Expandable Sheet Tensioning Frame With Edge-Bridging Corners

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Solution Overview

Problem

Existing sheet material tensioning apparatuses introduce planar discontinuities and stress points in the material due to abrupt edges, leading to deformities and weaknesses, particularly in canvas stretching applications where even tensioning and warping can cause cracks.

Innovation Solution

A sheet material tensioning apparatus with interconnected frame members forming a closed contour, featuring a material fastening mechanism and an edge-bridging mechanism that maintains planar continuity by spanning the separation between frame members as the contour expands, using a crossbar assembly with braces and expanding elements to apply tension evenly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If frame members are separated at interconnection points to enable expansion, then the frame can be adjusted and expanded, but planar discontinuities and abrupt edges are created that cause stress points and deformities in the sheet material

Engineering Contradiction:

Improveframe expandabilityVSAvoidstress points in material

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A corner assembly acts as an intermediary component between frame members, providing a transition piece that maintains the planar continuity of the material-supporting edge while allowing frame expansion. The corner assembly includes a first portion receiving one frame member and a second portion receiving another frame member, with a material-supporting edge that bridges the separation between members.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The corner assembly features a rounded or curved material-supporting edge instead of an abrupt corner, creating a smooth transition that eliminates stress concentration points. This curved geometry allows the sheet material to bend smoothly around the corner without creating sharp folds or stress points.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Force

If wedges are driven deeper into slots to apply tension, then the sheet material is stretched tighter, but the separation between frame members increases creating sharp corners and discontinuities

Engineering Contradiction:

Improvetension in sheet materialVSAvoidplanar continuity of material-supporting edge

Core Design Contradiction:

ForceVSShape

Solution Approach 1:

The corner assembly serves as a mediator that absorbs and distributes the separation force between frame members, preventing the formation of sharp corners. As wedges are driven into slots to apply tension, the corner assembly's material-supporting edge maintains a continuous, smooth surface that prevents stress concentration even as frame members separate.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If frame members are interconnected with mitre joints, then the frame structure is stable, but the joints create abrupt edges that introduce high stress points in the material

Engineering Contradiction:

Improveframe structural stabilityVSAvoidmaterial durability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The corner assembly replaces the abrupt mitre joint geometry with a curved or rounded material-supporting edge, eliminating sharp corners that create stress concentration points. This curved geometry maintains frame stability through proper mechanical connection while protecting material durability by distributing stress evenly across the sheet material.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The corner assembly acts as an intermediary between frame members, providing a transition element that maintains both structural stability and material integrity. It connects frame members securely while presenting a smooth, continuous surface to the sheet material, preventing stress concentration at joint locations.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution prevents abrupt transitions and maintains material continuity, reducing the likelihood of deformities and weaknesses, thereby extending the lifespan of the canvas and ensuring even tension across the surface.

Implementation Method 1

at least one expansion mechanism imposing a separation between frame members so as to expand the closed contour

Methodology Applied

Scientific EffectExpansion:

Implementation Method 2

An edge-bridging mechanism is provided to span the separation between each of the frame members to maintain continuity of the plane defined by the material-supporting edge

Methodology Applied

Scientific EffectMechanical bridging:

Data Source

PatentUS7735541B2Sheet material tensioning apparatus

Publication Date: 2010.06.15 LUCIUS HUDSON

AI summary

A sheet material tensioning apparatus includes frame members interconnected one with another to define a closed contour. The apparatus applies tension to sheet material by imposing a separation between frame members to expand the closed contour. Beneficially, the sheet material tensioning apparatus includes an edge-bridging mechanism, such as a spline, to span the gap between the separated frame members. The edge-bridging mechanism maintains the continuity of the edge supporting the sheet material. The sheet material apparatus may include a crossbar assembly to add rigidity to long frame members, while maintaining planar alignment even under considerable compression.