SHMS FEA Review

Prepared for: Jefferson LabPrepared 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 A36 Steel, σy = 36 ksi, σb = 21.6 ksi

• For ASTM A572 Steel, σy = 50 ksi, σb = 30 ksi

– Shear Stress Allowable, τb = 0.4*σy

• For ASTM A36 Steel, σy = 36 ksi, τb = 14.4 ksi

• For ASTM A572 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 A36 Steel, σy = 36 ksi, τy = 0.5*σy = 18 ksi

• For ASTM A572 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

Front pivot housing is constructed with ASTM A572 Steel

The majority of the carriage structure is constructed with ASTM A36 Steel

Full Model – Maximum Von Mises Stress

Scale is set to show elements above allowable in red

Overstress areas are localized and are examined further on following slides

Criteria Plot – Elements Above Allowable Bending Stress

Scale is set to show maximum stress

Maximum Von Mises Stress = 35.5 ksi, including both A36 and A572 Steel material

Front pivot housing is constructed with ASTM A572 Steel

Full Model – Maximum Shear Stress

Scale is set to show elements above allowable in red

Overstress areas are localized and are examined further on following slides

Criteria Plot – Elements Above Allowable Shear Stress

Scale is set to show maximum stress

Maximum Shear Stress = 17.4 ksi, including both A36 and A572 Steel material

Front pivot housing is constructed with ASTM A572 Steel

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