pad-eye calculations and frame stress verification...simulation of lifting @ 2.5 swl using 4 lifting...
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W-Industries, Inc.Subsea Control Project: 14035 - BLIND FAITH UPS PANEL11500 Charles Road Engineer: Haider KazzazHouston, TX 77041 Date: April 20, 2007
Revision: 0D, (ECN: 14035-11) Length from Bolt Hole Center to Padeye Edge ( R ) 2.5 inches
Height (H) 1.75 inchesPadeye Width (W) 5 inches
Padeye Thickness (t) 0.5 inchesHole Diameter (D) 1.125 inchesPadeye Radius (R) 2.5 inches
Shackle Pin Diameter (Dp) 1 inchessafe working load for the unit (SWL) 3158 lbs
Number of pad-eyes (n) 4 lbsLift Point SWL (LPSWL) = SWL / n 789.5 lbs
%Out of Plane (%OOP) 5 %Sling Angle (θ) 60 degrees from horizontal
Pad-Eye Design Load (Fr) = 3xSWL / (N-1) . Cos(90-θ) 3,647 lbsVertical Load (Fv) = Fr x Sin (θ) 3,158 lbs
Horizontal Load (Fh) = Fr x Cos (θ) 1,823 lbsWeld Metal tensile strength (Wt) 69,610 psi
Lug Material 316LLug Material Yield Stress (Fy) 24,650 psi
Case -1 : Pad-eye Shear Stress
Actual Shear Stress (fv)= 1,882 psi
Allowable Shear Stress (fv) =0.4xFy 9,860 psi
Shear stress case pass (safe) when the actual shear stress is lower than the allowable shear stress
Checking Shear stress is OK
Case-2 : Pad-eye Combined stress
Actual Combined Bending, Tension and Out of Plane Stress: = 4,326 psi
Allowable Combined Stress =0.6xFy 14,790 psi
Combined stress case pass (safe) when the actual combined stress is lower than the allowable combined stress
Checking Combined stress is OK
Case-3 : Pad-eye Bearing stress
Bearing Stress = 7,293 psi
Allowable Bearing Stress =0.9xFy 22,185 psi
Bearing stress case pass (safe) when the actual combined stress is lower than the allowable combined stress
Checking Bearing stress is OK
Case-4 : Tear - Out Shear Stress
Stress Concentration Factor (SCF) = 3
Tear Out Shear Stress = 5,646 psi
Allowable Tear Out Shear Stress =0.85xFy 20,953 psi
Tear Out Shear Stress pass (safe) when the actual stress is lower than the allowable Tear - Out Shear Stress
Checking Tear - Out Shear Stress is OK
Pad-Eye Calculations and Frame Stress Verification
=× p
r
DtF
Figure - 1
=
−××
22
DRt
Fr
=
×
××+
×+
×
×
6
%
6
22 tW
HFOOPWtF
Wt
HF rvh
=− tDtRFSCF
h
r
...2.
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Case-5 : Pad-eye FEA
Results
Criteria of checking the FEA results
The loading is safe when Von Mises Stress (Figure-3) is lower than the allowable stress:
14100 psi
Allowable Stress = 0.85 x Fy = 20,953 lbs
Checking Loading Stress OK
Material Steel : Structural ( SS 316L)
Young Modulus 2.751e+007psi
Poisson Ratio 0.27
Density 0.289lb_in3
Thermal Expansion 0.0000117
Yield Strength 24656.4psi
Applied Loads: > sling load (3647 lb)> Out of Plane-1 (5% of Sling Load-182 lbs)> Out of Plane-2 (5% of Sling Load-182 lbs)
Figure - 3
Figure - 2
( ) =+++−+−+−= ]6)()()([21 222222
. yzxzxyzyzxyxMisesV τττσσσσσσσ
AllowableMisesV σσ <.
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Pad-eye Weld Calculations:
Weld Modulus
Total Weld Length Wl: 11 inches
Weld Section Modulus 11 in2 (Treated as a line)
Combined Stress Calculation
Weld Bending 295 lb/in
Weld Shear 166 lb/in
Weld Tension 287 lb/in
Combined stress 605 lb/in
Allowable stress and force per in of leg Allowable force per in of leg = .707*.47*yield stress= 8190.9 (lb/in)/(1 in leg)
Allowable Weld Stress (0.47xWt) Weld Allowable 11,586 psi
Weld Fillet Calculation
= Minimum Fillet Weld Size (ω) = 0.0738 inch
Applied Fillet Weld Size Used (ωa)= 0.25 inch
Actual Effective Weld Throat Area (wa)= 1.94 in2
Transverse Load Capability= 22,525 lbs
Criteria of checking the weld lengthEach stress (Twisting, Bending, Shear, Tension and Combined) should be less than the allowable force per in of legCheckingWeld length and stresses are OK
Criteria of checking the Weld FilletThe actual applied weld fillet should be greater than the calculated minimum fillet size (w)CheckingApplied Fillet Weld size (Wa) OK
=×
=x
hb S
HFf
==LFf h
v
==LFf v
t
ω==legofinperforceallowable
fff actual
allowable
actual
=×+× tW 22
=+×=3
2WtWSx
( ) =++= 22vtbactual ffff
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Simulation of Diagonal Lifting @ 1.5 SWL
Results
Criteria of checking the FEA results
The loading is safe when Von Mises Stress (Figure-5) is lower than the allowable stress:
7010 psi
Allowable Stress =0.85xFy= 20,953
Checking Loading Stress OK
Material Steel : Structural ( SS 316L)
Young Modulus 2.751e+007psi
Poisson Ratio 0.27
Density 0.289lb_in3
Thermal Expansion 0.0000117
Yield Strength 24656.4psi
Testing @ 1.5 SWL = 1.5 x 3158 = 4737 lbs
Figure - 5
Figure - 4
( ) =+++−+−+−= ]6)()()([21 222222
. yzxzxyzyzxyxMisesV τττσσσσσσσ
AllowableMisesV σσ <.
Figure - 4
Page 4 of 6
Simulation of Lifting @ 2.5 SWL Using 4 Lifting Points
Results
Criteria of checking the FEA results
The loading is safe when Von Mises Stress (Figure-5) is lower than the allowable stress:
16800 psi
Allowable Stress =0.85xFy= 20,953
Checking Loading Stress OK
Material Steel : Structural ( SS 316L)
Young Modulus 2.751e+007psi
Poisson Ratio 0.27
Density 0.289lb_in3
Thermal Expansion 0.0000117
Yield Strength 24656.4psi
Testing @ 2.5 SWL = 2.5 x 3158 = 7900 lbs
Figure - 7
( ) =+++−+−+−= ]6)()()([21 222222
. yzxzxyzyzxyxMisesV τττσσσσσσσ
AllowableMisesV σσ <.
Figure - 6
Page 5 of 6
Summary and Conclusion
A) Pad-eye design verificationActual Allowable Fail if Actual Stress >= Allowable stress
Stress PSI Stress PSI Ok / Fail
1,882 9,860 OK
4,326 14,790 OK
7,293 22,185 OK
5,646 20,953 OK
14100 20952.5 OK
B) Pad-eye Weld length VerificationActual Allowable Fail if Actual Stress >= Allowable stress
Stress lb/in Stress (force per in of leg) lb/in Ok / Fail
Weld Bending 295 8190.9 OK
Weld Shear 166 8190.9 OK
Weld Tension 287 8190.9 OK
Combined stress 605 8190.9 OK
C) Pad-eye Weld Fillet Verification
Applied Minimum Calculated Fail if Applied fillet <= Minimum FilletFillet (in) Fillet (in) Ok / Fail
Weld Fillet Calculation 0.25 0.0738 OK
D) FEA for FrameActual Allowable Fail if Actual Stress >= Allowable stress
Stress lb/in Stress PSI Ok / Fail
Simulation of Diagonal Lifting @ 1.5 SWL 7010 20952.5 OK
Simulation of Lifting @ 2.5 SWL Using 4 Lifting Points 16800 20,953 OK
ConclusionThe pad-eye is designed using 1/2” SS 316L @ 3 SWL. The pad-eye shape and dimensions were determined using engineering analysis, geometry constrains as well as FMC guidelines G03.33.
All the above mentioned items for the pad-eye part and weldment show a safe operation under the 3 SWL applied load.
The simulation of diagonal lifting @ 1.5 SWL shows that the Von Mises Stress found to be lower than the allowable stress
The simulation of lifting @ 2.5 SWL shows that the Von Mises Stress found to be lower than the allowable stress
Case # and Description
Case-3 : Pad-eye Bearing stress
Case-4 : Tear - Out Shear Stress
Case-5 : Pad-eye FEA
Case # and Description
Case-2 : Pad-eye Combined stress
Case # and Description
Case -1 : Pad-eye Shear Stress
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