Monolithic Resilient Joint for Deployable Structures

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Solution Overview

Problem

Existing deployable structures face issues with 'dead band' due to cumulative clearance in two-piece joints and material strain exceeding design limits in monolithic joints, requiring external force for deployment and potentially failing under extreme conditions.

Innovation Solution

A monolithic joint using a resilient, deformable material attached to a rigid member and a structural node, with cavities and mating surfaces to limit bend radius and rotation, storing work energy for self-deployment without external force, utilizing materials like spring steel or shape memory alloys to manage strain within design limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If two-piece joints with sliding contact are used, then the structure can be deployed and collapsed, but cumulative clearance creates dead band and requires external force for deployment

Engineering Contradiction:

Improvedeployment operationVSAvoidmovement communication

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent merges two separate joint components into a single monolithic joint made of resilient material. This eliminates the clearance and dead band problems inherent in two-piece joints with sliding contact, while maintaining the deployable functionality through the resilient material's ability to flex and return to its original shape

Inventive Principle:

Principle #5Merging (Combining)

2Extent of automation

If monolithic joint material is deformed to enable collapse, then deployment can occur without external force, but the design strain limit may be exceeded at extreme positions

Engineering Contradiction:

Improveself-deploymentVSAvoidmaterial strain limit

Core Design Contradiction:

Extent of automationVSStrength

Solution Approach 1:

The patent incorporates restraining elements that prevent the joint from rotating beyond a predetermined angle, thereby limiting the strain on the resilient material to within its design limits. This preliminary constraint ensures that when the structure is deployed, the material does not exceed its strain capacity while still enabling self-deployment through elastic recovery

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The resilient material itself acts as a cushioning element that absorbs and limits the strain during deployment. By selecting material with appropriate elastic properties and incorporating strain-limiting features, the design ensures that extreme positions do not exceed the material's strain capacity while still allowing sufficient deformation for collapse and deployment

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If resilient material is used for monolithic joint, then dead band is avoided, but strain may exceed design limit without proper constraints

Engineering Contradiction:

Improvemovement communicationVSAvoidmaterial strain

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The restraining elements are built into the joint structure to prevent rotation beyond a predetermined angle, thereby limiting the strain on the resilient material to within its design limits before extreme positions are reached

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The joint combines resilient material with restraining elements to create a composite structure that maintains reliable movement communication while preventing strain from exceeding material limits

Inventive Principle:

Principle #40Composite materials

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 joint avoids 'dead band' and ensures material strain is within limits, enabling efficient collapse and deployment of structures without external force, maintaining structural integrity and reducing mass and complexity.

Implementation Method 1

A flexure 15 of resilient, deformable material... The work expended to bend the joint material is stored and subsequently used to restore the joint to its neutral position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

utilizing materials like spring steel or shape memory alloys to manage strain within design limits

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Data Source

PatentUS7435032B1Resilient joint for deployable structures

Publication Date: 2008.10.14 THE GOVERNMENT OF THE UNITED STATES AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE

AI summary

A resilient flexure has one end attached within a cavity in a rigid member, and the other end attached within a cavity in a structural mode. The cavities are shaped to limit the flexure's bend radius. The member and the node have mating surfaces that abut to constrain the amount of rotation of the member. The aforementioned elements are shaped to prevent the strain in the flexure from exceeding its design limit when the joint is at its maximum angular deflection and the attached member is fully collapsed.