Eurocode 3

Version: December 2010 Edition

List of Classification Parameters

Evaluation Distance: Reference distance to find the evaluation location from the weld element at which the stress values are extracted.
Weld Width: Width of the weld material from the web wall. This parameter is ignored if specifying the evaluation distance is done manually.
Note: Refer to - Find Evaluation Positions.
Safety Factor (Gmf): Used in calculation of the corrected weld detail category.
Fatigue Limit Slope - Normal Stress (Md): Slope of the curve at the fatigue limit for normal stress components of tensor. Refer to location 2 in the graph.
Fatigue Limit Slope - Shear Stress (Md): Slope of the curve at the fatigue limit for shear stress components of tensor. Refer to location 2 in the graph.
Cutoff Limit Slope - Normal Stress (Ml): Slope of the curve at the cutoff limit for normal stress components of tensor. Refer to location 3 in the graph.
Cutoff Limit Slope - Shear Stress (Ml): Slope of the curve at the cutoff limit for shear stress components of tensor. Refer to location 3 in the graph.
Number of Cycles at Fatigue Limit (Nd): Number of cycles in the S-N curve at the fatigue limit.
Number of Cycles at Cutoff Limit (Nd): Number of cycles in the S-N curve at the cutoff limit.
Desired Cycles Detail From: Parameter that will show where HL-WC is reading the desired number of cycles from.

Location Wise Parameters

Note: Where ‘X’ in the below parameters can be any evaluation location from 1-10.

Weld Detail Category - Transverse Location_X: Weld detail category from the image below that will be considered for the calculation of fatigue and cutoff limits of the normal stress component in the transverse direction (perpendicular to the axis of the weld) at ‘X’.
Weld Detail Category - Longitudinal Location_X: Weld detail category from the image below that will be considered for the calculation of fatigue and cutoff limits of the normal stress component in the longitudinal direction (parallel to the axis of the weld) at ‘X’.
Weld Detail Category - Shear Location_X: Weld detail category from the image below that will be considered for the calculation of fatigue and cutoff limits of the shear stress component at ‘X’.
Material Yield - Location_X: Material yield value used for the static evaluation.

Symbols

Weld detail category (Normal) - Δσ_c
Weld detail category (Shear) - Δτ_c
Safety factor for strength - γ_Mf

Static Assessment

The following process is followed for Static assessment:

Retrieve the six components of stress from the element at the evaluation location.
Calculate the von Mises stress value using these stress components.
Retrieve the material yield value from the Points context.
Determine the static strength ratio: element von Mises stress / material yield value

Formulation

Stress Component Considered for Evaluation

Δσ_T - Transverse component (perpendicular to the axis of the weld)

Δσ_L - Longitudinal component (parallel to the axis of the weld)

Δτ - Shear component

Corrected Weld Detail Category

Δ σ_{c} (C o r r e c t e d) = \frac{Δ σ_{c, B a s i c}}{γ_{M f}}

Where:

$Δ σ_{c, B a s i c}$ - Weld detail category before correction.

Note: The above formulas are for the normal component. Similar formulas are applicable to other shear components as well.

Calculation of the Assessment Stress

In the case of Eurocode, stress range is used as assessment stress.

Δ σ (S t r e s s R a n g e) = (σ_{\max} - σ_{\min})

If effective stress range is enabled in evaluation to account for mean stress influence on fatigue strength for non-welded and stress-relieved welds, then stress range is calculated as shown below:

Δ σ (E f f e c t i v e S t r e s s R a n g e) = | σ_{\max} | + 0.6 | σ_{\min} |

Fatigue Limit Calculation (Δσ_D)

For Normal Component:

Δ σ_{D} = Δ σ_{c} \cdot {(\frac{2, 0 e + 6}{N_{D}})}^{(1 / m_{D})}

For Shear Component:

Δ σ_{D} = \infty

Where:

Δσ_c - Corrected stress range value
N_D - Number of cycles at fatigue limit
m_D - Slope at fatigue limit

Cutoff Limit Calculation (Δσ_L)

For Normal Component:

Δ σ_{L} = Δ σ_{D} \cdot {(\frac{N_{D}}{N_{L}})}^{(1 / m_{L})}

For Shear Component:

Δ σ_{L} = Δ σ_{c} \cdot {(\frac{2, 0 e + 6}{N_{L}})}^{(1 / m_{L})}

Where:

Δσ_c - Corrected stress range value
Δσ_D - Fatigue limit stress value
N_D - Number of cycles at fatigue limit
N_L - Number of cycles at cutoff limit
m_L - Slope at cutoff limit

Permissible Number of Cycles (N_perm)

\begin{array}{l} If Δ σ \geq Δ σ_{D} \\ N_{p e r m} = N_{D} \cdot {(\frac{Δ σ}{Δ σ_{D}})}^{(- m_{D})} \\ If Δ σ_{D} > Δ σ \geq Δ σ_{L} \\ N_{p e r m} = N_{L} \cdot {(\frac{Δ σ}{Δ σ_{L}})}^{(- m_{L})} \\ If Δ σ < Δ σ_{L} \\ N_{p e r m} = \infty \end{array}

Damage Calculation

D = \frac{N}{N_{p e r m}}

Where:

N - Desired number of cycles per load case combination, derived either from the range data file or the classification area.

Resultant Damage Calculation (D)

D = D_{δ, y}^{3} + D_{δ, x y}^{5}

Where:

$D_{δ, y}$ - Damage in transverse direction (perpendicular to the axis of the weld)
$D_{τ, x y}$ - Damage in the shear direction

Calculation of Accumulated Damage

For the corresponding damage components:

$\begin{array}{l} D_{δ, x, a c c} = \sum D_{x, i} \\ D_{δ, y, a c c} = \sum D_{y, i} \\ D_{τ, x y, a c c} = \sum D_{x y, i} \end{array}$

For resultant accumulated damage calculation:

$D = D_{δ, y, a c c}^{3} + D_{δ, x y, a c c}^{5}$

Note: DIN is the copyright owner for

EN 1999-1-3:2011-11 (November
                        2011)

. Permission to use and reproduce information contained in the Eurocode 3 standards was granted by DIN.