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•Study of the volume conservation and the strain field homogeneousness of an AlSi-PE specimen during a Split Hopkinson Bar Pressure test.•Expression of experimental data by ...considering true stress and true strain values and adiabatic heating.•Standard Johnson–Cook law taking into account a dependence between temperature and strain-rate sensitivity.•Original and modified Johnson–Cook damage law introduction to experimental quasi-static tests that led to failure.
Abradable coatings are a part of dynamic seals used in aircraft engines to diminish inter-stage leakages by reducing rotor/stator clearances of the low and high-pressure compressors. However, interactions may occur during running between the rotating blades and the coating sprayed onto the casing. Due to the complexity of reproducing experimentally rotor/stator interactions, modeling approaches are used to optimize the choice of abradable coating, making constitutive laws necessary input data for rotor/stator interaction studies. Previous experimental researches were done to explore the dynamic and quasi-static compressive thermomechanical behavior of AlSi-PE abradable coating 1,2. Using results from these investigations and from a complementary experimental characterization coupled with a high speed camera, parameters of a standard Johnson–Cook constitutive law have been identified for the wide ranges of strain-rate and temperature explored. Although modeling data were in satisfactory agreement with the experimental results, an original constitutive law formulation has been proposed to better predict the thermomechanical behavior of AlSi-PE abradable material at high temperatures. As an introduction of damage into the modeling, a standard and modified Johnson–Cook damage law, describing a strain criterion from which failure theoretically begins, has been included and analyzed when modeling the coating’s behavior by considering only quasi-static conditions.
The new severe plastic deformation technique known as high-pressure tube twisting (HPTT) is a continuous process to obtain grain refinement in bulk metallic materials of tubular geometry. HPTT was ...applied to commercially pure aluminum up to a shear strain of 24. The mechanical properties were enhanced markedly and were characterized by compression and ring-hoop tensile tests. It was shown that the axial force during HPTT does not contribute to the plastic flow of the material; it is only controlled by the shear component of the applied stress. The microstructure and the crystallographic texture were examined in detail by electron backscatter diffraction, transmission electron microscopy, and X-ray diffraction, and these showed the existence of a gradient within the cross-section of the tube. The next-neighbor grain misorientation distribution showed a bimodal nature, of which the small-angle peak was attributed to the “internal” new grains originating from the interior of the initial grains and the second one from the new grains situated at the grain boundaries of the initial grains. The measured textures were typical shear textures with specific tilts in the sense of the shear direction at large strains, which can be attributed to the effect of strain rate sensitivity of slip. The main component of the textures was the C component, which continuously strengthened with the shear. The results obtained suggest that HPTT is an efficient processing way to transform the microstructure of Al tubes into ultra-fine-grained structures in one single operation.
Despite the identification of many susceptibility genes our knowledge of the underlying mechanisms responsible for complex disease remains limited. Here, we identified a type 2 diabetes disease ...module in endosomes, and validate it for functional relevance on selected nodes. Using hepatic Golgi/endosomes fractions, we established a proteome of insulin receptor-containing endosomes that allowed the study of physical protein interaction networks on a type 2 diabetes background. The resulting collated network is formed by 313 nodes and 1147 edges with a topology organized around a few major hubs with Cdk2 displaying the highest collective influence. Overall, 88% of the nodes are associated with the type 2 diabetes genetic risk, including 101 new candidates. The Type 2 diabetes module is enriched with cytoskeleton and luminal acidification-dependent processes that are shared with secretion-related mechanisms. We identified new signaling pathways driven by Cdk2 and PTPLAD1 whose expression affects the association of the insulin receptor with TUBA, TUBB, the actin component ACTB and the endosomal sorting markers Rab5c and Rab11a. Therefore, the interactome of internalized insulin receptors reveals the presence of a type 2 diabetes disease module enriched in new layers of feedback loops required for insulin signaling, clearance and islet biology.
A new version of an original tribometer has been developed to measure friction coefficients under high pressures in quasi-static conditions. This study describes the design of the new tribometer ...device and aims to cancel any defects noted in the previous release. This configuration, combined with the improvement of the tribometer’s guidance stiffness, increases the sliding distance from 1 to 30 mm while keeping a normal pressure accuracy and creates possible pressure tests ranging from 500 to 2000 MPa. In order to validate the assembly and to simulate testing conditions in severe plastic deformation processes of metals, two tribo-pairs consisting of interstitial free steels and aluminum alloy (Al 1050) samples sliding on 45NiCrMo16 steel matrices were tested. New results on the friction coefficient evolution throughout a sliding length of 10 mm were noted and all tests revealed good reproducibility for the whole pressure range.
The Sheep Mountain anticline (Wyoming, USA) is a well-exposed asymmetric, basement-cored anticline that formed during the Laramide orogeny in the early Tertiary. In order to unravel the history of ...strain during folding, we carried out combined anisotropy of magnetic susceptibility (AMS), anisotropy of P-wave velocity (APWV) and Fry strain analyses. The results are compared to previously published stress–strain data from calcite twins at the microscopic scale and from fracture sets at the mesoscopic scale, and are used to discuss the kinematics and mechanics of forced folding. The results obtained in sandstone and carbonate lithologies demonstrate a good agreement between (1) the principal axes of the AMS and APWV tensors, (2) stress–strain tensors derived from calcite twins, (3) Fry strain axes and mesoscopic fracture sets. Furthermore, these tensors are coaxial with the main structural trends of the anticline. The differences between AMS and APWV fabrics on one hand, and the differential stress values of the forelimb and the backlimb on the other hand, emphasize how the macroscopic asymmetry of Sheep Mountain anticline affects the strain pattern at the microscopic scale. The data set presented in this paper offers a consistent mechanical scenario for the development of Sheep Mountain anticline.
From the 16 laboratories participating in CMX-4, three laboratories (Buonarroti, Matisse, and Pollock) have utilized secondary ion mass spectrometry (SIMS) for the characterization of the samples. ...SIMS allows analysis of samples on micrometric scales and thus it can be used for the analysis of individual particles. The aim of the SIMS analysis was to identify any possible heterogeneity of isotopic composition of the uranium, and to make a quantitative characterization of this heterogeneity to look for unique identifiers of the material. The outcome of the SIMS analysis from the three laboratories is described and discussed in this paper.
Friction tests at high sliding velocity are carried out by subjecting specimens to an apparent normal pressure of 110MPa in the range of 40–64m/s to reproduce severe conditions of contact between the ...rotating blades and the rotor in aircraft engines. Therefore, impacts of a projectile against a fixed sample are carried out for the investigation of a pair of Ti6Al4V materials. A mean coefficient of friction has been ascertained by two types of method: a tribometer device and an energetic approach. A slight sensitivity of the coefficient of friction with respect to the sliding velocity is observed. Postmortem analyses of samples reveal a decomposition of the frictional subsurface in multiple distinct layers: initial microstructure, severe plastic deformation (shear strain up to 16), phase transformation (T>980°C) and material transfer. A scenario of the adhesive wear mechanism is proposed in four steps.
•Dry friction generated by a projectile impact against a couple of samples in titanium alloy in rest.•Sliding velocities ranging from 40m/s to 64m/s under an apparent normal pressure of 110MPa.•Analyses of the material microstructure: confirmation of a decomposition into sub-layers.•Adhesive wear rate depending on the sliding duration.
Abradable coatings are part of dynamic seals used in aircraft engines to reduce inter-stage leakages. However, during running, severe interactions may occur between the rotating blades and the ...coating of the casing leading to these parts getting damaged. Numerical approaches simulating these interactions could be a way to prevent these contact risks but they require both a characterization of the thermomechanical behavior of the abradable material and of the blade. This paper presents a quasi-static compression behavior study of a heterogeneous and porous AlSi-PE abradable used in the low-pressure compressor of aircraft engines. Combined with the results obtained for tests conducted at high compression strain-rates and extreme temperatures recently published in a previous paper (Skiba et al., in Dyn Behav Mater 6:213–223, 2020. 10.1007/s40870-020-00242-y), a thermoelastoviscoplastic bilinear constitutive law is proposed. This formulation allows the prediction of the macroscopic behavior of a heterogeneous and porous AlSi-PE abradable material from room temperature to 360 °C and with strain-rates ranging from 10
–3
to 10
3
s
−1
.
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