Research of engine pistons form point of view of thermal shocks

Experimental test results of thermal shocks for heavy duty pistons of combustion engines are presented in the paper. The range and the level of thermal loads were diverse and dependent from working engine conditions as well as the temperature ranges were adapted for real conditions in which pistons of the combustion engine work. temperature measurement results on crown and skirt of a piston during an engine operating under different conditions are presented in the paper. Measured temperature differences during engine operating were greatest in areas, where appeared greatest piston temperatures. Researches of thermal shocks were realized on the special testing device. The device this is automatic, controlled a computer, makes possible the realization of the cycle of research of thermal shocks in the necessary range of the temperature. Test results showed that in following cycles of thermal shocks took place stable changes ofdimensions ofthe piston too. Mainfactors effecting on the resistance of piston materials on thermal shocks are presented in the paper, at this essential parameters influent on the resistance of materials on thermal shocks are coefficients of thermal expansion and Young's modules. In particular thermal shock resistance of the different piston alloys, dependence of dimensional thermal tensions versus the undimensional heat flux, Basic parameters of the composite material AK12 +20%Al2O3 and standard, values of heat conductivity coefficient the and temperature on the composite piston surface, values of stresses due with the temperature field in piston, values strains in the composite piston due the temperature field, the example of the influence of the number of thermal shocks on the deformation of the piston sample are presented in the paper.