Burst pressure estimation considering the measured residual strain and 3-D profile of a Solid Rocket Motor hardware
- Paper number
IAC-20,C2,IP,4,x56282
- Author
Mr. Paul Murugan J, India, Indian Space Research Organization (ISRO)
- Coauthor
Mr. Shitij Arora, India, Vikram Sarabhai Space Centre (VSSC)
- Year
2020
- Abstract
As part of hardware acceptance protocols, the hardware assembly of the motor case made of 15CDV6 material and Nozzle convergent was subjected to the proof pressure along with the corresponding enclosures. Since the hoop strain measured was higher in the long seam weld location at a pressure level less than the maximum expected operating pressure (MEOP), the pressure was brought down to near zero pressure. During the unloading, the offset strain measured was above 0.2 percent proof strain. Due to this nonlinear behavior, additional strain gauges were deployed adjacent to higher strain location and acceptance test was successfully completed. Strains beyond acceptable level were recorded in hoop direction at the old and new strain gauge location also. Margin of safety over 0.2% PS was negative at this location. To investigate on this issue, profile casting was taken using 3-D mould at near the weld and parent metal location. 3-D CMM was used for measuring the profile coordinates. This data was used for 3-D finite element modeling of that profile. The challenge was the 3-D modeling of the larger amount of data measured from the 3-D CMM.Detailed analyses were carried out to capture the resided stress field at that location. Burst pressure estimation at the location was carried out considering the measured residual strain by iterating the stress-strain curve of this material. Burst pressure estimated was observed to be meeting design requirement. As the material exhibits strain hardening effect, acceptance of the hardware was no issue after the burst pressure estimation. This motor was designed for the pad abort test of the crew escape Motor. This paper covers the details of the pressure test, 3-D mould/casting details, profile measurement, 3-D finite element analysis and results.
- Abstract document
- Manuscript document
(absent)