# US 5,341,638 A · Low cost segmented structure for pressure vessels, rocket motors, piping > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,341,638 A - Document ID: US5341638A - Status: Granted - Kind: A - Application number: 07/847,169 - Filed: 1992-03-09 - Granted: 1994-08-30 - Earliest claimed: 1992-03-09 - Assignees: Thiokol Corporation - Inventors: Frederick W. Van Name; Michael A. Gerace; Victor Singer; Brendan M. Walsh - Web page: https://patentgrep.com/patent/US5341638A ## CPC - B29C 70/865: {completely encapsulated} - F02K 9/34: Casings; Combustion chambers; Liners thereof - F16J 12/00: Pressure vessels in general (covers therefor F16J13/00; for particular applications, see the relevant subclasses, e.g. B01J, F17C, G21C) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00) - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS ## Abstract A composite structure for rocket motors includes a longitudinal element of the composite structure, which is an assembly of segments of clamshell or barrel stave form. The element is held in place by a circumferential element, which is a composite overwrap of reinforcing fibers in a resin matrix. The matrix may be thermoplastic or thermosetting. The reinforcing fiber being high strength polyolefin thereby providing the rocket motor with insensitive munitions capability. ## Claims ### Claim 1 The method of assembling a rocket motor comprising a thermoplastic cartridge, a propellant grain, case segments, and a composite overwrap, said method comprising casting said propellant grain into said cartridge curing said propellant in said cartridge installing said case segments over said cartridge so that said segments are joined along mated edges overwrapping said case segments with said composite overwrap, and curing said composite overwrap, said composite overwrap comprising reinforcing fiber in a resin matrix, said reinforcing fiber being high strength polyolefin, thereby providing insensitive munitions capability to said rocket motor, said composite overwrap being overwrapped over said case segments and cured so as to maintain said joined edges in said joined position and so as to withstand the intended pressure on said segments. ### Claim 2 (depends on 1) The method of claim 1 wherein a closure or nozzle assembly is installed at the end of said cartridge before the segments are installed. ### Claim 3 A composite structure intended to withstand pressure for use as a rocket motor case containing propellant comprising two or more segments with adjacent abutting edges generally parallel to the length of said composite structure to form a part of said composite structure and said segments having joining means along at least one end for joining with a closure and a composite overwrap, wrapped over said segments so as to maintain said adjacent edges in the abutting position, said composite comprising reinforcing fiber in a matrix of a resin said fiber being hoop-wrapped in side-by-side fashion over the surface of said segments so that said reinforcing fiber will withstand the intended hoop loading on said composite structure while said segments will withstand the intended longitudinal loading due to said joining means and said reinforcing fiber being high strength polyolefin thereby providing said rocket motor with insensitive munitions capability by said reinforcing fiber melting below the temperature at which said contained propellant ignites spontaneously. ### Claim 4 (depends on 3) The segments of claim 3 wherein said mated edges are substantially straight. ### Claim 5 (depends on 3) The segments of claim 3 wherein said member is cylindrical. ### Claim 6 (depends on 3) The structure of claim 3 wherein said joining means is a means for crimping said end to fit crimps in a closure. ### Claim 7 A rocket motor comprising a thermoplastic cartridge, filled with a propellant, a segmented case containing said filled cartridge, a composite overwrap covering said segmented case, said segmented case having two or more segments abutting along mated edges parallel to the length of said case, at least one end of said segmented case having joining means for joining with a closure with strength sufficient to withstand the intended longitudinal loading on said case, said composite overwrap being wrapped over said segments so as to maintain said mated edges in said abutting position, said composite overwrap comprising reinforcing fiber in a matrix of a resin, said fiber being hoop-wrapped in side-by-side fashion over the surface of said segments so as to maintain said mated edges in the abutting position, and so that said reinforcing fiber will withstand the intended hoop loading on said case, and said reinforcing fiber being high strength polyolefin, thereby providing said rocket motor with insensitive munitions capability, by said reinforcing fiber melting below the temperature at which said contained propellant ignites spontaneously, said thermoplastic having sufficient elongation to withstand the intended pressure on said case. ### Claim 8 (depends on 7) The rocket motor of claim 7 wherein said cartridge is fitted with a closure at either end or nozzle assembly at the aft end. ### Claim 9 (depends on 7) The rocket motor of claim 7 wherein said thermoplastic is selected from the group consisting of polyphenylene sulfide, polyetherimide, polyetheretherketone, polyamide-imide and polybutyl terephthalate. ### Claim 10 (depends on 7) The rocket motor of claim 7 wherein said fiber is selected from the group consisting of graphite, carbon, aramid, high strength polyolefin and fiberglass. ### Claim 11 (depends on 7) The rocket motor of claim 7 wherein said matrix is thermosetting. ### Claim 12 (depends on 7) The rocket motor of claim 7 wherein said matrix is thermoplastic. ### Claim 13 (depends on 7) The rocket motor of claim 7 wherein said matrix is an epoxy. ### Claim 14 (depends on 12) The rocket motor of claim 12 wherein said epoxy is ultraviolet curable. ### Claim 15 (depends on 7) The rocket motor of claim 7 wherein the segments are metal. ### Claim 16 (depends on 10) The rocket motor of claim 10 wherein the metal is selected from the group consisting of steel, aluminum and titanium. ### Claim 17 (depends on 2) The rocket motor of claim 2 wherein the segments are a composite of reinforcing fiber in a matrix. ### Claim 18 (depends on 7) The rocket motor of claim 7 wherein said cartridge has at least one end portion with edges which are formed for a snap fit. ### Claim 19 (depends on 2) The structure of claim 2 wherein said joining means is a means for crimping said end to fit crimps in a closure.