SHMS FEA Review Prepared for Jefferson Lab Prepared
SHMS FEA Review Prepared for: Jefferson Lab Prepared by: AMSEC LLC
Introduction • • AMSEC LLC optimized the Jefferson Lab SHMS carriage design and performed a finite element analysis (FEA) Per ANSI/AISC 306 -05, the following stress criteria apply: – Bending Stress Allowable, σb = 0. 6*σy • For ASTM A 36 Steel, σy = 36 ksi, σb = 21. 6 ksi • For ASTM A 572 Steel, σy = 50 ksi, σb = 30 ksi – Shear Stress Allowable, τb = 0. 4*σy • For ASTM A 36 Steel, σy = 36 ksi, τb = 14. 4 ksi • For ASTM A 572 Steel, σy = 50 ksi, τb = 20 ksi Overstresses found will be examined with the following criteria: – Insure the overstress is a localized (peak) stress – Check to verify stress are below material yield strengths • For ASTM A 36 Steel, σy = 36 ksi, τy = 0. 5*σy = 18 ksi • For ASTM A 572 Steel, σy = 50 ksi, τy = 0. 5*σy = 25 ksi Per Jefferson Lab, the following buckling criteria apply: – Minimum Factor of Safety on Buckling = 1. 4 – Criteria applies only to buckling modes exhibiting downward gravity
Full Model The majority of the carriage structure is constructed with ASTM A 36 Steel Front pivot housing is constructed with ASTM A 572 Steel
Full Model – Maximum Von Mises Stress Overstress areas are localized and are examined further on following slides Scale is set to show elements above allowable in red
Criteria Plot – Elements Above Allowable Bending Stress Maximum Von Mises Stress = 35. 5 ksi, including both A 36 and A 572 Steel material Front pivot housing is constructed with ASTM A 572 Steel Scale is set to show maximum stress
Full Model – Maximum Shear Stress Overstress areas are localized and are examined further on following slides Scale is set to show elements above allowable in red
Criteria Plot – Elements Above Allowable Shear Stress Maximum Shear Stress = 17. 4 ksi, including both A 36 and A 572 Steel material Front pivot housing is constructed with ASTM A 572 Steel Scale is set to show maximum stress
Full Model – First Buckling Mode
Conclusion • • Weight of the SHMS carriage structure is approximately 103 tons, excluding concrete The Maximum Von Mises Stress was 35. 5 ksi – This was a peak stress, and was still found to be below yield The Maximum Shear Stress was 17. 4 ksi – This was a peak stress, and was still found to be below yield The first buckling mode had a factor of safety of 1. 4 – This accounts for the first real buckling mode
- Slides: 9