Study on Fatigue Design Method of an Engine Component Produced by Flake Graphite Cast Iron for Different Loading Modes and Mean Stresses

Shirato, Kiyoshi; Miyashita, Yukio; Nishimizu, Takahiro; Takahashi, Kouhei; Eto, Hirohito; Shinya, Nobuaki; Hirukawa, Kouji

doi:10.1007/s40962-017-0206-z

Cited by 8 publications

(2 citation statements)

References 11 publications

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“…This agreed with the fact that the crack initiated from the region R u of the bolt under-head that was opposite to the weld bead side in the full-circled sample as shown in Figure 5, because the cracks generate and propagate preferentially from the tensile side but not from the compressive side. 7,15,16 Accordingly, the strength decrease of 15% of the full-circled sample comparing with the bolt-only sample was mainly due to the tensile residual stress in the bolt under-head, because their fracture mechanisms were comparable as mentioned in the above section.…”

Section: Resultsmentioning

confidence: 74%

“…The hardness was 292 HV, and it is inferred that the carbon content was increased by weld penetrations from the plate and the bolt, as well as that the cooling rate was considerably fast after the welding. Based on Fe-C equilibrium phase diagram and continuous cooling transformation diagram of austenite phase (A), 5,16–18 the phase transformation process cooling from high temperature liquid (L) in the weld zone with the analysed alloying composition is expressed as follows …”

Section: Resultsmentioning

confidence: 99%

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Bending fatigue behaviour and microstructure in welded high-strength bolt structures

Oh¹,

Akiniwa

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

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Welded high-strength bolts are recently being applied to automobile part fixations, and it is important to clarify their fatigue behaviours and to carry out the fatigue strength designs for preventing fatigue failures. Using the spot and full-circled welded bracket samples in four kinds of weld shapes, bending fatigue strength properties of welded high-strength bolt structures were examined. Factors affecting fatigue to failure, such as weld bead shapes and metal structures, were identified through local stress measurements with strain gauges and X-ray diffractions, microscope observations and chemical composition analyses, as well as stress concentrations of finite element method computational simulation. Differences of bending fatigue strengths at 2 × 105 cycles in welded bolt structure samples when based on nominal stress are 15% to 60% compared with the bolt itself. Fatigue strengths corresponded to four kinds of fracture modes and did not decline greatly in the full-circled welded structure. The spot P sample, in which the connecting line between the two centres of the weld beads was perpendicular to the load direction, has higher strength due to the crack initiating from the weld zone of the gap between the plate and the bolt flange which has hard mixed phases of ferrite + martensite + bainite with high fatigue resistance, and its strength divided by weld length does not deteriorate. The strengths and fracture modes were analysed from the viewpoints of the shape effect relating to the stress concentration and residual stress and the material effect relating to the microstructure of the weld as well.

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Section: Resultsmentioning

confidence: 74%