Low-cost techniques for stress analysis of solid-rocket cases

Conclusions

In hydrotesting large solid-rocket casings, several hundred strain measurements at various locations and pressure levels are needed to adequately determine stress conditions. It is also required that the most efficient techniques of gage installation, recording and analyzing data are used in order to keep testing costs to a minimum.

For strain measurements to 10,000 micro-in./in., the Tatnall ype C6·121 gage bonded with Eastman 910 cement is preferred. For measurements to 3 percent strain load, the same gage with X-27 cement is preferred. For measurements to 10 percent strain level, the Tatnall Type HE-121 gage with unbonded tabs is preferred.

In the recording and analyzing of data, digital data-handling techniques are faster and more accurate than analog systems. With digital techniques, the data can be reduced, computed and plotted with automatic equipment at low cost and minimum elapsed time. An experimental digital recorder consisting of commercially available components has been successfully demonstrated for this application.