In this paper, for the first time, a safety assessment process is proposed for predicting
fatigue crack extension remaining life and crane load reduction use. The method is
based on fracture mechanics to establish a simulation model of the main girder of
a crane using on-site strain-gauge tests and related crack extension test
results. Establishing a statistical model based on the real work experience of a
crane, obtaining the stress-time history and load spectrum at the fatigue
calculation point on the crane girder through dynamic simulation. Expansion
simulations of a single initial crack with different deflection angles show that crack
deflection slows down the crack expansion rate, i.e., the smaller the deflection
angle, the smaller its lifetime. Expansion analyses of coplanar and adjacent
parallel surfaces multicracks were also performed to investigate the effects
of crack morphology changes during crack coalescence and coplanar crack
interactions on crack coalescence, as well as the effects of defect spacing on fatigue
life. For the single crack with a width of 4 mm, a load reduction analysis is
performed, and the simulation results indicate that the load reduction range is
–,
the fatigue remaining life of the crack is increased to
–
times the original value, the degree of load reduction and the remaining life is
compliant with the GB/T 41510-2022
Safety Assessment Rules for LiftingAppliances-General Requirements general requirements for crane safety
evaluation, indicating that the proposed approach in this paper for estimating fatigue
crack growth life and crane load reduction is viable and offers the benefits of a short
cycle and low cost.
