Neįmanoma pagerinti mašinų kokybę, padidinti jų patikimumą ir ilgaamžiškumą, jeigu darbo sąlygos ir medžiagų savybės nėra išanalizuotos. Mes privalome žinoti, medžiagos (kietėjimą, minkštėjimą arba ciklinį stabilumą), kas yra parinkta statinio mažaciklio apkrovimo tipuose, nes įtampos ir apkrovos kaita priklausys nuo šio tipo. Jei mes žinome apie medžiagos rūšį, mes galime nustatyti jos taikymo naudojimo sąlygos galimybes. / It is impossible to improve the quality of the machines, to increase their reliability and lifetime if the working conditions and the properties of the material are not analyzed. We must know the type of the material (hardening, softening or cyclically stabile), what is chosen for the constructions in low cycle loading, because strain and stress change during the exploitation and depend on this type. If we know the type of the material, we can determine the possibility of its application in concrete exploitation conditions.

Stulpinaitė A. Parameters of low cycle fatigue curves according to elastic and plastic strain: Master thesis of mechanical engineer / research advisor associate professor dr. R. Šniuolis; Šiauliai University, Technological Faculty, Mechanical Engineering Department. – Šiauliai, 2004. -60p. Parameters of fracture (parameters of low cycle fatigue curves m, C) are determined at homogeneous stress state and symmetric or asymmetric low cycle straining. Low cycle loading in structures appear near stress concentrators, cracks in little volumes of material which is limited of elastic strained zones. The elastic plastic loading may be in the welded joints, too. In the condition of variable loading the elastic strained metal impedes the accumulation of strain in these areas. Therefore the conditions of straining in these areas are similar to low cycle straining. At low cycle loading lifetime depends on reduction of areay. Coffin’s equation for calculation of constant C is not suitable for most materials and more complex equations must be used. Parameter C markedly differs from the experimental, therefore high errors occur in evaluating lifetime of the material. It is noticed in many works that parameter proposed by Coffin is close to experimental. Parameter m = 0,5, proposed by Coffin, is determined according the low cycle fatigue curves in coordinates . In some works the total strain e is used instead of plastic strain d . The difference of values of parameter m in this case is... [to full text]