Naslov
Creep Analysis

Autori
Čanađija, Marko

Izvornik
Encyclopedia of Thermal Stresses

Vrsta, podvrsta
Ostale vrste radova, natuknica u enciklopediji, leksikonu, rječniku i sl.

Godina
2014

Ključne riječi
creep; temperature; thermal stresses

Sažetak
Engineers designing structures operating at higher temperatures noticed that at the constant level of stress, structural deformation continue to increase. Such behavior is known as creep and strains that occur as creep strains. An opposite effect is also known: if a structure is subjected to a constant strain at elevated temperatures, the stress level will decrease. The phenomenon is known as the stress relaxation. Strain rate becomes an important factor in the design and it is assumed to be influenced by the stress level and temperature. This strain accompanies usual, elastic strain. Most applications involving creep are concerned with the behavior below yielding point, but creep can be accompanied by the instantaneous plastic strain as well. The creep process is not limited to constant levels of stress ; it occurs as well in the case of variable stress levels. Although higher temperatures are usually understood as a trigger for creep and relaxation behavior, the phenomenon is present at room temperature in the case of some polymers and even metals – lead for an example. Beside already mentioned temperature and stress as basic variables influencing creep - grain size, alloying, prestrain and recovery are additional factors influencing creep. This text is intended to give a brief introduction to the problems of creep and relaxation analysis. The outline is as follows - initially typical curves representing this behavior are described. Discussion of creep mechanisms follows. Relations between stress and strain are presented for the uniaxial case and extended to the multiaxial case. To familiarize reader with the problem, three different applications are selected: stress relaxation of an uniaxially loaded bar, creep of a thin-walled tube and stress relaxation in a beam. At the end, some conclusions are given

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo, Temeljne tehničke znanosti

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