Analysis of the impact of position in fatigue cracks on the fracture toughness of thick-walled pressure vessel material

AbstractThe testing of fracture toughness thick-walled pressure vessel material showed a vast range of different results. Pressure vessels were made by hot plastic deformation treatment. Three sets of specimens were cut-out from the vessel, each having a same orientation of fatigue cracks in relation to the vessel axis. Fracture toughness tests were performed on the SENB specimens in accordance with ASTM 1820-11. The results showed a large range of different results, even within each sets of specimens. The results of fracture toughness in the initiation zone of stable crack growth were processed by means of Weibull statistical analysis. Based on these results of a direction distribution coefficient m was obtained and results reliability interval of fracture toughness was defined

Analiza uspješnosti supstitucije primijenjenog materijala pomoću parametara mehanike loma

By replacing the S355 conventional structural steel with V/Nb base micro-alloy steel it is possible to achieve a considerable reduction in the structure mass itself without safety risk, which is also proved by testing fracture mechanics properties of the materials. The numerical results have been also confirmed by analyzing the reliability of the selected materials, with special reference to safety from fracture hazard in the steel welded joints under consideration. Presented in the paper are the results of the numerical evaluation of the bridge crane steel structure under static and dynamic conditions for two steel grades and dimensions. This testing methodology can be applied to any kind of mechanical structure. It can also stress the importance of fracture mechanics application to the evaluation of the condition and behaviour of significant mechanical structures. The immediate effect of this investigation is the saving in the mass of the material used, together with a considerable fracture risk reduction, as well as an improvement in the working properties of the bridge crane steel structure.Zamjenom konvencionalnog strukturnog čelika S355 s mikrolegiranim čelikom na bazi V/Nb moguće je postići značajno smanjenje vlastite mase konstrukcije bez ugrožavanja sigurnosti što potvrđuju ispitivanja ponašanja materijala i sa aspekta mehanike loma. Numerička rješenja su potvrđena i kroz analizu sigurnosti izabranih materijala s posebnim osvrtom na aspekt sigurnosti od loma u zavarenom spoju predmetnih čelika. U radu su prikazani rezultati numeričke evaluacije čelične konstrukcije mosne dizalice u statičkim i dinamičkim uvjetima za dva kvaliteta i dvije dimenzije čeličnih limova. Primjenom navedene metodologije ispitivanja, koja se može implementirati na bilo koju vrstu strojarske strukture, kao konačan rezultat istraživanja dobiva se ušteda u masi ugrađenog materijala uz značajno smanjenje opasnosti od pojave loma i uz poboljšanje eksploatacijskih svojstava konstrukcije

Trends in the Development of Machinery and Associated Technology

ABSTRACT The dynamic behavior of two-storey vibrating screens for dry sifting is measured after its installation