Steel Mechanical Properties And Failure Mechanism

The strands are twisted from high-tensile steel wires, and wire ropes are twisted from the strands. The good mechanical capabilities of wire ropes are due to its special structure. And its used reliability and structural diversity have also been demonstrated unique advantages. Therefore, wire ropes are widely used in various engineering fields. But there are still a lot of technical problems in the field of design, manufacture, usage, maintenance about wire ropes now. And even there is not certain safety factor in the usage. So the engineering structures of wire ropes come forth often unexpected accidents.There are some researches on the issue of failure mechanism and non destructive testing (NDT) of wire ropes in this paper. Firstly, the stresses of the core and side strands change in the axial load are analyzed by using Costello's linear mathematical model for numerical calculation from a macroscopic and linear point of view. And the solutions are proposed for the resulting failure form.Finite element analysis method is replenished effectively the lack of the Costello's linear model analysis in contact. There are some discussion in detail the similarities and differences of the axial stresses, contact stresses and Von Mises stresses of the core wires, middle wires and outer wires in both fixed-end and free-end case by finite element analysis method in this paper. And further the mechanism of geometric and plastic abrasion failure in different stress states is analyzed. As well as, the methods and measures resolving the failure are given.At the same time, there is a pioneering research of wire ropes in the NDT methods based on the dynamics in this paper. According to string vibration equation, the mathematical equation of broken wires based on the dynamics is established. And the mathematical relationship between the number of broken wires and vibration frequencies can be gained following above equation. A new research idea for wire rope's NDT method is provided.Finally, there reveals further that the difference of broken section owing to the different stresses, the differences of microstructure owing to different abrasion failure, as well as the difference of microstructure owing to the different corrosion failure about wire ropes and so on from a microscopic point of view.In short, because of the complex employment status of wire rope, the failure modes show very diversity. Analyzing the failure mechanism of wire rope from one aspect in isolation is obviously unscientific. So we must take into account various factors comprehensively. And replace new wire ropes in time according to the standard of wire rope discard as useless. Thereby, we can minimize the accidents. The theory of wire rope calculation, NDT and failure analysis are provided by this thesis.