Dynamic-seal-free quick open type testing method for material fatigue properties in high-pressure hydrogen environment

Abstract

The invention discloses a dynamic-seal-free quick open type testing method for material fatigue properties in a high-pressure hydrogen environment. A method for stimulating a test sample part to generate resonance under the condition that the loading frequency of reciprocating horizontal motion of an environment box bottom cover and the inherent frequency of the test sample part are the same is utilized, so that a fatigue test of a test sample under the high-pressure hydrogen environment is realized; and the testing of the material fatigue properties under the high-pressure hydrogen environment can be realized without the need of arranging a dynamic sealing structure, and particularly a high-cycle or high-frequency fatigue test under a high / low-temperature and high-pressure hydrogen environment is realized.

Description

technical field [0001] The invention belongs to the field of material mechanical performance testing equipment development, and in particular relates to a non-moving sealing quick-opening type high-pressure hydrogen environment material fatigue performance testing method. Background technique [0002] Hydrogen energy is an important secondary energy source in the new century, and high-pressure hydrogen storage is currently the dominant hydrogen energy storage method. However, if the material works in a high-pressure hydrogen environment for a long time, its mechanical properties will be damaged due to hydrogen embrittlement, especially under the action of fatigue load, the fatigue resistance of the material under high-pressure hydrogen will be seriously reduced. In order to ensure the long-term and reliable operation of the high-pressure hydrogen system, it is necessary to test and evaluate the mechanical properties (especially fatigue resistance) of materials in a high-pres...

AI Technical Summary

Problems solved by technology

Practice has shown that the existing dynamic seal structure has a very short service life, and often fails suddenly due to wear and hydrogen absorption expansion after a short period of use.

Especially during the fatigue test process, the loading rod reciprocates back and forth, which is more likely to aggravate the wear of the dynamic seal, and the higher the fatigue load frequency, the more serious the wear, which will easily lead to the failure of the seal wear and cause hydrogen leakage and the test is forced to stop

This is also difficult for the existing technology to achieve high-frequency (frequency greater than 10Hz) or high-cycle (cycles greater than 10) materials in a high-pressure hydrogen environment. 5 ) The crux of the fatigue test

[0006] (2) The friction power consumption is serious

Therefore, such equipment often suffers from severe frictional power consumption, which further aggravates the wear of seals

[0008] (3) It is necessary to set up a complex axial force balance structure

However, the axial force balance structure often needs to add a dynamic seal (such as the test device proposed in the patent [201110259252.2]), which further increases the possibility of hydrogen leakage and friction power consumption

At the same time, the increase of dynamic seals will inevitably further restrict the reliability and durability of the test device

[0010] (4) Lack of real-time monitoring of equipment health status

[0011] The working pressure of this kind of equipment is high (up to 140MPa), and the test medium is flammable and explosive hydrogen. Therefore, if there is a crack in the equipment and the hydrogen leaks and cannot be monitored in time, it will cause serious harm.

However, at present, such equipment often lacks a reasonable structural design, and cannot monitor the health status of the equipment in real time. It is difficult to activate the emergency braking system in time when the equipment leaks hydrogen to ensure the safety of the test personnel.

[0012] (5) Lack of reasonable temperature control structure

However, such equipment currently lacks a reasonable temperature control structure

For example, the patent [201510316095.2] discloses a high-temperature hydrogen environment material performance test device, which does not have the low-temperature test function. In addition, the resistance wire is used to directly heat the hydrogen to make direct contact between the strong electricity and the high-pressure hydrogen, which has great potential safety hazards.

As another example, the patent [201420753372.7] uses an external jacket heat exchange method to achieve high and low temperature functions, but the heat exchange medium must first exchange heat with the cylinder wall before exchanging heat with the gas in the environmental chamber, in order to be able to withstand high pressure The wall of the gas cylinder is often thick, so that the heat exchange medium in the jacket cannot effectively exchange heat for the gas in the cylinder. The overall heat exchange efficiency of this structure is low, and the jacket will also dissipate heat along the outer wall, causing heat serious waste of

[0014] (6) Lack of reasonable quick opening structure

For example, the patent [201110259252.2] adopts a pin-type quick-opening structure. This structure needs to open holes in the box body and sealing seat of the environmental chamber. Large stress concentration occurs at the opening, which is often the place where failure occurs.

In addition, the pins in this structure are prone to bending deformation under the action of shear stress, and often after a short period of use, the pins are too bent and deformed to be inserted into the pin holes and cannot work, and the reliability is low

Another example is that the patent [201420753372.7] adopts the quick-opening structure of the toothed clamp connection, but the tooth root of the structure is a place of high stress concentration, which seriously reduces the service life of the structure; at the same time, the size of the clamp and the toothed Often larger to increase the contact surface to bear the load, making this type of quick-opening structure often relatively bulky

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