SPF/DB Reinforced Exterior Panel for Reusable Hypersonic Thermal Protection

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Solution Overview

Problem

Current thermal management strategies for hypersonic vehicles are inadequate, as traditional materials like nickel alloys are heavy, expensive, and non-reusable, failing to effectively manage high temperatures at hypersonic speeds.

Innovation Solution

A superplastic formed and diffusion bonded (SPF/DB) exterior panel with a multicellular core and a superplastic formed reinforcement (SFR) layer, using materials like titanium-zirconium-molybdenum alloy, which provides reinforcement to the exterior skin when temperatures exceed titanium's limits, and is designed for reusability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If traditional thermal protection materials like nickel alloys are used for hypersonic vehicles, then thermal protection capability is improved, but weight increases and cost increases

Engineering Contradiction:
Improvethermal protection capabilityVSAvoidstructure weight
Core Design Contradiction:
TemperatureVSWeight of moving object

Solution Approach 1:

The patent employs a composite structure consisting of a titanium alloy exterior skin, a superplastic formed reinforcement layer, and a multicellular core. This composite construction provides effective thermal protection at hypersonic speeds while significantly reducing weight compared to traditional nickel alloy monolithic structures. The titanium alloy skin offers high-temperature resistance, the reinforcement layer provides structural support under thermal load, and the multicellular core contributes to both structural integrity and weight reduction.

Inventive Principle:
Principle #40Composite materials

2Temperature

If traditional thermal protection materials like nickel alloys are used for hypersonic vehicles, then thermal protection capability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvethermal protection capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The thermal protection structure is segmented into distinct functional layers: an exterior skin, a reinforcement layer, and a multicellular core. This segmentation allows each component to be manufactured separately using optimized processes and then assembled through diffusion bonding, reducing overall manufacturing complexity and cost compared to producing a monolithic nickel alloy structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes superplastic forming, a manufacturing process that changes the physical parameters of the material during forming to achieve complex geometries at lower costs. The reinforcement layer is formed through superplastic deformation followed by diffusion bonding, enabling cost-effective production of structurally optimized components with intricate shapes that would be expensive to manufacture using traditional methods.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If traditional thermal protection materials are used for hypersonic vehicles, then thermal protection is provided, but reusability is limited

Engineering Contradiction:
Improvethermal protection capabilityVSAvoidreusability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent designs a reusable thermal protection system where the titanium alloy exterior skin and reinforcement layer can withstand multiple thermal cycles. The structure is engineered to recover and maintain its structural integrity after thermal exposure, allowing it to be reused for multiple missions. The diffusion-bonded construction ensures that the joints maintain their strength through repeated thermal cycling, enabling the system to be recovered and reused rather than discarded after single use.

Inventive Principle:
Principle #34Discarding and recovering

4Weight of moving object

If titanium alloy exterior skin is used, then weight is reduced, but thermal protection capability deteriorates at hypersonic speeds

Engineering Contradiction:
Improvestructure weightVSAvoidthermal protection capability
Core Design Contradiction:
Weight of moving objectVSTemperature

Solution Approach 1:

The patent creates a composite system where the titanium alloy exterior skin is combined with a superplastic formed reinforcement layer and multicellular core. This composite construction allows the lightweight titanium skin to be supported by the reinforcement layer, which maintains structural integrity at hypersonic temperatures, thereby providing both weight reduction and adequate thermal protection capability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The reinforcement layer is strategically positioned and configured to provide enhanced structural support specifically in regions experiencing the highest thermal loads. The local reinforcement allows the titanium skin to maintain its lightweight advantage while the reinforcement layer compensates for the reduced thermal protection capability of titanium at hypersonic speeds in critical areas.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The SPF/DB exterior panel effectively manages high temperatures, providing tensile and compressive strength, and is lighter and less costly, enabling reusable thermal protection for hypersonic vehicles.

Implementation Method 1

A series of core sheets are superplastic formed and diffusion bonded together to form a multicellular core

Methodology Applied
Scientific EffectSuperplasticity: Superplasticity

Implementation Method 2

The exterior skin, the SFR layer, and the core sheets are diffusion bonded together in this way to form an integral structure

Methodology Applied
Scientific EffectDiffusion bonding: Diffusion Welding

Data Source

PatentEP3798117B1Reinforced superplastic formed and diffusion bonded structures
Publication Date: 2023.01.11 THE BOEING CO
  • EP3798117B1 patent drawingFigure 1~2A
  • EP3798117B1 patent drawingFigure 3~4
  • EP3798117B1 patent drawingFigure 5~6

AI summary

An exterior panel is formed of superplastic materials, including an exterior skin (12) of titanium to accommodate high thermal stresses imposed on hypersonic transport vehicles during hypersonic flight. The exterior skin (12) is fixed to an underlying reinforcing skeletal structure (18) consisting of a superplastic formable reinforcement (SFR) layer, for example a titanium, zirconium, and molybdenum (TZM) alloy, which supports the exterior skin (12) whenever the latter may be heated to temperatures exceeding 1200 degrees Fahrenheit (650°C). The exterior panel includes a separate interior skin (14) configured for attachment to a frame member such as a rib, stringer, or spar of the hypersonic transport vehicle. A multicellular core (16) is sandwiched between the exterior (12) and interior (14) skins to impart tensile and compressive strength to the exterior panel. In one disclosed method, the core is superplastic formed and diffusion bonded to the exterior and interior skins.