The ‘energy concept’ in critical groups of load calculation

• Published in: The International journal of pressure vessels and piping Vol. 38; no. 3; pp. 211 - 226
• Main Author: Jinescu, Valeriu V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1989
• ISSN: 0308-0161; 1879-3541
• DOI: 10.1016/0308-0161(89)90016-1

The critical load state generally results from achieving either a stress level (critical stress) or a deformation or strain level (critical deformation or critical strain). If the loads are of the same nature (mechanical, thermal, etc.) and produce the same effect (tension, compression, etc.), the critical load state is easily defined. However, if the loads are different in nature and effect, the critical state needs to be established. On the basis of the ‘energy concept’ this paper establishes a general relation defining the critical state produced by simultaneous action of loads differing in their nature and effect. The critical state is given by failure, by excessive deformation or by buckling. General and particular results are considered for the linear and nonlinear behaviour of materials. We have established some particular relationships which have been experimentally verified for critical groups of loads for mechanically and thermally loaded elements in buckling, creep, fatigue, etc. On this basis it is now possible to calculate the fatigue or creep lifetime under a group of different (mechanical, thermal, etc.) loads.