Study on fatigue test method for K-joints of crane lattice booms based on hot spot stress distribution
CAI Fuhai
WANG Xin
SHENG Lin
YIN Hongcheng
GAO Shunde
Abstract：[Objective]Crane lattice booms feature numerous welds and complex stress conditions,and their fatigue tests are plagued by difficulties such as limited samples,long test time,and high costs.Therefore,this paper aims to obtain a stress distribution in an individual K-joint that is equivalent to that of the integral boom,so as to simplify the analysis.[Methods]Firstly,five feasible fixture schemes for the K-joint were determined.Secondly,a quantitative comparison was carried out on the equivalent hot spot stress distribution in the critical region.Finally,fatigue tests were performed on two constraint modes with stress distributions relatively close to the actual situation,and the test results were analyzed.[Results]The results show that the hot spot stress distributions under the two constraint modes-axial loading on a single chord member and loading with auxiliary members,are relatively consistent with the actual stress distribution of joints in the integral boom,and are more reasonable than loading schemes where loads act simultaneously on the chord and brace members or solely on the brace members.The median error of fatigue life under the auxiliary member constraint loading scheme is no more than 10%.When low precision is acceptable for fatigue tests,single-chord loading is a relatively simple fatigue test method,with a median error not exceeding 20%.The two loading schemes(single-chord axial loading and auxiliary member loading)can be used to analyze critical joints of the integral booms,providing a reference for the selection of fatigue test methods for crane booms.
Keywords：CraneLattice boomK-jointFatigue test methodEquivalent hot spot stress distribution
Publication Date：2026-05-31
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：8( 75-82 )