Criteria of Equivalent Stress Concept

Kolupaev, Vladimir A.

doi:10.1007/978-3-319-73049-3_2

Cited by 5 publications

(1 citation statement)

References 104 publications

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“…To consider the influence of the second principal stress σ 2 on the stress concentration of a complex stress system, the von Mises stress (equivalent stress, σ eq ) was also calculated in this study. The von Mises hypothesis (i.e., the fourth strength theory) [33] holds that a material begins to yield when σ eq reaches the yield strength and that σ eq is given by Equation (6):σeq=(σ1−σ2)2+(σ2−σ3)2+(σ3−σ1)22. Meanwhile, to evaluate the stress triaxiality, which affects the initiation and growth of micro-voids and cracks [34] on the failure of the TLP bonded joint, the damage equivalent stress (σeq*) in the joint was also investigated. It can be written as follows [34]:σeq∗=σeq[23(1+ν)+3(1−2ν)(Tσ)2]12, where T σ is stress triaxiality, and Tσ=σm/σeq, …”

Section: Resultsmentioning

confidence: 99%

Stress Concentration Induced by the Crystal Orientation in the Transient-Liquid-Phase Bonded Joint of Single-Crystalline Ni3Al

Qin

Kuang

et al. 2019

Materials

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Single-crystalline Ni3Al-based superalloys have been widely used in aviation, aerospace, and military fields because of their excellent mechanical properties, especially at extremely high temperatures. Usually, single-crystalline Ni3Al-based superalloys are welded together by a Ni3Al-based polycrystalline alloy via transient liquid phase (TLP) bonding. In this study, the elastic constants of single-crystalline Ni3Al were calculated via density functional theory (DFT) and the elastic modulus, shear modulus, and Poisson’s ratio of the polycrystalline Ni3Al were evaluated by the Voigt–Reuss approximation method. The results are in good agreement with previously reported experimental values. Based on the calculated mechanical properties of single-crystalline and polycrystalline Ni3Al, three-dimensional finite element analysis (FEA) was used to characterize the mechanical behavior of the TLP bonded joint of single-crystalline Ni3Al. The simulation results reveal obvious stress concentration in the joint because of the different states of crystal orientation between single crystals and polycrystals, which may induce failure in the polycrystalline Ni3Al and weaken the mechanical strength of the TLP bonded joint. Furthermore, results also show that the decrease in the elastic modulus of the intermediate layer (i.e., polycrystalline Ni3Al) can relieve the stress concentration and improve the mechanical strength in the TLP bonded joint.

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