DEVELOPMENT OF THE THEORETICAL BASIS OF THE MRT METHOD OF WIRE ROPE TESTING TO KEEP UP WITH THE GROWING PROBLEMS OF WIRE ROPE OPERATION

Summary

This article presents the development, theoretical basis and current status of the magnetic rope testing (MRT) method. The importance of magnetic rope testing of modern structures has increased immeasurably because:

-      Visual testing of ropes does not ensure the safe operation of lifting equipment,

-      The dynamics of crane equipment operations has increased, and a low safety factor for ropes is still maintained.

-      Rope diameters of up to 150 [mm] have increased, as well as the number of wires in the rope,

-      Crane equipment uses multi-layered ropes with a low-torsion design, in which damage is mainly localized inside the rope,

-      Broken wires, abrasion, corrosion and deformation of wires occur together inside the rope especially at the boundary of the strand layers, which poses new challenges for the MRT method.

The development of the MRT method and apparatus required the development of a theoretical basis for understanding and correctly interpreting the test results.  The article presents an original mathematical description of the physical phenomena governing the MRT method. This allowed for the description and elimination of the influence of measurement interference factors such as the eccentricity of the position of broken wires, the length of the resulting gap and the density of the damage on the damage cross-sectional value determined from MRT tests.

Author(s): M. Martyna and R. Martyna