Influence Of Indentation Research Articles

Influence of Indentation on the Fatigue Strength of Carbonitrided Plain Steel

To study the influence of indentation on the fatigue strength of untreated and carbonitrided specimens of S38C steel, the fatigue limit of specimens with and without indentations was tested. Fracture surfaces were observed using scanning electron microscopy (SEM). The results show that the fatigue strength of the untreated specimen decreases with increasing dimension of indentation, without significant difference compared to the predicted results. Compared to the fatigue limit of the untreated specimen, those of the carbonitrided specimen and the carbonitrided specimen whose compound layer was polished were improved by 12% and 40%, respectively. The fatigue strength of the carbonitrided specimen decreased sharply with increasing indentation size because of the presence of microcracks in the compound layer. When the compound layer was removed, the fatigue limit was observed to be less sensitive to indentation than that of the carbonitrided specimen.

Influence of Indentation on the Critical Current of Nb3Sn Strands

The Japan Atomic Energy Agency (JAEA) is procuring Central Solenoid (CS) conductorsfor all modules forITER. The superconducting properties of the Nb3Sn CS conductors will have to sustain 60,000 electromagnetic (EM) cycles. The current sharing temperatures (Tcs) were stable with EM cycles in short twist pitch conductors.However, the short twist pitch and tight cabling increases indented strands at the contact point between strands before heat treatment. The results of Ic measurement on artificially indented Nb3Sn strands indicate that Ic was almost constant within a critical depth of the indentations.

Influence of indenter and base sizes on push-out test: FEA

Influence of indenter and base sizes on push-out test: FEA

Computational prediction of the lifetime of self-healing CMC structures

Self-healing Ceramic–Matrix Composites (CMCs) are good candidates for structural applications at high temperatures in oxidizing environments. These materials generate complex couplings between the thermal and mechanical fields. A multiphysics macroscopic model of both the mechanical behavior and the lifetime of CMC structures was proposed previously and was validated on the material’s level. Here its effectiveness in dealing with structural calculations with heterogeneous fields is analyzed and a nonlocal fracture criterion is proposed for high-gradient cases. All the simulations were carried out using Abaqus/Standard. The main interest of the model is its ability to predict the evolution of each of the material’s mechanisms throughout the structure until final fracture. Another advantage is the ability to predict the fracture zone and the influence of indentations on the lifetime of the structure (damage tolerance analysis), both of which are very important for industrial developments.

Simulation on the Indentation of Large Grain in the Semi-Fixed Abrasive Plate with Discrete Element Method

This paper analyses the influence of indenter’s vertex angle on the ‘trap’ effect of the semi-fixed abrasive plate (SAP) with discrete element method. The indenters of different degree vertex angle are generated by discrete element method, then the indenter is applied processing velocity, which let the indenter press into the SAP, finally three curves of normal force and displacement are gained. From the curves, the normal force of the indenters doesn’t increase quickly and stay in stable in the beginning, because the SAP is full of pore, which let the indenter easily press into the SAP. Through the above indenter simulation, the relations between the lasting time of the ‘trap’ effect and the indenter’s vertex angle are in reverse proportion, if the indenter’s vertex angle is smaller, the lasting time of the ‘trap’ effect of SAP is longer, and the size of large grain is an influence factor in the ‘trap’ effect of SAP.

Deformation history of the southwestern Taiwan foreland thrust belt: insights from tectono-sedimentary analyses and balanced cross-sections

Analysis of the basin-scale and local deformation history and estimates of shortening rates are performed in the southwestern foreland thrust belt of the Plio-Pleistocene Taiwan orogen. Timing of deformational events is constrained using both syntectonic unconformities and other markers of syndepositional tectonic activity. Three cross-sections are investigated and balanced. Intermediate shortening rates are estimated based on balanced and restored cross-sections. The total amount of shortening along studied balanced sections results from superimposed thin-skinned and thick-skinned styles. A shallow aseismic thick décollement is located to depth of 6–8km at the base of thick Late Miocene shales that behaves as ductile layer. The occurrence of a deep seismic décollement to depth of 12–15km is confirmed by seismicity, fault plane solutions of focal mechanisms and a seismic reflection profile providing evidence of reactivated and inverted inherited extensional features beneath the Coastal Plain. Three major tectonic stages are recognized within the southwestern Foothills, which are correlated with local thrusting events. The first stage begins at 5Ma with the onset of the Taiwan collision and ends at 2–1.6Ma. It reflects an initial submarine accretionary stage associated with moderate tectonic activity. The second major stage occurs during Late Pliocene–Early Pleistocene. This “intermediate” collision stage sealed the evolution of the southern foreland thrust wedge from submarine to continental environment in relation with exhumation and denudation of the Central Range. The last stage of deformation begins in the Middle Pleistocene and continues until present. It is associated with high rates of sedimentation and most of the thrusts are activated or reactivated at that time and out-of-sequence thrusting occurs. The collision started synchronously near 5Ma throughout the southwestern Taiwan. Total and intermediate shortening rates are more or less constant through time in studied sections; that may suggest that long-term deformation in the Taiwan foreland thrust belt occurred more or less at steady-state. Since 5Ma, the southward decrease of rates of shortening from 3.6 to 4.8mm/year in northern sections to 2.2mm/year in southern section might be related to both influence of indentation by the Peikang High to the north and southward transition, at the scale of the southwestern Foothills, from collision to subduction setting; the effect of the obliquity of the convergence resulting in regional southward migration of the collision cannot be definitely inferred from this analysis. Our results place new kinematic and time constraints, which must be taken into account in forthcoming geodynamic models of the Taiwan collision.

Laminar jet impingement on an indented wall

The Navier-Stokes equations are solved numerically to study the problems of laminar, axisymmetric jet impinging normally on an indented wall. The results obtained for three different wall geometries and Reynolds number range upto 25 are compared with those for the impingement on a plane wall to study the influence of indentation. The overall flow picture remains similar to the plane wall case qualitatively but the wall shear stress and pressure distribution get altered in the indented region.