Increased pitting allowed
| Symbol | - |
|---|---|
| Unit | - |
| Attribute-ID | abs_increased_pitting_permitted |
| Numeric ID | 17753 |
| Value Type | PMBoolean |
The life factor ZN for the tooth flank explains the higher permissible stress, including static load, permitted for a limited life (number of load cycles lower than fatigue strength) compared to the maximum permissible stress for fatigue strength.
The following options are available:
- Direct specification
Direct specification, exclusively for calculation acc. to ABS. - acc. to ABS
If not specified, the life factor for limited life time ZN is determined by using the table 4 (ABS 2019, 4-3-1A1).
When "increased pitting allowed" is activated, the curve represented as a dashed line is used for ZN.
| ZN | Life factor for the tooth flank |
| NL | Number of load cycles |
| 1 | Material group 1 : St, V, GGG (perl. bai.), GTS (perl.), Eh, IF a |
| 2 | Material group 2 : St, V, GGG (perl. bai.), GTS (perl.), Eh, IF |
| 3 | Material group 3 : GG, GGG (ferr.), NT (nitr.), NV (nitr.) |
| 4 | Material group 4 : NV (nitrocar.) |
| a | When limited pitting is permitted |
Examples:
- Material group 2 with number of load cycles NL=6*105 → ZN=1.4
- Material group 4 with number of load cycles NL=5*108 → ZN=0.9
Source: American Bureau of Shipping (ABS): Rules for Building and Classing Steel Vessels, Paramus, New Jersey - edition 2011 and 2019, 4-3-1A1/Table 4.