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IRED Conference Presentation

Finite Element Analysis of Metal Spinning

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IRED Conference Presentation

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  1. Prediction of Residual Stresses and Springback in Multi-pass Sheet Metal Spinning Using Finite Element Analysis Co-authors: Prof. Mahmoud Hamed Eng. Mohamed Abd-Alrazzaq Prof. Mohammad A. Younes

  2. Outline • Background • Recent Research Trends • Building of the FE Model • Validation of the FE Simulation • FE Results • Conclusions • Recommendations

  3. Background Multi-pass Sheet Metal Spinning Process

  4. Background Terminology:

  5. Brief History • Originated in ancient Egypt. • Travelled to China in the 10th century. • England during the reign of Edward III. • USA in the 19th century. • 1930s, first electrically driven spinning machine. • 1945, the first hydraulic lathes and template copying control (automatic spinning). • Mid 20th century: aircraft and aerospace industries in UK, USA, Germany and Sweden. • 1980’s, CNC spinning machines. • 21st century, novel components in automotive, aerospace, marine, defense and industrial applications

  6. Modern Applications Standard Nozzles Stainless Head 16" Nose Cone Rocket Fuel Tank Bottom Venturi Fuel Float for Aerospace Industry High-pressure gas bottles Bullets

  7. Recent Research Trends • The research in Multi-pass sheet metal spinning is still quite limited. • According to SCOPUS database:

  8. Recent Research Trends

  9. Springback Cont’d According to Han et al. (2013)

  10. Knowledge Gaps • Limited research regarding residual stresses has focused on multi-pass spinning process. • Mainly the effect of speed parameters such as feed ratio and mandrel speed was investigated for both springback and residual stresses • Very limited research on friction coefficient and number of spinning passes as influencing factors. • Limited work on the impact of the sheet thickness. • Severity of circumferential tensile residual stresses should be highlighted as an indicator of possible crack formation. • Consequently, the present study is intended to cover these knowledge gaps particularly for large size tanks and pressure vessel segments under difficult service conditions.

  11. Building of the FE Model • ABAQUS/CAE 6.13 software. • The sheet blank is modeled as a pure aluminum (A 1050-O). • A dynamic explicit analysis step has been used. • An 8-node reduced integration linear continuum shell elements (SC8R) • The simulations were conducted on a workstation of eight cores Intel® Xeon® CPU L5630, 2.13 GHz (2 processors) and 24 GB RAM. • Parallelization method was used to reduce the computational time significantly without affecting the accuracy of results

  12. Building of the FE Model

  13. Building of the FE Model • The FE simulations in this study were developed from the process settings of computer numerically controlled (CNC) multi-pass spinning experiments. • A retrofitted CNC spinning machine was operated using the Computer-Aided Manufacturing (CAM) software - Eding CNC Release 4.00.46 to establish the roller tool path as a CNC program. • The spinning FE simulation results obtained using ABAQUS/Explicit were imported to ABAQUS/Implicit to estimate the residual stresses and springbackin the spun cups using FE analysis with relaxation time of 3 seconds.

  14. Demo

  15. Considered Process Parameters Phase I Phase II

  16. Validation of the FE Simulation • Experimental Validation: Maximum Error: 6.09 %

  17. Validation of the FE Simulation • Experimental Validation: Maximum Error: 5.46%

  18. Validation of the FE Simulation • Experimental Validation: Maximum Error: 7.57 %

  19. Validation of the FE Simulation • Experimental Validation:Maximum Error: 7.36%

  20. Validation of the FE Simulation • Energy-based Validation (during process):

  21. Validation of the FE Simulation • Energy-based Validation (during relaxation):

  22. FE Results (Processing)

  23. FE Results (Relaxation)

  24. FE Results • Residual Stresses:

  25. FE Results • Residual Stresses:

  26. FE Results • Residual Stresses:

  27. Friction Coefficient FE Results • Residual Stresses:

  28. Number of spinning passes FE Results • Residual Stresses:

  29. FE Results • Springback: Controlling parameters:feed ratio, radial forceacting normal to cup wall surface, friction forcein line with the roller displacement along the cup wall (≅ radial force x friction coefficient), and unloading momentwhich is directly proportional to the sheet thickness cubed.

  30. FE Results • Springback: Using small number of spinning passes, the loading rate per pass is higher leading to larger unloading reaction with greater value of springback..

  31. FE Results • Springback: • As the process progresses, the plastic deformation increases and the springback value decreases. • At the final roller pass, the large radial force contributes to further increase in springback value.

  32. Conclusions • The final spinning pass has a major role in the development of springback and residual stresses in the spun cup. • The tensile residual stresses particularly in the tangential (hoop) direction are the controlling parameter of crack initiation and propagation during the service life of spun components especially those used in high-pressure vessels. • Mostly, the tangential (hoop) residual stresses are more serious on the performance of spun cups than the radial residual stresses. • Minimum tangential (hoop) residual stresses for safe tank bottoms can be achieved using higher sheet thickness, minimum feed ratio, small coefficient of friction and large number of spinning passes. • Minimum springback values for accurate aerospace and industrial components are obtained using smaller sheet thickness, minimum feed ratio, low coefficient of friction, and large number of passes. • Optimum combination between small springback and safe spun component can be realized using low levels of feed ratio and friction coefficient with large number of spinning passes. • There appears to be some dependence of springback values on wall thickness reduction of the spun cups, which can be attributed to strain hardening effect associated with thickness reduction and leading to higher yield stress σo to Young’s modulus E ratio (σo/E).

  33. Recommendations • Further experimental investigation of residual stresses using XRD technique in both the tangential (hoop) and radial directions. • Investigation of the correlation between springback relaxation and the level of residual stresses immediately after the spinning process which is still a dark area in the spinning knowledge. • Examination of other meshing strategies particularly for complex geometry spun parts.

  34. Thank You Contact Information: E-mail: mohammad.a.younes@gmail.com Tel.: +20-1221037855

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