Slip Type Research Articles

Orientation-dependent irradiation hardening in pure Zr studied by nanoindentation, electron microscopies, and crystal plasticity finite element modeling

Orientation-dependent irradiation hardening phenomena in pure Zr have been studied, and the corresponding mechanisms investigated based on the combined use of SEM, TEM, and CPFEM. Nanoindentation was conducted on ten grains at room temperature before and after ion irradiation (0.3 dpa, 250 °C). The hardness decreases as the declination angle (the angle between c-axis and sample surface normal) increases, both before and after irradiation. However, the irradiation induced maximum absolute and relative increment of hardness occur when the declination angle is about 55° and 60°, respectively. The hardness increment was found to be proportional to the relative activation of the <a> type slip with increase of declination angle, at low angles. However for angles higher than 55–60° the hardness increment was found to be reduced by the activation of deformation twinning and cross slip. A peak increment of irradiation hardening is therefore observed due to the orientation-dependent combination of different deformation mechanisms. CRSS values of all slip systems and for {10–12} <-1011> tension twinning before and after irradiation were obtained by fitting to a crystal plasticity finite element model (CPFEM). The obstacle strength of heavy ion induced <a> type dislocation loops generated at 250 °C on subsequent room temperature slip was thus calculated to be approximately 0.29 ± 0.05.

SLIPS OF THE TONGUE MADE BY THE ENGLISH STUDY PROGRAM STUDENTS

The purpose of this research is to identify the types of slip of the tongue made by English Education Study Program students of Bengkulu University in their proposal seminar presentation and to identify the dominant type of slip of the tongue made by English Education Study Program students of Bengkulu University in their proposal seminar presentation. The samples of this study were 5 Students English Education Study Program students of Bengkulu University who carry out seminars of each student proposal on February 23rd, 2018 and on April 27th, 2018. The instrument used in this research was the writer herself. The data were collected by using documentary method. To analyze the data, the qualitative and quantitative methods were applied. The results of this research show that there are 60 data which are taken from the proposal seminar presentation of English students. In those data there are 6 of 8 types of slip of the tongue found in students’ presentation; Anticipation, Perseveration, Exchange, Substitution, Addition and Deletion. The dominant type occurred was Substitution

The Recent Small Earthquakes around Lembang Fault, West Java, Bandung, Indonesia

On May 14th and 18th, 2017 felt earthquakes were occurred around western part of Lembang area, Bandung, West Java, Indonesia with magnitude of M2.8 and M2.9, respectively. The first earthquake (M2.8) was felt by some people around epicenter area. We determined the earthquake location through re-picking of P-and S-wave arrival time recording by Indonesian Agency for Meteorological, Climatological and Geophysics (BMKG), network. Earthquake location was determined by using Hypoellipse code that employs a single event determination method. We also conducted focal mechanism analysis to estimate the type of fault slip. The results indicate the hypocenters location in the north and south of the western part of Lembang fault with the focus depth of ∼ 5 km, respectively. Source mechanism solutions showed the type of earthquake is strike-slip fault. The occurrence of two recent small earthquakes need more attention about the activity of Lembang fault. The destructive earthquake related to displacement of the fault occurred on August 28, 2011 (M3.3) located at the western end of the Lembang fault. For further study, we have been deploying 6 temporary seismometers stations around Lembang fault in attempt to detect small events and to delineate subsurface seismic structure by applying tomography method.

Spatial and temporal distributions of b-values related to long-term slow-slip and low-frequency earthquakes in the Bungo Channel and Hyuga-nada regions, Japan

Long-term slow-slip events (SSEs) and low-frequency earthquakes (LFEs) repeatedly occur in the area encompassing the Bungo Channel and Hyuga-nada region in Japan. SSEs are slow earthquake events with a duration of months to years, characterized by a type of slip that is considered transitional between the fast rupture of regular earthquakes and stable sliding along a plate interface, and have characteristics sensitive to stress states near the plate interface. In addition, since LFEs are also thought to occur at the plate interface, it would be useful to infer the stress state in this region. This study focuses on the stress-dependent characteristics of the b-values of regular earthquakes, SSEs, and LFEs, as well as the spatio-temporal relationships between b-values and these events in this area, using the Japan Unified high-resolution relocated Catalog for Earthquakes (JUICE). The b-value, which represents the relative proportion of large to small earthquakes, is inversely related to differential stress or effective stress. The b-values are moderate to low (b = 0.6–1.1) in regions with a high incidence of long-term SSEs. This spatial b-value anomaly is attributed to the partial release of accumulated stress in regions with a relatively high differential stress due to SSE activity. Furthermore, the b-value distributions estimated in this study provide constraints on the mechanisms that generate LFEs. On the other hand, the b-values increase and decrease before and during periods of enhanced LFE activity in the Bungo Channel, respectively. The increase and following decrease in b-values are thought to reflect episodes of low and high shear strength along the plate interface, which were caused by the presence of abundant slab-derived fluids under undrained conditions above the plate interface, and decreased pore pressure related to fluid depletion via LFE generation, respectively.

Seismic damage of gravity abutment in liquefied ground

Purpose Abutment damage in liquefied ground is an important form of seismic damage of bridge structure. This paper aims to further research the effect of beam restriction on seismic damage mode of abutment in liquefied ground. Design/methodology/approach Based on the investigation of the seismic damage of Shengli Bridge in Tangshan earthquake, the finite element software dynamic effective stress analysis for ground (UWLC) is used to simulate the seismic damage of Shengli Bridge, and the results were compared with the actual seismic damage results. Then, the influences of the horizontal binding force of the beam, the liquefaction layer thickness, the top weight of the abutment, the peak acceleration, the liquefaction layer buried depth and the type of the foundation soil on the abutment seismic damage model are studied. Findings The results show that numerical simulation results are consistent with the actual seismic damage, and it is feasible to use UWLC software to simulate seismic damage. The results show that the seismic failure mode of the gravity abutment in liquefied ground is slip–rotation coupling type, not single slip type or rotation type. The large deformation of abutment bottom layer, horizontal binding force of the beam and post-stage soil pressure are the main reasons for abutment rotation or even destruction. Research limitations/implications A series of basic assumptions are used in the calculation process in this paper. The gravity abutment is defined as the elastic body and neglects its local deformation. The soil layer is a homogeneous isotropic. The consolidation process and the drainage boundary problem are not considered in the calculation process. Therefore, the paper may have some limitations. Originality/value To further research the seismic damage mode and influencing factors of abutment in liquefied ground, in this paper, based on the investigation of the seismic damage of Shengli Bridge in Tangshan earthquake, the finite element software UWLC is used to simulate the seismic damage of Shengli Bridge, and the results were compared with the actual seismic damage results. The seismic damage mode and influencing factors of gravity abutment in liquefied ground have been studied.

SENYAPAN DAN KILIR LIDAH BERDAMPINGAN DALAM PRODUKSI UJARAN

This study examines sequencial hesitation disfluencies and slip of the tongue in Bahasa Indonesia from psycholinguistic reviews. The aim is to find (1) the type of sequencial hesitation disfluencies and slip of the tongue and (2) the relation between hesitation disfluencies and slip of the tongue in a speech production. The data in this study were taken from spontaneous speeches in the speech titles Mata Najwa and Kick Andy with the reading method and then analyzed with a slime technique. This study produced two findings. First , the type of sequencial hesitation disfluencies and slip of the tongue, namely (a) Freudians Slip- Filled Pauses, (b) Freudian Slip-Silence Combinations, (c) Blend-Filled Pauses, (d) Anticipation — Filled Pauses, (e) Transposition Filled Pauses, and (f) Transposition-Silence Combinations. Second , Hesitation Disfluencies arises as a result of slip of the tongue because speakers need additional time to retrieve the required vocabulary.

Continual models of layered and block media with slippage and delamination

Continual models of solid media with a discrete set of slip planes (layered, block media) and with nonlinear viscous-plastic type slip conditions at the contact boundaries of structural elements are constructed. The resulting system of equations contains a small viscosity parameter in the denominator of nonlinear free terms. For a stable numerical solution of a system of differential equations, an explicit-implicit method is proposed with an explicit approximation of the equations of motion and an implicit approximation of the constitutive relations containing a small parameter. Examples of numerical solutions of dynamic problems on the scattering of waves on layered cluster in an elastic medium, on the formation of slip and delamination zones at the boundaries of structural elements are given.

Effects of CaO addition and strain rate on the texture evolution of AZ31 alloy

The controlling alloying elements and deformation parameters are significant factors of the plastic deformation of Mg alloys due to their low formability and difficult-to-control texture. In this study, we investigated the effect of both CaO addition and the strain rate on the texture evolution and flow behavior of AZ31 alloys by carrying out hot torsion. The dislocation components of the deformed AZ31 alloys were evaluated using X-ray line profile analysis (XLPA). The XLPA results showed that the strain rate variation significantly affected the dislocation components and dislocation density of the alloys while CaO addition has only dislocation density effect. According to the results, weaken texture evolution by CaO addition is based on not variation of slip modes but grain boundary mobility. Also, it was determined that high strain rate deformation affect texture evolution by fortifying <a>-type slip mode.

Global-scale control of extensional tectonics on CO2 earth degassing

Earth degassing of CO2-rich fluids has been proven to contribute significantly to the global carbon budget. The presence of ubiquitous outgassing reveals some degree of permeability of the crust that often coincides with seismically active zones. In this study, we took advantage of the most recent global geological datasets to better understand earth degassing and how it correlates with tectonic regimes. Here we use an ad hoc point pattern analysis to show that there is a spatial correlation between CO2 discharges and the presence of active fault systems, in particular with those characterized by a normal slip type. Seismic data demonstrate the existence of a positive spatial correlation between gas discharges and extensional tectonic regimes and confirms that such processes would play a key role in creating pathways for the rising gases at micro- and macro-scales, increasing the rock permeability and connecting the deep crust to the earth surface.

Bifurcation and stability analyses for a pad-on-disc frictional system

Friction-induced vibration of a pad-on-disc frictional system is analyzed in this paper. Equations of motion are established considering the moving load simulation and using the Stribeck-type friction model. The partial differential equation of the disc vibration is reduced to the 1st-order mode by the Galerkin method, then the obtained frictional coupled ODE equations are solved by the Runge–Kutta method. The system stability is investigated by the complex eigenvalue analysis, which shows that the relative-equilibrium of the braking pad loses its stability through super-critical Hopf bifurcation in tangential direction, no matter where the contact position is. Simulations show that the pure-slip limit cycle is resulted at the initial stage of the friction-induced instability. When the rotating speed decreases to a turning point, the pure-slip vibration turns to be stick–slip one as the amplitude increases to a certain level. Then the amplitude of stick–slip type limit cycle vibration decreases with the further decreasing speed. The Hopf point and turning point are influenced by the contacting stiffness. Three types of limit-cycle vibrations are analyzed both in time- and frequency-domains, which shows the critical speeds (Hopf points) under 1:2 and 1:4 internal resonances are much higher than that under non-internal resonance The higher the critical speed is, the earlier the instability occurs. That is to say the strong dynamical coupling between the moving elements of a structure brings earlier occurrence of the frictional instability during braking procedure. As a counterpart of the pad, the disc vibrates also with large amplitude transversely. Influences of the braking initial displacement and the normal pressure between the pad and disc on the instability are also discussed.

Model of the Source of the Mw = 5.8 Onor Earthquake, August 14, 2016, Sakhalin

On August 14, 2016, at 11 h 15 min UTC, an earthquake with Mw = 5.8 occurred at ~9 km depth in the central part of Sakhalin, near its western coast. The shaking intensity in the epicentral zone was up to VII on the MSK-64 scale. Based on the aggregated seismotectonic data, we find that the slip occurred on the cutting fault joining two large regional fault zones of submeridional trends, the West Sakhalin and Central Sakhalin ones. By the method of waveform inversion we determine the seismic moment tensor and model the earthquake source. In the source, we reveal subhorizontal NE–SW-directed compressional stresses which agree with the contemporary character of deformations in the central part of the island. The slip type is a NW-dipping reverse fault with an insignificant strike-slip component. On the basis of reconstructed slips in the earthquake source, we calculate the coseismic deformations of the earth’s surface in the epicentral zone.

Variations in precursory slip behavior resulting from frictional heterogeneity

Precursory seismicity is often observed before a large earthquake. Small foreshocks occur within the mainshock rupture area, which cannot be explained by simple models that assume homogeneous friction on the entire fault. In this study, we consider a frictionally heterogeneous fault model, motivated by recent observations of geologic faults and slow earthquakes. This study investigates slip behavior on faults governed by a rate- and state-dependent friction law. We consider a finite linear fault consisting of alternating velocity-weakening zones (VWZs) and velocity-strengthening zones (VSZs). Our model generates precursory slip before the mainshock that ruptures the entire fault, though the activity level of the precursory slip depends on the frictional parameters. We investigate variations in precursory slip behavior, which we characterize quantitatively by the background slip acceleration and seismic radiation, using parameter studies of the a value of the VWZs and VSZs. The results reveal that precursory slip is very small when VWZs are strongly locked and when VSZs consume only a small amount of energy during seismic slip. Precursory slip is significant around the stability boundary of the fault. Furthermore, the type of precursory slip (seismic or aseismic) is controlled by the amplitude of the frictional heterogeneity. Active foreshocks obeying an inverse Omori law associated with background aseismic slip can be interpreted as the nucleation of the mainshock, though this is different from classical nucleation because the monotonic increase in slip velocity is significantly perturbed by the occurrence of foreshocks. Frictional heterogeneity also affects interseismic slip behavior. Modeled variations in precursory slip behavior and interseismic activity can qualitatively explain the along-dip and among-subduction-zone variations in real seismicity patterns. Because even simple frictional heterogeneity produces complex seismicity, it is necessary to further investigate the slip behavior of frictionally heterogeneous faults, which could be utilized for modeling various real seismicity patterns.

Effect of deformation twinning on forming limit analysis of polycrystalline magnesium

A formability assessment using the crystal plasticity model is conducted to investigate the effect of deformation twinning on the formability of polycrystalline magnesium sheet. For presenting the polycrystalline behaviors of magnesium, the homogenization-based finite element method is introduced, and the Marciniak-Kuczyńsk type sheet necking analysis is demonstrated. Two kinds of deformation twinning model, i.e., the asymmetric slip type and van Houtte’s models are adopted, and the effect of those models on the forming limit analysis is numerically discussed. It is revealed that the lattice reorientation due to deformation twinning plays an important role in plastic flow localization of magnesium, while shear deformation caused by deformation twinning has an insignificant effect.

Flows of incompressible viscous liquids with anisotropic wall slip

This paper deals with a boundary-value problem for the Stokes equations with a general direction-dependent Navier type slip boundary condition. This problem models the steady laminar flow of an incompressible linearly viscous liquid in a bounded domain with an impermeable rough boundary with variable and anisotropic roughness. It is proved that the problem has a unique weak solution.

Impact of military type footwear and workload on heel contact dynamics during slip events

IntroductionSlips, trips and falls due to an induced loss balance have been identified as the leading cause of occupational injuries. This study aimed to analyze the impact of two military boots, standard boot (STD) and minimalist boot (MIN) on slip events, before (PRE) and after (POST) a military type load carrying task. MethodsSixteen male participants (age: 27 ± 3.9 years; height: 178 ± 6.2 cm, mass: 87 ± 12.4 kg) were tested for heel kinematics using motion capture, during unexpected (US) and expected slips (ES) both before and after the task. Slip parameters of heel slip distance (HSD) and mean heel slip velocity (MHSV) were analyzed with a 2 (STD × MIN) × 2 (PRE × POST) × 2 (US × ES) repeated measures ANOVA. ResultsSignificantly greater HSD (p = 0.002) and MHSV (p = 0.001) were demonstrated in STD compared to MIN, regardless of the load carrying workload and the type of slip. No significant interactions between boots, workload and slip type were found. MIN exhibited a greater percent of non-hazardous slips compared to STD. ConclusionsGreater HSD and MHSV seen in STD, suggests that MIN performed better under slippery conditions. The military type workload and the type of slip did not appear to influence slip parameters, with boot differences seen as the major influence on these slip outcomes. MIN boot's better performance could be attributed to the minimalist sole, tread and groove pattern, lighter mass and flexible shaft aiding in better maneuvering under slippery conditions. Relevance to industrySlip outcomes in two different military boots, before and after a military type load carrying workload are addressed. The lighter minimalist tactical boot outperformed the standard tactical boot, under slippery conditions. Findings from this study will help offer suggestions for footwear design in the military, especially for maneuvering slippery environment.

Dislocation structure in textured zirconium tensile-deformed along rolling and transverse directions determined by X-ray diffraction line profile analysis

Specimens of cold-rolled zirconium were tensile-deformed along the rolling (RD) and the transverse (TD) directions. The stress-strain curves revealed a strong texture dependence. High resolution X-ray line profile analysis was used to determine the prevailing active slip-systems in the specimens with different textures. The reflections in the X-ray diffraction patterns were separated into two groups. One group corresponds to the major and the other group to the random texture component, respectively. The dislocation densities, the subgrain size and the prevailing active slip-systems were evaluated by using the convolutional multiple whole profile (CMWP) procedure. These microstructure parameters were evaluated separately in the two groups of reflections corresponding to the two different texture components. Significant differences were found in both, the evolution of dislocation densities and the development of the fractions of <a> and <c+a> type slip systems in the RD and TD specimens during tensile deformation. The differences between the RD and TD stress-strain curves are discussed in terms of the differences of the microstructure evolution.

Effect of initial texture and grain size on geometrically necessary dislocations density distribution during uniaxial compression of Ti-6Al-4V

Effect of initial texture (transverse and basal) and grain size on compression behavior, slip system activity and density of geometrically necessary dislocation (GND) in Ti64 has been evaluated. It was clearly showed that deformation behavior of Ti64 alloy is strongly dependent to initial texture and grain size of alpha phase. In the case of transverse and basal texture, TD and ND specimens reveal higher resistance to deformation, respectively. Texture and grain size contributions on deformation response are accurately investigated after 10% plastic strain in ND using Schmid factor, Kernel average misorientation and GND maps. In the case of transverse texture with coarse grains, high Schmid factor value of a→-type slip system and high misorientation frequency associated with high GND storage. In the case of basal texture with fine grains, low Schmid factor value of a→-type slip system and low misorientation frequency resulting in activation of high energy <c→+a→> type slip system and eventually low GND storage has been generated.

Influence of Slip and Lubrication Regime on the Formation of White Etching Cracks on a Two-Disc Test Rig

A common cause for maintenance and downtime in multiple fields of the mechanical transmission industries are premature rolling bearing failures due to white etching cracks (WEC). Within this work, WEC have been successfully recreated on a two-disc test rig under rolling contact loading without additional loading such as hydrogen pre-charging. This paper summarizes the state of the investigations regarding the influence of the slip type and the lubrication regime on the WEC formation on the two-disc test rig.

Development of cataclastic foliation in deformation bands in feldspar-rich conglomerates of the Rio do Peixe Basin, NE Brazil

In this work we describe the deformation mechanisms and processes that occurred during the evolution of cataclastic deformation bands developed in the feldspar-rich conglomerates of the Rio do Peixe Basin, NE Brazil. We studied bands with different deformation intensities, ranging from single cm-thick tabular bands to more evolved clustering zones. The chemical identification of cataclastic material within deformation bands was performed using compositional mapping in SEM images, EDX and XRD analyses. Deformation processes were identified by microstructural analysis and by the quantification of comminution intensity, performed using digital image processing. The deformation bands are internally non homogeneous and developed during five evolutionary stages: (1) moderate grain size reduction, grain rotation and grain border comminution; (2) intense grain size reduction with preferential feldspar fragmentation; (3) formation of subparallel C-type slip zones; (4) formation of S-type structures, generating S-C-like fabric; and (5) formation of C′-type slip zones, generating well-developed foliation that resembles S-C-C′-type structures in a ductile environment. Such deformation fabric is mostly imparted by the preferential alignment of intensely comminuted feldspar fragments along thin slip zones developed within deformation bands. These processes were purely mechanical (i.e., grain crushing and reorientation). No clays or fluids were involved in such processes.

Deformation behaviour of [001] oriented MgO using combined in-situ nano-indentation and micro-Laue diffraction

We report a coupled in-situ micro-Laue diffraction and nano-indentation experiment, with spatial and time resolution, to investigate the deformation mechanisms in [001]-oriented single crystal MgO. Crystal plasticity finite element modelling was applied to aid interpretation of the experimental observations of plasticity. The Laue spots showed both rotation and streaking upon indentation that is typically indicative of both elastic lattice rotation and plastic strain gradients respectively in the material. Multiple facets of streaking of the Laue peaks suggested plastic slip occurring on almost all the {101}-type slip planes oriented 45° to the sample surface with no indication of slip on the 90° {110} planes. Crystal plasticity modelling also supported these experimental observations. Owing to asymmetric slip beneath the indenter, as predicted by modelling results and observed through Laue analysis, sub-grains were found to nucleate with distinct misorientation. With cyclic loading, the mechanical hysteresis behaviour in MgO is revealed through the changing profiles of the Laue reflections, driven by reversal of plastic strain by the stored elastic energy. Crystal plasticity simulations have also shown explicitly that in subsequent loading cycles after first, the secondary slip system unloads completely elastically while some plastic strain of the primary slip reverses. Tracking the Laue peak movement, a higher degree of lattice rotation was seen to occur in the material under the indent, which gradually decreased moving laterally away. With the progress of deformation, the full field elastic strain and rotation gradients were also constructed which showed opposite lattice rotations on either sides of the indent.