PARAMETERS
Screw Parameter (As per AAMA TIR A9-14)
D 5.5mm 0.217 in Nominal Thread Diameter
24
N Threads per inch
1in
4
FUB 600MPa 8.702 10 psi Minimum Ultimate Tensile Strength - Screw
4
FYB 450MPa 6.527 10 psi Minimum Tensile Yield Strength - Screw
KNMAX 0.1810in Maximum minor dia of internal thread
ESMIN 0.1850in Minimum pitch diameter of external thread
DSMIN 0.208in Minimum major dia of external thead
ENMAX 0.1930in Maximum pitch diameter of internal thread
Ply 1 Parameter - Fastened material
M P1 "Aluminum" Ply1 material type
4
FUP1 90MPa 1.305 10 psi Minimum Ultimate Tensile Strength - Ply1
4
FYP1 135MPa 1.958 10 psi Minimum Tensile Yield Strength - Ply1
HT1 "Normal" Hole type on ply 1
t1 3mm Thickness of ply 1
e1 12mm Edge distance for ply1
Ply 2 Parameter - Material not in-contact with screw head
M P2 "Aluminum" Ply2 material type
4
FUP2 210MPa 3.046 10 psi Minimum Ultimate Tensile Strength - Ply2
4
FYP2 160MPa 2.321 10 psi Minimum Tensile Yield Strength - Ply2
HT2 "Normal" Hole type on ply 2
t2 4mm Thickness of ply2
e2 12mm Edge distance for ply2
Allowable Tensile Stress Parameters
SF 3 Safety Factor
FUB
FT min 0.75FYB 200 MPa Allowable tensile stress
SF
2
AS D
π 0.9743 2
15.685 mm Tensile Stress Area
4 N
2
AT AS 0.024 in
2
AR D
π 1.2263 2
13.869 mm Thread Root Area
4 N
2
AR 0.021 in
Allowable Tension
TA FT AT 3.137 kN Allowable Tension
TA 705.226 lbf
Allowable Shear
FT
VA1 AR 1.601 kN Allowable shear
3
VA1 360.014 lbf
tp 10mm Packing thickness
9 D
βp 0.669 Reduction due to packing; note this formula is
8 D 3 tp based on BS EN as AAMA does not have a
section for packing
VA βp VA1 1.071 kN Allowable shear with reduction due to packing
VA 240.82 lbf
Allowable bearing at Ply
Note: All edge distance is more than twice the diameter of the screw
PAS1 if M P1 = "Steel" Allowable bearing for Ply1
3
if t1 in
16
0.333 t1 e1 FUP1 if e1 2.7D
0.9D t1 FUP1 otherwise
2.4 D t1 FUP1 otherwise
if M P1 = "Aluminum"
0.667 D t1 FUP1 if e1 2 D
0.333 t1 e1 FUP1 otherwise
PAS1 0.99 kN
PAS2 if M P2 = "Steel" Allowable bearing for Ply2
3
if t2 in
16
0.333 t2 e2 FUP2 if e2 2.7D
0.9D t2 FUP2 otherwise
2.4 D t2 FUP2 otherwise
if M P2 = "Aluminum"
0.667 D t2 FUP2 if e2 2 D
0.333 t2 e2 FUP2 otherwise
PAS2 3.082 kN
0.5 t2
1.4 t2 D
3
PAST FUP1 if 2.5
t1
min VA PAS1 PAS2 otherwise
PAST 2.364 kN
PB PAST 2.364 kN Allowable bearing
Allowable Pull-out
ATSE π KNMAX 0.57735 ESMIN KNMAX 8.49 mm
1
2N
2
2
ATSE 0.013 in External thread stripping area
TA SF 3 TA 3
tm1 max 9.676 mm Minimum thickness to develop the allowable
N ATSE FUP2 0.75 N ATSE FYP2 tension based on external threads
tm1 0.381 in
t2 N ATSE FUP2 t2 N ATSE 0.75FYP2
PA1 min 1.297 kN
SF 3 3
PA1 291.541 lbf Allowable external stripping strength
2 N 0.57735 DSMIN ENMAX 12.434 mm2
1
ATSI π DSMIN
2
ATSI 0.019 in Internal thread stripping area
Steel parameter for pull-out (applicable only if ply2 is steel)
0.85 D t2 FUP2
PE 1.309 kN Thin region capacity for steel
SF
0.375in N ATSI FUP2
PF 4.523 kN Transition region capacity
SF 3
TA SF Minimum thickness to develop the allowable
tm2s if t2 0.25in
0.85 D FUP2 tension based on internal threads if steel
0.125TA 0.375 PE 0.25PF
in if 0.25in t2 0.375in
PF PE
TA SF 3
otherwise
N ATSI FUP2
tm2s 0.377 in
0.85 D t2 FUP2
PAS if tm2s 0.25in
SF
3 N ATSI FUP2 1.7 D FUP2
t2 0.25in S 3 0.375in t2 S if 0.25in tm2s 0.375in
F F
t2 N ATSI FUP2
if tm2s 0.375in
SF 3
PAS 1.899 kN
Aluminum parameter for pull-out (applicable only if ply2 is aluminum)
0.665 π D FYP2 in
C1
SF 3
2 N ATSI FUP2 in
C2
SF 3
TA SF Minimum thickness to develop the allowable
tm2a if t2 0.08in
0.56 D FYP2 tension based on internal threads if aluminum
TA SF 3
if 0.08in t2 0.125in
0.665 D FYP2
TA 0.25 C1 0.125C2
in if 0.125in t2 0.25in
C2 C1
TA SF 3
otherwise
N ATSI FYP2
tm2a 0.258 in
0.85 D t2 FUP2
PAA if tm2a 0.25in
SF
3 N ATSI FUP2 1.7 D FUP2
t2 0.25in S 3 0.375in t2 S if 0.25in tm2a 0.375in
F F
t2 N ATSI FUP2
if tm2a 0.375in
SF 3
PAA 0.269 kN
Actual force occuring on single screw
v 0.35kN Actual shear
t 0.73kN Actual tension
Summary of capacity of the screw
VA 1.071 kN Shear capacity
TA 3.137 kN Tension capacity
PB 2.364 kN Bearing capacity of both plys
PA PAS if M P2 = "Steel" 0.269 kN Allowable pull-out capacity
PAA otherwise
Unity check
Bearing
v
RM1 0.148
PB Result1 "RM1 < 1; Therefore OK"
Pull-out
t
RM2 2.717
PA Result2 "RM2 > 1.0; revise"
Combined shear and tension
2 2
RM3
v
t
0.161 Result3 "RM3 < 1; Therefore OK"
VA TA
As per AAMA TIR A9-14 the unity ratio is
utilizied with the shear and tension not with
the bearing and pull-out capacity (formula 7.6)
