Source Of Deformation Research Articles

Production Assessment of Hybrid Directed Energy Deposition Manufactured Sample with Integrated Effective Structural Health Monitoring channel (eSHM)

Additively manufactured components are questioned for their fatigue performance and therefore not adopted for safety critical applications so far. The components might contain material imperfections and residual stresses due to the high temperature gradients during the printing process. These stresses alter the component’s structural integrity and are one of the main sources of component deformation and cracking. The effective Structural Health Monitoring system (eSHM), developed and patented by the Vrije Universiteit Brussel, fully exploits the flexibility offered by the 3D printing process by integrating a smart continuous monitoring technology inside additively manufactured parts. The system is based on the detection of pressure changes in 3D-curved internal channels embedded in the fatigue critical regions of the component. The pressure is continuously monitored at the channel extremities by externally mounted pressure sensors. The system is capable of detecting the presence and finding the location of a fatigue crack. This paper proposes an assessment of the production of a fatigue sample with integrated eSHM-system using the MiCLAD in-house hybrid Directed Energy Deposition machine developed by the Additive Manufacturing Research Group of the VUB. It has the particularity to allow the combination of both additive and subtractive milling operations for the production of a part. Different printing strategies are presented and compared in terms of final geometry and internal channel roughness, known to be crucial to avoid undesired fatigue initiation and to obtain an accurate detection and localization of the fatigue crack. The encountered difficulties during the production process are identified and solutions are proposed.

Finite Element Study of Mixed Fracture: Velocity-Dependent Insertion Of Pointed Blades Into Soft Material

This study concerns the effect of applied velocity on the energy state and stress state related to the puncture-cutting of soft material. A finite element modeling (FEM) of combined puncture and cutting of neoprene rubber by a pointed blade was established at 17 velocities (from 10[Formula: see text]mm/min to 1500[Formula: see text]mm/min). The proposed FEM takes into consideration, the nonlinear material behavior of the elastomeric substrate. First, puncture-cutting tests are conducted and the evolution of puncture-cutting force with increased velocity is investigated. Second, the commonly used puncture-cutting energy criterion, including the fracture toughness of material and the friction energy occurring between the material and the pointed blade, are summarized and analyzed. Finally, an analysis of the stress state in the fracture process zone is proposed. Results show that the puncture-cutting force increases significantly with increasing insertion velocity. A low velocity of the pointed blade is dominated by a uniaxial tension with a constant energy, while a medium velocity causes a dominant biaxial tension with increasing energy, which may be the source of the viscoelastic deformation involved around the crack tip. However, an increase of the velocity increases the shear stress up to a maximum value and, therefore, shows a toughening of material.

Mechanical stress in InP and GaAs ridges formed by reactive ion etching

The mechanical deformation induced by reactive ion etching (RIE) of rectangular ridge waveguides in GaAs and InP has been investigated by photoluminescence and cathodoluminescence techniques. Several trends were identified and are discussed. First, it is concluded that the RIE process itself is the source of the mechanical deformation. A compressive volume change occurs mainly within the ridge (with a maximum close to the vertical etched sidewalls), extending outside the ridges, up to several micrometers below the bottom etched surface. An anisotropic deformation also appears, again mainly close to the etched sidewalls and below the bottom etched surface. A narrow area under tensile stress was also identified, localized outside the ridges and in a shallow region below the bottom etched surface. Cumulative, overlapping effects are seen inside the ridges where the compressive stress fields originating at the vertical etched sidewalls contribute to an overall compression inside the ridge which increases as the ridge width decreases. In addition, a tensile stress is also observed outside the ridge, strongly enhanced by the presence of neighboring ridges. These conclusions are significant for the design of photonic structures. Because of the photoelastic effect, which is important in GaAs and InP, the properties of devices such as waveguides might be affected by the mechanical stress described herein.

Анализ механизмов наследования в живой природе и технике

The evolution of ideas on inheritance is analyzed and basic types of inheritance in animate nature are presented. Reasoning from the analysis of terms adopted in genetics and engineering technique there is carried out the analysis of inheritance mechanisms at machining and machinery operation. There is shown the evolution of ideas on hereditary information: first the part manufactured the accuracy dimensions of which were “copied” (inherited) in the course of engineering procedure; further – a thin surface layer formed during the engineering process and within the frames of the scientific investigation carried out – material of the deformation source where a plastic metal flow takes place. An analysis is carried out and the directions of the development of scientific investigations in the field of technological inheritance are presented.

Geopositioning time series from offshore platforms in the Adriatic Sea

We provide a dataset of 3D coordinate time series of 37 continuous GNSS stations installed for stability monitoring purposes on onshore and offshore industrial settlements along a NW-SE-oriented and ~100-km-wide belt encompassing the eastern Italian coast and the Adriatic Sea. The dataset results from the analysis performed by using different geodetic software (Bernese, GAMIT/GLOBK and GIPSY) and consists of six raw position time series solutions, referred to IGb08 and IGS14 reference frames. Time series analyses and comparisons evidence that the different solutions are consistent between them, despite the use of different software, models, strategy processing and frame realizations. We observe that the offshore stations are subject to significant seasonal oscillations probably due to seasonal environmental loads, seasonal temperature-induced platform deformation and hydrostatic pressure variations. Many stations are characterized by non-linear time series, suggesting a complex interplay between regional (long-term tectonic stress) and local sources of deformation (e.g. reservoirs depletion, sediment compaction). Computed raw time series, logs files, phasor diagrams and time series comparison plots are distributed via PANGAEA (https://www.pangaea.de).

SUBSIDENCE IN MACEIO, BRAZIL, CHARACTERIZED BY DINSAR AND INVERSE MODELING

Abstract. The city of Maceió has been historically affected by cracks and sink events in buildings and city infrastructure. Availability of a consistent Sentinel 1 Mission dataset between 2014 and 2019 allows characterizing the undergoing crustal deformation process that provokes such effects. We processed a dataset of 81 SAR scenes using the DInSAR-SBAS time-series technique, which allowed us to obtain mean velocity of deformation and deformation time series. Detected displacement patterns show subsidence concentrated in the Mundaú lagoon coast in front of Mutange, Pinheiro and Levada neighbourhoods. Inversion of the results, using analytical models, locates a sill-like source at ∼400 m depth and with a radius of ∼0.8 km. Its depth would be compatible with re-activation of the Mutange fault system, possibly related to salt mining operations in the area. Further investigation is needed to better constrain the deformation source and to identify if the observed process was active before the analysed time span.

On the use of adjoints in the inversion of observed quasi-static deformation

SUMMARY An adjoint-based conjugate gradient algorithm provides an efficient means for imaging sources of deformation within the Earth, such as volume stresses associated with fluid flow in aquifers and reservoirs. For time intervals over which the overburden deforms elastically, one can calculate the gradient elements for a single model update using just two numerical simulations. The first is a forward run that is used to compute the residuals associated with the given iteration. The second simulation is to evaluate the application of the adjoint operator to the residuals. In this adjoint calculation, the residual displacements are applied as sources at the measurement locations, driving the deformation in the simulation. The volume stress on the source grid blocks, in response to the residual displacements, provide the gradient components. We apply this technique to satellite-based interferometric synthetic aperture radar (InSAR) line-of-sight displacements that were observed over an oil reservoir in California’s Central Valley. We find that the adjoint-based gradient estimates, requiring 18 CPU seconds, agree with conventional numerical calculations that take over 3700 CPU seconds to compute. Conjugate gradient algorithms utilizing the conventional approach and adjoint-based gradient computations give roughly the same reductions in misfit and similar final estimates of reservoir volume change.

Postseismic deformation following the 2016 Kumamoto earthquake detected by ALOS-2/PALSAR-2

I have been conducting a study of postseismic deformation following the 2016 Kumamoto earthquake using ALOS-2/PALSAR-2 acquired till 2018. I apply ionospheric correction to interferograms of ALOS-2/PALSAR-2. L-band SAR gives us high coherence enough to reveal surface deformation even in vegetated or mountainous area for pairs of images acquired more than 2 years. Postseismic deformation following the Kumamoto earthquake exceeds 10 cm during 2 years at some spots in and around Kumamoto city and Aso caldera. Westward motion of ~ 6 cm/year was dominant on the southeast side of the Hinagu fault, while westward shift was detected on both sides of the Futagawa fault. The area of latter deformation seems to have correlation with distribution of pyroclastic flow deposits. Significant uplift was found around the eastern Futagawa fault and on the southwestern frank of Aso caldera, whose rate reaches 4 cm/year. There are sharp changes across several coseismic surface ruptures such as Futagawa, Hinagu, and Idenokuchi faults. Rapid subsidence between Futagawa and Idenokuchi faults also found. It is confirmed that local subsidence continued along the Suizenji fault, which newly appeared during the mainshock in Kumamoto City. Subsidence with westward shift of up to 4 cm/year was also found in Aso caldera. Time constant of postseismic decay ranges from 1 month to 600 days at selected points, but that postseismic deformation during the first epochs or two is dominant at point in the Kumamoto Plain. This result suggests multiple source of deformation. Westward motion around the Hinagu fault may be explained with right lateral afterslip on the shallow part of this fault. Subsidence along the Suizenji fault can be attributed to normal faulting on dipping westward. Deformation around the Hinagu and Idenokuchi faults cannot be explained with right lateral afterslip of Futagawa fault, which requires other sources. Deformation in northern part of Aso caldera might be the result of right lateral afterslip on a possible buried fault.

Rhyolitic volcano dynamics in the Southern Andes: Contributions from 17 years of InSAR observations at Cordón Caulle volcano from 2003 to 2020

In this article I present a review of InSAR observations of ground deformation at Cordón Caulle volcano, whose 2011–2012 VEI 4-5 eruption is the best scientifically observed and instrumentally recorded rhyolitic eruption to date. I document a complete cycle of pre-eruptive uplift, co-eruptive subsidence and post-eruptive uplift with InSAR data between March 2003 and May 2020, and produced by a complex interplay of magmatic processes. Pre-eruptive data show ~0.5 m of ground uplift in three distinct episodes between 2003 and 2011, with uplift rates between ~3 and ~30 cm/yr. The uplift was likely caused by magma injection resulting in pressurization of the magmatic system at depths of 4–9 km. Data spanning the first 3 days of the eruption show ~1.5 m of deflation produced by two distinct sources at 4–6 km depth located 18 km from each other and up to 10 km from the eruptive vent -- suggesting hydraulic connectivity of a large magma mush zone. A third source of deformation was recorded during the rest of the eruption at a depth of ~5 km, resulting in a total subsidence of ~4.2 m during the whole eruption. On a much smaller spatial scale (~25 km2), InSAR-derived digital elevation models recorded ~250 m of uplift in the area of the eruptive vent interpreted as the intrusion of a shallow laccolith during the first 2.5 months of the eruption and time averaged lava discharge rates up to ~150 m3/s. The co-eruptive time series of reservoir pressure drop and extruded volume follow exponential trends that can be explained by a model of magma reservoir depressurization and conduit flow. Since the end of the eruption, the surface of the volcano was uplifted ~1 m in a sequence of three transient episodes of unrest during 2012 and 2019, with uplift rates between 6 and 45 cm/yr and lasting between 0.5 and 3.2 years. These pulses can be modeled by the same source, a sub-horizontal sill at a depth of ~6 km. Viscoelastic relaxation is not significant on these time scales, hence I interpret these uplift signals as being produced by episodic pulses of magma injection in the crystal mush that likely underlies the volcano. The episodic and abrupt changes of the ground deformation suggest a restless trans-lateral magmatic system at depths of 4–9 km, and active across multiple spatial and temporal scales. Finally, I also discuss challenges of the InSAR technology that should be addressed to detect ground deformation on short time scales, particularly under the low coherence conditions of Cordón Caulle.

Quantitative assessment to the impact of InSAR ionospheric and tropospheric corrections on source parameter modelling: application to the 4th nuclear test, North Korea

SUMMARYAlthough many studies have revealed that the atmospheric effects of electromagnetic wave propagation (including ionospheric and tropospheric water vapour) have serious impacts on Interferometric Synthetic Aperture Radar (InSAR) measurement results, atmospheric corrections have not been thoroughly and comprehensively investigated in many well-known cases of InSAR focal mechanism solutions, which means there is no consensus on whether atmospheric effects will affect the InSAR focal mechanism solution. Moreover, there is a lack of quantitative assessment on how much the atmospheric effect affects the InSAR focal mechanism solution. In this paper, we emphasized that it was particularly important to assess the impact of InSAR ionospheric and tropospheric corrections on the underground nuclear explosion modelling quantitatively. Therefore, we investigated the 4th North Korea (NKT-4) underground nuclear test using ALOS-2 liters-band SAR images. Because the process of the underground nuclear explosion was similar to the volcanic magma source activity, we modelled the ground displacement using the Mogi model. Both the ionospheric and tropospheric phase delays in the interferograms were investigated. Furthermore, we studied how the ionosphere and troposphere phase delays could bias the estimation of Mogi source parameters. The following conclusions were drawn from our case study: the ionospheric delay correction effectively mitigated the long-scale phase ramp in the full-frame interferogram, the standard deviation decreased from 1.83 to 0.85 cm compared to the uncorrected interferogram. The uncorrected estimations of yield and depth were 8.44 kt and 370.33 m, respectively. Compared to the uncorrected estimations, the ionospheric correction increased the estimation of yield and depth to 9.43 kt and 385.48 m, while the tropospheric correction slightly raised them to 8.78 kt and 377.24 m. There were no obvious differences in the location estimations among the four interferograms. When both corrections were applied, the overall standard deviation was 1.16 cm, which was even larger than the ionospheric corrected interferogram. We reported the source characteristics of NKT-4 based on the modelling results derived from the ionospheric corrected interferogram. The preferred estimation of NKT-4 was a Mogi source located at 129°04′22.35‘E, 41°17′54.57″N buried at 385.48 m depth. The cavity radius caused by the underground explosion was 22.66 m. We reported the yield estimation to be 9.43 kt. This study showed that for large-scale natural deformation sources such as volcanoes and earthquakes, atmospheric corrections would be more significant, but even if the atmospheric signal did not have much complexity, the corrections should not be ignored.

Mechanical Imaging of a Volcano Plumbing System From GNSS Unsupervised Modeling

AbstractIdentification of internal structures in an active volcano is mandatory to quantify the physical processes preceding eruptions. We propose a fully unsupervised Bayesian inversion method that uses the point compound dislocation model as a complex source of deformation, to dynamically identify the substructures activated during magma migration. We applied this method at Piton de la Fournaise. Using 7‐day moving trends of Global Navigation Satellite System (GNSS) data preceding the June 2014 eruption, we compute a total of 15 inversion models of 2.5 million forward problems each, without a priori information. Obtained source shapes (dikes, prolate ellipsoids, or pipes) show magma migration from 7–8 km depth to the surface, drawing a mechanical “tomography” of the magma pathway. Our results also suggest source geometries compatible with observed eruptive fissures and seismicity distribution. In case of finite magma volume involved in final dike injection, source volume estimates from this method allow forecasting volumes of erupted lava.

Deformation and stress in hydrothermal regions: The case of a disk-shaped inclusion in a half-space

Hydrothermal regions are affected by a wide variety of phenomena, including ground inflation and deflation episodes. Among them, calderas offer the opportunity to study the complex interactions between magmatic processes at depth and permeable rocks saturated with fluids in the upper sedimentary layers. One of such regions is the Campi Flegrei caldera in southern Italy, where several source models have been applied over the years to reproduce the ground displacement and seismicity observed during the most recent phase of major unrest (1982–1984). The present work aims at introducing a new source model consisting of a thermo-poro-elastic inclusion embedded in a homogeneous poroelastic half-space. The inclusion is meant to represent a permeable rock layer stressed and strained by hot and pressurized volatiles released upward by an underlying magmatic reservoir and is modeled as a thin horizontal disk inside which a sudden change of temperature and pore pressure occurs. We provide semi-analytical solutions for the displacement and stress fields both within and outside the source and check them by comparison with those obtained through a fully numerical approach. Results provided by our model are compared with two other deformation source models often used to describe volcanic environments in terms of pressurized cavities describing a spherical magma chamber (Mogi source) or a sill-like magma intrusion (Fialko source). For the Campi Flegrei 1982–84 unrest, our model provides a better reproduction of ground deformation data and manages to explain the widespread presence of compressive focal mechanisms, since the stress field promoted both inside and outside the thermo-poro-elastic inclusion is very different from pressurized cavities.

Water Molecule-Triggered Anisotropic Deformation of Carbon Nitride Nanoribbons Enabling Contactless Respiratory Inspection

The exploitation of the interaction between nanostructured matter and small molecules, such as H2O at interfaces via dynamic hydrogen bonding, is essentially the key for smart, responsive nanodevic...

TimeFun-InSAR algorithm to investigate physical changes at Bromo volcano by using ALOS/PALSAR data sets

Mt. Bromo is geographically located in eastern of Java Island at 112°57'30'' longitude and 7°56' latitude, with a large area of caldera ~10 Km2. The land over the volcano is a perfect area for farming, one of the important factor affects the level of soil fertility is the most mineral rich soils. Volcanic activities at Mt. Bromo has been recorded in 1775 which characterized by small eruptions with cycles ranging from one to five years. Regarding this evidence, we tried to investigate the surface changes over the Mt. Bromo by using Time-Series InSAR with TimeFun algorithm. TimeFun is an extension of SBAS to allow incorporating various functions such as seasonal oscillations, polynomials, and step functions as generally it estimates DEM errors as well and allows missing observation. The maximum allowed baseline value is defined and used to constrain the interferogram pair by selecting manual after differential InSAR processing in single face working. The proposed analysis is based on 27 SAR data sets acquired by the ALOS/PALSAR sensors during the 2007–2017 time interval. The result shows us deformation occurred up to ~10 cm at summit of Mt. Bromo during the eruption period. Time-series monitoring of surface deformation to infer volume changes, geometries and locations of sources of deformation involved in the future eruption

A multiscale-indentation study of deformation and fracture in 6H polycrystalline silicon carbide

ABSTRACT The mechanical behaviour of a polycrystalline silicon carbide across length scales was studied using Vickers indentation, focusing on the hardness, fracture toughness and failure mechanism of the material. For macroscopic and microscopic indentations, the hardness decreased with an increase in load, which was associated with the well-known indentation size effect as well as the internal flaws. For nanoindentation, severe plastic deformation was discovered beneath the imprints on the basal plane (0001) which is the most favourable crystallographic plane for dislocation movement. Alternative sources of plastic deformation, including deformation twinning and stacking faults, were found for nanoindentations with an increased load. Also, cracking was observed for indents made at 100 mN and above, which was used to study the fracture toughness.

Source Model for Sabancaya Volcano Constrained by DInSAR and GNSS Surface Deformation Observation

Sabancaya is the most active volcano of the Ampato-Sabancaya Volcanic Complex (ASVC) in southern Perú and has been erupting since 2016. The analysis of ascending and descending Sentinel-1 orbits (DInSAR) and Global Navigation Satellite System (GNSS) datasets from 2014 to 2019 imaged a radially symmetric inflating area, uplifting at a rate of 35 to 50 mm/yr and centered 5 km north of Sabancaya. The DInSAR and GNSS data were modeled independently. We inverted the DInSAR data to infer the location, depth, and volume change of the deformation source. Then, we verified the DInSAR deformation model against the results from the inversion of the GNSS data. Our modelling results suggest that the imaged inflation pattern can be explained by a source 12 to 15 km deep, with a volume change rate between 26 × 106 m3/yr and 46 × 106 m3/yr, located between the Sabancaya and Hualca Hualca volcano. The observed regional inflation pattern, concentration of earthquake epicenters north of the ASVC, and inferred location of the deformation source indicate that the current eruptive activity at Sabancaya is fed by a deep regional reservoir through a lateral magmatic plumbing system.

The Role of Seismic and Slow Slip Events in Triggering the 2018 M7.1 Anchorage Earthquake in the Southcentral Alaska Subduction Zone

AbstractThe M7.1 2018 Anchorage earthquake occurred in the bending part of the subducting North Pacific plate near the geometrical barrier formed by the underthrusting Yakutat terrane. We calculate the triggering potential related with stress redistribution from deformation sources including the M9.2 1964 earthquake coseismic slip, postseismic deformation, slip from regional M > 5 earthquakes, and the cumulative slip of previously detected slow slip events over the past 55 years. We investigate the deeper shallow depth (20–60 km) seismicity response to these perturbations using an epidemic type aftershock sequence model to describe earthquake‐to‐earthquake interactions. The statistical forecast captures the triggered seismicity during the 1983 M6+ aftershocks in Columbia Bay but performs poorly during the slow slip event period between 1992.0 and 2004.8 that presents a statistically significant rate change (β, Z > 2; M < 4.0). We find that stress effects from the 1964 postseismic source and the 12‐year‐long slow slip event (~M7.8) contribute to the 2018 Anchorage earthquake occurrence and that slow slip events modulate the deeper shallow depth seismicity patterns in the region.

Snapshot of a magmatic/hydrothermal system from electrical resistivity tomography and fumarolic composition, Whakaari/White Island, New Zealand

Combined interpretation of Electrical Resistivity Tomography (ERT) data, with plume and fumarolic gas emissions provides a snapshot of the Whakaari/White Island hydrothermal system 11 months prior to an eruption on December 9, 2019. Two and three dimensional inversion of the ERT data images the F0 fumarole as a low resistivity (2–5 Ωm) feature reflecting the two-phase zone surrounding the single phase vapour conduit. Crucially, interpretation of the inversion images is well constrained by a large existing dataset of rock electrical properties, including surface conductivity, porosity and intrinsic formation factor, alongside new measurements of liquid phase electrical conductivity taken from a range of hot-springs on the island. Pore-filling liquids are an order of magnitude more conductive than sea-water with their low to very low pH (3.4 to −0.3) contributing to their extremely conductive nature. An extensive low-resistivity feature (0.2 Ωm) at ~125 m depth is therefore interpreted as a liquid saturated layer exposed to hydrothermal alteration by acid fluids. The intersection of the F0 fumarole trace with this layer is coincident with a previously determined source of deformation, suggesting that heat transport inside the fumarole conduit pressurises surrounding liquid and vapour filled pore space, generating the deformation signal. The timeseries of fumarolic and plume emissions in the year prior to the ERT survey show that the gases transported by the fumarole are a mixture of high temperature magmatic vapour and lower temperature gas equilibrated within the hydrothermal environment. Interpretation of the gas data suggests that the snapshot captured by the ERT image shows the single-phase vapour and two-phase vapour-liquid regions adjacent to the conduit were likely at close to their smallest extent, consisting of mostly hydrothermal derived gases.

The effect of in-plane shear properties on the ballistic performance of polyethylene composites

Using developed experimental and analytical methods for in-plane shear characterization of quasi-statically loaded polyethylene (PE) laminates, this work evaluates the effect of the in-plane shear behavior has on ballistic performance (limit velocity and back face deflection). As in-plane shear is a matrix-dominated phenomena and processing pressure is known to noticeably influence the shear properties of polyethylene composites, the matrix materials and processing conditions are varied in order to probe an array of configurations. The in-plane shear properties are assessed through quasi-static tensile testing of laminates with [±45°] orientation and the ballistic performance is evaluated using a laboratory gas gun and high speed DIC. It is found that the in-plane shear strain for the more compliant HB 212 material is twice that of the HB 210 material during a ballistic event, which corresponds to the 5% increase in limit velocity of HB 212 over HB 210. The source of the shear deformation in PE materials is fiber rotation as evidenced by the quasi static tests.

Tiltmeter data inversion to characterize a strain tensor source at depth: application to reservoir monitoring

Surface deformation measured by geodetic data is the sum of single-strain sources deforming at depth. A combination of volume changes from several analytical models (e.g. a point source or dislocation along a plane) can be used to model the different sources. However, solving for the best fit of volume variations, dislocations, position and orientation parameters of all sources is a nonlinear problem, and its solution is generally non-unique. This problem can be converted into a linear one by assimilating the sum of sources to a simplified model formed by three orthogonal planes of dislocations at fixed position and orientation. This strain source model is equivalent to having all neighbouring deformation sources contained in a small size volume. The determination of the strain tensor components can be performed by inverting geodetic data. Because of their high resolution, tiltmeters are well adapted to survey shallow deformation of volcanoes and geological reservoirs. However, they are known to display unknown long-term drift. We propose an approach to jointly estimate the temporal evolution of the strain source and time-dependent instrumental parameters. We verify the approach using synthetic data, giving confidence intervals for each component of the strain tensor. Finally, we link geological information to the internal deformation by interpreting the strain tensor as principal directions of deformation. This approach seems promising for the identification of fracture onset and fault reactivation in geothermal, hydrocarbon exploitations or volcanic systems.