New calls for global security today, since operations the era of uncontested military superiority of western forces is fading and western response can't simply be to avoid operating in these environments but we should start to think about essential to protection of our potential in industry, population and infrastructure. It brings us back to refitting of rock massifs for fallout shelters requires an increasingly better knowledge of the composition, internal structure, geometry and depth extent of the individual rocks. This paper focuses on the long-term strength of a wide range of rock types that can be refitted for shelters.
The paper contains the results of a non-destructive laser ultrasound internal structure analysis made on specially prepared friction stir welded joints made of aluminum samples. The process was conducted using four different groups of welding parameters. Different tool rotation speeds and tool traverse speeds were used. The main purpose of the research was to analyze the joint quality using a non-destructive laser amplified ultrasound method. A microstructure analysis was also conducted to compare the results of both tests.