Full-field Analysis Research Articles

Manipulate Vibration Propagation by Anisotropic Honeycomb Structure

As a new type of acoustic metamaterial, the pentamode material has extensive application prospect in controlling acoustic wave propagation because of its fluid properties. Firstly, a kind of pentamode material unit cell is designed, which is a two-dimensional honeycomb truss structure. Then, the asymptotic homogenization method is used to calculate static parameters of the unit cell, and also the influence of the geometric parameters and material composition of the unit cell on its mechanical properties is studied. Besides, based on transformation acoustics and the design method of the cylindrical cloak proposed by Norris, an acoustic cloak with isotropic density and gradient elastic modulus is constructed by periodically assembling the unit cell to guide the wave to bypass obstacles. Finally, the full displacement field analysis is carried out to prove the stealth effect of the acoustic cloak.

A new accelerated technique for validation of cyclic plasticity models

This contribution presents a new methodology of fatigue tests evaluation based on digital image correlation application. The full-field strain analysis brings the possibility of 3D strain measurement evaluation on a curved part of specimen standardly used under axial-torsional loading. Resulting strain response curves can subsequently serve for evaluation of cyclic plasticity model predictions. The crucial idea is the way of FE model creation to can evaluate simulation in the same points of the structure as in the DIC measurement. The new methodology saves amount of material and leads to a shorter experimental time.

Full-field Stress Analysis of a Crane Hook Model Performed by Finite Element Analysis and Digital Image Correlation Method

The contribution deals with a full-field stress analysis of the crane hook model. The investigation was realized using numerical as well as experimental analysis. In numerical analysis, the software based on finite element method was used. Experimental analysis was performed in laboratory conditions via non-contact optical method of digital image correlation. The results in a form of von Mises stress obtained by both approaches along identical virtual line gages, were depicted and compared. The paper briefly describes the methodologies of both, experimental and numerical types of modeling.

Full-field analysis of AL/FE explosive welded joints for shipbuilding applications

Nowadays explosion weld is widely used in marine structures, thanks to its reliability. AL/FE explosive welded joints, used in shipbuilding applications, were investigated in this research activity. Static and fatigue bending tests were carried out on rectangular specimens made of ASTM A516 low carbon steel, clad by explosion welding with A5086 aluminum alloy and provided with an intermediate layer of pure aluminum. Two full-field techniques were applied during the bending tests: Digital Image Correlation and Infrared Thermography. The digital image correlation technique allowed determining the displacement and strain fields showing that the aluminium side has a higher strain with respect to the steel side, and Infrared Thermography was used to detect the superficial temperature of the specimen allowing the determination of the fatigue limit. The fatigue limit values, predicted using the Thermographic Method during static and fatigue tests, are in good agreement with the experimental values of the fatigue limit.

In situ temperature sensing with fluorescent chitosan-coated PNIPAAm/alginate beads

The interest in the development of non-contact temperature sensors for particle image velocimetry (PIV) is continuously growing. The integration of thermochromic tracers in PIV represents a critical step forward in experimental fluid mechanics, which would enable detailed full-field analysis of thermal and environmental flows. In this paper, interpenetrated polymer networks (IPN) PNIPAAm/alginate loaded with Nile Red (NR) fluorescent dye are used to develop beads for simultaneous non-contact temperature sensing and flow tracing in fluids. The novel IPN beads are coated with chitosan to properly modulate particle permeability in water. The thermochromic response of the fluorescent tracers is studied through fluorescence spectroscopy, evidencing an increase in the NR fluorescence emission up to twenty times above the lower critical solution temperature of PNIPAAm. These findings confirm the potential of fluorescent chitosan-coated PNIPAAm/alginate beads for in situ temperature in PIV.

Modelling the effect of process-induced anisotropy on the constitutive behavior of chopped fiber composites

This study aims at understanding the influence of process-induced anisotropy on the mechanical behavior of chopped fiber composites up to the onset of failure. Due to the specific microstructure of these materials – neither laminates nor reinforced plastics – a new specimen geometry must be devised for their characterization. Experimental investigations coupled with full field analyses led to the definition of a geometry that avoids edge effects and minimizes strain heterogeneity along the free length. Specimens adopting this geometry were cut out of plates manufactured with a controlled process-induced anisotropy, in different directions. Monotonic and cycled loading paths were applied to these coupons and an elastic–plastic damageable behavior is observed, with little strain rate effects in quasi-statics. Both linear and nonlinear mechanisms display a significant anisotropy, which is found to evolve monotonously with process-induced strains. Simple scalar evolution laws for irreversible strains and loss of stiffness may nevertheless be identified.

Influence of specimen pre-shear and wrinkling on the accuracy of uniaxial bias extension test results

The influence of unintended specimen pre-shear and out-of-plane wrinkling on the accuracy of shear angle and axial force results, measured during a uniaxial bias extension (UBE) test on engineering fabrics, is examined. Three techniques of measuring test kinematics are investigated, including manual image analysis, 2-D and 3-D full-field analysis. Error introduced by specimen pre-shear is shown to influence test results in different ways, depending on analysis technique. Procedures to take specimen pre-shear error into account when interpreting results are demonstrated, though an important recommendation resulting from this investigation is to minimise pre-shear as much as possible. Out-of-plane wrinkling is shown to create significant errors in kinematic data when using 2-D analysis methods (up to 20% overestimates of measured shear angle). It is shown that wrinkle-error can be corrected if 3-D stereoscopic analysis methods are employed.

Field Quality and Fabrication Analysis of HQ02 Reconstructed Nb3Sn Coil Cross Sections

Author(s): Holik, EF; Ambrosio, G; Carbonara, A; Dietderich, DR; Dimarco, J; Pong, I; Sabbi, GL; Santini, C; Schmalzle, J; Wang, X | Abstract: The U.S. LHC Accelerator Research Program (LARP) quadrupole HQ02 was designed and fully tested as part of the low-beta quad development for Hi-Lumi LHC. HQ02's design is well documented with full fabrication accounting along with full field analysis at low and high current. With this history, HQ02 is an excellent test bed for developing a methodology for measuring turn locations from magnet cross sections and comparing with CAD models and measured field. All four coils of HQ02 were cut in identical locations along the magnetic length corresponding to magnetic field measurement and coil metrology. A real-time camera and coordinate measuring equipment was used to plot turn corners. Measurements include systematic and random displacements of winding blocks and individual turns along the magnetic length. The range of cable shifts and the field harmonic range along the length are in agreement, although correlating turn locations and measured harmonics in each cross section is challenging.

Material characterization for plane and curved sheets using the in-plane torsion test – an overview

Abstract The in-plane torsion test offers a broad range of applications for the characterization of mechanical properties of sheet metal materials and components. True plastic strains up to 1.0 can be achieved. Such data can be used for the numerical analysis without extrapolation of the flow curve. The stress and strain state correspond to ideal simple shear during the entire process. The application range of the plane torsion test has been constantly expanded by different approaches and a more sophisticated evaluation has been developed. The full-field analysis of the test area makes it possible to determine an almost arbitrary number of cyclic flow curves with only one single specimen. By using a grooved specimen, the ideal simple shear state can be obtained until fracture of the material without inhomogeneities. New investigations show that the in-plane torsion test is also suitable for the determination of flow curves for curved surfaces. Investigations on curved rotationally symmetrical as well as a tubular shape were performed. Finally, first results for the local determination of the strength’ arbitrary locations of a component are presented.

Thermal and volumetric property analysis of polymer networks and composites using elevated temperature digital image correlation

Digital Image Correlation (DIC), which exploits non-contact advantages and full-field analysis, provides more data in-situ that are not possible with traditional techniques. In this work, elevated temperature digital image correlation techniques were applied to a glassy polymer network via thermal expansion and contraction experiments to study volumetric behavior during the curing process. A glassy epoxy network was tested in both cured and under-cured states and heated to the ultimate cure temperature. Matrix volume changes due to both thermal expansion and cure shrinkage were quantified. Concurrently, the thermal expansion of aerospace-grade composite laminates was also observed in matrix and fiber-dominant directions. Additionally, the strain-free temperature of a non-symmetric composite laminate was identified through thermal compensation of process-induced curvatures. Finally, laminate dimension changes were related to the strain-free temperature as means to probe process-induced strains within composite laminates. Thermal properties of the neat matrix and composite laminates were compared to traditional techniques, validating the benefit of elevated temperature digital image correlation for composite matrix qualification.

Examination of Hurricane Sandy's (2012) structure and intensity evolution from full-field and anomaly-field analyses

An anomaly-based field analysis approach and a set of simple beta-advection models (BAMs) have been used to examine the structure evolution and unusual left turn of Hurricane Sandy (2012) before it made the landfall and caused severe damage along the eastern US coast. Results show that the anomaly-based analysis approach can clearly reveal Sandy's structure evolution, including its interaction with other synoptic-scale systems as well as the intensification and extratropical transition (ET) processes. During its lifetime, Sandy experienced two consecutive periods of intensification caused by the merging of anomalous vortices on 27 and 29 October. The unusual left turn and the ET process prior to the landfall are respectively influenced by an anomalous anticyclone to the northeast and an anomalous cold vortex at the 300–850 hPa layer to the northwest, which is confirmed by the experiments using the generalised BAM.

Upper Cervical Spine Loading Simulating a Dynamic Low-Speed Collision Significantly Increases the Risk of Pain Compared to Quasi-Static Loading With Equivalent Neck Kinematics.

Dynamic cervical spine loading can produce facet capsule injury. Despite a large proportion of neck pain being attributable to the C2/C3 facet capsule, potential mechanisms are not understood. This study replicated low-speed frontal and rear-end traffic collisions in occiput-C3 human cadaveric cervical spine specimens and used kinematic and full-field strain analyses to assess injury. Specimens were loaded quasi-statically in flexion and extension before and after dynamic rotation of C3 at 100 deg/s. Global kinematics in the sagittal plane were tracked at 1 kHz, and C2/C3 facet capsule full-field strains were measured. Dynamic loading did not alter the kinematics from those during quasi-static (QS) loading, but maximum principal strain (MPS) and shear strain (SS) were significantly higher (p = 0.028) in dynamic flexion than for the same quasi-static conditions. The full-field strain analysis demonstrated that capsule strain was inhomogeneous, and that the peak MPS generally occurred in the anterior aspect and along the line of the C2/C3 facet joint. The strain magnitude in dynamic flexion continued to rise after the rotation of C3 had stopped, with a peak MPS of 12.52 ± 4.59% and a maximum SS of 5.34 ± 1.60%. The peak MPS in loading representative of rear-end collisions approached magnitudes previously shown to induce pain in vivo, whereas strain analysis using linear approaches across the facet joint was lower and may underestimate injury risk compared to full-field analysis. The time at which peak MPS occurred suggests that the deceleration following a collision is critical in relation to the production of injurious strains within the facet capsule.

Robust full-field measurement considering rotation using digital image correlation

Digital image correlation (DIC) has been widely accepted as a method for displacement and strain measurement and is applied in a variety of engineering fields. Most DIC algorithms encounter errors in measuring the deformation in conditions that involve rotation since they are designed without considering rotation of the deformed object. In this paper, a robust and automated DIC method capable of determining full-field displacement and strain components with random rotations has been presented. The algorithm starts with the determination of the initial position of the seed point in the integer-pixel domain. An approximate rotational angle between the reference and the deformed subset is estimated using an automated feature matching technology. A two-step Newton–Raphson algorithm has been developed for optimizing a suite of variables including displacement, strain and the rotational angle to achieve subpixel accuracy. A reliable propagation scheme, which enables rapid determination of the initial guess for full-field analysis is also proposed. Results from numerical simulations are used to validate the feasibility of the proposed DIC method. An application to 3-point bending with large deflection shows that the algorithm can be employed to measure displacement or strain parameters of the deformed object with arbitrary angles of rotation.

A Direct Approach to In-Plane Stress Separation using Photoelastic Ptychography.

The elastic properties of materials, either under external load or in a relaxed state, influence their mechanical behaviour. Conventional optical approaches based on techniques such as photoelasticity or thermoelasticity can be used for full-field analysis of the stress distribution within a specimen. The circular polariscope in combination with holographic photoelasticity allows the sum and difference of principal stress components to be determined by exploiting the temporary birefringent properties of materials under load. Phase stepping and interferometric techniques have been proposed as a method for separating the in-plane stress components in two-dimensional photoelasticity experiments. In this paper we describe and demonstrate an alternative approach based on photoelastic ptychography which is able to obtain quantitative stress information from far fewer measurements than is required for interferometric based approaches. The complex light intensity equations based on Jones calculus for this setup are derived. We then apply this approach to the problem of a disc under diametrical compression. The experimental results are validated against the analytical solution derived by Hertz for the theoretical displacement fields for an elastic disc subject to point loading.

Technology Focus: Intelligent Fields Technology

Technology Focus Over the last couple of decades, we have seen a steady stream of “intelligent” innovations go from ideas to infancy to catalog solutions. Advances in metering, measurement, control, automation, and modeling have changed our daily routine such that our decisions are better informed, and, as a result, we produce in more-challenging environments, at lower cost, and with better recoveries. Whether deployed in the office or in the field, the majority of these advances have pertained to improvements in our organizations, in our production facilities, and in our wells. While still not routine, tools based on artificial intelligence, large-scale model integration, and automated data/model integration are finding their way into the typical practitioner’s toolbox. What is clearly emerging now are practical solutions that take the next step into the reservoir and across solution types and discipline boundaries. In the coming years, artificial-intelligence applications will steer our exploration and appraisal processes. While we push model integration (e.g., between static and dynamic and for entire production systems), artificial intelligence will be working behind the scenes to find model inconsistencies, to narrow uncertainties, and to improve our forecasts and option assessments. These advances are coming at an opportune time in that they can support better decision making in some of our most-costly decisions (e.g., helping us to improve our productive drilling rates and demonstrating the real costs of deviating from reservoir-management plans). The papers highlighted in this section provide clear illustrations of how some of this will be achieved. JPT Recommended additional reading at OnePetro: www.onepetro.org. OTC 26209 Proactive and Reactive Strategies for Optimal Operational Design: An Application in Smart Wells by A.C.A. Abreu, PUC-Rio, et al. SPE 176760 Leveraging Intelligent-Field Data for Full-Field Pressure-Transient Analysis by B. Al-Wehaibi, Saudi Aramco, et al. SPE 177829 Smart Proxy: An Innovative Reservoir-Management Tool; Case Study of a Giant Mature Oil Field in the UAE by S.D. Mohaghegh, Intelligent Solutions, et al.

Measurement of birefringence using polarization phase-shifting Mach–Zehnder interferometer

An interferometric method for quantitative evaluation of the magnitude and direction of birefringence of an arbitrarily oriented birefringent sample is developed and presented. The analysis shows that full-field analysis of a spatially varying birefringence is possible by suitably combining several interferogram frames obtained by varying the polarization parameters involved. The preliminary experimental result for a uniformly birefringent sample with a known direction of birefringence is presented. © 2015 Society of Photo-Optical Instrumentation Engineers

THz Polarizer Controller Based on Cylindrical Spoof Surface Plasmon Polariton (C-SSPP)

Spoof surface plasmon polariton (SSPP) based devices have recently garnered a great deal of attention owing to their ability to propagate THz signal without dispersion and very low signal attenuation. In this paper, a rigorous mathematical model has been proposed by performing full-field analysis on the periodically corrugated cylindrical waveguide. It has been shown that this structure has the capability of propagating localized spoof surface plasmons polariton (SSPP) mode of EM waves. The variation of band diagrams as a function of different groove dimensions has been investigated. Finally, by employing cylindrical SSPP a new polarizer controller has been designed that can be utilized to design THz Boolean gates.

Simulation of axisymmetric scramjet inlet flow fields using anti-diffusive WENO Navier-Stokes solver

This study is based on the theory of gas dynamics and uses the Navier-Stokes equations as the governing equations to solve the hypersonic flow problems of the scramjet. For the turbulent flow, we use the Spalart-Allmaras one equation turbulence model, which produces better results for near wall and boundary layer flow field problems. The lower-upper symmetric Gauss-Seidel implicit scheme, which enables results to converge efficiently under steady state conditions, is combined with the anti-diffusive weighted essentially nonoscillatory (WENO) scheme to yield an accurate and efficient simulation tool for an axisymmetric scramjet flow field analysis. Using the WENO scheme’s high-order accuracy and its non-oscillatory solution at discontinuous regions, we can solve the hypersonic flow problems involving complex shock-shock/shock-boundary layer interactions inside the flow path. This simulation procedure is first verified against two existing partial examples to ensure its accuracy, and is then applied to a complete scramjet model with different initial conditions for a full flow field analysis. The aerodynamic data of Mach number, density, static temperature and pressure are obtained and the results discussed. The anti-diffusive WENO scheme produces more accurate resolution of shock and slip lines and their complex multiple interactions than other numerical approaches. This is of crucial importance for the scramjet complete flow field analysis as multiple shock-boundary layer and discontinuities interactions often occur within the long flow path.

Stability and bearing capacity of arch-shaped corrugated shell elements: experimental and numerical study

Abstract The paper presents problems related to the numerical modeling of profiled steel sheets used as self-supporting arch structures for roof covering. The rules of preparing and full analysis of a set of numerical models of these elements with a different level of complexity are given. The models are evaluated by comparing numerical results with the results of extended experimental tests performed by 3D Digital Image Correlation (DIC) method. For each model the comparison of numerical and experimental results has been made for samples of a single-wave trapezoidal profile with corrugated web and lower flanges subjected to compression and bending. The full-field analysis allows to determine the allowed simplification of numerical models which do not affect in significant way the reliability of the results. The proposed methodology is the first step in the development of full assessment methodology for different types of self-supporting arch structures produced by ABM technology.

Analysis of a Denisov Launcher for 420 GHz High Order Mode Gyrotron

A Denisov launcher operating at 420 GHz with TE17,4 mode is designed and optimized through theoretical analysis and numerical simulations. The launcher consists of a mode converted waveguide and a helical cut. Instead of using the conventional perturbations, a sinusoid type perturbation is used in this converted waveguide. Operations of the launcher are analyzed by the coupled mode theory. The field at the output aperture of the launcher has a nice Gaussian profile distribution. The conversion efficiency is more than 98.1 %. The parasitic modes in the launcher and the aperture field profile were analyzed. The wall field of the launcher is analyzed in case that the input wave is rotating left-hand. A full 3D electromagnetic field analysis of the integrated launcher has been done. The results are in good agreement with the numerical calculation results.