Limited projection based in-situ X-ray tomography for hard material characterization

Area of Science:

• Materials Science
• Mechanical Engineering
• Imaging Science

Background:

• Conventional mechanical loading systems for in-situ CBCT use X-ray transparent materials, limiting load capacity for hard materials.
• Enclosed sample chambers restrict sample adjustment, hindering operational flexibility.
• Steel components in loading systems cause X-ray attenuation, invalidating projections in limited-angle CBCT.

Purpose of the Study:

• To develop a flexible steel support system for in-situ CBCT enabling high-stress mechanical testing of hard materials.
• To address invalid projections caused by X-ray attenuation in limited-projection CBCT.
• To enhance operational flexibility and expand the stress loading capacity of mechanical testing systems.

Main Methods:

• Integration of a structurally flexible steel support system with limited-projection in-situ CBCT.
• Development of an improved prior image constrained compressed sensing reconstruction method (NLR-PICCS) incorporating total variation and non-local low-rank regularization.
• Quantitative analysis and optimization of core parameters like prior weight, registration error, and missing angle limits for missing projection angles (90°, 120°, 180°).

Main Results:

• The proposed NLR-PICCS method effectively reconstructs images from limited-projection CBCT data, overcoming X-ray attenuation issues from steel components.
• Optimized parameters demonstrated superior performance across various missing angle scenarios (90°, 120°, 180°).
• Simulations and experiments confirmed the method's superiority over existing limited-projection reconstruction techniques.

Conclusions:

• The developed flexible steel support and NLR-PICCS reconstruction method significantly expand stress loading capacity and improve operational flexibility for in-situ mechanical testing.
• This approach enables more accurate and reliable evaluation of material stress-strain characteristics for hard alloys under high stress.
• The study offers a promising advancement for in-situ mechanical non-destructive testing, particularly for challenging materials.