Journal of Material Science and Mechanical Engineering (JMSME) Print ISSN: 2393-9095; Online ISSN: 2393-9109; Volume 2, Number 10; April-June, 2015 pp. 18-23 © Krishi Sanskriti Publications http://www.krishisanskriti.org/jmsme.html Qualification of Upper Stage Composite Rocket Motor Casing Lokesh Srivastava 1 , V. Veena 2 , S.K. Behera 3 , J.K. Mishra 4 , A.S. Srinivas Gopal 5 1,2,3,4,5 ASL Hyderabad, DRDO E-mail: 1 veena.drdo@gmail.com Abstract—Qualification approach of upper stage Composite Rocket Motor Casing (CRMC) fabricated by Filament winding methodology is presented in this paper.The Qualification and validation of CRMC as a system to a level of flawlessness begins with stringent quality requirements for manufacturing as there are no standard procedures available.This paper also discussesan insight of various stringent quality control requirementsat each and every stepprogressing right from raw materials to in-process checks/inspections during manufacturing and final component acceptance/qualification test, which are important for process improvement leading to reliability enhancement, cost reduction, and schedule optimization. Design validation starts right from the selection of composite raw materials by characterizing their physical andmechanical properties and entire cycle of processing where there is no scope for post corrective action for any major non-conformance condition.The mechanical and physical properties thus obtained from material characterization will define the basic material properties required to be considered for design.The results obtained arealso utilized to understand structural characteristics of filament woundpressure vessels with integrated end domes.Based on our experiences during the development of different configurations of CRMC’s and subsequent results of non-destructive testing (NDT), Acceptance & Qualification testing a conclusion is arrived at on the effectiveness to realize consistent quality products. Keywords: Acceptance test, Burst Test, Composite Rocket Motor Casing, Filament Winding, Non-Destructive Testing, Proof Pressure Test, Qualification Test, Static Test and Structural Load Test. 1. INTRODUCTION A rocket motor casing is basically a pressure vesselwith two end domes designed to withstand high pressures.A typical rocket motor casing alsoincorporates an integral fore and aft end skirt attachments. Composite materials withtheir higher specific strength, specific modulus and strength tailoribility characteristics willresult in reduction of weight of the structure. The choice of composite as primary material in design and manufacturing of the casing is dictated by the fact that the performance factor (‘n’ = PV/W) is consistently higher for composite casings as compared to that of metallicones. The casing is insulated internally by nitrile based rubber to protect from hot combustion gases. The key aspects of Quality Assurance which are involved and of great importance during the entire manufacturing cycle & various mandatory acceptance/ qualification testing are discussed in this paper.As the realization of CRMC is process dominant, a greater focus is placed on understanding and controlling the critical process parameters which affects the overall quality of CRMC [3]. The upper stage CRMCis designedto achieve increase volume of propellant, better specific impulse, weight saving (strength tailoribility, higher specific strength & modulus, versatility of filament winding), higher manufacturing rate, no stress corrosion cracking,lower Factor of Safety (FOS)and higher performance factor. Full scale burst test, structural load test and static tests are done to evaluate design adequacy and to demonstrate fabrication concepts. The overall qualification approach is divided into three categories - Material characterization, In-process tests and Full-scaleAcceptance Test (AT)&QualificationTest (QT). 2. BRIEF ON CONSTRUCTION DETAIL AND DESIGN ASPECTS 2.1 Construction Details The general arrangement of casing comprises of a) Composite Casing It takes primarily the internal pressure load. b) The Encapsulated Metallic Polar Boss The metallic bosses reinforce the vessel ends whereas, the encapsulating rubber accommodates the differential deformation between metal and composite. c) Igniter & Nozzle end Skirt Sub-assembly Studs are provided for fastening to respective airframe sections at both ends.To prevent galvanic corrosion on aluminum bulkhead, an in-situ protective layer of E- glass/epoxy is provided. Typically, a combination of shear- plies of nitrile based rubber is laid-up around the skirt at the Y-joint. Skirts are realized and analyzed for axial compression & Bending moment.