DVS 1608

Version: September 2011 Edition

List of Classification Parameters

Figure 1.

Formulation

Stress Component considered for evaluation

• ${\sigma }_T$ : Transverse component perpendicular to the axis of the weld
• ${\sigma }_L$ : Longitudinal component parallel to the axis of the weld
• $\tau$ : Shear Component

Corrected stress calculation

The stress value correction is carried out using the effective weld thickness.

Note: Refer to - Common Classification Parameters

Calculation of the Assessment stress value (numerator in utilization formulae)

(1)

$${\sigma }_{TA}\left(StressAmplitude\right)=\text{ (}{\sigma }_{T\max }-{\sigma }_{T\min }\text{)/2}$$

The stress amplitude is used as the numerator for the utilization calculation.

Fatigue Limit Calculation

The fatig98ue limit values ( ${\sigma }_{Tzul}$ , ${\sigma }_{Lzul}$ , and ${\tau }_{zul}$ ), are calculated based on the following regimes of Stress Ratio ®,

Reference: the DVS1608 regulation document section 7.2.2.

For nominal stress (longitudinal ${\sigma }_{Lzul}$ and transverse ${\sigma }_{Tzul}$ )

Regime 1: $\left(R_{\sigma }>1\right)$

$${\sigma }_{zul}=54\cdot {1.04}^{-x}\left(MPa\right)$$

Regime 2: $\left(-\infty \le R_{\sigma }\le 0\right)$

$${\sigma }_{zul}=46\cdot {1.04}^{-x}\left(\frac{1}{1+M_{\sigma }\frac{1+R_{\sigma }}{1-R_{\sigma }}}\right)\left(MPa\right)$$

Regime 3: $\left(0<R_{\sigma }<0.5\right)$

$${\sigma }_{zul}=42\cdot {1.04}^{-x}\left(\frac{1}{1+\frac{M_{\sigma }}{3}\left(\frac{1+R_{\sigma }}{1-R_{\sigma }}\right)}\right)\left(MPa\right)$$

Regime 4: $\left(0.5\le R_{\sigma }<1\right)$

$${\sigma }_{zul}=36.5\cdot {1.04}^{-x}\left(MPa\right)$$

$M_{\tau }$ is the mean stress sensitivity, the exponent x in the above equations is queried from the below notch detail tables:

Curve	B	B-	B+	C	C-	C+	D	D-
x	6	7	8	9	10	11	12	13

Curve	E1+	E1	E1-	E4+	E4	E4-	E5+	E5	E5-	E6+	E6	E6-
X	14	15	16	17	18	19	20	21	22	23	24	25

Curve	F1+	F1	F2
x	26	27	28

For shear stress, ${\tau }_{zul}$ ,

Regime 2: $(-1\le R_{\tau }\le 0)$

$${\tau }_{zul}=28\cdot {1.04}^{-x}\left(\frac{1}{1+M_{\tau }\frac{1+R_{\tau }}{1-R_{\tau }}}\right)\left(MPa\right)$$

Regime 3: $(0<R_{\tau }<0.5)$

$${\tau }_{zul}=26.5\cdot {1.04}^{-x}\left(\frac{1}{1+\frac{M_{\tau }}{3}\left(\frac{1+R_{\tau }}{1-R_{\tau }}\right)}\right)\left(MPa\right)$$

Regime 4: $(R_{\tau }\ge 0.5)$

$${\tau }_{zul}=24.4\cdot {1.04}^{-x}\left(MPa\right)$$

$M_{\tau }$ is the mean stress sensitivity, the exponent x in the above equations is queried from the below notch detail table:

Curve	G	H
x	0	9

The grinding bonus and the thickness factor is applied to the calculated fatigue limit for longitudinal and transverse and just the thickness factor to the calculated shear fatigue limit.

Utilization Factor Calculation

$U_T$ = ${\sigma }_{TA}/{\sigma }_{Tzul}$

$U_L$ = $U_L$ = ${\sigma }_{LA}/{\sigma }_{Lzul}$

$U_{\tau }$ = ${\tau }_A/{\tau }_{zul}$

Resultant Utilization Calculation

$$U_R=\sqrt[2]{{(U_T)}^2+{(U_L)}^2+{(U_{\tau })}^2+(U_{T}X{U}_L)}$$