Aircraft Fuselage Specimen Testing via Inverted Pressure
Solution Overview
Problem
Current aircraft strength testing methods using internal pressure tests face issues such as high pressure risks, difficulty in observing damage, large cavity volumes, sealing challenges, and uneven stress distribution due to internal structural members, leading to increased costs and time-consuming processes.
Innovation Solution
A testing apparatus that applies internal pressure to a curved specimen by reducing pressure inside a cavity formed between the specimen and a pressure vessel, allowing for safe stress application, easy damage observation, reduced cavity volume, reliable sealing, and cost-effective operation using a pressure reducing pump, while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If internal pressure is applied by pressurizing the cavity inside the specimen, then the desired stress can be applied to the specimen, but the pressure may become too high and burst the specimen
Solution Approach 1:
Instead of pressurizing the cavity from the inside outward, the invention applies pressure from the outside inward by pressurizing the space between the specimen and the pressure vessel. This reverses the pressure application direction, allowing controlled stress application without risking specimen burst
2Loss of time
If the cavity volume is reduced to decrease testing time, then the pressurization time is reduced, but the internal structural members require a predetermined interval that increases cavity volume
Solution Approach 1:
The invention reverses which space is pressurized - instead of pressurizing the internal cavity of the specimen, it pressurizes the external space between the specimen and pressure vessel. This allows the cavity volume to be minimized for rapid pressurization while the interval required by internal structural members does not interfere with the testing efficiency
3Reliability
If a sealing member is installed on the flat surface portion of the specimen, then sealing is achieved, but the stress distribution becomes uneven due to absence of internal structural members
Solution Approach 1:
The invention reverses the sealing location from the internal flat surface to the external surface of the specimen. The sealing member is installed on the outer surface where it does not interfere with internal structural members, maintaining both sealing reliability and uniform stress distribution across the specimen
4Reliability
If a large jig is used to press the specimen against the pressure vessel to prevent seal breakage, then sealing reliability is improved, but the device complexity and size increase
Solution Approach 1:
The invention reverses the sealing approach by sealing from the outside rather than requiring large internal jigs. The sealing member installed on the outer surface naturally prevents seal breakage under pressure without requiring additional complex restraining structures, simplifying the overall device
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
Enables safe, quick, and reliable stress application to aircraft specimens, allowing for efficient observation of damage and reduced testing time, while minimizing costs and structural interference.
Implementation Method 1
a pressure reducing pump that reduces the pressure inside the cavity by suctioning
Data Source
AI summary
To provide an aircraft strength testing apparatus that, using a curved specimen, can produce a desired stress safely and quickly by reliably applying an internal pressure, and moreover allows any resulting damage to be reliably observed. A testing apparatus 1 that applies an internal pressure, equivalent to a differential pressure between the outside and the inside of a section to be tested of a fuselage of an aircraft, to a curved specimen 10 corresponding to the section to be tested, includes: a pressure vessel 22 between which and the specimen 10 a cavity 23 is formed; and rods 25 that restrain the specimen 10 against the internal pressure. The pressure vessel 22 faces the outer side of the specimen 10. By reducing the pressure inside the cavity 23, an internal pressure is applied to the specimen 10.