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Fundamental and applied issues of mining

2020 year, number 2

INVESTIGATION OF THE THERMOELASTIC STATE AT ELECTROFUSION WELDING OF POLYETHYLENE PIPES AT VARIOUS TEMPERATURES OF THE ENVIRONMENT

N. P. Starostin, R. S. Tikhonov
The Yakut Scientific Centre of the Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
Keywords: Polyethylene pipes, electrofusion welding, mathematical modeling, thermoelastic problem, finite element method, stress-strain state

Abstract

The work is devoted to the actual problem of welding of polyethylene pipes at low ambient temperatures used in the mining industry. The numerical solution of the thermoelastic problem shows the distinctive features of the thermal and stress-strain states of the welded joint of polyethylene pipes using couplings with a built-in heater at various temperatures of the environment. It is shown that welding in conditions of low temperatures of the environment, the size of the molten zone is substantially less than at permissible temperatures. In this connection, insufficient pressure is created between the coupling and the pipe for high-quality welding. It is also shown that at the time of melt crystallization, the maximum stresses during welding at low temperatures are higher than during welding in the allowable temperature range, which causes high values of residual stresses. The results obtained can be used in the development of welding technology at low temperatures.