# US 2021/0340933 A1 · Hybrid metal composite structures, rocket motors including hybrid metal composite structures, and related methods

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2021/0340933 A1
- Document ID: US20210340933A1
- Status: Published application
- Kind: A1
- Application number: 17/330,040
- Filed: 2021-05-25
- Published: 2021-11-04
- Earliest claimed: 2016-12-27
- Assignees: Northrop Grumman Systems Corporation
- Applicants: Northrop Grumman Systems Corporation
- Inventors: Benjamin W.C. Garcia; Brian Christensen; David R. Nelson; Braden Day
- Web page: https://patentgrep.com/patent/US20210340933A1

## CPC

- F02K 9/34: Casings; Combustion chambers; Liners thereof
- B32B 3/26: characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids {(foam layer B32B5/18; layer of synthetic resin characterised by fillers that create voids or cavities B32B27/205); characterised by an apertured layer}
- B32B 3/263: {characterised by a layer having non-uniform thickness}
- B32B 3/266: {characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12}
- B32B 3/28: characterised by a layer comprising a deformed thin sheet {, i.e. the layer having its entire thickness deformed out of the plane}, e.g. corrugated, crumpled (B32B29/08 takes precedence)
- B32B 3/30: characterised by a layer formed with recesses or projections, e.g. {hollows, grooves, protuberances, ribs (apertured layer B32B3/266; layer with cavities or internal voids B32B3/26)}
- B32B 5/02: characterised by structural features of a {fibrous or filamentary} layer {(layer formed of metallic wires B32B15/02; layer formed of natural mineral fibres B32B19/02; layer formed of wood fibres B32B21/02)}
- B32B 5/022: {Non-woven fabric}
- B32B 5/024: {Woven fabric}
- B32B 5/026: {Knitted fabric}
- B32B 5/028: {Net structure, e.g. spaced apart filaments bonded at the crossing points}
- B32B 5/04: characterised by a layer being specifically extensible by reason of its structure or arrangement {, e.g. by reason of the chemical nature of the fibres or filaments}
- B32B 5/06: characterised by a fibrous {or filamentary} layer {mechanically connected, e.g. by needling} to another layer, e.g. of fibres, of paper
- B32B 5/10: characterised by a fibrous {or filamentary} layer reinforced with filaments
- B32B 5/12: characterised by the relative arrangement of fibres or filaments of {different layers, e.g. the fibres or filaments being parallel or perpendicular to each other}
- B32B 7/04: Interconnection of layers
- B32B 15/04: comprising metal as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042)}
- B32B 15/14: next to a fibrous or filamentary layer
- B64G 1/40: Arrangements or adaptations of propulsion systems
- B64G 1/403: {Solid propellant rocket engines}
- F02K 9/97: Rocket nozzles (thrust or thrust vector control F02K9/80)
- F05D 2300/6032: Metal matrix composites [MMC]
- 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)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B64G: COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

A hybrid metal composite (HMC) structure comprises a first tier comprising a first fiber composite material structure, a second tier longitudinally adjacent the first tier and comprising a first metallic structure and a second fiber composite material structure laterally adjacent the first metallic structure, a third tier longitudinally adjacent the second tier and comprising a third fiber composite material structure, and a fourth tier longitudinally adjacent the third tier and comprising a second metallic structure and a fourth fiber composite material structure laterally adjacent the second metallic structure. At least one lateral end of the second metallic structure is laterally offset from at least one lateral end of the first metallic structure most proximate thereto. Methods of forming an HMC structure, and related rocket motors and multi-stage rocket motor assemblies are also disclosed.

## Claims

### Claim 1

A hybrid metal composite (HMC) structure, comprising stacked tiers comprising:
first tiers comprising a fiber composite material, within each of the first tiers the fiber composite material comprising:
a fiber platform comprising a single, wound tow comprising fibers substantially aligned with one another in a single direction; and
a matrix material surrounding the fiber platform; and
second tiers longitudinally alternating with the first tiers and comprising metallic structures, the fiber composite material directly adjacent opposing lateral sides of the metallic structures, and the opposing lateral sides of each of the metallic structures laterally offset from corresponding ends of a longitudinally neighboring one of the metallic structures most longitudinally proximate thereto.

### Claim 2 (depends on 1)

The HMC structure of claim 1, further comprising:
metal plates overlying and underlying the stacked tiers; and
one or more fasteners longitudinally extending through each of the metal plates, the metallic structures, and the fiber composite material, the one or more fasteners comprising a material composition different than a material composition of the metallic structures.

### Claim 3 (depends on 2)

The HMC structure of claim 2, wherein the opposing lateral sides of at least some of the metallic structures are substantially the same distance from one of the fasteners.

### Claim 4 (depends on 1)

The HMC structure of claim 1, wherein the metallic structures constitute from about 25 percent to about 45 percent of a volume of the stacked tiers of the HMC structure and comprise one or more of titanium, a titanium-containing alloy, a nickel-containing alloy, and a stainless steel.

### Claim 5 (depends on 1)

The HMC structure of claim 1, wherein the fiber composite material comprises carbon fibers individually having a diameter within a range of from about 5 μm to about 10 μm.

### Claim 6 (depends on 1)

The HMC structure of claim 1, wherein the fiber composite material comprises ceramic fibers embedded in the matrix material, the ceramic fibers comprising one or more of alumina fibers, alumina-silica fibers, and alumina-boria-silica fibers.

### Claim 7 (depends on 6)

The HMC structure of claim 6, wherein at least the matrix material of the fiber composite material exhibits a coefficient of thermal expansion within a range of from about 45×10−6/K to about 65×10−6/K at about 25° C.

### Claim 8 (depends on 1)

The HMC structure of claim 1, wherein each of the metallic structures individually exhibits a thickness of about 0.01 inch, the opposing lateral sides of the metallic structures laterally offset by a distance of about 0.1 inch from the corresponding ends on one of the opposing lateral sides of a longitudinally neighboring one of the metallic structures, and the corresponding ends of the metallic structures substantially laterally aligned through the thickness of the HMC structure on the other of the opposing lateral sides.

### Claim 9 (depends on 1)

The HMC structure of claim 1, wherein each of the metallic structures exhibits substantially the same lateral width as each other of the metallic structures, the metallic structures individually comprising:
a lateral center offset in a lateral direction from another lateral center of another of the metallic structures most longitudinally proximate thereto and substantially aligned with an additional lateral center of at least one other of the metallic structures; and
lateral ends defined by the opposing lateral sides, the lateral ends offset in the lateral direction from corresponding additional lateral ends of the another of the metallic structures and substantially aligned in the lateral direction with corresponding further lateral ends of the at least one other of the metallic structures.

### Claim 10

A method of forming an HMC structure, comprising:
forming an uncured fiber composite material comprising a single tow of fibers substantially aligned with one another in a single direction by infiltrating the single tow of the fibers with an uncured matrix material during at least one filament winding process;
forming first tiers using the at least one filament winding process, the first tiers comprising portions of the uncured fiber composite material;
forming second tiers using the at least one filament winding process, the second tiers longitudinally alternating with the first tiers and comprising metallic structures and additional portions of the uncured fiber composite material directly adjacent opposing lateral sides of the metallic structures, each of the metallic structures exhibiting ends laterally offset from corresponding ends of a longitudinally neighboring one of the metallic structures; and
subjecting the first tiers and the second tiers to at least one curing process.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
trimming portions of one or more of the metallic structures; and
extending one or more fasteners longitudinally through each of the metallic structures and metal plates overlying and underlying the metallic structures.

### Claim 12 (depends on 10)

The method of claim 10, further comprising selecting the uncured fiber composite material to comprise polymeric fibers comprising one or more of polyetherketone (PEK) fibers, polyetheretherketone (PEEK) fibers, polyaryletherketone (PAEK) fibers, polyetherketoneetherketoneketone (PEKEKK) fibers, and polyetherketoneketone (PEKK) fibers.

### Claim 13 (depends on 10)

The method of claim 10, wherein forming the uncured fiber composite material comprises selecting the fibers to have a tensile moduli within a range of from about 275 GPa to about 350 GPa.

### Claim 14 (depends on 10)

The method of claim 10, wherein subjecting the first tiers and the second tiers to the at least one curing process comprises exposing an uncured HMC structure comprising the first tiers and the second tiers to a temperature within a range of from about 200° C. to about 300° C.

### Claim 15 (depends on 10)

The method of claim 10, further comprising selecting the uncured matrix material to comprise an epoxy material.

### Claim 16

A rocket motor, comprising:
a casing comprising:
a first hybrid metal composite (HMC) structure;
a second HMC structure laterally adjacent to the first HMC structure, each of the first HMC structure and the second HMC structure comprising alternating tiers of metallic structures and fiber composite material structures, each of the metallic structures exhibiting lateral surfaces laterally offset from corresponding lateral surfaces of the metallic structures most longitudinally proximate thereto; and
at least one fastener assembly connecting the first HMC structure to the second HMC structure, the at least one fastener assembly comprising elongate structures individually extending through one of the first HMC structure and the second HMC structure as well as joining structures overlying and underlying the first HMC structure and the second HMC structure;
a propellant structure within the casing; and
a nozzle assembly connected to an aft end of the casing.

### Claim 17 (depends on 16)

The rocket motor of claim 16, wherein the at least one fastener assembly comprises capping structures connected to opposing ends of each of the elongate structures.

### Claim 18 (depends on 16)

The rocket motor of claim 16, wherein a thickness of individual metallic structures is substantially equal to a thickness of individual fiber composite material structures, the lateral surfaces of each of the metallic structures laterally offset from the corresponding lateral surfaces of each other of the metallic structures most longitudinally proximate thereto by a distance equal to about ten times the thickness of one of the metallic structures.

### Claim 19 (depends on 16)

The rocket motor of claim 16, wherein some of the lateral surfaces of the metallic structures of the second HMC structure are located proximate an end of the second HMC structure, each of the some of the lateral surfaces laterally offset from the end of the second HMC structure by substantially the same distance.

### Claim 20 (depends on 16)

The rocket motor of claim 16, wherein the metallic structures individually extend within one of the first HMC structure or the second HMC structure without laterally extending across an entirety of both the first HMC structure and the second HMC structure.