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scientific edition of Bauman MSTU

SCIENCE & EDUCATION

Bauman Moscow State Technical University.   El № FS 77 - 48211.   ISSN 1994-0408

Constructional Material Processing in Machine Building

77-30569/289392 Effect of natural frequency timing of weld metal crystallization oscillatory mechanism and frequency of external periodic influence on technological strength in welding process.
# 12, December 2011
V.P. Morozov
Existence of oscillatory mechanism of solidification of metal welded bath in the form of recurrent formation isotherms of crystallization is characteristic for different metals and alloys. It was found that under the influence of heat from an external periodically active source with the frequency corresponding to natural frequency of crystallization of weld material, resonance conditions which contribute to crushing the cast structure of seam and heat-affected zone are created. Fine structure of the welded joint obtained by effective control of the oscillatory mechanism of the crystallization front, can significantly improve hot cracking resistance and, probably, cold cracking due to changes in conditions of structural transformations, unachievable by conventional welding. Frequency of external action which creates conditions for parametric resonance can have several meanings according to the theory of oscillations.
77-30569/286150 Hidden heat evolution’s role in the control of process formalization of molten metal crystallization in the process of welding
# 11, November 2011
V.P. Morozov
Oscillations in the process of molten metall crystallization appears when welding as a periodic formation of cristallization isotherms; this is a characteristic of different metals and alloys. Cycling of commercial pure metal crystallization process is caused by temperature oscillations when hidden heat evaluating on the phase boundary. Frequency mechanism of hidden heat evaluation grouped with concentration subcooling mechanism appeared to be significantly difficult including both non-equilibrium cooling conditions and cycling. External thermal factors’ influence on the frequency of heat evaluation when welding pure metals and alloys allowed to increase the capabilities of structure forming. It was found out that thermal influence from external periodic source with the frequency corresponding to the natural frequency of welded seam crystallization created conditions for resonance that led to the increasing of penetration, interval of temperature oscillation and also to the reduction os welded seam’s cast structure. 
77-30569/281952 Structural defect estimation of carbon fibers and polymer composites based on these fibers
# 11, November 2011
Yu.M. Mironov, Yu.V. Hrapovickaya, M.O. Makeev, V.A. Nelyub, A.S. Borodulin, I.V. Chudnov, I.A. Buyanov
 The results of structural survey of carbon fibers and epoxy micro carbon fiber composite were presented in this article. Attempt to determine damage mechanism of micro carbon fiber composite while in long operation was made, based upon the obtained results.
77-30569/282012 Raman spectroscopy of nanomodified polymer composite materials exposed to mechanical load
# 12, December 2011
Yu.M. Mironov, Yu.V. Hrapovickaya, M.O. Makeev, V.A. Nelyub, A.S. Borodulin
In this article the authors present a research of physicochemical properties of constructional polymer composite materials (PCM) with addition of nanomodificatiors – astralene by method of Raman spectroscopy (RS). The authors conducted a research of polymer matrix chemical bonds with nanomodificators and parameters of packing characteristic of macromolecule. The authors made a conclusion of applicability of Raman spectroscopy method for estimation of on-stream PCM deformation degree when PCM are exposed to mechanical load.
77-30569/282085 Characteristic patterns of transition of liquid molten metal in the solid state at the crystallization front in the framework of the phenomenological model.
# 12, December 2011
V.P. Morozov
The process of metal melt during welding with subsequent crystallization is characterized by several features. Transition of liquid melt to solid state occurs simultaneously at the interface in the so-called germ band. It is in the embryonic area that during crystallization there appears an oscillatory mechanism which is considered within the framework of a phenomenological model. Modeling the dynamics of particle motion in simple liquids confirms transition from the chaotic state of the particles into the ordered one with preliminary formation of clusters of several particles. The mechanism of layer-wise phased transition of the particles occurs at establishing a specific frequency and mode of unstable equilibrium or breakdown. Using an external source of fluctuations synchronous with the process of crystallization rate, you can control the formation of the structure by creating a resonance condition. This would be a significant improvement in the properties of welded joints by grinding the cast structure of the weld metal.
77-30569/256359 The dynamic of cathode spots movement along the cathode surface in transverse magnetic field
# 01, January 2012
D.V. Duhopel'nikov, D.V. Kirillov, S.A. Schurenkova
The effect of the value of arc magnetic field induction and discharge current on the speed of cathode spots on a cold cathode of vacuum-arc evaporation system in inert and reactive gas atmosphere was explored. The cathode spots’ speed dependence from the value of the magnetic field induction and discharge current was investigated. It was shown that the induction and discharge current increasing leads to a rise of the cathode spots’ speed. In this case, it doesn’t matter whether we use reactive or inert gas.
 
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