Flexible Actuator Sidewall Reaction Feature for Rupture Resistance
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Solution Overview
Problem
Pneumatic actuators with flexible members face issues of excessive expansion leading to potential rupture and difficulty in returning to a collapsed position due to sidewall stiffness, which affects durability and functionality.
Innovation Solution
Incorporating a reaction feature on the flexible member's sidewall, such as a wedge-shaped protrusion, that governs sidewall movement and stiffness, preventing excessive pivoting and aiding in the return to a collapsed position by distributing material effectively across the transition area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sidewall stiffness of the flexible member is increased to resist rupture, then the resistance to rupturing is improved, but the flexible member has difficulty returning to a collapsed position and develops high stresses leading to durability issues
Solution Approach 1:
The flexible member is divided into distinct functional zones: a transition area with higher stiffness (containing the reaction feature) and a work area with lower stiffness. This segmentation allows different regions to perform different functions - the transition area resists excessive expansion and aids collapse, while the work area maintains flexibility for actuation.
Solution Approach 2:
The reaction feature creates a localized region of increased stiffness at the transition area through non-uniform material distribution. This local quality change enables the transition area to provide structural support and govern sidewall movement without making the entire flexible member overly stiff, thus resolving the contradiction between rupture resistance and collapseability.
2Strength
If the sidewall stiffness is increased to prevent excessive expansion, then the resistance to rupturing is improved, but high stresses are developed in the flexible member which lead to durability issues
Solution Approach 1:
By segmenting the flexible member into transition and work areas with different stiffness characteristics, the stress distribution is optimized. The transition area absorbs and manages stresses through its reaction feature, preventing stress concentration in the work area, thus improving durability while maintaining rupture resistance.
Solution Approach 2:
The localized stiffness enhancement at the transition area through the reaction feature allows stress to be distributed more effectively. This local quality change prevents excessive stress development in critical regions while maintaining overall structural integrity, thereby improving reliability without sacrificing strength.
3Ease of operation
If the flexible member is made more compliant to ease return to collapsed position, then the ease of operation is improved, but the resistance to rupturing is reduced
Solution Approach 1:
The flexible member is segmented into a compliant work area that easily collapses and a stiffer transition area that provides structural support. This segmentation allows the work area to be highly compliant for easy collapse while the transition area maintains sufficient stiffness to prevent rupture.
Solution Approach 2:
The reaction feature creates a local quality difference where the transition area has enhanced stiffness properties compared to the work area. This allows the bulk of the flexible member to remain compliant for easy operation while the localized transition region provides the necessary strength to prevent rupture.
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 reaction feature enhances the flexible member's ability to resist rupture and maintain appropriate stiffness, ensuring effective expansion and contraction while reducing stress and improving durability.
Implementation Method 1
The reaction feature can be made of the same material as the sidewall or different materials. The reaction feature does not need to be placed on the entire transition area, but can be placed on sections of the transition area where pivoting about the transition area is likely to occur
Implementation Method 2
Pneumatic actuators utilize pressurized gas, such as air, to push against workpieces. When the air chamber fills with pressurized air, the pressure from the air forces the flexible member away from the stiff base member
Data Source
Figure 1~2
Figure 3~5
AI summary
An actuator includes a stiff base member defining a bottom of the actuator; a flexible member connected to the stiff base member and having a sidewall and a contact surface on top of the flexible member, the flexible member and the stiff base member defining a fluid chamber therebetween, the sidewall having a first end connected to the stiff base member and a second end, the second end and the contact surface defining a transition area therebetween, the flexible member being configured to expand when the fluid chamber is filled with fluid; and a reaction feature placed on the transition area that is configured to govern movement of the sidewall.