Deployable Rocket Nozzle Stiffener Vibration Control
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Solution Overview
Problem
Deployable rocket nozzles face mechanical stress issues due to vibrations during launch, leading to potential cracking or breaking of the movable divergent segment, which hinders proper operation and reduces the nozzle's performance.
Innovation Solution
A transverse stiffener prestressed in tension is integrated into the movable divergent segment, extending between specific points on the inner wall, to block eigenmodes of vibration and reduce mechanical stress, allowing for thinner walls while maintaining structural integrity and preventing interference during deployment and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the walls of the movable divergent segment are made thin to reduce mass, then the mass of the nozzle is reduced and engine performance is optimized, but the segment becomes overly flexible and vulnerable to vibration-induced cracking or breaking
Solution Approach 1:
The patent applies local quality by introducing a transverse stiffener at a specific location (near the downstream end) of the movable divergent segment. This stiffener provides localized reinforcement exactly where vibration-induced stresses are most severe, allowing the rest of the segment walls to remain thin and lightweight. The stiffener creates a local structural enhancement without requiring global thickening of the entire segment.
Solution Approach 2:
The patent employs composite materials by combining the movable divergent segment (made of thin-walled material for low mass) with a transverse stiffener (made of higher-strength material for vibration resistance). This composite structure integrates two different materials with complementary properties: the thin segment provides low mass while the stiffener provides localized strength and stiffness to block eigenmodes of vibration.
2Productivity
If the walls are made thin to optimize performance, then mass is reduced, but the segment becomes vulnerable to vibration damage during launch and refolding operations
Solution Approach 1:
The transverse stiffener performs preliminary anti-action by being installed in advance to counteract the harmful effects of vibrations before they can cause damage. The stiffener is positioned to block eigenmodes of vibration, preventing the thin-walled segment from resonating at dangerous amplitudes during launch vibrations and refolding operations, thereby protecting the segment structure.
Solution Approach 2:
The stiffener provides preliminary action by pre-establishing structural rigidity in the critical region before the nozzle undergoes vibrational stresses. By installing the stiffener beforehand, the structure is prepared to resist vibration-induced loads, ensuring the thin-walled segment maintains its integrity during subsequent vibrational events without requiring reactive reinforcement after damage occurs.
3Strength
If a transverse stiffener is added to reduce vibrations, then mechanical strength is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the reinforcement function into a separate, modular transverse stiffener component rather than integrating it into the main segment structure. This allows the stiffener to be designed, manufactured, and installed as an independent element, simplifying the overall manufacturing process and reducing the complexity of forming integrated thickened walls or complex monolithic structures.
Solution Approach 2:
The transverse stiffener acts as an intermediary element between the thin-walled movable divergent segment and the vibrational loads. Rather than directly modifying the segment walls to increase their strength, the stiffener serves as an intermediate structural component that transfers and distributes vibrational stresses, blocking eigenmodes while allowing the segment itself to remain thin and simple in design.
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 stiffener effectively reduces mechanical stress and allows for thinner nozzle walls, enhancing performance by blocking primary eigenmodes of vibration, thus improving the nozzle's reliability and reducing the risk of damage from vibrations, while maintaining efficient combustion gas flow.
Implementation Method 1
a transverse stiffener prestressed in tension extending transversely to the movable divergent segment
Implementation Method 2
the stiffener being prestressed in tension, the at least two points are coupled so that their relative displacements due to the vibrations are limited or even blocked
Data Source
Figure 1~3
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Figure 5~6
AI summary
Deployable nozzle for a rocket motor, comprising at least one fixed divergent segment (12) and one mobile divergent segment (14) coaxial with the fixed divergent segment (12) and able to move along the fixed divergent segment (12) from a withdrawn position to a deployed position, said deployable nozzle being characterized in that it further comprises a transverse stiffener (16) which is tension preloaded and extends transversely to the mobile divergent segment (14), near a downstream end (14b) of the mobile divergent segment (14), between at least two points on the periphery of an interior wall of the mobile divergent segment (14).