Development of a cryogenic in situ mechanical loading device for synchrotron radiation x-ray computed tomography (SR-CT).

The study of material damage evolution under combined cryogenic temperature and mechanical stress is crucial for aerospace and cryogenic applications but hindered by a lack of suitable in situ characterization tools. This work presents the development and validation of a novel in situ tensile loading device compatible with synchrotron radiation x-ray computed tomography for operation down to 53 K. The device employs an innovative "three-layer chamber" design based on functional decoupling and sealed negative-pressure insulation principles, utilizes polyetherimide for its cryogenic and x-ray transparent properties, and integrates a dual-circuit (liquid nitrogen/liquid helium) temperature control system. It achieves a 5 kN tensile load capacity, rapid cooling (room temperature to 53 K in <9 min), and stable temperature maintenance (±1 K). Its compact, rotationally symmetric design ensures compatibility with synchrotron beamline constraints. Performance was verified through mechanical calibration, thermal simulation, and integrated testing. An application demonstrates the device's functionality by capturing the 3D damage evolution within a 2219 aluminum alloy weld during in situ tensile testing at 53 K. This apparatus effectively bridges a critical technological gap, providing a robust platform for future 4D (3D + time) investigations of material behavior under cryogenic conditions.