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971.
The propagation of torsional waves in a prestressed compound (bi-layered) hollow circular cylinder is in vestigated within
the frame work of a piecewise homogeneous body model, with the use of a three-dimensional linerized theory of elastic waves
in initially stressed bodies. The elasticity relations for components of the compound cylinder are obtained from the Murnaghan
potential. Numerical investigations are performed for bronze and steel. According to the results obtained, the effect of variations
in the geometric (the ratio between the thickness of the cylinder and its inner radius) and mechanical parameters on the dispersion
curves are analyzed.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 1, pp. 103–116, January–February, 2008. 相似文献
972.
973.
A. S. Andrushchak Ya. V. Bobitski M. V. Kaidan B. G. Mytsyk A. V. Kityk W. Schranz 《Optics & Laser Technology》2005,37(4):23-328
We present the interferometric technique which allows to measure piezooptical and photoelastic characteristics of crystal materials of any symmetry. The offered two-fold interferometric method enables to determine all independent non-zero piezooptic and photoelastic constants by measuring pressure induced changes of optical path. As advantage to known acoustooptical techniques this method allows to measure both the absolute magnitude and sign of photoelastic constants. In general case the determination of 36 components of piezooptic tensor needs to carry out 57 measurements on 16 samples. The corresponding relationships are derived. As an example we apply here the interferometric technique to measure the piezooptic and photoelastic constants in trigonal β-BaB2O4 crystals. 相似文献
974.
975.
The first part of the paper deals with homogenization models of unidirectional composites, in which each phase of the material
is bounded by parallel cylindrical surfaces. For a GFRP with epoxy resin and glass fibres, five elastic constants for six
models of the composite are calculated. In the second part, the results of strain gauge tests, photoelasticity investigations,
and scanning electron inspection are discussed. With these data, some elastic constants of the composite in tension and compression
are found. A comparison of experimental and analytical results is presented.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 195–206, March–April, 2008. 相似文献
976.
The elegant method proposed by Michelsen [M.L. Michelsen, Calculation of multiphase equilibrium, Comput. Chem. Eng. 18 (1994) 545–550] for solving multiphase Rachford–Rice (RR) equations as a bound constrained minimization is extended to the negative flash region; this method is definitely much more robust than any method based on equation solving. The problem is reformulated as an unbounded linearly constrained minimization. The feasible domain is limited by (only few of the) hyperplanes defined by equilibrium constants. The proposed method is applied to several three-phase cases. 相似文献
977.
Based on a relativistic quark model approach, the transition properties of the first nucleon resonance △(1232), and the coupling constants gπNN, g△πN are investigated. Tvo different vays to remove the center of mass motion are considered. The results of the relativistic approaches with and without center ofmass correction are compared with those of nonrelativistic constituent quark model. Moreover, pion meson cloud effect on these calculated observables is explicitly addressed. Better results are obtained by taking the pion meson cloud into account. 相似文献
978.
H. Yuksel Guney 《Journal of Polymer Science.Polymer Physics》2005,43(20):2862-2873
The elastic properties of PVDF have been investigated as a function of temperature. The propagation velocity and absorption of longitudinal and transverse ultrasonic waves have been measured at a constant frequency of 2 MHz and temperatures between –20 and 100 °C. Hence, the temperature dependences of storage and loss elastic constants have been obtained for temperatures between –20 and 100 °C. It has been seen that the relaxation behavior is affected from the form of mechanical disturbance. For the longitudinal mode, only one relaxation peak at 42 °C, but for transverse mode three relaxation peaks at 28 °C, 60 °C, and 94 °C have been observed. The results have been compared with the literature values obtained previously for PVDF. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2862–2873, 2005 相似文献
979.
Wolfgang S.M. Werner 《Surface science》2007,601(10):2125-2138
A simple procedure is developed to simultaneously eliminate multiple scattering contributions from two reflection electron energy-loss spectra (REELS) measured at different energies or for different experimental geometrical configurations. The procedure provides the differential inverse inelastic mean free path (DIIMFP) and the differential surface excitation probability (DSEP). The only required input parameters are the differential cross section for elastic scattering and a reasonable estimate for the inelastic mean free path (IMFP). No prior information on surface excitations is required for the deconvolution. The retrieved DIIMFP and DSEP can be used to determine the dielectric function of a solid by fitting the DSEP and DIIMFP to theory. Eventually, the optical data can be used to calculate the (differential and total) inelastic mean free path and the surface excitation probability. The procedure is applied to Fe, Co and Ni and the retrieved optical data as well as the inelastic mean free paths and surface excitation parameters derived from it are compared to values reported earlier in the literature. In all cases, reasonable agreement is found between the present data and the earlier results, supporting the validity of the procedure. 相似文献
980.