Field of Application
Welding is the most prevalent process used for joining steel elements. For the creation of a suitable weld numerous parameters must be complied with. Static loads can be tolerated up to a determined value. When the same load is cyclically applied local cracks form, gradually grow, and lead to failure.
The replacement or repair of dynamically stressed steel constructions that suffer from fatigue give rise to expenditures amounting to billions of Euros each year. Weld toes are often the root cause of crack formation with later growth of the cracks. In many cases they are limiting the service life of the constructions. Additionally unforeseeable variations in the operating conditions which could not be taken into consideration during the design phase, e.g. longer operating times, higher loads, and the wish for longer use further limits the service life. On new welded constructions the steels with higher strength cannot efficiently be used, since the welded joint often is decisive for the service life.
Well known mechanical processes like the internal grinding, the shot peening or the remelting-on indeed improve the fatigue resistance, however the results can not be proved and are less effective and almost non-reproducible.
The high-frequency peening process HiFIT however is:
- steel bridges
- building machines
- load suspension means
- wind power plants
- roller coasters
Analyses made in the University of D-Braunschweig have shown that in the building sector there is a strong shift in investment allocation from newer structures towards restoration and maintenance. The need for efficient and cost-effective restoration concepts becomes more urgent.
(Source: Institut für Bauwerkserhaltung und Tragwerk TU Braunschweig)