#round 3 "Lug Analysis 'This calculator evaluates the load capacity of a lug with a pin-loaded hole by checking three failure modes: bearing, net tension, and shear tearout. The governing capacity is the minimum of the three. "References 'Ref 1: Bruhn, E.F., 1973, Analysis and Design of Flight Vehicle Structures, Jacobs Publishing "Inputs '

Lug Geometry

' Lug thickness -'t = ? {20}mm ' Lug width -'w = ? {80}mm ' Hole diameter -'D_h = ? {26}mm ' Edge distance from hole centre to lug end -'e = ? {40}mm '

Material Properties

' Ultimate tensile strength -'f_tu = ? {500}MPa ' Yield strength -'f_y = ? {355}MPa '

Applied Load

' Applied axial load on lug -'P = ? {100000}N "Calculations '

'Click to expand/collapse detailed calculations '

Material Allowables

f_br = 1.5*f_y ' Bearing allowable stress -'f_br '

[Ref 1, Ch. D1]

f_su = 0.6*f_tu ' Shear ultimate strength -'f_su '

[Ref 1, Ch. D1]

Bearing Check

A_br = D_h*t ' Bearing projected area -'A_br P_br = f_br*A_br ' Bearing capacity -'P_br '

[Ref 1, Ch. D1]

Net Tension Check

A_nt = (w - D_h)*t ' Net tension area -'A_nt P_nt = f_tu*A_nt ' Net tension capacity -'P_nt '

[Ref 1, Ch. D1]

Shear Tearout Check

A_st = 2*(e - D_h/2)*t ' Shear tearout area -'A_st P_st = f_su*A_st ' Shear tearout capacity -'P_st '

[Ref 1, Ch. D1]

Governing Capacity

P_gov = P_br #if P_nt < P_gov P_gov = P_nt #end if #if P_st < P_gov P_gov = P_st #end if ' Governing lug capacity -'P_gov '

Utilization

util = P/P_gov ' Utilization ratio -'util '

"Results 'Bearing Capacity: P_br 'Net Tension Capacity: P_nt 'Shear Tearout Capacity: P_st 'Governing Capacity: P_gov 'Applied Load: P 'Utilization: util '

Assessment

#if util ≤ 1 '

PASS - Lug Analysis

Utilization = 'util' is less than or equal to 1.0

Applied load of 'P' is within the governing capacity of 'P_gov'

#else '

FAIL - Lug Analysis

Utilization = 'util' is greater than 1.0

Applied load of 'P' exceeds the governing capacity of 'P_gov'

Increase lug thickness, width, or edge distance.

#end if '

Failure Mode Summary

σ_br = P/A_br|MPa ' Bearing stress -'σ_br util_br = P/P_br ' Bearing utilization -'util_br σ_nt = P/A_nt|MPa ' Net tension stress -'σ_nt util_nt = P/P_nt ' Net tension utilization -'util_nt τ_st = P/A_st|MPa ' Shear tearout stress -'τ_st util_st = P/P_st ' Shear tearout utilization -'util_st "Conclusion 'The lug with thickness 't', width 'w', and hole diameter 'D_h' has been analyzed for three failure modes. Bearing capacity is 'P_br', net tension capacity is 'P_nt', and shear tearout capacity is 'P_st'. The governing capacity is 'P_gov' giving a utilization of 'util'.

Lug Analysis

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