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.
INAF-OAA

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.