Cryogenic Material Testing Wedge Mechanism
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Solution Overview
Problem
Current methods for testing composite materials at cryogenic temperatures and under tension are complex, expensive, and deviate from real-world conditions, requiring cylindrical or semi-spherical specimens that are costly to manufacture and assemble, and do not efficiently simulate the strain and permeation challenges faced by cryogenic hydrogen tanks.
Innovation Solution
A device and method using a rectangular parallelepipedic material sample with fastening elements, an intermediate frame, and wedges to elongate the sample, maintaining tension and allowing for permeability testing under cryogenic conditions, while minimizing thermal expansion and operator risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cylindrical or semi-spherical specimens are used for testing, then the test can simulate real tank conditions, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent uses flat panel specimens that copy the essential mechanical and thermal characteristics of curved tank walls without requiring actual cylindrical or spherical geometries. This allows testing of material behavior under cryogenic conditions and tension while avoiding the complex manufacturing of curved specimens, thereby resolving the contradiction between test accuracy and manufacturing complexity
Solution Approach 2:
The patent changes the geometric parameter of the specimen from curved (cylindrical/spherical) to flat, while compensating by carefully controlling boundary conditions and loading parameters to achieve representative stress states. This parameter change simplifies manufacturing while maintaining the ability to simulate real tank conditions through controlled testing parameters
2Stress or pressure
If the specimen thickness is reduced to achieve higher strain levels, then the strain simulation improves, but the specimen becomes more susceptible to handling damage and thermal gradients
Solution Approach 1:
The patent employs a flexible loading system with adjustable boundary conditions that can dynamically adapt to different specimen thicknesses. The loading apparatus can apply controlled tension while accommodating thermal contraction, allowing optimal thickness selection without compromising either strain simulation or specimen integrity
Solution Approach 2:
The patent implements protective measures before testing by pre-conditioning specimens in controlled environments and using gradual loading protocols. This cushioning approach prevents sudden thermal shocks or mechanical overloads that could damage thin specimens, thereby maintaining integrity while achieving required strain levels
3Ease of operation
If pressure caps and plates are assembled to close specimen surfaces, then the test setup is complete, but the assembly time and operational complexity increase
Solution Approach 1:
The patent divides the testing system into modular segments: flat panel specimens, separate loading frames, and independent cryogenic chambers. This segmentation allows parallel preparation of components and rapid assembly, reducing overall setup time while maintaining complete test configuration
Solution Approach 2:
The patent prepares specimens and loading fixtures in advance at room temperature, pre-assembling boundary conditions and instrumentation before cryogenic cooling. This preliminary action eliminates time-consuming assembly steps during the actual test, reducing operational complexity and setup time
4Reliability
If larger specimens are used to represent real tank scales, then the test representativeness improves, but the cryogenic cooling efficiency decreases
Solution Approach 1:
The patent changes the size parameter to small flat panels while compensating by carefully controlling thermal parameters through extended boundary exposure and controlled cooling rates. This allows achieving uniform cryogenic temperatures throughout the specimen while maintaining representative material behavior through proper boundary condition management
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 efficient, cost-effective, and safe testing of materials under conditions simulating cryogenic hydrogen tank environments, reducing waste and allowing for the evaluation of micro-cracking and permeability in a compact, easily reproducible manner.
Implementation Method 1
the wedge and the intermediate frame are adapted to maintain said test distance between the first fastening element and the second fastening element against an elastic retraction force exerted by said material sample
Implementation Method 2
the first fastening element and the second fastening element are adapted to be pulled away from each other, up to at least a predetermined distance, called test distance, so as to elongate the material sample
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
The invention relates to a device and a method for testing a material sample (10) in which the material sample is attached to a first fastening element (11) and a second fastening element (12), with and intermediate frame (13) in between, and the material sample is elongated along a longitudinal direction (18) by pulling the first fastening element (11) apart from the second fastening element (12), while at least one wedge (14.1, 14.2) is inserted between the intermediate frame (13) and a fastening element (11, 12) as the material sample deforms in order to maintain the elongation of the material sample (10) against an elastic retraction force.