Defining the stress fields for the safety design of the LBT adaptive secondary mirror - FEMLAB/MATLAB set of functions to define and compute shell overstressing

Del Vecchio C., Busoni L., Riccardi, A.

This paper presents the most important safety issues of the thin glass shell of the LBT Adaptive Secondary Mirror. Two overstressing conditions are investigated: the condition in which the mirror shell is passively supported and the condition of a failure of the control system governing the actuator forces.

The two stress analyses determine the portion of the mirror which may exceed a certain stress limit: in the first case we define the basic criterion for the choice of a safe restraint system, in the second case we give the limit parameters to be adopted by the control system logic.