Locking Sheet Structure for Thin Variable-Stiffness Forming
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Solution Overview
Problem
Existing shape-formable devices face limitations in achieving a thin, sheet-like configuration with variable bending stiffness, as bulk media jamming requires significant volume and lacks extensibility, while thin layer jamming systems struggle with conformability and rigidity.
Innovation Solution
A shape-formable apparatus comprising overlapping locking sheets with patterned solid and open regions, allowing relative movement within a major surface, which can be evacuated to change from a flexible, formable state to a rigid state by reducing pressure, and vice versa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If bulk media jamming is used to achieve variable bending stiffness, then the device can transition between flexible and rigid states, but the device requires significant volume and lacks extensibility
Solution Approach 1:
The bulk media is segmented into multiple discrete particles contained within separate chambers. Each chamber can be independently evacuated to control the jamming state of its particles. This segmentation allows the device to achieve variable stiffness while maintaining a compact form factor, as the particles only occupy significant volume when in the expanded flexible state, and collapse to a compact configuration when jammed in the rigid state.
Solution Approach 2:
The device employs dynamic control of internal pressure to transition between flexible and rigid states. By evacuating chambers to create negative pressure, the discrete particles are drawn together into a jammed configuration that provides rigidity. Releasing the vacuum allows particles to return to their expanded state, restoring flexibility. This dynamic state change enables the device to adapt its mechanical properties on demand while maintaining compact storage volume.
2Volume of moving object
If thin layers of material are used to reduce device volume, then the device achieves a thin form factor, but the layers cannot be easily extended within the plane and conformability is limited
Solution Approach 1:
The device uses thin-walled chambers containing discrete particles instead of solid bulk media. These thin film chambers provide the necessary containment while allowing the overall structure to remain flexible and conformable. The thin film construction enables the device to achieve a compact form factor when collapsed, while still allowing extensive deformation and conformability when in the flexible expanded state.
Solution Approach 2:
The device employs a porous or open-structure approach through discrete particles separated by void space when expanded. This porous configuration allows the thin-walled chambers to flex and deform extensively while containing the particle media. The open structure between particles when expanded provides the necessary compliance and conformability, while the same particles provide rigidity when drawn together under vacuum.
3Strength
If individual layers with high Young's Modulus are used, then the layers have high stiffness, but they generate wrinkles instead of smoothly assuming arbitrary shapes
Solution Approach 1:
The device changes the effective mechanical parameters of the structure by transitioning the particle media between expanded and jammed states. When particles are expanded and separated, the structure exhibits high compliance and can smoothly assume arbitrary shapes. When particles are jammed together under vacuum, the structure transitions to a high-stiffness state that maintains the achieved shape. This parameter change allows the same structure to provide both smooth conformability and shape stability as needed.
Solution Approach 2:
The device creates a composite structure combining thin flexible chambers with discrete particle media. The thin chamber walls provide flexibility and smooth deformation capability, while the discrete particles provide adjustable stiffness when jammed. This composite approach allows the structure to smoothly conform to arbitrary shapes in the flexible state, then lock in those shapes with high rigidity when particles are drawn together, eliminating the wrinkle formation problem of homogeneous high-modulus 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 apparatus achieves a compact, sheet-like form with enhanced conformability and rigidity, overcoming the volume and extensibility limitations of bulk media devices and the rigidity issues of thin layer systems, enabling effective tissue manipulation and other applications.
Implementation Method 1
The apparatus can be changed from the first state to the second state by evacuating the chamber to reduce the pressure in the chamber to below ambient pressure
Implementation Method 2
Some existing shape-formable devices employ discrete particles (i.e., bulk media) in a gas impermeable envelope that normally move freely with respect to one another, but 'jam' together and resist relative motion when the internal pressure of the envelope is reduced below ambient pressure
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Method of using a shape-formable apparatus. A shape-formable apparatus can include an envelope defining a chamber, a port positioned to fluidly couple the chamber with ambience, and at least two locking sheets positioned in the chamber in an at least partially overlapping configuration. Each locking sheet can include a major surface, and at least a portion of each locking sheet can be patterned to include solid regions and open regions, the solid regions being movable with respect to one another within the major surface. The method can include providing the shape-formable apparatus in a first state; forming the apparatus into a desired shape; and reducing the pressure in the chamber to change the apparatus from the first state to a second state in which the apparatus is substantially less formable than in the first state.