FKM Classification Parameters (Non-Welded)

The parameters for non-welded calculations are listed in both the Assign Material tab and the My Material tab of the Assign Material dialog.

The defaults are with respect to material = steel.

The following are the parameters listed in Assign Material tab.


Parameter	Description
Effective Diameter ( $D e f f$ )	Effective diameter of the semi-finished product (default = 7.5mm)
Anisotropy factor ( $K A$ )	Default = 0.9
Plastic Notch Factor – Nominal ( $K p_s i g m a$ )	Default = 1
Plastic Notch Factor – Shear ( $K p_t a u$ )	Default = 1
Relative Stress Gradient X ( $G_s i g \max$ )	Relative stress gradient in normal direction (Default = 0.1 mm-1)
Relative Stress Gradient Y ( $G_s i g m a y$ )	Relative stress gradient in normal direction (Default = 0.1 mm-1)
Relative Stress Gradient XY ( $G_s i g \max y$ )	Relative stress gradient in shear direction (Default = 0.1 mm-1)
Overload Factor (Overloading)	Parameter to decide overload situation. Options: F1, F2, F3, F4. Based on the selection, the fatigue limit calculation formula may vary. (Default – F2)
Surface Roughness ( $R x$ )	Average roughness of the component surface, (default = 100 μm)
Surface Treatment Factor ( $K v$ )	Default = 1
Coating Factor ( $K s$ )	Default = 1
Temperature Factor ( $K t d$ )	Default = 1
Material Safety factor ( $j F$ )	Material safety factor for non-welded steel based on regular inspection (default = 1.5)
Load Safety factor ( $j S$ )	Safety factor defined by design loads (default = 1.0)
Partial safety factor for allowable defects in castings ( $j G$ )	Material safety factor for Casted materials (default =1, as just steel is supported)
Total Safety Factor ( $j D$ )	Total safety factor, based on $j F$ , $j S$ , $j D$ and $K T$ , $D$ , $j D$ = $j S$ . ( $j F$ / $K T$ , $D$ )

The following are the parameters listed in My Material tab.


Parameter	Description
Tensile Strength ( $R m$ )	Listed in SN tab (default = 300 N/mm2)
Yield Strength ( $R p$ )	Listed in SN tab (default = 180 N/mm2)
Elastic Modulus ( $E$ )	Listed in SN tab (default = 2e5 N/mm2)
Strain At Break Point (A%)	Listed in SN tab (default = 10% or 0.1)
Normal Fatigue Limit ( $σ_w z d$ )	Listed in SN tab (default = 140 N/mm2)
Shear Fatigue Limit ( $τ_w z d$ )	Listed in SN tab (default = 80 N/mm2)
Number of Cycles at Knee Point, Normal Stress ( $N d_σ$ )	Listed in SN tab (default = 1e6 cycles)
Number of Cycles at Knee Point, Shear Stress ( $N d_τ$ )	Listed in SN tab (default = 1e6 cycles)
SN curve slope, Normal Stress ( $K_σ$ )	Listed in SN tab (default = 5)
SN curve slope, Shear Stress ( $K_τ$ )	Listed in SN tab (default = 8)
Fatigue Stress Factor, Fully Reversed, Normal ( $f w_σ$ )	Listed in Other tab (default = 0.4)
Fatigue Stress Factor, Fully Reversed, Shear ( $f w_τ$ )	Listed in Other tab (default = 0.577)
Constant, Technological Size Factor for Tensile Strength ( $a d m$ )	Listed in Other tab (default = 0.15)
Constant, Technological Size Factor for Yield Strength ( $a d p$ )	Listed in Other tab (default = 0.4)
Constant, Technological Size Factor @ adm ( $D e f f, N, m$ )	Listed in Other tab (default = 40mm)
Non-linear Strain Stress Factor under bending – $G J L$ ( $K N L$ )	Listed in Other tab (default = 1.0)
$a G$ Constant for ( $K t - K f$ ) ratio for Fatigue Strength Factor ( $a G$ )	Listed in Other tab (default = 0.4)
$b G$ Constant for ( $K t - K f$ ) ratio for Fatigue Strength Factor (\ $b G$ )	Listed in Other tab (default = 2400)
Constant For Roughness Factor, Normal Stress ( $a R_σ$ )	Listed in Other tab (default = 0.22)
Minimum permissible tensile strength constant ( $R m, N, \min$ )	Listed in Other tab (default = 400 N/mm2)
Constant for Mean Stress Sensitivity ( $a M$ )	Listed in Other tab (default = 0.35)
Constant for Mean Stress Sensitivity ( $b M$ )	Listed in Other tab (default = -0.1)
Compression Strength Factor, for tension, compression ( $f_σ$ )	Listed in Other tab (default = 1.0)
Compression Strength Factor, Shear ( $f_τ$ )	Listed in Other tab (default = 1.0)
Material Parameter Epsilon_0 (Epsilon_0)	Listed in Other tab (default = 0.05)
Ductility factor (q)	Listed in Other tab (default = 0)

Formulation

Current support in the evaluation build is for steel only.

Cyclic degree of utilization for normal and shear stresses:

Assessment

[ Stress amplitude / (critical amplitude/total safety factor)]

$a B K x = σ a x / (σ B K x / j D) \leq 1,$

$a B K y = σ a y / (σ B K y / j D) \leq 1,$

$a B K x y = T a x y / (T B K x y / j D) \leq 1,$

Master Assessment Calculation

a_{N H} = \frac{1}{2} \cdot (| a_{B K, x} + a_{B K, y} | + \sqrt{{(a_{B K, x} - a_{B K, y})}^{2} + 4 \cdot a_{B K, τ}^{2}})

$a_{G H} = \sqrt{a_{B K, x}^{2} + a_{B K, y}^{2} - a_{B K, x} \cdot a_{B K, y} + a_{B K, τ}^{2}}$

$a_{B K, σ v} = q \cdot a_{N H} + (1 - q) \cdot a_{G H} \leq 1$

Formulation for Static Assessment

The following process is followed for Static Assessment (non-welded):

Equivalent Stress ( $σ_{V}$ ) = Maximum combined stress across all loadcases in the event.
Calculate Static Strength ( $σ_{S K}$ ).
$σ_{S K} = R p * n p l$
$R_{p}$ = Modified yield strength calculated from Size factor, Anisotropy factor and Yield strength.
$n_{p l}$ = Plastic support factor.
Calculate Static Utilization ( $a_{S K}$ )
Figure 1.

$a_{S K} = (\frac{σ_{V}}{(\frac{σ_{S K}}{j_{D}})}) \leq 1$

$j_{D}$ = Total safety factor.