“…Nevertheless, previous experiments showed that the damage evolution pattern of U75V steel was quite different from that of tempered 42CrMo steel: a large damage evolution rate was exhibited initially and diminished gradually with increasing the cycle number, as shown in Figure 2 Figure 2. Damage evolutions of heat-treated U75V steel. (the data are extracted from Figure 1). The decaying feature of damage evolution rate was also found in other materials (Chen and Zhao, 2018; Kang et al., 2008; Plumtree et al.,2010; Shi et al., 2017; Zhang et al., 2019). Bonora (1997) suggested that the higher damage evolution rate at the primary stage may be derived from the nucleation of many micro voids.…”
In the framework of continuum damage mechanics, a new damage-coupled cyclic plastic model is proposed to describe the nonlinear evolution of whole-life ratchetting and its dependence on the stress level. The characteristic that the damage evolution rate of U75V heat-treated steel decays in the initial load cycles is considered by introducing a modified term into classic damage evolution equation. A hybrid fatigue failure criterion considering both the fatigue and ratchetting strain-induced failures is established based on the fatigue failure rule concluded from experiments. Comparisons between simulated and experimental stress–strain hysteresis loops, ratchetting strains, damage evolutions, and fatigue lives are performed to validate the proposed model.
“…Nevertheless, previous experiments showed that the damage evolution pattern of U75V steel was quite different from that of tempered 42CrMo steel: a large damage evolution rate was exhibited initially and diminished gradually with increasing the cycle number, as shown in Figure 2 Figure 2. Damage evolutions of heat-treated U75V steel. (the data are extracted from Figure 1). The decaying feature of damage evolution rate was also found in other materials (Chen and Zhao, 2018; Kang et al., 2008; Plumtree et al.,2010; Shi et al., 2017; Zhang et al., 2019). Bonora (1997) suggested that the higher damage evolution rate at the primary stage may be derived from the nucleation of many micro voids.…”
In the framework of continuum damage mechanics, a new damage-coupled cyclic plastic model is proposed to describe the nonlinear evolution of whole-life ratchetting and its dependence on the stress level. The characteristic that the damage evolution rate of U75V heat-treated steel decays in the initial load cycles is considered by introducing a modified term into classic damage evolution equation. A hybrid fatigue failure criterion considering both the fatigue and ratchetting strain-induced failures is established based on the fatigue failure rule concluded from experiments. Comparisons between simulated and experimental stress–strain hysteresis loops, ratchetting strains, damage evolutions, and fatigue lives are performed to validate the proposed model.
“…Therefore, it is not always simple to assess the hot workabilities of different aluminum materials using only Q. Shi et al [24] reported that Q mainly reflected the free-energy barrier to dislocation movement, which was affected by the deformation temperature and strain. In recent years, the concept of activation energy mapping was explored instead of treating Q as a constant to study the hot workabilities of aluminum alloys [25,45,46]. 5.…”
Section: Variation In Activation Energy With the Deformation Strainmentioning
“…Subsequently, they also measured the thermo-mechanical deformation of solder joints in flexible and rigid printed circuit assemblies [ 36 ]. Shi et al [ 37 ] used X-ray μ-CT for the in situ characterization of the microstructural evolution of the reflow cavity in an SAC305 solder joint under shear ratchet fatigue. Although these studies have great significance for the investigation of the mechanical properties of solder joints, they are still insufficient for understanding the failure mechanism and improving the reliability of solder joints.…”
The fracture behavior of the Cu/Sn-3.0Ag-0.5Sn (SAC305)/Cu solder joint was investigated by conducting tensile tests with in situ X-ray micro-computed tomography (μ-CT) observation, and finite element (FE) simulation. The tensile fracture process of solder joints with a real internal defect structure was simulated and compared with the experimental results in terms of defect distribution and fracture path. Additionally, the stress distribution around the defects during the tensile process was calculated. The experimental results reveal that the pores near the intermetallic compound (IMC) layers and the flaky cracks inside the solder significantly affected the crack path. The aggregation degree of the spherical pores and the angle between the crack surface and the loading direction controlled the initiation position and propagation path of the cracks. The fracture morphology indicates that the fracture of the IMC layer was brittle, while the solder fracture exhibited ductile tearing. There are significant differences in the fracture morphology under tensile and shear loading.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
