On the basis of principle of critical energy, one establishes a general relation for the correlation of the mechanical properties with the deterioration due to preloading. The effect of preloading and its sign on the fatigue strength and fatigue life is evaluated. The influence of thermal fatigue preloading on high temperature mechanical characteristics of a Cr-Mo steel quasi-static loaded was investigated.
We have provided a comparative analysis of the current international computing standards (European Standard EN 13445-3; ASME-Code, Section VIII, Division 2; British Standard (PD 5500: 2009)) that take into consideration only the static loading of flanges and bolts, if the temperatures of the flanges, bolts and sealing gasket are equal to each other and lower than creep temperature. The paper has put forth relations for completion the calculation method for flange joints in situations not taken into consideration by standards, namely: -static loading if flange temperature and bolt temperature are different; -thermal transient loading; -creep stress; -fatigue loading in the general case of a sequence of blocks of normal stresses. Furthermore, relationships have been proposed for the calculation of the maximum allowable difference between a flange and a bolt so as to ensure both the tightness and the mechanical strength of the flange joint.
The critical state of structures simultaneous loaded with different loads is analised taking into account the principle of critical energy. The general case is considered when the material behavior is non-linear according to the power law. The critical state is correlated with the deterioration produced by cracks and with the residual stresses. General relationships have been deduced for the correlation of loads or stresses acting on a cracked structure having residual stresses. The theoretical relationships were verified against results reported in literature.
This paper describes the analytical evaluation of the thermo - mechanical stresses developed in the circular flange assemblies, of optional type, welded to the cylindrical shell of a pressure vessel. In this case, the structure is formed by welding the cylindrical shell on the inner circumference of the flange ring. Based on the theory of deformation compatibility (radial displacements and rotations), the expressions for the evaluation of radial unitary bending moments and the unitary shear forces are deduced. Subsequently, stress values can be calculated and their concentration can be evaluated along the cylindrical shell, below the separation plane of the flange ring.
In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.