Failure analysis of a pull rod actuator of an ATOX raw mill used in the cement production process

Ruben Barata, Rui F. Martins, Tiago Albarran, Tiago Santos, A. Mourão

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


A failure analysis of a forged and machined pull rod made of a quenched and tempered high strength steel – namely DIN 34CrNiMo6 – is presented in this paper. The pull rod under study is one of the three rods that connect the three existing hydraulic cylinders to the roller mill and it is used to exert grinding pressure on the roller in an ATOX raw mill. The study of the failure involved the mechanical system's simulation, as well as the fatigue damage assessment based on the application of the Rainflow Method and Fracture Mechanics principles. The pull rod's stress state was determined from in situ strain gages rosettes measurements, and system's simulation showed that the pull rod was designed to support axial loadings only. To ensure this stress state, a proper functioning of the plain bearings and a good condition of the elastomers of the horizontal rod buffer are required. According to the stress-life approach given in the FKM guideline, the current design solution should provide a useful life of 50 years to the pull rod. However, fatigue crack growth calculations made with the strain spectra registered demonstrated that the presence of an initial surface crack is extremely harsh to the lifespan of the rod, which will reach a critical value in a much shorter period of time. Surface finish, corrosion protection and maintenance actions to ensure the correct functioning of the plain bearings, could be important to ensure the desired longevity of the pull rod.

Original languageEnglish
Pages (from-to)99-114
Number of pages16
JournalEngineering Failure Analysis
Publication statusPublished - Jun 2017


  • ATOX raw mill
  • Failure analysis
  • Fatigue life prediction
  • FKM-Guideline
  • Strain gages


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