**Sreelakshmi Pradeep**

Faheem K K

Faheem K K

**Pad Eye Design**

Shackles

Lifting Legs (Slings)

Chain Slings

Wire Rope Slings

Pad eyes

Anchor Shackles

Chain Shackles (D)

Lifting

Set

Miscellaneous

Dimension Fixing

Pad eye check

Shackle

& Sling

Load factors

& Safe Working Load

Design Procedure

What are the inputs ???

Rating or

Total weight to be lifted

But that is not the only load acting during lifting !!!

LOAD FACTORS !!

Dynamic Amplification Factor

Tilt effect

Skew load factor

Contingency factor

Additional FoS

Resultant Sling Load (RSL) =

Number of Pad eyes X Cos (Theta)

Rating x Load Factors

Important !!

Sling Angle (theta)

2.

Shackle

Working load limit

Select a standard shackle

Sling

Ultimate breaking strength

Select a standard sling

We have the RSL !!

Other Classification

Pin Diameter

Inside Width

Inside Length

Values to be considered

Inside width of the shackle > Thickness of pad eye = Tm + Tch > 0.75 x Inside width

Inside length of the shackle > Top Plate Clearance = Rm - Hd/2 > 0.75 x Inside length

Pin Dia < Hole Dia < 1.06 x Pin Dia

Allowable Stresses

1. Allowable shear stress : 0.4 Fy

2. Allowable bearing stress : 0.9 Fy

3. Allowable bending stress : 0.6 Fy

4. Allowable tension / compression stress : 0.6 Fy

5. Allowable shear in fillet weld : 0.3 Ft

6. Von Mises Stress: 0.9 Fy

Important Dimensions

Main plate thickness

Main plate radius

Cheek plate radius

Cheek plate thickness

Hole diameter

Checks

1. Strength Check

at the pad eye hole

2. Strength Check

at the pad eye base

3. Weld Check

Shear Check

Bearing Check

Tension Check

Hertzian Contact Stress Check

Shear check in Y-dir

Shear check in Z-dir

Tensile check

Bending check (Bending about Y-dir)

Bending check (Bending about Z-dir)

Von Mises Stress

Weld between main plate and 1st cheek plate

Weld between 1st cheek plate and 2nd cheek plate

Weld between main plate and deck plate

Strength Check

at the Pad eye Hole

1. Shear Check

Shear Stress

= F/(2 x A)

2. Bearing Check

Bearing Stress

= F/A

3. Tensile Check

Tensile Stress

= F/A

4. Contact Check

Contact Stress

=

Strength Check

at the Pad eye base

2. Shear Check Z-Z direction

Shear Stress

= F/A

6. Von Mises Stress

5. Tensile Check

Tensile Stress

= F/A

3. Bending Check - Z-Z Direction

Bending Stress

= BM/SMz

1. Shear Check Y-Y direction

Shear Stress

= F/A

4. Bending Check - Y-Y Direction

Bending Stress

= BM/SMy

σ11=Bending stress-Y + Bending stress-Z + Tensile stress

σ22=0

σ33=0

σ12=0

σ23=Resultant of Shear Stress in Y-dir and Z-dir

σv = sqrt( σ11^2 + 3 x σ23^2 )

Weld Check

Weld between main plate and deck plate

Weld between 1st cheek plate and 2nd cheek plate

Weld Stress

=

Weld between main plate and 1st cheek plate

Weld Stress

=

F

(pi x R1 x a)

x

t1 + t2

T

F

(pi x R2 x a)

x

t2

T

Tx=Bending -Y + Bending -Z + Tensile stress

Ty=Shear Stress in Y-dir

Tz=Shear Stress in Z-dir

T = sqrt( Tx^2 + Ty^2 + Tz^2 )

**Thank You !**

Deck plate thickness

Bracket size

Stiffener size underneath

Stiffener spacing

Stiffener span

Weld size

p - Load per unit length along line of contact between pad eye and shackle pin