Research on Mechanical Performance Parameter of Metal Rubber
Metal Rubber is special materials and used in aerospace, especially under extreme conditions. It has characteristics of strong adaptability, corrosion resistance, radiation resistance and designability. In this paper, we have manufactured Metal Rubber components, and done some research on the influence of previous deformation to Metal Rubber material's structure and performance, its characteristic parameters such as Poisson's ratio, Elastic modulus were studied. Research results are basic but essential for finite element analysis of Metal Rubber materials; these results also play an important role of engineering application.
Control of elastichysteretic characteristics of multilayer allmetal vibration insulators with structural damping
The use of all-metal vibration insulators is one of the most effective ways to eliminate the harmful effects of vibrations in mechanical systems. However, a similar type of parametrically controlled all-metal vibration insulators is little studied. In this research, the possibility of control of elastic-hysteretic characteristics of multilayer vibration insulators from metal is proved on the basis of the theory of similarity and theory of structural damping. It was found that the use of the square law of distribution of the friction coefficient on the height of the multilayer package and uniform compression of layers provides the high damping at resonance. The obtained results can be useful for design of effective parametrically controlled systems of vibration protection for any field of technology.
New Sweet-Tasting C21-Pregnane Glycosides from Pericarps of Myriopteron extensum.
Ten novel C21 pregnane glycosides, extensumside C-L (1-10), were isolated as highly sweet-tasting substances from the edible pericarps of Myriopteron extensum (Wight) K. Schum by sensory-guided fractionation and purification. Their structures were determined through 1D and 2D NMR, such as HSQC, HMBC, 1H-1H COSY, HSQC-TOCSY, and ROESY, as well as other spectroscopic analysis combined with chemical evidence. These compounds shared the same aglycone, 3β,16α-dihydroxy-pregn-5-en-20-one, and contained the deoxysugar chain and the glucose chain which were linked to C-3 and C-16 of the aglycone, respectively. The sweetness potency was evaluated by a human sensory panel test and preliminary structure-taste relationship was discussed. The sweetness intensities of these compounds are between 50 and 400 times greater than that of sucrose. Furthermore, quantitation analyses of compounds 1, 3, 4, and 6 in different parts of M. extensum indicated that the concentrations of these sweet components in the pericarps are obviously higher than those in stems and roots.