Nacelle Panel Housing for Blind Actuator Attachment
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Solution Overview
Problem
The challenge of attaching actuators to thrust reversers in aircraft engines is complicated by the need for lower vibration frequencies, increased panel thickness, and reduced space between inner and outer panels due to high expansion ratios and wider diameters, leading to issues like dimpling and increased cost and weight.
Innovation Solution
A nacelle panel assembly with a housing in the central layer and a linking member that connects the actuator without passing through the entire panel thickness, using blind attaching elements to secure the linking member to the inner and outer skins, allowing for a smaller space between panels and reducing mechanical discontinuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the central layer is increased to attenuate lower vibration frequencies, then the vibration attenuation performance is improved, but the space available for placing the fitting between inner and outer panels is reduced
Solution Approach 1:
The invention transitions from a conventional through-thickness attachment approach to a blind attachment approach that utilizes the depth dimension of the central layer. The linking member is embedded within the central layer at a depth that does not compromise the inner or outer skins, effectively using the third dimension (depth) to resolve the space constraint while maintaining vibration attenuation performance through adequate embedment length.
2Strength
If through fittings are used to attach the actuator to the panel, then the attachment is secure, but dimpling occurs on the skin surface particularly during use of attachments with milled heads
Solution Approach 1:
The invention extracts the attachment function from the conventional through-skin fitting approach and relocates it to the central layer. The linking member is embedded within the central layer material itself, eliminating the need for fittings that penetrate and deform the inner or outer skins. This extraction of the attachment mechanism from the skin surface resolves the dimpling problem while maintaining secure attachment through the bonding and mechanical interlocking within the central layer.
3Shape
If the space between inner and outer panels is reduced to bring aerodynamic lines closer, then the aerodynamic performance is improved, but the space available for placing the fitting is limited
Solution Approach 1:
The invention resolves the space constraint by transitioning from a lateral placement approach to a depth-based embedding approach. The linking member is positioned within the depth of the central layer rather than requiring lateral space between the panels. This allows the aerodynamic lines to be brought closer together while the attachment function is fulfilled through the blind embedding of the linking member within the central layer's thickness.
4Volume of moving object
If a pandown is made in the inner panel to house the attachment fitting, then the fitting can be accommodated, but the mechanical behavior is degraded by geometrical discontinuity
Solution Approach 1:
The invention extracts the attachment function from the inner panel skin and relocates it to the central layer. By embedding the linking member within the central layer's material volume rather than creating a discontinuity in the inner panel skin, the solution avoids the mechanical degradation associated with pandowns. The central layer acts as the primary attachment medium, preserving the integrity and continuous mechanical behavior of both the inner and outer skins.
Data Source
AI summary
An assembly includes a nacelle panel of an aircraft engine, the nacelle panel including an outer skin, an inner skin and a central layer interposed between the outer and inner skins. The central layer has a housing, the outer skin has an opening which opens into the housing, and a linking member extends in the opening and in the housing, the linking member to be connected to an actuator.