE, RMMACANDER, ABRoger M. Crane:isa materials engineer in the Ship Materials Engineering Department of the David W. Taylor Naval Ship Research and Development Center (DTNSRDC)
Annapolis Md. He is presently involved in the development of fiber reinforced advanced composite materials for various naval applications. He received his B.S. degree in physics/engineering and his B.A. degree in mathematics: physical applications from Loyola College. He has finished his course work for his M.S. degree in materials science at the University of Delaware and is currently enrolled at the Johns Hopkins University. Mr. Crane is a member of Society of Experimental Stress Analysis and the Society of Physics Students. Aleksander B. Macander:is a materials engineer in the Ship Materials Engineering Department
DTNSRDC Annapolis Md. He is presently involved in the development of fiber reinforced advanced composite materials for various naval applications. Prior to joining DTNSRDC in 1973 he was associated with the Johns-Manville Corporation Denver Colo and also with the Naval Applied Science Laboratory Brooklyn N.Y. He received his B.S. degree in mechanical engineering from Fairleigh Dickinson University and his M.S. degree in mechanical engineering (plastics) from Stevens Institute of Technology. Mr. Macander is a member of ASTM the Severn Technical Society and the International Organization for Standardization/Technical Committee 61 on Plastics.
There are a limited number of nondestructive techniques available for field inspection of large composite structures and practically none for inservice inspection. An innovative damage assessment system is proposed wh...
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There are a limited number of nondestructive techniques available for field inspection of large composite structures and practically none for inservice inspection. An innovative damage assessment system is proposed which uses an optical fiber mesh implanted into the body of a fiber reinforced composite structure. This mesh would become an integral part of the structure on fabrication. The selection of the mesh fibers would be predicated on their strain to failure characteristics and strain compatibility with the base composite reinforcing fibers. This optical system will be capable of locating damage, assessing severity and monitoring damage growth. A successful implementation of the total damage assessment system would involve the interaction of the optical fiber mesh with an adequately designed interrogative electronic package. This paper focuses on the former aspect of the total system. It will address some recent experimental work showing the practicality of the concept for large, complex composite structure.
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