Finite Element Analysis of a Mechanical Fuse Failure

• Published in: Journal of failure analysis and prevention Vol. 20; no. 2; pp. 370 - 375
• Main Authors: Pimenta, A. R., Tavares, S. S. M., Diniz, M. G., Roco, R. A. A., Oliveira, M. J., Galiza, J. A. G., Gomes, A. V., Ferreira, D. S. R., Freitas, R. P.
• Format: Journal Article
• Language: English
• Published: Materials Park Springer Nature B.V 01.04.2020
• Subjects: Analytical chemistry; Chemical analysis; Crack propagation; Design engineering; Dimensional changes; Equipment costs; Error analysis; Error compensation; Failure analysis; Fatigue cracks; Fatigue failure; Finite element method; Fractography; Identification methods; Industrial equipment; Intergranular fracture; Mathematical analysis; Numerical methods; Quenching and tempering; Rolling mills; Safety factors; Stress concentration; Surface cracks; X ray fluorescence analysis
• ISSN: 1547-7029; 1864-1245
• DOI: 10.1007/s11668-020-00839-4

Industrial equipment is usually high in cost. Design engineering needs to specify fuses that have the role of protecting the main parts of the equipment. The aim of this work is to identify the reason that led to a high number of fractures in mechanical fuses of a rolling mill and suggest improvements to fix the problem. Two components were analyzed: one that failed and one that was used inside the equipment but did not fail. According to their datasheet, the components are made of quenched and tempered type 4140 (UNS G41400) steel. Chemical analysis of the fuse was performed using x-ray fluorescence. Microstructural and fractographic aspects were investigated by optical and scanning electron microscopy. The existence of surface cracks is investigated by liquid penetrant test. Tensile analyses in the component are made using analytical and numerical methods. Numeric analyses are performed by the finite element method. The chemical analysis is in agreement with that expected for type 4140. The fractographic analysis shows intergranular brittle fracture. No surface cracks are found by the liquid penetrant, and no evidence of fatigue mechanism fracture is found the fractographic analysis. All results indicate that the component fractured due to the action of overload. By comparing the numerical and analytical methods, it is possible to identify that the stress concentration in the fuse analyzed results has a value of 9.44% lower when the analytical method is used. It is possible to conclude that the analytical method causes an error in the design, which was not covered by the safety factor because mechanical fuses did not use a safety factor in their projects. Increasing the radius of stress concentration can compensate the error, without requiring dimensional changes in the component. A new component is manufactured according to this concept, which is in operation without any issues.