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 (Deff)	Effective diameter of the semi-finished product (default = 7.5mm)
Anisotropy factor (KA)	Default = 0.9
Plastic Notch Factor – Nominal (Kp_sigma)	Default = 1
Plastic Notch Factor – Shear (Kp_tau)	Default = 1
Relative Stress Gradient X (G_sigmax)	Relative stress gradient in normal direction (Default = 0.1 mm-1)
Relative Stress Gradient Y (G_sigmay)	Relative stress gradient in normal direction (Default = 0.1 mm-1)
Relative Stress Gradient XY (G_sigmaxy)	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 (Rz)	Average roughness of the component surface, (default = 100 μm)
Surface Treatment Factor (Kv)	Default = 1
Coating Factor (Ks)	Default = 1
Temperature Factor (Ktd)	Default = 1
Material Safety factor (jF)	Material safety factor for non-welded steel based on regular inspection (default = 1.5)
Load Safety factor (jS)	Safety factor defined by design loads (default = 1.0)
Partial safety factor for allowable defects in castings (jG)	Material safety factor for Casted materials (default =1, as just steel is supported)
Total Safety Factor (jD)	Total safety factor, based on jF, jS, jD and KT,D , jD = jS . (jF/ KT,D)

The following are the parameters listed in My Material tab.

Parameter	Description
Tensile Strength (Rm)	Listed in SN tab (default = 300 N/mm2)
Yield Strength (Rp)	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_wzd)	Listed in SN tab (default = 140 N/mm2)
Shear Fatigue Limit (τ_wzd)	Listed in SN tab (default = 80 N/mm2)
Number of Cycles at Knee Point, Normal Stress (Nd_σ)	Listed in SN tab (default = 1e6 cycles)
Number of Cycles at Knee Point, Shear Stress (Nd_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 (fw_σ)	Listed in Other tab (default = 0.4)
Fatigue Stress Factor, Fully Reversed, Shear (fw_τ)	Listed in Other tab (default = 0.577)
Constant, Technological Size Factor for Tensile Strength (adm)	Listed in Other tab (default = 0.15)
Constant, Technological Size Factor for Yield Strength (adp)	Listed in Other tab (default = 0.4)
Constant, Technological Size Factor @ adm (Deff,N,m)	Listed in Other tab (default = 40mm)
Non-linear Strain Stress Factor under bending – GJL (KNL)	Listed in Other tab (default = 1.0)
aG Constant for (Kt-Kf) ratio for Fatigue Strength Factor (aG)	Listed in Other tab (default = 0.4)
bG Constant for (Kt-Kf) ratio for Fatigue Strength Factor (bG)	Listed in Other tab (default = 2400)
Constant For Roughness Factor, Normal Stress (aR_σ)	Listed in Other tab (default = 0.22)
Minimum permissible tensile strength constant (Rm,N,min)	Listed in Other tab (default = 400 N/mm2)
Constant for Mean Stress Sensitivity (aM)	Listed in Other tab (default = 0.35)
Constant for Mean Stress Sensitivity (bM)	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 ( $a_{S K}$ )(1)
$a_{S K} = (\frac{σ_{V}}{(\frac{σ_{S K}}{j_{D}})}) \leq 1$

$j_{D}$ = Total safety factor.