Iscan 3D Measurement

Operation features of many devices, machine components, instruments depend substantially on state of their surfaces. Selective surface processing by high-intensity energy beam (ion, electron, laser treatment) is one of the most perspective directions in modern material science and surface engineering. These techniques permit to effectively increase microhardness, wear- , heat- and corrosion- resistance for metal products, including complex geometry. Most of the surface treatment techniques are based on heating, melting and impact loading processes. Successful realization of surface treatment technologies requires precise prediction and on-line control of thermal influence and melt depths, heating and cooling rates, and front velocities. Precise quantitative analysis of energy beam action requires simultaneous consideration of unsteady nonlinear heat transfer and thermoelasticity problems, with temperature dependencies of parameters and complex geometry of treated samples been taken into account.

The objectives of the project are:

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Software development (LSCAN-3D, FEPAS) and complex analysis of 2D and 3D temperature and thermo-elastic fields induced by scanning energy beam in finite-size steel and ferrous-based products. *

Software development (MELT-2D) and complex analysis of dynamics of phase transformations: melting, evaporation, crystallization, in homogeneous and multi-layer materials irradiated by ultra-short high-power energy pulses. *

Determination of optimal regimes for operations of surface treatment: surface amorphisation, placating, cladding of metals and alloys.

To reach the objectives, universal approach for computational algorithms construction will be developed that unify finite-difference approach to unsteady multidimensional heat transfer problems and finite-element approach to elasticity problems. Multifront free boundary problems with explicit front tracking will be solved using dynamically adaptive computational grids. The numerical algorithms will be realized in the form of software.

Results:

Operation features of many devices, machine components, instruments depend sub-stantially on state of their surfaces. Selective surface processing by high-intensity energy beam (ion, electron, laser treatment) is one of the most perspective direc-tions in modern material science and surface engineering. These techniques permit to effectively increase microhardness, wear- , heat- and corrosion- resistance for metal products, including complex geometry. Most of the surface treatment tech-niques are based on heating, melting and impact loading processes. Successful im-plementation of surface treatment technologies requires precise prediction of thermal influence zones, melt bath size, heating and cooling rates, phase front velocities. Precise quantitative analysis of energy beam action requires simultaneous consid-eration of unsteady nonlinear heat transfer and thermoelasticity problems, with tem-perature dependencies of parameters and complex geometry of treated samples been taken into account.

The execution of the project permitted to obtain several substantial scientific results in this field:

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Lscan-3D software is developed for modeling of scanning laser processing of materials. The software allows: to predict 3D thermal field, size of heat-affected zone, heating and cooling rates, induced by moving laser beams; to account for temperature dependencies of heat conductivity, specific heat and absorptivity; to specify extended set of implemented laser beam parameters: peak intensity, pulse duration, pulses repetition frequency, focal radius, intensity distribution on space (rectangle, Gaussian) and time (rectangle, triangle, Gaussian), beam initial position, scanning velocity and scanning area sizes.

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Combined Finite-Difference - Finite-Element Method for the Computation of Tem-perature and Thermal Stress Fields is developed and implemented, numerical studies are executed for laser treatment of semi-conductors. A peculiarity of the en-ergy beam treatment of semiconductors consists in the occur-rence of higher stress fields than in case of metals. High energy beam induced stresses may lead to crack formation and destroy thin semiconductor films, but also can be used for specific sur-face texturing.

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The numerical method for two-dimensional multi-front Stefan problem is developed that allows the problem solution with explicit tracking of interface boundaries. The approach is based on dynamic adaptation of computation grid, that is reached by means of automatic transformation of co-ordinates, governed by solution-dependent transformation function. Main complexities of the problem are due to presence of two phase transformations: melting-crystallization and evaporation, and great difference between typical sizes of considered domain and energy re-lease zone (focal spot). The effectiveness of the proposed approach is demon-strated on test freezing problem and laser keyhole welding of iron and lead. The obtained results indicates that there is no principle restriction to generalize algo-rithm for the case of more moving boundaries.

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