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We investigate the coherent population trapping (CPT) resonances excited in rubidium atoms by the femtosecond optical comb in magnetic field. The light shift of resonances was observed and studied.

Values of deformations of the piston grooves of the piston head are determined. On the basis of the experiment, a simulation of the stress-strain state of the piston head was performed using the parameters corresponding to the experimental conditions as boundary conditions. It is determined that when the model is divided, an error ε occurs, the permissible value of which is 10%. A regularity is derived in the form of an expression that allows us to determine the most acceptable size of the finite element for calculating the heads of pistons with a flat bottom. It is established that the shape of the change in the shape of the upper and lower working surfaces of the piston grooves has the form of conicity. The small contact area of the working surfaces of the groove and the ring is caused by the tilting moment in the cross-section of the ring from the action of the working pressure, which, in a compartment with the conicity of the groove from the action of thermal expansion, leads to considerable specific pressures both on the contacting area of the groove and the ring. Due to a violation of the mutual arrangement of the contact surfaces of the groove and the ring, they will be subject to increased wear.Keywords: finite elements method, piston crown of the low speed propulsion marine diesel engine, the error in the discretization of the model, the conicity of the working surfaces of the piston grooves, the modeling of the strained state, the size of the finite element, flat bottom piston, the tipping moment, the height of the piston groove, thermal expansion. For citation:Kuleshov, Igor I., and Vladimir M. Khodakovskiy. "Experimental rationale for the election size of the finite element in the calculation of the piston crowns." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S.O. Makarova 9.3 (2017): 603-611. DOI: 10.21821/2309-5180-2017

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