Rope & Load Service

Minimum Breaking Load kN

Sustained Applied Load kN

Rope Length m

Hours Under Load h

Creep Behaviour Fibre data

Creep Rate at Reference %/1000 h

From a sustained-load creep test on the actual rope.

Reference Load Fraction %

Load Exponent n

Service Temperature °C

Reference Temperature °C

Rate Factor per 10 °C ×

Retirement Strain Limit %

Accumulated Creep Strain

— %

Permanent extension accumulated over the service hours

Creep Behaviour

Creep Rate in Service: — %/1000 h
Load as Fraction of MBL: — %
Load Acceleration: — ×
Temperature Acceleration: — ×
Permanent Elongation: — m
Hours to Retirement Strain: — h

Secondary creep at a steady rate is what this models, and it will not warn you about the end. Tertiary creep accelerates into creep rupture, which arrives without any change in appearance and is the actual failure mode for HMPE held at high load fraction — a line well inside its strain limit can still be close to rupture if the load fraction is high enough. Creep-resistant HMPE grades behave quite differently from standard ones and their constants are not interchangeable. Load is also assumed constant; cyclic and shock loading are separate mechanisms this does not cover. **Rope in lifting or life-safety service must be specified, inspected and retired under the applicable standards, not on the basis of this estimate.**

Synthetic Winch Line Creep & Permanent Elongation — free, with the formula and a worked example, at Textile School.