scholarly journals Effects of Particle Size on Fault Gouge Frictional Characteristics and Associated Acoustic Emission

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yang Liu ◽  
Cai-Ping Lu ◽  
Tong-bin Zhao ◽  
Heng Zhang
Keyword(s):  
Particle Size ◽  
Acoustic Emission ◽  
Surface Defects ◽  
Dynamic Instability ◽  
Shear Velocity ◽  
Fault Gouge ◽  
Stick Slip ◽  
Compaction Rate ◽  
Fault Strength ◽  
Stable Sliding

Our experimental work was designed to explore the particle size effect of simulated fault gouge on slip characteristics by the conventional double-direct shear friction configuration combined with acoustic emission (AE). The following conclusions were drawn: (1) smaller particles allow for an initially higher compaction rate at a higher speed and longer duration for force chain formation and destruction. The larger the particle size is, the higher the slipping displacement rate is; (2) the smaller the particle size is, the larger the friction coefficient is, and thus the higher the fault strength is. In addition, the larger the shear velocity is, the higher the fault strength is; (3) the smaller the particle size is, the higher the shear stress drop generated by the stick-slip is, and the stronger the dynamic slip intensity for a stick-slip period is; and (4) surface defects of forcing blocks possibly help to embed foregoing “stability” and “stable sliding” into the normal stick-slip stage. Especially, the “stable sliding” is possibly related to formation of stubborn force chains. These findings may shed some insights into further clarification of slipping characteristics and discrimination of precursory signs of fault dynamic instability with different-sized gouge particles.

Seal Lubrication of an Automotive Water Pump

Tribology ◽  
2006 ◽  
Author(s):  
Massimo Antonini ◽  
Rodolfo Faglia ◽  
Carlo Remino ◽  
Marco Pedersoli
Keyword(s):  
Acoustic Emission ◽  
Theoretical Model ◽  
Working Conditions ◽  
Automotive Industry ◽  
Dynamic Instability ◽  
Mechanical Seal ◽  
Water Pump ◽  
Stick Slip ◽  
Grave Problem ◽  
Water Pumps

A noisy mechanical seal is a grave problem, especially in water pumps designed for the automotive industry. The noisiness is often caused by dynamic instability (stick-slip behavior), which occurs when the seal lubrication changes from hydrodynamic to mixed. Starting from this hypothesis, the paper shows a theoretical model that describes the interaction between the seal disks. Therefore this model correlates the acoustic emission to the working conditions of the water pump.

scholarly journals Evolution of shear fabric in granular fault gouge from stable sliding to stick slip and implications for fault slip mode

Geology ◽  
2017 ◽  
pp. G39033.1 ◽  
Author(s):  
M.M. Scuderi ◽  
C. Collettini ◽  
C. Viti ◽  
E. Tinti ◽  
C. Marone
Keyword(s):  
Fault Slip ◽  
Fault Gouge ◽  
Slip Mode ◽  
Stick Slip ◽  
Stable Sliding

The role of heterogeneity in fault zone weakening and stability

2020 ◽  
Author(s):  
John Bedford ◽  
Daniel Faulkner ◽  
Nadia Lapusta
Keyword(s):  
Friction Coefficient ◽  
Shear Bands ◽  
Fault Gouge ◽  
Stress Concentrations ◽  
Plate Interface ◽  
Stick Slip ◽  
Fine Grained ◽  
Total Displacement ◽  
Fault Strength ◽  
Frictional Strength

<p>Heterogeneity is abundant in crustal fault zones from the micron-scale to the plate interface scale. Despite this, it is still uncertain how different scales of heterogeneity interact and influence the mechanical properties of natural faults. Here we present experimental results where heterogeneous faults are simulated in the laboratory by placing patches of different fault gouge materials next to each other in a direct shear arrangement. These laterally heterogeneous experimental faults (50 mm in total length) are then sheared and the frictional strength evolution is measured with increasing displacement. Two types of fault gouge are used: (1) a fine-grained quartz gouge which obeys Byerlee friction (coefficient of friction = 0.6-0.7) and is rate weakening, and (2) a clay gouge comprised predominantly of kaolinite which has a low friction coefficient (approx. 0.25) and is rate strengthening. We find that with the addition of only a small amount of clay gouge the bulk fault strength weakens considerably after only a few millimetres of slip. Although clay is preferentially smeared along localized Y-shear bands, the observed weakening cannot be explained by clay smear as the total displacement on the fault is far too small for the clay to be smeared through the entire length of the quartz patches. Instead we propose stress concentrations at the boundary between clay and quartz patches, driven by slip on the weaker clay patch, produce enhanced weakening and shear at an overall low stress within the quartz patches.</p><p>The scale of heterogeneity also controls the frictional stability of the experimental fault. When clay patches are small and comprise <20% of the total fault area, instabilities occur within the unstable quartz gouge leading to stick-slip behaviour. However when patches of clay comprise >20% of the total sliding area, instabilities within the quartz are supressed leading to stable sliding. In this case, the bulk fault also becomes increasingly rate-strengthening with slip, tending towards the behaviour of a fault comprised of 100% clay. These results demonstrate how natural geological heterogeneity and the interplay between different geologic materials can help explain fault weakness and also control the seismogenic potential of tectonic faults.</p>

Irregular stick-slip and the role of cohesion in an ice friction experiment

2021 ◽  
Author(s):  
Evangelos Korkolis ◽  
Florent Gimbert ◽  
Jérôme Weiss ◽  
François Renard
Keyword(s):  
Acoustic Emission ◽  
High Speed ◽  
Water Tank ◽  
Sliding Velocity ◽  
Sampling System ◽  
Stick Slip ◽  
Fault Strength ◽  
Asymmetric Shape ◽  
Frictional Interface ◽  
Fault Gouges

<p>Understanding the evolution of fault strength over multiple interseismic periods is crucial to quantifying seismic hazard. According to Coulomb’s failure criterion, restrengthening, or healing, may result from an increase in friction and/or in cohesion. Classic sliding experiments on rocks and fault gouges are not able to resolve the contribution of cohesion to the healing of frictional interfaces. Here, we present a zero nominal normal stress friction experiment capable of large displacements that exhibits similar complexity as the deforming lithosphere (intermittent, aperiodic deformation; Gutenberg-Richter-type scaling of event sizes). This Couette-type apparatus is designed to shear millimeter-thick layers of columnar ice, grown in-situ in a meter scale circular water tank. When the system is driven at low sliding velocities, the ice plate fractures and sliding occurs along a complex, non-prescribed frictional interface. Water beneath the ice can percolate through the sliding interface and freeze, increasing its strength. A torque gauge and an array of acoustic emission transducers are used to measure the shear strength of the frictional interface and to monitor acoustic activity. Previous work, using constant values of sliding velocity, showed that deformation occurs via a combination of slow and fast slip events, and that the “seismic” part consists of two populations of acoustic emission (AE) events: standalone and correlated, with different Gutenberg-Richter b-values. The asymmetric shape of the shear stress (torque) fluctuations was attributed to cohesion-dominated strength recovery. We are currently using a new, high speed sampling system to investigate the relationship between the stress fluctuations and the concurrent AE activity in constant as well as variable sliding velocity experiments. This work aims to evaluate the effect of time-dependent processes on systems that deform intermittently.</p>

Structures developed in fault gouge during stable sliding and stick-slip

1978 ◽  
Vol 44 (1-4) ◽  
pp. 161-171 ◽  
Author(s):  
J. Byerlee ◽  
V. Mjachkin ◽  
R. Summers ◽  
O. Voevoda
Keyword(s):  
Fault Gouge ◽  
Stick Slip ◽  
Stable Sliding

scholarly journals Opening Material as the Possibility of Elimination Veining in Foundries

2016 ◽  
Vol 16 (3) ◽  
pp. 157-161 ◽  
Author(s):  
M. Hrubovčáková ◽  
I. Vasková ◽  
M. Benková ◽  
M. Conev
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Cast Iron ◽  
Granular Material ◽  
Surface Defects ◽  
Silica Sand ◽  
Iron Castings ◽  
Thermal Dilatation

Abstract The main bulk density representation in the molding material is opening material, refractory granular material with a particle size of 0.02 mm. It forms a shell molds and cores, and therefore in addition to activating the surface of the grain is one of the most important features angularity and particle size of grains. These last two features specify the porosity and therefore the permeability of the mixture, and thermal dilatation of tension from braking dilation, the thermal conductivity of the mixture and even largely affect the strength of molds and cores, and thus the surface quality of castings. [1] Today foundries, which use the cast iron for produce of casts, are struggling with surface defects on the casts. One of these defects are veining. They can be eliminated in several ways. Veining are foundry defects, which arise as a result of tensions generated at the interface of the mold and metal. This tension also arises due to abrupt thermal expansion of silica sand and is therefore in the development of veining on the surface of casts deal primarily influences and characteristics of the filler material – opening material in the production of iron castings.

Large-Scale Evaluation of Constrained Bearing Elements Made of Thermosetting Polyester Resin and Polyester Fabric Reinforcement

2006 ◽  
Vol 128 (4) ◽  
pp. 681-696 ◽  
Author(s):  
P. Samyn ◽  
W. Van Paepegem ◽  
J. S. Leendertz ◽  
A. Gerber ◽  
L. Van Schepdael ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Large Scale ◽  
Elastic Recovery ◽  
Small Scale ◽  
Practical Implementation ◽  
Fiber Failure ◽  
Stick Slip ◽  
Composite Surface ◽  
Pull Out ◽  
Stable Sliding

Polymer composites are increasingly used as sliding materials for high-loaded bearings, however, their tribological characteristics are most commonly determined from small-scale laboratory tests. The static strength and dynamic coefficients of friction for polyester/polyester composite elements are presently studied on large-scale test equipment for determination of its bearing capacity and failure mechanisms under overload conditions. Original test samples have a diameter of 250 mm and thickness of 40 mm, corresponding to the practical implementation in the sliding surfaces of a ball-joint, and are tested at various scales for simulation of edge effects and repeatability of test results. Static tests reveal complete elastic recovery after loading to 120 MPa, plastic deformation after loading at 150 MPa and overload at 200 MPa. This makes present composite favorable for use under high loads, compared to, e.g., glass-fibre reinforced materials. Sliding tests indicate stick-slip for pure bulk composites and more stable sliding when PTFE lubricants are added. Dynamic overload occurs above 120 MPa due to an expansion of the nonconstrained top surface. A molybdenum-disulphide coating on the steel counterface is an effective lubricant for lower dynamic friction, as it favorably impregnates the composite sliding surface, while it is not effective at high loads as the coating is removed after sliding and high initial static friction is observed. Also a zinc phosphate thermoplastic coating cannot be applied to the counterface as it adheres strongly to the composite surface with consequently high initial friction and coating wear. Most stable sliding is observed against steel counterfaces, with progressive formation of a lubricating transfer film at higher loads due to exposure of PTFE lubricant. Composite wear mechanisms are mainly governed by thermal degradation of the thermosetting matrix (max. 162°C) with shear and particle detachment by the brittle nature of polyester rather than plastic deformation. The formation of a sliding film protects against fiber failure up to 150 MPa, while overload results in interlaminar shear, debonding, and ductile fiber pull-out.

Influence of the Structure of a Gouge-Filled Fault on the Parameters of Acoustic Emission

2019 ◽  
Vol 105 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Alexey A. Ostapchuk ◽  
Kseniya G. Morozova ◽  
Dmitry V. Pavlov
Keyword(s):  
Acoustic Emission ◽  
Laboratory Experiments ◽  
Shear Crack ◽  
Kinematic Parameters ◽  
Stick Slip ◽  
Omori Law ◽  
Shear Loads ◽  
Initial Stage ◽  
Slip Event ◽  
Model Setup

Presented are the results of laboratory experiments on investigating manifestations of acoustic emission (AE) of a gouge-filled fault during stick-slip. The laboratory experiments were held at the slider-model setup, when a granite block slides along a rough granite base under normal and shear loads. In the course of experiments we altered the structure of the two-component filler of the fault and focused on variations of the AE parameters. The kinematic parameters of fault slip events in all the realizations remained approximately the same. The eff ect of gouge structure on the statistics of AE has been revealed. An alteration of proportion of quartz sand / glass beads in the filler of the fault was accompanied by an alteration of the b-value of frequency-energy distribution from 0.53 to 0.85, and the p-value of Omori law from 1.00 to 2.06. Also, it has been demonstrated that the nucleation of a slip event is accompanied by an alteration of the mechanism of AE generation – at the initial stage the 'tensile crack' signals prevailed, while at the final stage – the 'shear crack' signals did. The alteration of AE genesis manifested vividly in a corresponding alteration of the emitted waveforms for all the realizations.

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