EXAMINING THE ACCURACY OF SPACE-SHUTTLE SUPPORT LOADS USING PROBABILISTIC ANALYSIS TECHNIQUES

To understand unexpectedly erratic load measurements in the launch pad supports for the Space Shuttle, the sensitivities of the load cells i n the supports were analyzed using simple probabilistic techniques. NA SA engineers use the loads in the Shuttle's supports to calculate crit ical stresses in the Shuttle vehicle just before liftoff. The support loads are measured with ''load cells,'' which actually are structural components of the mobile launch platform that have been instrumented w ith strain gauges. Although these load cells adequately measure vertic al loads, horizontal load measurements have been erratic. Load measure ments were simulated in this study using Monte Carlo simulation proced ures. The simulation studies showed that the support loads are sensiti ve to small deviations in strain and calibration. In their current con figuration, the load cells will not measure loads with sufficient accu racy to reliably calculate stresses in the Shuttle vehicle.