Liquid Hydrogen Projects

To design components for LH₂ applications, it is essential to understand their mechanical properties at the extremely low temperatures they will experience. For testing at 20 K, we integrate a dewar into our universal testing machine. Samples can either be fully submerged in liquid helium (LHe) to reach 4 K, or exposed to a regulated LHe flow to maintain a stable testing temperature of 20 K. Strain measurement is possible using either strain gauges or an extensometer.

By adapting the test setup, we can perform not only tensile tests but also a wide range of mechanical tests at LH₂ temperatures, including bending tests (3PB and 4PB), interlaminar shear strength (ILSS), and compression tests.

We regularly perform tests to characterize the bulge behaviour of CFRP membranes with an outer diameter of 156 mm. The sealed outer area surrounds a pressurized section with a diameter of 128 mm. Multiple sensors for temperature and strain monitoring can be applied directly to the sample. The membrane can be pressurized up to 20 bar, while helium permeation is tracked using a leak detector. Both the setup and the sample can be cooled to a wide range of cryogenic temperatures, including 90 K (LOX), 77 K (LN₂), and 20 K (LH₂).

To verify the resistance of an LH₂ valve to cryogenic shock, the valve seat body was repeatedly cycled between immersion in liquid helium (LHe) and heating to +85 °C. Our LHe-lift setup was used for this purpose. Despite the specimen’s large thermal mass and the required dwell times at both 4 K and +85 °C, a cycle time of less than 90 minutes was achieved.

Repeated cryogenic shocks involving liquid hydrogen can cause significant thermal stress and microstructural changes in materials, potentially leading to embrittlement or cracking. These effects are critical for the safety and durability of storage tanks and pipelines in hydrogen applications. Understanding and mitigating these impacts is essential for the reliable use of liquid hydrogen in energy and aerospace industries.