Mechanical analysis of mirror panels used in CTA (Cherenkov Telescope Array)

Abstract

This paper presents results of numerical simulations of a three-layer rectangular plate and a rotationally symmetric plate, as well as panels of mirrors produced for the project Cherenkov Telescope Array - the CTA. Calculations were based on the finite element m ethod and were prepared using ANSYS program. The problem of the three-layer rectangular plate and the rotationally symmetric plate loaded by bending moments on the edge was presented, with appropriate assumptions in the analysis. The theory of small and large deflections were analyzed and compared by the calculations. The curvature values at the middle and the end of plates were searched. Also bending moments needed to obtain the appropriate values of curvature were examined. Glass panels as a main part of CTA mirrors were described. The boundary conditions and loads, material properties were showed as well as the adopted assumptions in the analysis. Two cases were considered with two values of different radius of curvature. State of deformations and stresses which prevails in those parts of mirrors were checked. The results were depicted in the form of graphs of the radius of curvature and values of stresses for different values of mirror panel radius. Two methods, simple geometric and polynomial approximation, were used by which it was possible to approximate of radius of curvature changes in different places of panels after unloading the system.