A Snapback Evaluation Technique for Synthetic Lines
Abstract
A technique is proposed for quantifying the amount of energy released when synthetic lines fail and recoil, called snapback. Ten synthetic line material/construction combinations are investigated by bending the line around a 1 in. diameter pin fixture and loading until failure occurs at the pin. High-speed photography is used to calculate the velocity of the line at failure and the attending kinetic energy. Three parameters are proposed to quantify snapback; (a) the Storage Energy Potential is a measure of how much energy a line stores as load is applied to it, (b) Snapback Energy Potential is a measure of the kinetic energy that the line possesses after failure occurs and the line recoils, and (c) the Energy Release Ratio indicates the proportion of stored energy that becomes kinetic energy after the line parts. In addition to discussing the evaluation technique, the various lines tested are compared to determine if some materials or constructions have a lower potential to snapback. The failure mechanism (i.e., the sequence of yarn failures that culminate in complete failure) of each line construction is observed using high-speed photography to determine if lines with a cascading failure mechanism (i.e., failure over a relatively long period of time) have lower snapback potential. The path that a line follows during snapback is also observed. Lines snap back directly toward the fixed end if the failure occurs in clear line. If a line retracts around the curved surface as a bollard, significant lateral velocity is imparted to the line and it sweeps a wide area.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1982
- Accession Number
- ADA119070
Entities
People
- Kenneth R. Bitting
Organizations
- United States Coast Guard Research & Development Center