Failure Prediction of Superheater Tubes in Rotary Tube Bending Process Using GTN Damage Model

2018 ◽  
Vol 72 (2) ◽  
pp. 475-486 ◽  
Author(s):  
R. Safdarian
Keyword(s):  
Damage Model ◽  
Failure Prediction ◽  
Tube Bending ◽  
Bending Process ◽  
Gtn Damage Model

scholarly journals Experimental Investigation of the Effects of Irradiating Schemes in Laser Tube Bending Process

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1123
Author(s):  
Mehdi Safari ◽  
Ricardo J. Alves de Sousa ◽  
Jalal Joudaki
Keyword(s):  
Laser Beam ◽  
Contact Process ◽  
Steel Tube ◽  
Thickness Variation ◽  
Tube Bending ◽  
Lateral Bending ◽  
Bending Angle ◽  
Laser Tube ◽  
Bending Process ◽  
Thickness Variations

The laser tube bending process (LTBP) process is a thermal non-contact process for bending tubes with less springback and less thinning of the tube. In this paper, the laser tube bending process will be studied experimentally. The length of irradiation and irradiation scheme are two main affecting process parameters in the LTBP process. For this purpose, different samples according to two main irradiation schemes (Circular irradiating scheme (CIS) and axial irradiating scheme (AIS)) and different lengths of laser beam irradiation (from 4.7 to 28.2 mm) are fabricated. The main bending angle of laser-bent tube, lateral bending angle, ovality, and thickness variations is measured experimentally, and the effects of the irradiating scheme and the length of irradiation are investigated. An 18 mm diameter, 1 mm thick mild steel tube was bent with 1100 Watts laser beam. The results show that for both irradiating schemes, by increasing the irradiating length of the main and lateral bending angle, the ovality and thickness variation ratio of the bent tube are increased. In addition, for a similar irradiating length, the main bending angle with AIS is considerably higher than CIS. The lateral bending angle by AIS is much less than the lateral bending angle with CIS. The results demonstrate that the ovality percentage and the thickness variation ratio for the laser-bent tube obtained by CIS are much more than the values associated with by AIS laser-bent tube.

scholarly journals Forming limit diagram prediction of 6061 aluminum by GTN damage model

2018 ◽  
Vol 19 (2) ◽  
pp. 202 ◽  
Author(s):  
Rasoul Safdarian
Keyword(s):  
Damage Model ◽  
Forming Limit Diagram ◽  
Numerical Results ◽  
Experimental Results ◽  
Correct Selection ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Gtn Model ◽  
Gtn Damage Model

Forming limit diagram (FLD) is one of the formability criteria which is a plot of major strain versus minor strain. In the present study, Gurson-Tvergaard-Needleman (GTN) model is used for FLD prediction of aluminum alloy 6061. Whereas correct selection of GTN parameters’ is effective in the accuracy of this model, anti-inference method and numerical simulation of the uniaxial tensile test is used for identification of GTN parameters. Proper parameters of GTN model is imported to the finite element analysis of Nakazima test for FLD prediction. Whereas FLD is dependent on forming history and strain path, forming limit stress diagram (FLSD) based on the GTN damage model is also used for forming limit prediction in the numerical method. Numerical results for FLD, FLSD and punch’s load-displacement are compared with experimental results. Results show that there is a good agreement between the numerical and experimental results. The main drawback of numerical results for prediction of the right-hand side of FLD which was concluded in other researchers’ studies was solved in the present study by using GTN damage model.

Analysis for the Propagation of Edge Crack of Silicon Steel during Cold Rolling Process Based on GTN Damage Model

2012 ◽  
Vol 482-484 ◽  
pp. 487-492
Author(s):  
Yu Xi Yan ◽  
Quan Sun ◽  
Jian Jun Chen ◽  
Hong Liang Pan
Keyword(s):  
Cold Rolling ◽  
Edge Crack ◽  
Damage Model ◽  
Rolling Process ◽  
Silicon Steel ◽  
Damage Distribution ◽  
Initiation And Propagation ◽  
Gtn Damage Model ◽  
Edge Cracks ◽  
Good Agreement

Silicon steels tend to develop edge cracks during cold rolling, which need to be removed and cause rupture of the steel in the rolling mill. Hence, it is necessary to understand the formation of edge cracks. The damage distribution and the initiation and propagation of edge cracks occur around the notch tip during cold rolling process was investigated by using GTN damage model. The damage parameters f0, fcand fFare determined by tension experiments and SEM observation. The influence of various rolling parameters on damage distribution and crack length was simulated by using ABAQUS. The numerical results show that the GTN damage model is available to prediction the initiation and propagation of edge cracks during rolling process. Parametric study carried out in this present work reveals that the possible occurrence of edge cracks is higher at larger reduction, higher friction coefficient, smaller roll radius and stronger unit tension. The simulation and experimental results have a good agreement .

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