Variable Moment of Inertia Beam for Ballistic Energy Absorption
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Solution Overview
Problem
Current ballistic containment structures for gas turbine engines face challenges in balancing ballistic requirements with weight and size constraints, as increasing material thickness or complexity leads to weight penalties and complex manufacturing processes, while existing non-additive manufacturing techniques are limited in creating complex geometries for energy absorption.
Innovation Solution
A variable moment of inertia beam or sandwich panel structure with a compliant tension flange and gapped compression flange, manufactured using additive manufacturing techniques, which allows for tailored stiffness response and energy absorption through a multi-layer construction with truss-style shear web or core, effectively attenuating sharp load spikes during ballistic events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If material thickness is increased to improve ballistic performance, then strength and energy absorption are improved, but weight increases
Solution Approach 1:
The beam structure implements variable moment of inertia along its length, creating local variations in stiffness and strength. The flange width changes at different positions to concentrate material where needed for ballistic resistance while reducing material in less critical areas, thereby improving ballistic performance without proportionally increasing overall weight.
Solution Approach 2:
The beam employs a composite cross-sectional structure combining web and flange elements with different geometric properties. This composite arrangement creates a moment of inertia distribution that optimizes ballistic performance by positioning material strategically to resist impact loads while minimizing total material usage and weight.
2Strength
If material thickness is increased to improve ballistic performance, then strength and energy absorption are improved, but device size increases
Solution Approach 1:
The variable moment of inertia design concentrates structural thickness and material in specific regions where ballistic resistance is most needed, while reducing thickness in other areas. This local differentiation achieves the required strength and energy absorption without proportionally increasing the overall volume of the beam.
Solution Approach 2:
The beam utilizes a composite cross-sectional geometry with web and flange components that distribute material in three-dimensional space. This dimensional arrangement allows the structure to achieve high moment of inertia and ballistic performance without increasing linear dimensions uniformly, thereby controlling overall size.
3Strength
If complex geometries are created to improve energy absorption, then ballistic performance is improved, but manufacturing complexity increases
Solution Approach 1:
The beam cross-section is segmented into distinct web and flange components, each with specific geometric functions. This segmentation allows the complex variable moment of inertia geometry to be manufactured using standard additive manufacturing processes by building up the structure layer by layer, reducing manufacturing complexity compared to monolithic complex geometries.
Solution Approach 2:
The beam geometry is designed to be dynamic in its response to loading, with the variable moment of inertia allowing the structure to adapt its stiffness characteristics during deformation. This dynamic behavior improves energy absorption while the geometry can be achieved through additive manufacturing which naturally handles complex shapes without requiring complex tooling or assembly processes.
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
This solution provides energy absorbing characteristics and weight savings by allowing for less material usage while achieving desired ballistic performance, with progressive stiffening characteristics that can be tailored for specific ballistic response, and can be fabricated using current additive manufacturing machinery.
Implementation Method 1
Energy absorbing beam and sandwich panel structure... effectively attenuating the shock of sharp load spikes experienced in ballistic event settings
Implementation Method 2
The progressive stiffening characteristics of the structure effectively attenuate the shock of sharp load spikes
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An apparatus includes first (66;94;142;162), second (68;96;144;164), and third (70;98;146;166) layers. The first layer (66;94;142;162) includes a plurality of flanges (72;102;168). The second layer (68;96;144;164) includes a deformable membrane (74;104;170). The second layer (68;96;144;164) is connected to the first layer (66;94;142;162) along a first major surface (114) of the deformable membrane (74;104;170). The third layer (70;98;146;166) is connected to the second layer (68;96;144;164) along a second major surface (116) of the deformable membrane (74;104;170) opposite the first major surface (114). The third layer (70;98;146;166) includes a first series of internal structures (76;106;172).