Optical Mounting Flexure Stress Isolation
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Solution Overview
Problem
Guided projectiles with brittle optical components face high shock loads during launch, causing stress and challenging their survival, and there is a need to shift optical components like windows in limited volume with efficient stress management.
Innovation Solution
An optical mounting system featuring a frame, a translatable shuttle with inner and outer portions mechanically coupled by flexures that twist rather than bend under axial loads, and a latching mechanism using a shape memory alloy wire for secure positioning, allowing for stress isolation and compact operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If optical components are mounted rigidly to withstand high shock loads, then strength is improved, but stress concentration and component failure increase
Solution Approach 1:
The mounting structure is divided into separate components: a rigid outer portion for structural strength and a flexible inner portion for stress isolation. The flexures segment the load path to prevent direct transmission of shock loads to the optical component, resolving the contradiction between needing strength and avoiding stress concentration.
Solution Approach 2:
Flexures serve as intermediary elements between the rigid mounting structure and the optical component. These flexures mediate the interaction by providing a compliant connection that isolates the optical component from high shock loads while still allowing the mounting to withstand structural stresses.
2Adaptability or versatility
If optical components are made movable to shift positions during flight, then adaptability is improved, but device complexity increases
Solution Approach 1:
The mounting system incorporates movable elements that allow the optical component to be repositioned during flight. The shuttle mechanism provides dynamic positioning capability, enabling the system to adapt to different operational requirements without requiring a completely complex redesign.
Solution Approach 2:
The inner portion containing the optical component is nested within the outer portion, allowing the optical element to be shifted relative to the mounting structure. This nested configuration enables compact movement within limited space while maintaining structural integrity.
3Productivity
If volume for optical components is limited, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The inner portion is nested within the outer portion, creating a compact configuration that maximizes volume efficiency. This nested structure allows the optical component to be positioned within limited space while maintaining adequate manufacturing precision through controlled flexure deformation rather than requiring extremely tight tolerances on the entire assembly.
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 system effectively reduces stress on optical components by isolating bending and twisting forces, ensuring high survivability and efficient movement of optical elements within the limited space of projectiles, maintaining low stress levels akin to an infinitely rigid mount.
Implementation Method 1
The flexures may be thin linking strips of material between the outer and inner portions. The flexures may have a thickness that is greater in an expected load direction, than in a direction perpendicular to the load direction. This may cause the flexures to twist rather than bend, as a load is applied along an axis of a missile or projectile
Implementation Method 2
The locking mechanism may include a latch that is activated and de-activated by selectively applying current to a wire made of a shape memory alloy
Data Source
AI summary
An optical element mounting includes a frame, and a shuttle that is translatable relative to the frame. The shuttle includes inner and outer portions that are mechanically coupled together by a plurality of flexures that effectively bending and twisting of the shuttle from being transmitted to an optical element, such as an optical window, that is mounted on the inner portion of the shuttle. The flexures may be thin linking strips of material between the outer and inner portions. The flexures may have a thickness that is greater in an expected load direction, than in a direction perpendicular to the load direction. The optical mounting may include a locking mechanism, for example including a shape memory alloy wire, to lock the shuttle in a predetermined location relative to the frame.