**Oleksandr Kapustynskyi , Nikolaj Višniakov \* , Darius Zabulionis and Artur Pišˇcalov**

Faculty of Mechanics, Vilnius Gediminas Technical University, Sauletekio al. 11, 10221 Vilnius, Lithuania; ˙ oleksandr.kapustynskyi@vgtu.lt (O.K.); darius.zabulionis@vgtu.lt (D.Z.); artur.piscalov@vgtu.lt (A.P.)

**\*** Correspondence: nikolaj.visniakov@vgtu.lt; Tel.: +370-5-2745053

Received: 10 June 2020; Accepted: 3 July 2020; Published: 10 July 2020

**Abstract:** This paper is devoted to investigating numerically, by finite element analysis (FEA), and analytically the influences and effects of laser processing of the surface of thin-plate, low-carbon structural steel. The plate mechanical properties—axial and flexural stiffnesses, force-deflection behavior and cross-section force-strain behavior—are investigated after different laser treatments. An analytical methodology of the estimation of the cross-section area of the laser-processed metal is also proposed in the present article, that can be applied to choosing the reasonable distance between the centers of the laser-processed tracks. The methodology takes into account the width of the laser-processed tracks and the distances between these tracks. The experimental, finite element numerical and analytical analyses showed that the laser treatments of the surface of the steel plate increase the yield point of the laser-processed metal and the axial and flexural stiffnesses of the plate.

**Keywords:** reinforcing; laser treatment; strengthening; bending; low-carbon steel; thin steel plate
