Simultaneous Shearing Research Articles

Improving the phase reconstruction accuracy of simultaneous phase-shifted lateral shearing interferometry using a polarization redundant sub-region interpolation method.

In a simultaneous phase-shifted lateral shearing interferometry, a division of focal plane polarization camera is generally used as the phase-shifting device. However, acquiring simultaneous phase-shift interferograms in a single frame suffers from a lack of spatial resolution, significantly affecting the phase reconstruction accuracy. A polarization redundant sub-region interpolation (PRSI) method is proposed to solve this problem. This interpolation method distinguishes smooth regions from stripe fringe regions by calculating the polarization redundancy error of the synchronous phase shift interferogram. After sub-regional processing, resolution reconstruction is performed in the smoothed area using a fast convolutional bilinear interpolation method. In the streak detail region, the resolution reconstruction is performed based on the strength of the correlation between the orthogonal and non-orthogonal polarization channels crossing the streak region. The PRSI method can quickly reconstruct the lost pixels and accurately recover the stripe detail information. Experiment results show that the proposed interpolation method outperforms the existing dominant methods in terms of visual reconstruction effect and quantitative index of phase reconstruction.

Simultaneous two-step phase-shifting lateral shearing interferometry for aspherical surface based on an orthogonal shear displacer

A novel simultaneous two-step phase-shifting lateral shearing interferometry for aspherical surface based on an orthogonal shear displacer (OSD) is proposed, it is an effective technological measure of aspherical surface measurement, to effectively solve the non-uniformity of light intensity and limited transmission order caused by the beam displacer device. The OSD system is formed by the adoption of two-crystal polarization parallel beam displacers (PBDs), which makes it achieve the orthogonal shearing in the x- and y-directions simultaneously. A quarter-wave plate (QWP) is used to generate the desired phase-shifting, and four beam lateral shearing interference waves are simply generated in OSD orthogonal directions without any bulky and complicated optical components. The phase maps of the aspherical surface can be instantly obtained using the spatial phase-shifting technique with a polarization pixelated mask (or called micro-polarization array: MPA) integrated into CCD. In this study, the proposed method was theoretically described and simulation results were analyzed. The simultaneous two-step phase-shifting lateral shearing interference fringes can be extracted in real-time with the MPA. The experiment results compared with the ZYGO interferometer were performed, and proved that the measurement error is not more than 2%. This interferometry has made it possible to improve the stability and feasibility of aspherical surface testing experiments.

Heat-induced whey protein microparticulation under continuous shear in acidic conditions

Investigations were undertaken into the effect of shear rate, temperature profile, pH and protein concentration on aggregate formation upon heating of whey protein solutions at pH 2.0 and 3.5. Shear rate, protein concentration and pH had notable effects, while the temperature profile was found to have a minimal effect on the final aggregate size. At higher concentrations, aggregate sizes decreased as shear increased, while at lower concentrations, the opposite was observed. Additionally, pH impacted the extent of change in aggregate size at the two concentrations investigated. Based on previous findings in the literature and the results obtained herein, it is proposed that particle size is governed, not just by concentration, but the effective concentration and that it is the primary driver in determining the aggregate size produced from whey protein solutions exposed to simultaneous heating and shearing. A mechanism has been proposed to explain the effects of pH, concentration and shear rate on whey protein aggregate size.

Shearing with solvent vapor annealing on block copolymer thin films for templates with macroscopically aligned nanodomains

A template with macroscopically aligned nanopatterns can be an effective vehicle for arranging nanoscale particles or rods in a particular orientation to achieve their anisotropic properties. A room-temperature process is also desirable for nanoscale patterning of heat-sensitive functional molecules such as organic fluorophores. Here, large-area orientation of nanodomains of block copolymers is demonstrated by simultaneous shearing and solvent vapor annealing at room temperature. The shear-aligned nanodomains are applied to a chemical template for nanoscale patterning of green fluorescent molecules. In addition, the grooved nanochannels obtained from the macroscopically aligned nanodomains work as a physical template for guiding Au nanorods to end-to-end assemblies which exhibit the polarization-dependent plasmonic extinction.

Complex shearing of extruded tube (CSET) method for production of tubes with ultra-fine-grained structure

A novel combined route for production of tubes by severe plastic deformation, called Complex Shearing of Extruded Tube (CSET), is introduced. This technique combines sequential extrusion and equal channel angular pressing accompanied by simultaneous friction-induced shearing. The effect of this new route on the microstructure of pure Al and an Al-Mn-Cu alloy is demonstrated which proves the capability of CSET technique to refine the grain size in both materials.

PIXUL-ChIP: integrated high-throughput sample preparation and analytical platform for epigenetic studies.

Chromatin immunoprecipitation (ChIP) is the most widely used approach for identification of genome-associated proteins and their modifications. We have previously introduced a microplate-based ChIP platform, Matrix ChIP, where the entire ChIP procedure is done on the same plate without sample transfers. Compared to conventional ChIP protocols, the Matrix ChIP assay is faster and has increased throughput. However, even with microplate ChIP assays, sample preparation and chromatin fragmentation (which is required to map genomic locations) remains a major bottleneck. We have developed a novel technology (termed ‘PIXUL’) utilizing an array of ultrasound transducers for simultaneous shearing of samples in standard 96-well microplates. We integrated PIXUL with Matrix ChIP (‘PIXUL-ChIP’), that allows for fast, reproducible, low-cost and high-throughput sample preparation and ChIP analysis of 96 samples (cell culture or tissues) in one day. Further, we demonstrated that chromatin prepared using PIXUL can be used in an existing ChIP-seq workflow. Thus, the high-throughput capacity of PIXUL-ChIP provides the means to carry out ChIP-qPCR or ChIP-seq experiments involving dozens of samples. Given the complexity of epigenetic processes, the use of PIXUL-ChIP will advance our understanding of these processes in health and disease, as well as facilitate screening of epigenetic drugs.

Effect of Nano-SiC on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy Processed by Thixomolding

Magnesium injection molding technology was used to produce Mg based nanocomposites. AZ91 chips were mixed with 5 wt.% of β-SiC nanoparticles in solid state and fed to pre-heated cylinder of prototype injection molding machine. Using screw rotation, granules were transferred to nozzle area at simultaneous intensive shearing and mixing of slurry containing reinforcement phases. Injection process was conducted at 595 °C, which corresponded to about 90% liquid phase and cast to steel die preheated to 150 °C. Detailed characterization of microstructure was performed using SEM and TEM microscopes. Composite microstructure consisted of α(Mg) globular grains with size of about 60 μm and volume of 7-10% surrounded by mixture of proeutectic magnesium solid solution with irregular shape and average size of 12 μm as well as fine eutectic mixture (α(Mg) + β-Mg17Al12). Additionally, TEM-BF image showed β-SiC nanoparticles with size of 20-50 nm in the area of eutectic. Hardness and compression strength of AZ91 nanocomposites increased from 58 to 75 HV and from 200 to 235 MPa, respectively.

Multiple-aperture one-shot shearography for simultaneous measurements in three shearing directions

A new shearography configuration was developed to simultaneously acquire images of a specimen in three different shearing directions, the proposed configuration is capable of performing measurements of shearography with multiple shearing directions using just one single interferogram. The device uses a three aperture mask and a single imaging lens to produce interference speckles with carrier fringes in three different directions. A set of three wedge prisms are used in combination with the three apertures to produce simultaneous shearing interferograms for three different orientations. A single high-resolution image of the specimen is captured for each loading level and the phase maps are computed by FTM (Fourier Transform Method). Additionally, as the device has no movable parts and just a single shot image is acquired, it is very compact, robust and can be successfully used outside the optical bench. The paper presents the optical setup and a practical application for the new technique.

Polarized digital shearography for simultaneous dual shearing directions measurements.

The selection of the direction of sensitivity for digital shearography is determined by its shearing direction. As a result, directionally shaped defects could be missed in non-destructive testing using a digital shearography system with only one shearing direction. This paper reports a polarized digital shearography system based on two Mach-Zehnder interferometers, which can create two orthogonal shearing directions and record shearograms in the two orthogonal directions simultaneously. The two shearograms are separated from each other by proper polarization design so that no cross interference occurs. The phase maps of the shearograms are generated by spatial phase shift methods through the introduction of different carrier frequencies in the two orthogonal shearograms and use of the Fourier transform method. This enabled simultaneous dual directional non-destructive testing during continuous loading. Theory derivation, spectrum analysis, and non-destructive testing application results are shown in detail.

Joining Experiment of Aluminum Sheets Using High-Speed Shearing

A novel method for joining of sheet edges was investigated. It makes use of the sheared faces under high-speed. The temperature remarkably elevates and the material softens in the thin severely deformed layer. The cut faces are contacted each other with sliding motion immediately after shearing. Sheet materials are a pure aluminum A1050 and its alloy A5052. Two similar sets of circular shearing punch, die and sheet are concentrically stacked in the device for performing the simultaneous shearing. The upper sheared circular sheet slides into the hole of the lower one for joining shortly after the shearing. Strain-rate order was about 104/s in shearing, where the punches were driven by a drop-weight. Quasi-static test was also conducted for comparison. Joining was achieved only in the high-speed test. Joining boundary was not visible at the central portion in thickness, though the gap openings were seen near both sheet surfaces. Joining efficiency was evaluated as the relative strength to the tensile strength of the material. It was improved as the shearing clearance becomes smaller. The maximum efficiency was about 30 % for A1050 material. It is about 25 % for A5052. It was at most 10 % in the joining of A1050 and A5052.

Qualitative Behaviour of Elastic-Plastic Solutions for a Class of Damage Mechanics Models Near Bimaterial Interfaces: A Simple Analytical Example

The paper presents an exact analytic solution for a class of elastic-plastic models with damage evolution. The boundary value problem consists of a planar deformation comprising the simultaneous shearing and expansion of a hollow cylindrical specimen of material and involves a bimaterial interface at which the materials stick to each other. With no loss of generality for understanding the qualitative behaviour of the solution near the bimaterial interface, an extreme case when the hard material is rigid is considered. The solution is reduced to a transcendental equation for the value of the equivalent plastic strain at the bimaterial interface. This equation predicts that the equivalent plastic strain attains a maximum under certain conditions. The existence of the solution of the boundary value problem depends on the value of the damage parameter at fracture, which is a material constant. In particular, if this value is larger than the value of the damage parameter at the bimaterial interface corresponding to the maximum possible value of the equivalent strain at this interface, then no solution exists. Experimental data available in the literature are used to assess whether Lemaitre’s model is applicable.

Mechanical disruption of mammalian cells in a microfluidic system and its numerical analysis based on computational fluid dynamics

The lysis of mammalian cells is an essential part of different lab-on-a-chip sample preparation methods, which aim at the release, separation, and subsequent analysis of DNA, proteins, or metabolites. Particularly for the analysis of compartmented in vivo metabolism of mammalian cells, such a method must be very fast compared to the metabolic turnover-rates, it should not affect the native metabolite concentrations, and should ideally leave cell organelles undamaged. So far, no such a method is available. We have developed a microfluidic system for the effective rapid mechanical cell disruption and established a mathematical model to describe the efficiency of the system. Chinese hamster ovary (CHO) cells were disrupted with high efficiency by passing through two consecutive micronozzle arrays. Simultaneous cell compression and shearing led to a disruption rate of ≥90% at a sample flow rate of Q = 120 μL min(-1) per nozzle passage, which corresponds to a mean fluid velocity of 13.3 m s(-1) and a mean Reynolds number of 22.6 in the nozzle gap. We discussed the problem of channel clogging by cellular debris and the resulting flow instability at the micronozzle arrays. The experimental results were compared to predictions from Computational Fluid Dynamics (CFD) simulations and the critical energy dissipation rate for the disruption of the CHO cell population with known size distribution was determined to be 4.7 × 10(8) W m(-3). Our model for the calculation of cell disruption on the basis of CFD-data could be applied to other microgeometries to predict intended disruption or undesired cell damage.

Diffractive simultaneous bidirectional shearing interferometry using tailored spatially coherent light

Measurements of wavefront deformations can be carried out with the help of lateral shearing interferometers. Here the focus is on a setup providing two shears along orthogonal directions simultaneously to generate the data needed for a reconstruction. We describe a diffractive solution using Ronchi phase gratings with a suppressed zeroth order for both the doubling of the wavefront under test and the bidirectional shearing unit. A series arrangement of the gratings offers an on-axis geometry, which minimizes the systematic errors of the test. For illumination, an extended incoherent monochromatic light source is used. High-contrast fringes can be obtained by tailoring the degree of coherence via a periodic intensity distribution.

Crack-seal microstructure evolution in bi-mineralic quartz–chlorite veins in shales and siltstones from the RWTH-1 well, Aachen, Germany

In core samples from the deep geothermal well RWTH-1 we studied Variscan quartz–chlorite veins formed by crack-seal processes in siliciclastics at the brittle to ductile transition. These sheared veins are common in sections of the well, which are interpreted as Variscan thrust zones based on image logs and seismic data. Microstructures interpreted to reflect different stages in the evolution of such crack-seal veins suggest the veins started in microcracks sealed by quartz and chlorite, to veinlets crossing multiple grains, and bundles of veinlets evolving by progressive localization into low-angle extensional shear veins and high-angle dilational jog veins. In the sheared veins, chlorite and quartz ribbons show evidence for crack-seal and simultaneous ductile shearing during vein evolution, forming peculiar fin-shaped microstructures in quartz ribbons. In high-angle dilational jogs fibrous crystals of quartz and chlorite point to multiple crack-seal events with simultaneous growth of two different mineral phases. This is interpreted to be the basic microstructural process in the veins. We extend earlier models of polycrystal growth in fractures and present a series of 2D simulations of the kinematics of crystal growth in these bi-mineralic veins for both localized and non-localized cracking. Results are compared with the observed microstructures. We show that when the relative growth rates of the two mineral phases are different, serrated grain boundaries evolve. The similarities between observation and model suggest that the assumption of our model is valid, although many second order processes require a more detailed study. We propose that the principles observed here can be applied to other bi-mineralic crack-seal veins.

On numerical implementation of an isotropic elastic–viscoplastic constitutive model for bulk metallic glasses

An efficient algorithm within the finite deformation framework is developed for finite element implementation of a recently proposed isotropic, Mohr–Coulomb type material model, which captures the elastic–viscoplastic, pressure sensitive and plastically dilatant response of bulk metallic glasses. The constitutive equations are first reformulated and implemented using an implicit numerical integration procedure based on the backward Euler method. The resulting system of nonlinear algebraic equations is solved by the Newton–Raphson procedure. This is achieved by developing the principal space return mapping technique for the present model which involves simultaneous shearing and dilatation on multiple potential slip systems. The complete stress update algorithm is presented and the expressions for viscoplastic consistent tangent moduli are derived. The stress update scheme and the viscoplastic consistent tangent are implemented in the commercial finite element code ABAQUS/Standard. The accuracy and performance of the numerical implementation are verified by considering several benchmark examples, which includes a simulation of multiple shear bands in a 3D prismatic bar under uniaxial compression.

Shear strength of geosynthetic composite systems for design of landfill liner and cover slopes

Torsional ring shear tests were performed on composite specimens that simulate the field alignment of municipal solid waste (MSW) landfill liner and cover system components. Simultaneous shearing was provided to each test specimen without forcing failure to occur through a pre-determined plane. Composite liner specimens consisted of a textured geomembrane (GM) underlain by a needle-punched geosynthetic clay liner (GCL) which in turn underlain by a compacted silty clay. Hydrated specimens were sheared at eleven different normal stress levels. Test results revealed that shear strength of the composite liner system can be controlled by different failure modes depending on the magnitude of normal stress and the comparative values of the GCL interface and internal shear strength. Failure following these modes may result in a bilinear or trilinear peak strength envelope and a corresponding stepped residual strength envelope. Composite cover specimens that comprised textured GM placed on unreinforced smooth GM-backed GCL resting on compacted sand were sheared at five different GCL hydration conditions and a normal stress that is usually imposed on MSW landfill cover geosynthetic components. Test results showed that increasing the GCL hydration moves the shearing plane from the GCL smooth GM backing/sand interface to that of the textured GM/hydrated bentonite. Effects of these interactive shear strength behaviors of composite liner and cover system components on the possibility of developing progressive failure in landfill slopes were discussed. Recommendations for designing landfill geosynthetic-lined slopes were subsequently given. Three-dimensional stability analysis of well-documented case history of failed composite system slope was presented to support the introduced results and recommendations.

Two-stage collision-related extrusion of the western Dabie HP–UHP metamorphic terranes, central China: Evidence from quartz c-axis fabrics and structures

The western Dabie orogen (also known as the Hong'an block) forms the western part of the Dabie–Sulu HP–UHP belt, central China. Rocks of this orogen have been subjected to pervasive ductile deformation, and include numerous quartz schists and felsic mylonites cropping out in ductile shear zones. Quartz textures in these mylonites contain important clues for understanding the movement sense of late-collisional extrusion and exhumation of high-pressure–ultrahigh-pressure (HP–UHP) rocks from the lower crustal level to the upper crustal level during Middle Triassic and Early Jurassic. The orientation and distribution of quartz crystallographic axes were used to confirm the regional shear sense across the orogen. The asymmetry of c-axis patterns consistently indicates top-to-the-southeast thrusting across the orogen in early structural stages. Later stages of deformation show different senses of movement in northern and southern parts of the orogen, with top-to-the-northwest sinistral shearing recorded in rocks north of the Xinxian HP–UHP eclogite-facies belt, and top-to-the-southeast dextral shearing south of the same unit. Based on our study on quartz c-axis fabrics and marco- to micro-scale structures, simultaneous southeastward shearing within a large part of the orogen and normal faulting north of the Xinxian HP–UHP unit is explained by upward extrusion in early stages of deformation. The extrusion process has been attributed to syn- and late-collisional processes, accounting for some earlier deformation in the western Dabie orogen such as metamorphic sequences around the core of the Xinxian HP–UHP eclogite-facies unit. Much higher pressure of deformation is also indicated in the aligned glaucophane and omphacite from blueschist and eclogite in the field. An orogen-parallel eastward extrusion of the Xinxian HP–UHP eclogite-facies unit, however, occurred diachronously in later stages of deformation. Therefore, a tectonic model combining an early upward extrusion with a later eastward extrusion is presented. Two different stages and types of extrusion for exhumation of HP–UHP rocks are suitable to all of east central China. Geochronological data shows that the first, upward extrusion occurred during Middle Triassic, the second, eastward extrusion occurred during Late Triassic to Early Jurassic. These two extrusions are correlative with two stages of rapid exhumation of the Dabie HP–UHP rocks, respectively. These two-stage late-collisional (Middle Triassic to Early Jurassic) extrusion events bridge the gap between syn-collisional (Early to Middle Triassic) vertical extrusion and post-collisional (Cretaceous) eastward-directed lateral escape and provide vital clues to understanding the more detailed processes of exhumation of HP–UHP rocks.

Qualitative behaviour of viscoplastic solutions in the vicinity of maximum-friction surfaces

The maximum-friction surface is a source of singular solution behaviour for several rate-independent plasticity models. Solutions based on conventional viscoplastic models do not show such behaviour. For a class of materials, there is a range of temperatures and/or strain rates where a necessity of the consideration of rate effects depends on the area of application of the final result. Hence, the same material under the same conditions can be represented by either rate-independent or rate-dependent models. In this case, a reasonable requirement is that viscous effects should not be very significant and, in particular, the qualitative behaviour of viscoplastic solutions should be similar to that of solutions based on rate-independent models. The present paper deals with this issue by means of the solution for simultaneous shearing and expansion of a hollow cylinder under plane-strain deformation. One of the goals of the paper is to show that there is a class of viscoplastic models satisfying the requirement formulated. The other goal is to find an asymptotic representation of the solution in the vicinity of the maximum-friction surface and compare it with the rigid perfectly plastic solution.

The emplacement mode of Upper Cretaceous plutons from the southwestern part of the Sredna Gora Zone (Bulgaria): structural and AMS study

The emplacement mode of Upper Cretaceous plutons from the southwestern part of the Sredna Gora Zone (Bulgaria): structural and AMS study Several plutons located in the southwestern part of the Sredna Gora Zone — Bulgaria are examples of the Apuseni-Banat-Timok-Sredna Gora type of granites emplaced during Late Cretaceous (86-75 Ma) times. The studied intrusive bodies are spatially related to and deformed by the dextral Iskar-Yavoritsa shear zone. The deformation along the shear zone ceased at the time of emplacement of the undeformed Upper Cretaceous Gutsal pluton, which has intruded the Iskar-Yavoritsa mylonites. A clear transition from magmatic foliation to high-, moderate- and low-temperature superimposed foliation and lineation in the vicinity of the Iskar-Yavoritsa and related shear zones gives evidence for simultaneous tectonics and plutonism. Away from the shear zones, the granitoids appear macroscopically isotropic and were investigated using measurements of anisotropy of magnetic susceptibility at 113 stations. The studied samples show magnetic lineation and foliation, in agreement with the magmatic structures observed at a few sites. Typical features of the internal structure of the plutons are several sheet-like mafic bodies accompanied by swarms of mafic microgranular enclaves. Field observations indicate spatial relationships between mafic bodies and shear zones as well as mingling processes in the magma chamber which suggest simultaneous shearing and magma emplacement. Structural investigations as well as anisotropy of magnetic susceptibility (AMS) data attest to the controlling role of the NWSE trending Iskar-Yavoritsa shear zone and to the syntectonic emplacement of the plutons with deformation in both igneous rocks and their hosts. The tectonic situation may be explained by partitioning of oblique plate convergence into plate-boundary-normal thrusting in the Rhodopes and plate-boundary-parallel transcurrent shearing in the hinterland (Sredna Gora).

A coupled consolidation shear model for the process of formation of glaciated soils

It has been generally observed that the measured preconsolidation pressure values for glaciated soils are not compatible with the measured effective pressure values at the bed of the glacier if one-dimensional consolidation alone is considered as the formation process for these soils. In this paper, a new model for the process of formation of glaciated soil, termed the coupled consolidation shear (CCS) model, is developed using the frameworks of critical state soil mechanics and small-strain consolidation theory. The CCS model includes simultaneous shearing and consolidation of subglacial sediments and is able to simulate profiles of preconsolidation pressure versus depth that closely resemble those observed in glaciated soils. The CCS model is validated by successfully simulating the profile of preconsolidation pressure versus depth for an 80 m deep Battleford till layer in Birsay, Saskatchewan, Canada. The CCS model suggests the existence of anisotropic yield strength and stiffness in glaciated soils as a consequence of coupling subglacial shear and consolidation.