Vibration
S. J. Zakavi; B. Shiralivand; M. Nourbakhsh
Abstract
In this paper, the ratcheting behavior of carbon steel (ASTM A106B) and stainless steel (304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening ...
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In this paper, the ratcheting behavior of carbon steel (ASTM A106B) and stainless steel (304L) elbows is studied under steady internal pressure and in-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear isotropic/kinematic (combined) hardening model is used to evaluate ratcheting behavior of the elbows. Material parameters are obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The rate of ratcheting depends significantly on the magnitudes of the internal pressure, dynamic bending moment and material constants for combined hardening model. The results show that the maximum ratcheting occurs in the hoop direction at the crown. Also, the results show that initially, the calculated rate of ratcheting is large and then decreases with the increasing cycles. Also, the results obtained by using the combined hardening model gives acceptable adaptation in comparison with the other hardening models (AF and Chaboche hardening models); however, this model gives overestimated values comparing with the experimental data.
Manufacturing Processes
Ghader Faraji*; Mahmoud Mosavi Mashhadi; Karen Abrinia
Abstract
The current study conducted a finite element (FE) and experimental investigation on tubular channel angular pressing as a noble severe plastic deformation technique for producing ultrafine grained and nanostructure tubular components. To examine the effects of the TCAP process on the strain distribution ...
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The current study conducted a finite element (FE) and experimental investigation on tubular channel angular pressing as a noble severe plastic deformation technique for producing ultrafine grained and nanostructure tubular components. To examine the effects of the TCAP process on the strain distribution and deformation behavior, FE simulations were employed. The FE results demonstrated that equivalent plastic strain of 2.1-2.9 was developed after applying one pass TCAP. Analytical investigations were carried out to calculate the accumulated strain during the process. Tube thinning in the early stages of the process was observed as a result of tensile circumferential strains but this could be compensated for by the back pressure effect resulting from the next shear zones and also compressive circumferential strain resulting from decreasing the tube diameter. Microstructural observations showed significant grain refinement after one pass TCAP on AZ91 magnesium alloy at 300 ºC. Microhardness measurements demonstrated increasing hardness to 78 HV from the initial value of 51 HV.
