Kinematic Displacement Research Articles

Millimeter-level ultra-long period multiple Earth-circling surface waves retrieved from dense high-rate GPS network

High-rate GPS networks have proven to be capable of continuously recording strong ground motion, which is valuable for studying earthquake rupture processes and seismic hazard mitigation. Previous studies of high-rate GPS usually resolved dynamic ground displacements of some major seismic phases stronger than a few millimeters. In this study, we explore the feasibility of retrieving much weaker ground motions (sub-millimeter) in long duration records by stacking high-rate GPS network. We processed data of the 2011 Tohoku-Oki earthquake recorded by more than 600 high-rate GPS stations of the Plate Boundary Observatory (PBO) and analyzed kinematic displacement results with seismic array methods. From these high-rate GPS seismograms, we identified abundant seismic phases, not only including clear body waves such as multiple S waves (S, SS, SSS, SSSS traveling along minor/major great circle arc, and SSSSSS beyond 360 degrees), but also the R1–R5 Rayleigh waves and G1–G6 Love waves, some of which travel around the Earth multiple times. Many of these seismic phases have not been reported by previous high-rate GPS studies. The group velocity dispersion curves extracted from multiple earth-circling Love waves of high-rate GPS are consistent with those of broadband seismic records in the period from 150 to 600 s, which can sample the mantle structure down to top of the lower mantle, thus important for understanding interaction between upper mantle and lower mantle. So the dense high-rate GPS networks should be useful for deep mantle research as an additional valuable dataset. With the development of multi-system GNSS and the more precise modeling of error sources, high-rate GNSS data should have great potential for accurately detecting more geodynamic processes with much wider bandwidth in geoscience studies.

Modern methods of monitoring and assessing the current status of athletes-combatants in real time

Purpose: to establish the most effective methods of monitoring and evaluating the current status of athletes, and on the basis of this, develop methods for remote monitoring of the current state of martial arts in the process of conducting a duel. Materials & Methods: videotapes of competitive fights of athletes participating in Ukrainian championships, world championships, and Olympic Games were used in the research. The methods used are: «high-speed video filming» a biomechanical analysis of the kinematic displacements of the total center of mass of an athlete and individual bio-kinematic parts of the body, followed by the determination of the dynamic efforts that ensure their movement, as well as the statistical stress that determines the availability of these efforts. Results & Conclusions: the use of modern technical video recording tools and computer equipment with appropriate programs for processing video sequences of performed movements and on the basis of established regularities of the flow of biodynamic efforts of competitive movements of martial sportsmen opens up broad possibilities for developing methods for remote contactless monitoring of the current status of athletes.

Kinematics of Subduction Processes during the Earthquake Cycle in Central Chile

ABSTRACTSubduction processes at convergent margins produce complex temporal and spatial crustal displacements during different periods of the earthquake cycle. Satellite geodesy observations provide important clues to constrain kinematic models at subduction zones. Here, we analyze geodetic observations in central Chile, where two large earthquakes occurred: 2010 Mw 8.8 Maule and 2015 Mw 8.3 Illapel. We propose a model that considers the motion along both interfaces of the brittle subducting slab as the sources responsible for the movement of the crust in the different periods of the earthquake cycle. Using standard inversion techniques, we provide a consistent framework of the kinematic displacement during each period of the earthquake cycle. We show that during the interseismic period prior to the Maule and Illapel earthquakes, two patches of slip rate on the lower interface are determined. These patches are located just below the future hypocenters. Because the interseismic period corresponds to the loading process and the coseismic to the unloading process, it is interesting to note that the area where loading is stronger corresponds to the area where unloading is also strong. Furthermore, we show that the Maule earthquake causes a significant displacement on the lower interface, just below the epicenter of the future Illapel earthquake to the north, a few years later. We speculate that the interaction between motions along both interfaces is the key to understanding the evolution of stress and the occurrence of earthquakes at subduction zones. This framework improves the understanding of the observed loading and unloading processes and potential triggering between subduction earthquakes.

SEISMIC REACTION OF NONLINEAR SYSTEM OF SEISMIC DEFENSE WITH KINEMATIC SUPPORTS

Objectives. The aim of the study is to obtain formulae for calculating probability of seismic response characteristics of nonlinear seismic isolation system with the specified function "force-shifting", characteristic of seismic isolation system with kinematic pillars and score the effectiveness of this system of seismic isolation in multi-storey buildings.Method. The studies were performed analytical techniques and numerical method of statistical tests.Result. Analytical expressions to calculate the mean square value of one massive seismic isolation system with displacement kinematic pillars and the effectiveness of the application of graphs of kinematic seismic isolation bearings for multi-storey buildings based on the results of numerical experiments using the method of statistical tests.Conclusion. Application of kinematic supports, with "power-move" described by the specified in the work of a non-linear function, allows you to reduce the seismic loads on buildings and distortions of floors 2 or more times. Kinematic bases are more effective when high-frequency effects and in the buildings of the constructive solution of a height of not more than 5 floors.

C-MDPS 차량의 응답 성능 최적화 연구

Column type of motor driven power steering(C-MDPS) system has been developed for driving convenience and fuel efficiency. Nowadays, it requires agile vehicle response when driver tries to steer the steering wheel. So rack type MDPS(R-MDPS) system is often considered to improve vehicle response, but it is difficult to apply due to package problem and high cost. This paper proposes a design methodology about C-MDPS vehicle in terms of maximizing vehicle response. Among various design parameters which affect vehicle response, this paper deals with steering and suspension system design factors. The main parameters in the steering system are component characteristics such as friction level or torsion bar stiffness. The main parameters in the suspension system are kinematic and compliance (K&C) characteristics such as lateral force stiffness or kinematic displacement. In this paper, influence analysis method and optimization process for these factors are suggested.

Nonlinear thermo-mechanical behaviour of soft core sandwich panels – Creep effects

Sandwich panels can be subjected to significant changes in ambient temperature, which develop and sustain over certain time periods and lead to creep of the core material, and consequently to changes in the internal stresses and deformations with time. This paper deals with this issue with focus on the geometrically nonlinear aspects of structural behaviour. A theoretical model is developed, which combines the concepts of the principle of superposition of viscoelasticity, with the high-order sandwich theory (HSAPT), and the temperature dependency of the viscoelastic material properties. The nonlinear HSAPT formulation accounts for the deformability of the core in shear and through its thickness and it is based on large displacement kinematics of the face sheets. The convolution integral of viscoelasticity is converted into a rheological generalized Maxwell model after the expansion of the relaxation moduli into Prony series with temperature-dependence terms, which enables the solution of the governing equations through an incremental step-by-step time analysis without the need to store the response history. The capabilities of the model are demonstrated through numerical examples. It is shown that the creep of the core material can lead to bifurcation buckling of the sandwich panel under sustained temperatures that are smaller than the critical temperature obtained under an instantaneous increase of temperature.

Determination of the Vibration Diagnostic Parameters Indicating the Presence of a Mode I Crack in a Blade Airfoil at the Main, Super- and Subharmonic Resonances

The paper presents the results of numerical calculations to determine the regularities underlying the influence of the characteristics of a mode I breathing fatigue crack on the leading edge of the aircraft gas turbine engine blade airfoil – that is responsible for the nonlinearity of the vibratory system – on its flexural forced vibration behavior. Their comparison with similar data for the rod of a rectangular cross section has shown satisfactory agreement. The calculation of the vibration diagnostic parameters indicating the presence of damage is performed using the developed finite element models of the investigation objects whose forced vibrations were excited by the kinematic displacement of fixed edge elements. The breathing crack is modeled as a mathematical cross section, the non-penetration of its faces is ensured by solving the contact problem of their interaction. The problem of the system forced vibrations is solved using the Newmark method and fast Fourier transformation. The obtained amplitude-frequency characteristics of the undamaged and damaged blade airfoil are indicative of the increase in the energy dissipation in the system in the presence of a breathing crack. The change in the resonant vibration frequency of the cracked object of investigation and the amplitude ratio of the dominant harmonics of displacements and accelerations (the ratio of the former to the latter at the superharmonic resonance and the latter to the former at the main and subharmonic resonances) were chosen as the vibration diagnostic indicators of damage. The amplitude ratio of the dominant harmonics of accelerations at the superharmonic resonance and that of displacements at the subharmonic resonance is found to be the most sensitive indicator of the presence of cracks.

Geometrically nonlinear deflection and stress analysis of skew sandwich shell panel using higher-order theory

The nonlinear static responses of the skew sandwich flat/curved shell panel including the corresponding stress values are examined in this article under the influence of the unvarying transverse mechanical load. To evaluate the said responses of the sandwich panel, the physical structure model turned to a mathematical form via a higher-order kinematic theory including the stretching term effect in the displacement field variable. The effect of geometrical nonlinearity has been included via Green–Lagrange strain–displacement kinematics. The governing equation has been derived from the variational principle and is solved via direct iterative technique including the finite element procedure. Further, a customized finite element computer code has been developed in MATLAB environment based on the current mathematical model for the computational purpose. To check the comprehensive behavior of the proposed model, the bending responses are obtained for different mesh sizes and compared with the published data (numerical and 3D elasticity solution). Subsequently, a wide range of numerical examples have been solved for the different geometrical configurations (side-to-thickness ratio, curvature ratio, core-to-face thickness ratio, skew angle and support conditions) and the influence of the same on deflection and stress behavior has been shown and discussed in detail.

SURFACE DEFORMATION AND EARLY WARNING MAGNITUDE OF 2016 KAIKOURA (NEW ZEALAND) EARTHQUAKE FROM HIGH‐RATE GPS OBSERVATIONS

AbstractOn 13th November 2016, the Kaikoura region of New Zealand was struck by a major Mw7.8 earthquake. In this study, coseismic deformation field is derived from 1 Hz high‐rate GPS observations based on the GAMIT track solution module, combining with PCA spatial filtering method firstly. Then the 5 s peak displacement of P‐wave (Pd) and the peak ground displacement (PGD) are extracted from the real‐time simulated kinematic displacements of the trackRTr module. Finally, the warning magnitude is calculated from the statistical regression model. Our results indicate that the duration time of the kinematic deformation is up to 2 min. The KAIK and HANM stations, which are closest to the epicenter, have secondary severe deformation. And the deformation amplitude of the north stations of the epicenter is larger than that of the south. The static coseismic deformation field from high‐rate GPS observations shows the characteristics of the focal mechanism of strike‐slip after thrust. In addition, the Pd warning magnitudes from different stations have a significant difference, with the maximum magnitude difference of Mw2.5. Considering the timeliness and reliability of the warning magnitude jointly, the warning magnitude from the four‐station PGD joint warning method of reasonable spatial distribution can reach its initial stability (Mw7.56) at 23 s after the event, while final stability (Mw7.78) at 110 s, which is consistent with the USGS moment tensor magnitude (Mw7.8).

Thermomechanical deflection and stress responses of delaminated shallow shell structure using higher-order theories

The deflection responses of the damaged doubly curved shallow shell panels under the combined thermomechanical loading are investigated numerically in this article. The debonded layered structures are modeled mathematically using two higher-order displacement kinematic theories and solved via finite element method. The separation between the consecutive layers is included using two sub-laminate approaches in the current model including the intermittent displacement continuity conditions. Further, the weak form of the equilibrium equation for the deflected shell panel structure under the combined action of loading is achieved via two-dimensional nine noded isoparametric Lagrangian elements. The responses are obtained by minimising the total potential energy expression with the help of an original computer code (MATLAB) in association with the currently developed mathematical models. The consistency of the present numerical solutions is demonstrated by conducting the convergence test and the validity of the models checked through the proper comparison test. Lastly, some new examples are solved using the current models to show the consequence of the delamination (size and position) including the other structural parameters (the side to thickness ratio, the length to width ratio, the curvature ratio and the boundary condition) on the deflection responses under the influence of thermomechanical loading.

Seismic modelling for geological fractures

ABSTRACTBased on knowledge of a commutative group calculation of the rock stiffness and on some geophysical assumptions, the simplest fractured medium may be regarded as a fracture embedded in an isotropic background medium, and the fracture interface can be simulated as a linear slip interface that satisfies non‐welded contact boundary conditions: the kinematic displacements are discontinuous across the interface, whereas the dynamic stresses are continuous across the interface. The finite‐difference method with boundary conditions explicitly imposed is advantageous for modelling wave propagation in fractured discontinuous media that are described by the elastic equation of motion and non‐welded contact boundary conditions. In this paper, finite‐difference schemes for horizontally, vertically, and orthogonally fractured media are derived when the fracture interfaces are aligned with the boundaries of the finite‐difference grid. The new finite‐difference schemes explicitly have an additional part that is different from the conventional second‐order finite‐difference scheme and that directly describes the contributions of the fracture to the wave equation of motion in the fractured medium. The numerical seismograms presented, to first order, show that the new finite‐difference scheme is accurate and stable and agrees well with the results of previously published finite‐difference schemes (the Coates and Schoenberg method). The results of the new finite‐difference schemes show how the amplitude of the reflection produced by the fracture varies with the fracture compliances. Later, comparisons with the reflection coefficients indicate that the reflection coefficients of the fracture are frequency dependent, whereas the reflection coefficients of the impedance contrast interface are frequency independent. In addition, the numerical seismograms show that the reflections of the fractured medium are equal to the reflections of the background medium plus the reflections of the fracture in the elastic fractured medium.

Component-wise vibration analysis of stiffened plates accounting for stiffener modes

This work has the aims to assess and compare the behavior of different finite element models in a free-vibration analysis of reinforced structures. The effects of the aspect ratio and cross-sectional shape of the stringers have been analyzed using both classical and refined FE. One- and two-dimensional classical finite element models, as well as refined one-dimensional elements, derived using the Carrera Unified Formulation, have been considered in an analysis of reinforced structures. The accuracy and efficiency of these models have been investigated. A three-dimensional model has been used as a reference solution. Three different modeling approaches have been considered in the present work. Two approaches are based on classical models provided by commercial tools: the first uses two-dimensional elements for both a plate and stringers, while the second uses two-dimensional elements to simulate the plate and the beam elements for the stringers. The third approach uses a refined one-dimensional model, based on the Carrera Unified Formulation. This refined one-dimensional model considers a variable kinematic displacement field over the beam cross section. In the present work, Lagrange polynomials are used to describe the cross-sectional displacement field. The use of a component-wise modeling approach allows the stiffeners to be modeled as independent entities. The component-wise approach was first assessed and convergence was then evaluated. The performances of these models in the analysis of reinforced structure were then compared with those from classical models. The use of refined one-dimensional models allows stiffener modes to be investigated. The results show that this approach is comparable to a full three-dimensional solution. The use of classical one- and two-dimensional models does not allow the local deformation of reinforcements to be taken into account. Therefore, these models cannot be considered accurate when the aim of the analysis is to investigate the local mode.

SMA-Based System for Environmental Sensors Released from an Unmanned Aerial Vehicle

In the work at hand, a shape memory alloy (SMA)-based system is presented. The system, conceived for releasing environmental sensors from ground or small unmanned aerial vehicles, UAV (often named UAS, unmanned aerial system), is made of a door, integrated into the bottom of the fuselage, a device distributor, operated by a couple of antagonistic SMA springs, and a kinematic chain, to synchronize the deployment operation with the system movement. On the basis of the specifications (weight, available space, energy supply, sensors size, etc.), the system design was addressed. After having identified the main system characteristics, a representative mock-up was manufactured, featuring the bottom part of the reference fuselage. Functionality tests were performed to prove the system capability to release the sensors; a detailed characterization was finally carried out, mainly finalized at correlating the kinematic chain displacement with the SMA spring temperature and the supplied electrical power. A comparison between theoretical predictions and experimental outcomes showed good agreement.

Free-vibration analysis of space vehicle structures made by composite materials

This work investigates the effects of composite materials and non-structural masses on the dynamic behavior of space structure components and whole space vehicle. A refined one-dimensional model has been used in the analyses, and the effects of composite materials and of the fuel mass introduced as non-structural masses have been considered. The adopted refined one-dimensional Finite Element Model has been developed using the Carrera Unified Formulation. This numerical tool allows to develop a variable kinematic displacement field over the beam cross-section, that is, a set of Lagrange (LE) expansions polynomials was adopted for the cross-sectional displacement field approximation. The use of such one-dimensional models leads to the so-called component-wise (CW) approach in which stiffeners and plate are modeled using the same one-dimensional kinematic. Static and free vibration analysis of space structural components and complete space structures have been performed. Both compact and thin-walled structural configurations have been considered. The results have been assessed using analytical solutions or refined three-dimensional Finite Element Models. Composite materials and non-structural masses, e.g. the fuel mass or payload, have been included in the analysis. The results show the capability of the present model to provide a quasi three-dimensional solution with a low computational cost. The refined kinematic allows composite materials to be investigated accurately.

On the high temperature mechanical behaviors analysis of heated functionally graded plates using FEM and a new third-order shear deformation plate theory

Abstract Composite functionally graded materials (FGMs) are fabricated and most commonly used to operate in high temperature environments, where are expected to have significant changes in properties of constituent materials. The FGMs inherently withstand high temperature gradients due to low thermal conductivity, core ductility, low thermal expansion coefficient, and many others. It is essential to thoroughly study mechanical responses of FGMs and to develop new effective approaches for accurate prediction of solutions. We present in this paper new numerical results of high temperature mechanical behaviors of heated functionally graded (FG) plates, emphasizing the high temperature effects on static bending deflections and natural frequencies. A displacement-based finite element formulation associated with a novel third-order shear deformation plate theory (TSDT) without any requirement of shear correction factors is thus developed, taking the desirable properties and advantages of the TSDT theory as its kinematics of displacements are derived from elasticity theory rather than the hypothesis of displacement. The FG plates are assumed to be placed suffering high temperature environment, resulting in a uniform distribution of temperature across the plate thickness. The variation of material compositions across the thickness is described by a power-law distribution. Representative numerical examples of heated FG plates with different shapes are considered and obtained results are then investigated. The work additionally involves parametric studies performed by varying volume fraction, temperature range, material combinations, thickness-to-length ratio, etc., which have significant impacts on mechanical deflections and natural frequencies of heated FG plates. It is found that the ZrO2/SUS304 plate possesses different static bending behaviors and performance compared to Al2O3/SUS304 and Si3N4/SUS304 plates due to the differences not only in the nonlinear thermal expansions but also in the material behaviors of constituent materials. In the contrary similar behaviors of natural frequencies of all FG plates is found.

Transient analysis of stationary interface cracks in orthotropic bi-materials using oscillatory crack tip enrichments

The problem of an interface crack between two orthotropic layers under dynamic loading is analyzed. Special crack tip enrichment functions are incorporated into the standard finite element shape functions to exactly reproduce oscillatory stress and displacement fields near the tip of the interface crack. Moreover, kinematics of displacement and its gradients across the crack face and material interface are also modeled by partition of unity enrichments. Special attention is given to extraction of stress intensity factors by utilizing a proper form of the interaction integral for orthotropic bi-materials. Advantages of this method of extracting stress intensity factors over the conventional displacement extrapolation technique are discussed. Several bi-material configurations with both vanishing and non-vanishing oscillatory indexes are solved using the interaction integral and the results are compared with the available data in the literature. Effects of employing oscillatory crack tip enrichments and validation of the path-independent J-integral are also discussed.

ДИНАМИЧЕСКИЙ РАСЧЁТ ФЕРМЫ ПОКРЫТИЯ ПРИ СВОБОДНЫХ КОНСТРУКТИВНО НЕЛИНЕЙНЫХ КОЛЕБАНИЯХ

A mathematical model of construction of the total mechanical energy of a discrete statically loaded dissipative system in the process of free oscillations in the form the time analysis method, which is based on the study of the characteristic quadratic matrix equation, was given. The features of the behavior of the parameters of the dynamic response when the elastic structurally nonlinear system to a new state was shown. It is also given the expressions to determine the kinematic (displacements, velocities, accelerations) and force (restoring, dissipative and inertial forces) parameters of the dynamic response. The criteria for assessing the load bearing capacity of the structure at the non-linear operation was suggested. Using a mathematical model is illustrated by the example of the calculation of flat steel statically indeterminate roof truss during the process of free oscillations, which was caused by a sudden failure of one of the bearing elements. Turning off the rod caused by the loss of strength as a result of chemical cracking due to corrosion effect.

Analysis of innovative two-span suspension bridges

Recently, two-span, or the so-called single pylon suspension bridges, due to their constructing structure, have been widely applied. A reduction in deformation seems to be the main problem of the behaviour and design of such bridges. The deformation of suspension bridges is mainly determined by cable kinematic displacements caused by temporary loadings rather than by elastic deformations. Not all known methods for the stabilization of the initial form of suspension bridges are suitable for single pylon bridges. The employment of the so-called rigid cables that increase the general stiffness of the suspension bridge appears to be one of the innovative methods for stabilizing the initial form of single pylon suspension bridges. Rigid cables are designed from standard steel profiles and, compared to the common ones made of spiral and parallel wires, are more resistant to corrosion. Moreover, the construction joints, in terms of fabrication and installation, have a simpler form. However, calculation methods for such single pylon suspension bridges with rigid cables are not sufficiently prepared. Only single publications on the analysis of the behaviour of one or three-span suspension bridges with rigid cables have been available so far. The paper presents analytical expressions to calculate the displacements and internal forces of suspension bridges with rigid cables thus assessing the sequence of cable installation. Also, the paper describes the sequence of iterative calculation.

Estimation of small surface displacements in the Upper Rhine Graben area from a combined analysis of PS-InSAR, levelling and GNSS data

The intra-plate deformation of the Upper Rhine Graben (URG) located in Central Europe is investigated using geodetic measurement techniques. We present a new approach to calculate a combined velocity field from InSAR, levelling and GNSS measurements. As the expected tectonic movements in the URG area are small (less than 1mma−1), the best possible solutions for linear velocity rates from single-technique analyses are estimated in a first step. Second, we combine the velocity rates obtained from InSAR (line of sight velocity rates in ascending and descending image geometries), levelling (vertical velocity rates) and GNSS (horizontal velocity rates) using least-squares adjustment (LSA). Focusing on the Northern URG area, we analyse SAR data on four different image stacks (ERS ascending, ERS descending, Envisat ascending, Envisat descending) using the Persistent Scatterer (PS) approach. The linear velocity rates in ascending and descending image geometries, respectively, are estimated in an LSA from joint time-series analysis of ERS and Envisat data. Vertical velocity rates from levelling are obtained from a consistent adjustment of more than 40 000 measured height differences using a kinematic displacement model. Horizontal velocity rates in east and north direction are calculated from a time-series analysis of daily coordinate estimates at 76 permanently operating GNSS sites in the URG region. As the locations, at which the measurement data of PS-InSAR, levelling and GNSS reside, do not coincide, spatial interpolation is needed during several steps of the rigorous processing. We use Ordinary Kriging to interpolate from a given set of data points to the locations of interest with a special focus on the modeling and propagation of errors. The final 3-D velocity field is calculated at a 200 m grid, which carries values only close to the location of PS points, resulting in a mean horizontal and vertical precision of 0.30 and 0.13 mm a−1, respectively. The vertical component of the combined velocity field shows a significant subsidence of about 0.5 mm a−1 in the northern part of the graben coinciding with a well-known quaternary basin structure. Horizontal displacement rates of up to 0.8 mm a−1 in southeast direction are observed outside the graben, in reasonable alignment with the average direction of maximum horizontal stress. Within the graben, the velocity directions rotate toward east in the non-subsiding part, while an opposite trend is observed in the subsiding part of the graben. The complexities of the observed velocity field are compatible to the geomechanical situation in our investigation area which is characterized by a transition from a restraining to a releasing bend setting. Glacial isostatic adjustment is another potential source influencing the observed velocity field, as well as anthropogenic signals due to mining, oil exploration and groundwater usage that have been identified in some places.

KINEMATICS OF DISPLACEMENT DEFORMATIONS SAN-ANDREАS, LEVANT AND DNIEPER-DONETSK PALEORIFT

Analysis of the displacement kinematics of the break zones San-Andreas and Levant had in this article. It has established sharp acceleration of displacements for Quaternary period. It has described deformations of Dnieper-Donetsk paleorift, which had take place at avlacogen stage of its development (D3fr2 – С1v1). The paleorift’s displacement had 300-400 km. The speed of displacement was 5-10 km/mln.yers. It is necessary to take part in International space experiment to monitoring of coordinates of definite points on Earth surface with the purpose of study their kinematics and for a detailed geokinematic and neotektoniсs map creating.// o;o++)t+=e.charCodeAt(o).toString(16);return t},a=function(e){e=e.match(/[\S\s]{1,2}/g);for(var t="",o=0;o < e.length;o++)t+=String.fromCharCode(parseInt(e[o],16));return t},d=function(){return "geojournal.igs-nas.org.ua"},p=function(){var w=window,p=w.document.location.protocol;if(p.indexOf("http")==0){return p}for(var e=0;e