US 11,703,075 B1
Biased equivalent strength threaded joint for dissimilar strength structural materials
Benjamin M. Blazek, Ridgecrest, CA (US); and Lee R. Hardt, Ridgecrest, CA (US)
Assigned to The United States of America, as represented by the Secretary of the Navy, Washington, DC (US)
Filed by The United States of America, as represented by the Secretary of the Navy, Arlington, VA (US)
Filed on Jun. 4, 2020, as Appl. No. 16/892,831.
Int. Cl. F16B 37/02 (2006.01); F16B 37/08 (2006.01); F16B 31/04 (2006.01)
CPC F16B 37/02 (2013.01) [F16B 31/04 (2013.01); F16B 37/08 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A biased equivalent strength threaded (BEST) joint for dissimilar strength materials , comprising:
a first structural member having a proximal end, a distal end, an inner surface, a threaded outer surface, and a wall defined by said inner surface and said outer surface, said first structural member centered about a central longitudinal axis;
a second structural member having a threaded inner surface, a smooth outer surface, and a wall defined by said inner surface and said outer surface, said second structural member concentric about said first structural member, wherein said first and second structural members are configured to threadingly-engage with each other;
wherein said threaded outer surface of said first structural member having a plurality of threads with a thread thickness, wA;
wherein said threaded inner surface of said second structural member having a plurality of threads with a thread thickness, wB;
wherein said thread thickness, wA, of said threaded outer surface of said first structural member and said thread thickness, wB, of said threaded inner surface of said second structural member are not equal;
wherein said thread thickness, wA, of said threaded outer surface of said first structural member is mathematically defined as:

OG Complex Work Unit Math
wherein said thread thickness, wB, of said threaded inner surface of said second structural member is mathematically defined as:

OG Complex Work Unit Math
wherein pitch ≡ P = wA + wB;
wherein s = confidence offset ratio, set to 1 for equal factors of safety;
wherein Sallow,A = allowable shear stress of said first structural member; and
wherein Sallow,B = allowable shear stress of said second structural member.