AIRCRAFT HARDWARE, CONTROL CABLES, AND TURNBUCKLES

3. How does this all work to insure a fully analyzed Bolted joint Installation??? As follows..

3.1 MIL-HDBK-5 Para 8.1.5 discusses how to analyze for “standard bolts” [not shear head, because reduced fasteners may fail the head in pin bending when shear-loaded... think-about-it].

3.2 MIL-HDBK-5 Table 8.1.5(a) defines absolute shear strength of generic “bolts”, based on known [heat treat] shear-stress capability. ANXX bolts are roughly 75-KSI and NAS62XX Bolts are 95-KSI [approx values ONLY]. NOTE: the NASM3—20 spec actually provides max rated strength for each bolt size. Example form this table for a 0.250-In diameter 75-KSI shear bolt: P (shear-ult) = 3680-lbs

3.3 MIL-HDBK-5 Table 8.1.5.1. Unit Bearing Strength of Sheet and Plate in Joints With Threaded Fasteners or Pins; Fbru = 100 KSI. This defines bearing-tear-out for “generic 100-KSI material [try finding it]. The intent is to match fastener [hole] diameter and sheet thickness to determine a “shear ultimate”… based on 100-KSI material. This number is then factored up/down based on the FBru of the “real-world” alloy being analyzed. Example [MIL-HDBK-5J, Table 8.1.5.1]: 0.250-In Dia Hole thru 0.10-thick material (at 100-KSI Fbru) = 2500-lbs bearing force. For 7075-T6 sheet, 0.10-thick, 2-D edge distance, from table 3.7.6.0(b1), Fbru (A) = 156-KSI. Therefore max allowable bearing load for this sheet metal is 156/100 x 2500-lbs = 1.56 x 2500 = 3900-lbs

3.3 Comparing shear ultimate VS material Bearing ultimate determines MAX allowed P (shear) at this location. Example [for the 0.250-dia bolt in 0.100-thick sheet]: Bolt Shear Ult = 3680-lbs Hole Bearing Ult = 3900-lbs Therefore, Ult allowable load at this hole is the lesser of these loads = 3680-lbs [bolt fails slightly before the hole fully-tears-out, not a bad joint if I do say-so]. Note: this analysis presumes a "standard head bolt" with a shear-rated nut [W/WO a washer].
Regards, Wil Taylor