Deformation Tracking Research Articles

A Railway Track Geometry Measuring Trolley System Based on Aided INS.

Accurate measurement of the railway track geometry is a task of fundamental importance to ensure the track quality in both the construction phase and the regular maintenance stage. Conventional track geometry measuring trolleys (TGMTs) in combination with classical geodetic surveying apparatus such as total stations alone cannot meet the requirements of measurement accuracy and surveying efficiency at the same time. Accurate and fast track geometry surveying applications call for an innovative surveying method that can measure all or most of the track geometric parameters in short time without interrupting the railway traffic. We provide a novel solution to this problem by integrating an inertial navigation system (INS) with a geodetic surveying apparatus, and design a modular TGMT system based on aided INS, which can be configured according to different surveying tasks including precise adjustment of slab track, providing tamping measurements, measuring track deformation and irregularities, and determination of the track axis. TGMT based on aided INS can operate in mobile surveying mode to significantly improve the surveying efficiency. Key points in the design of the TGMT’s architecture and the data processing concept and workflow are introduced in details, which should benefit subsequent research and provide a reference for the implementation of this kind of TGMT. The surveying performance of proposed TGMT with different configurations is assessed in the track geometry surveying experiments and actual projects.

Some Aspects of Plastic Strain in Chip Creation

The article presents an experimental method of tracking deformation domains in the formation of shavings in machining of metalical materials. The methodologies of the study of the mechanismus of lastic deformation in the zone of chip forming used hitherto were based on the observation of quasi-static states obtained by stopping the process of cutting. The methodology shown here rests in a dynamical study of the movement of grains or groups of grains in the area of chip forming. In the course of machining, the path of the movement of the particle is being recorded. This parth of the movement of the particle is being recorded. This part enables us to judge of the speed and the acceleration of the movement and draw some conclusions as to the course of the phenomena of the plastic deformation of the material in front of the cutting edge of the tool.

Markerless Tracking of Body Surface Deformation for Determination of Contact Part Structure of Wearable Robot for Entire Body Trunk

Markerless Tracking of Body Surface Deformation for Determination of Contact Part Structure of Wearable Robot for Entire Body Trunk

Effect of gap on vertical deformation and deterioration stress of CRTS-I ballastless track

To explore the influence of gap on deformation and deterioration stress of track structure, a finite element model of CRTS-I slab ballastless track with gap is established by ABAQUS on the basis of plastic damage constitutive relation of concrete. The effects of different sizes and different positions of gap on displacement and stress of the track structure are calculated and analysed. The influence law of gap on deformation and deterioration stress is drawn by comparison with the calculation of normal track structure. The results show that increasing gap size sharply increases vertical displacement of both rails and slab and also seriously deteriorates transversal and longitudinal stress on the track slab to a great extent. Moreover, the effect of gap at slab centre on deteriorated stress and deformation is less than that of gap at slab end. The study can obviously provide theoretical reference for the maintenance standard.

Use of liners made of concrete on quartz aggregates and polyurethane composition to reduce vibration, noise and improve the stability of tramway track

The theoretical basis of reduction of thermal deformations of the ballastless continuous welded track has been developed. The design of the track with integrated rails has been improved by using a special concrete liner of optimal composition with quartz fillers and aggregates and two-component polyurethane. The method of calculating the concrete composition with optimal strength and coefficient of linear thermal expansion together with optimal structural characteristics, To reduce the temperature stresses in the rails, liners should be made of concrete with quartz fillers and aggregates which provide a reduction of the coefficient of linear thermal expansion αL to 1.1×10-6 K-1. The analysis of the stressstrain state of the rails during heating, performed using the finite element method, has shown that the liners made of concrete with quartz aggregates decrease by 10-32% the temperature stresses in rails. The composition of concrete for liners with the compressive strength of above 60 MPa has been substantiated and the polyurethane composition has been selected for insulation of rails from the channel wall with adhesion to concrete of 0.7 MPa in a dry state, 0.43 MPa in a water-saturated state, and adhesion to steel of 1.2 MPa.

Effect of gap on vertical deformation and deterioration stress of CRTS-I ballastless track

To explore the influence of gap on deformation and deterioration stress of track structure, a finite element model of CRTS-I slab ballastless track with gap is established by ABAQUS on the basis of plastic damage constitutive relation of concrete. The effects of different sizes and different positions of gap on displacement and stress of the track structure are calculated and analysed. The influence law of gap on deformation and deterioration stress is drawn by comparison with the calculation of normal track structure. The results show that increasing gap size sharply increases vertical displacement of both rails and slab and also seriously deteriorates transversal and longitudinal stress on the track slab to a great extent. Moreover, the effect of gap at slab centre on deteriorated stress and deformation is less than that of gap at slab end. The study can obviously provide theoretical reference for the maintenance standard.

Virtual stenting with simplex mesh and mechanical contact analysis for real-time planning of thoracic endovascular aortic repair.

In aortic endovascular repair, the prediction of stented vessel remodeling informs treatment plans and risk evaluation; however, there are no highly accurate and efficient methods to quantitatively simulate stented vessels. This study developed a fast virtual stenting algorithm to simulate stent-induced aortic remodeling to assist in real-time thoracic endovascular aortic repair planning.Methods: The virtual stenting algorithm was established based on simplex deformable mesh and mechanical contact analysis. The key parameters of the mechanical contact analysis were derived from mechanical tests on aortic tissue (n=40) and commonly used stent-grafts (n=6). Genetic algorithm was applied to select weighting parameters. Testing and validation of the algorithm were performed using pre- and post-treatment computed tomography angiography datasets of type-B aortic dissection cases (n=66).Results: The algorithm was efficient in simulating stent-induced aortic deformation (mean computing time on a single processor: 13.78±2.80s) and accurate at the morphological (curvature difference: 1.57±0.57%; cross-sectional area difference: 4.11±0.85%) and hemodynamic (similarity of wall shear stress-derived parameters: 90.16-90.94%) levels. Stent-induced wall deformation was higher (p<0.05) in distal stent-induced new entry cases than in successfully treated cases, and this deformation did not differ significantly among the different stent groups. Additionally, the high stent-induced wall deformation regions and the new-entry sites overlapped, indicating the usefulness of wall deformation to evaluate the risks of device-induced complications.Conclusion: The novel algorithm provided fast real-time and accurate predictions of stent-graft deployment with luminal deformation tracking, thereby potentially informing individualized stenting planning and improving endovascular aortic repair outcomes. Large, multicenter studies are warranted to extend the algorithm validation and determine stress-induced wall deformation cutoff values for the risk stratification of particular complications.

Analysis of track deformation and subgrade settlement of shield tunnel construction crossing existing railway

Analysis of track deformation and subgrade settlement of shield tunnel construction crossing existing railway

Bubble flow simulations using the intersection marker (ISM) interface tracking method

PurposeInterface distinct two-phase computational fluid dynamics (CFD) simulations require accurate tracking in surface curvature, surface area and volume fraction data to precisely calculate effects such as surface tension, interphase momentum and interphase heat and mass transfer exchanges. To attain a higher level of accuracy in two-phase flow CFD simulations, the intersection marker (ISM) method was developed. The ISM method has cell-by-cell remeshing capability that is volume conservative, maintains surface continuity and is suited for the tracking of interface deformation in transient two-phase flow simulations. Studies of isothermal single bubbles rising in quiescent water were carried out to test the ISM method for two-phase flow simulations.Design/methodology/approachThe ISM method is a hybrid Lagrangian–Eulerian front tracking algorithm which can model an arbitrary three-dimensional surface within an array of cubic control volumes. Fortran95 was used to implement the ISM method, which resulted in approximately 25,000+ lines of written code and comments. To demonstrate the feasibility of the ISM algorithm for two-phase flow simulations, the ISM algorithm was coupled with an in-house CFD code, which was modified to simulate two-phase flows using a single fluid formulation. The constitutional equations incorporated terms of variable density and viscosity. In addition, body force source terms were included in the momentum equation to account for surface tension and buoyancy effects.FindingsThe performance of two-phase flow simulations was benchmarked against experimental data for four air/water bubbles with 1, 2.5, 5 and 10 mm of diameter rising in quiescent fluid. A variety of bubble sizes were tested to demonstrate the accuracy of the ISM interface tracking method. The results attained were in close agreement with experimental observations.Practical implicationsThe results obtained show that the ISM method is a viable means for interface tracking of two-phase flow CFD simulations. Other applications of the ISM method include simulations of solid–fluid interaction and other immersed boundary flow problems.Originality/valueThe ISM method is a novel approach to front tracking, and the results shown are original in content.

A Method to Estimate Cadaveric Femur Cortical Strains During Fracture Testing Using Digital Image Correlation

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral surface obtained from mechanical testing. This optical method requires a texture of many contrasting fiduciary marks on a solid white background for accurate tracking of surface deformation as loading is applied to the specimen. Immediately prior to testing, the surface of interest in the camera view is painted with a water-based white primer and allowed to dry for several minutes. Then, a black paint is speckled carefully over the white background with special consideration for the even size and shape of the droplets. Illumination is carefully designed and set such that there is optimal contrast of these marks while minimizing reflections through the use of filters. Images were obtained through high speed video capture at up to 12,000 frames/s. The key images prior to and including the fracture event are extracted and deformations are estimated between successive frames in carefully sized interrogation windows over a specified region of interest. These deformations are then used to compute surface strain temporally during the fracture test. The strain data is very useful for identifying fracture initiation within the femur, and for eventual validation of proximal femur fracture strength models derived from Quantitative Computed Tomography-based Finite Element Analysis (QCT/FEA).

A Method to Estimate Cadaveric Femur Cortical Strains During Fracture Testing Using Digital Image Correlation.

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral surface obtained from mechanical testing. This optical method requires a texture of many contrasting fiduciary marks on a solid white background for accurate tracking of surface deformation as loading is applied to the specimen. Immediately prior to testing, the surface of interest in the camera view is painted with a water-based white primer and allowed to dry for several minutes. Then, a black paint is speckled carefully over the white background with special consideration for the even size and shape of the droplets. Illumination is carefully designed and set such that there is optimal contrast of these marks while minimizing reflections through the use of filters. Images were obtained through high speed video capture at up to 12,000 frames/s. The key images prior to and including the fracture event are extracted and deformations are estimated between successive frames in carefully sized interrogation windows over a specified region of interest. These deformations are then used to compute surface strain temporally during the fracture test. The strain data is very useful for identifying fracture initiation within the femur, and for eventual validation of proximal femur fracture strength models derived from Quantitative Computed Tomography-based Finite Element Analysis (QCT/FEA).

Wear behaviour at 600°C of surface engineered low-alloy steel containing TiC particles

ABSTRACTThe work aimed to develop surfaces that could resist wear at high temperatures, thus achieving a prolonged component life. Surface modification of a low-alloy steel by incorporating TiC particles has been undertaken by melting the surface using a tungsten inert gas torch. The dry sliding wear behaviour at 600°C of the original and modified surfaces was compared. Microscopic examination of both surfaces showed glazed layers across the wear tracks, with differing amounts of oxide and homogeneity. Extensive wear occurred on the steel surface, which showed deformation of the wear scar tracks and a steadily increased friction coefficient. The TiC addition reduced the wear loss, coinciding with a glazed layer 33% thinner than that on the low-alloy steel sample.

Non-rigid Reconstruction of Casting Process with Temperature Feature

Off-line reconstruction of rigid scene has made a great progress in the past decade. However, the on-line reconstruction of non-rigid scene is still a very challenging task. The casting process is a non-rigid reconstruction problem, it is a high-dynamic molding process lacking of geometric features. In order to reconstruct the casting process robustly, an on-line fusion strategy is proposed for dynamic reconstruction of casting process. Firstly, the geometric and flowing feature of casting are parameterized in manner of TSDF (truncated signed distance field) which is a volumetric block, parameterized casting guarantees real-time tracking and optimal deformation of casting process. Secondly, data structure of the volume grid is extended to have temperature value, the temperature interpolation function is build to generate the temperature of each voxel. This data structure allows for dynamic tracking of temperature of casting during deformation stages. Then, the sparse RGB features is extracted from casting scene to search correspondence between geometric representation and depth constraint. The extracted color data guarantees robust tracking of flowing motion of casting. Finally, the optimal deformation of the target space is transformed into a nonlinear regular variational optimization problem. This optimization step achieves smooth and optimal deformation of casting process. The experimental results show that the proposed method can reconstruct the casting process robustly and reduce drift in the process of non-rigid reconstruction of casting.

NUMERICAL MODELING OF BREAKING SOLITARY WAVE RUN UP IN SURF ZONE USING INCOMPRESSIBLE SMOOTHED PARTICLE HYDRODINAMICS (ISPH)

This paper presents a numerical model for simulating wave run-up on rough sloping surfaces. Incompressible smoothed particle hydrodynamics (ISPH) has been utilized, which is capable of efficient tracking of free surface deformation in a Lagrangian coordinate system. Many of the existing models have focused on inviscid wave run-up on a smooth surface, but few numerical models and especially experimental studies have investigated the effect of beach roughness on the run up. In the present study two methods have been deployed to study the effect of roughness on wave run up. In the first method, the mass unit force, which is a coefficient of the fluid viscosity, and is dependent on the roughness of the solid boundary, has been used. In the second method, mass unit force obtained from the wall functions was utilized to enforce the friction on the particles near the boundaries. The comparisons of the numerical simulations with the analytical solutions and experimental data confirmed the capability of the model in simulating wave propagation and wave breaking. It was also concluded that the effect of roughness on wave run up depends on both the roughness itself and the beach slope. The results also indicated small roughness effect on waves running up over steep slopes.

Zoned and staged construction of an underground complex in Shanghai soft clay

Construction of an underground complex in congested urban areas calls for excavation of a group of foundation pits, referred to as a pit complex, which are usually surrounded by existing facilities. In such circumstances, the safety of the pit complex and facilities during the construction are of great concern. This paper presents a case of an underground complex construction in Shanghai soft clay. A pit complex composed of two deep excavations was excavated for a Comprehensive Transport Hub (CTH) and a commercial retail area and pedestrian concourse known as South Square (SS), which were connected to an operating metro station and a railway station. During the excavation, potential deformation of metro tracks and railway tracks were expected due to extensive soil unloading. To safeguard the railway and the subway, a zoned and staged construction technology was proposed, in which several temporary partition walls were constructed in addition to necessary supporting structures, to allow the large-scale deep excavations to be divided into several independent small-scale excavations. This paper discusses the rational construction sequence of these excavations as well as reinforcement measures in detail. The construction technology was examined by extensive field data. It is found that the maximum horizontal displacement of diaphragm walls ranged between 0.05% He and 0.4% He, where He is the excavation depth. The vertical displacements of the railway tracks were well controlled, whereas the metro tracks heaved significantly due to unloading effect.

Spatiotemporally Controlled Mechanical Cues Drive Progenitor Mesenchymal-to-Epithelial Transition Enabling Proper Heart Formation and Function

During early cardiogenesis, bilateral fields of mesenchymal heart progenitor cells (HPCs) move from the anterior lateral plate mesoderm to the ventral midline, undergoing a mesenchymal-to-epithelial transition (MET) en route to forming a single epithelial sheet. Through tracking of tissue-level deformations in the heart-forming region (HFR) as well as movement trajectories and traction generation of individual HPCs, we find that the onset of MET correlates with a peak in mechanical stress within the HFR and changes in HPC migratory behaviors. Small-molecule inhibitors targeting actomyosin contractility reveal a temporally specific requirement of bulk tissue compliance to regulate heart development and MET. Targeting mutant constructs to modulate contractility and compliance in the underlying endoderm, we find that MET in HPCs can be accelerated in response to microenvironmental stiffening and can be inhibited by softening. To test whether MET in HPCs was responsive to purely physical mechanical cues, we mimicked a high-stress state by injecting an inert oildroplet to generate high strain in the HFR, demonstrating that exogenously applied stress was sufficient to drive MET. MET-induced defects in anatomy result in defined functional lesions in the larval heart, implicating mechanical signaling and MET in the etiology of congenital heart defects. From this integrated analysis of HPC polarity and mechanics, we propose that normal heart development requires bilateral HPCs to undergo a critical behavioral and phenotypic transition on their way to the ventral midline, and that this transition is driven in response to the changing mechanical properties of their endoderm substrate.

Visual Tracking of Deformation and Classification of Non-Rigid Objects with Robot Hand Probing

Performing tasks with a robot hand often requires a complete knowledge of the manipulated object, including its properties (shape, rigidity, surface texture) and its location in the environment, in order to ensure safe and efficient manipulation. While well-established procedures exist for the manipulation of rigid objects, as well as several approaches for the manipulation of linear or planar deformable objects such as ropes or fabric, research addressing the characterization of deformable objects occupying a volume remains relatively limited. The paper proposes an approach for tracking the deformation of non-rigid objects under robot hand manipulation using RGB-D data. The purpose is to automatically classify deformable objects as rigid, elastic, plastic, or elasto-plastic, based on the material they are made of, and to support recognition of the category of such objects through a robotic probing process in order to enhance manipulation capabilities. The proposed approach combines advantageously classical color and depth image processing techniques and proposes a novel combination of the fast level set method with a log-polar mapping of the visual data to robustly detect and track the contour of a deformable object in a RGB-D data stream. Dynamic time warping is employed to characterize the object properties independently from the varying length of the tracked contour as the object deforms. The proposed solution achieves a classification rate over all categories of material of up to 98.3%. When integrated in the control loop of a robot hand, it can contribute to ensure stable grasp, and safe manipulation capability that will preserve the physical integrity of the object.

Feasibility of digital image correlation for railroad tie inspection and ballast support assessment

Abstract Structural Health Monitoring (SHM) of aging railway tracks is important for safety, to prevent catastrophic failure, and to reduce maintenance costs. The tracks and foundations are complex systems that may contain defects or damage including internal rail cracks, pitting or surface erosion, degradation of ballast support, or railway crosstie-ballast failures. In recent years, interest has grown in performing SHM by measuring structural deformation, full-field strain, and geometry profiles using three-dimensional (3D) Digital Image Correlation (DIC) systems. In this study, a novel approach to use DIC and pattern projection to assess the deformation of railway tracks is proposed. The proposed sensing approach should allow a railcar mounted sensing system to perform interrogation while moving at typical operating speeds (e.g. 60 mph). The feasibility of the proposed 3D DIC system is evaluated through extensive laboratory testing. The approach’s ability to measure the crosstie’s full-field displacement and shape (i.e. at levels similar to what is found in the field) as different loading conditions are applied is demonstrated. The influence of motion similar to what might be found in a railroad service environment on the accuracy of the measurements is also quantified.

Исследования накопления деформаций железнодорожного пути на участке испытаний вагонов с осевой нагрузкой 27 тс

Повышение провозной способности сети железных дорог влечет за собой повышение осевых нагрузок и масс поездов. Для этого требуется подготовка линий, поскольку движение тяжеловесных поездов по земляному полотну, спроектированному в конце XIX - начале XХ в. совсем для других нагрузок, может вызвать возникновение деформаций пути. В рамках испытаний, проводимых на участке Ковдор - Мурманск Октябрьской железной дороги в 2014-2016 гг., был апробирован и применен метод численного расчета параметров длинных неровностей, получаемых по данным путеизмерителей, позволяющий производить мониторинг участков с нестабильным земляным полотном без применения трудоемких геодезических работ.

DESIGN OF DOUBLE-SIDED LINEAR PERMANENT MAGNET EDDY CURRENT BRAKING SYSTEM

This work tries to design an Eddy current braking system that can brake at a very high speed within a short time or a short distance. In order to maximize the braking force and reduce lateral forces that can cause track deformation or damage, a double-sided linear permanent magnet Halbach array is proposed in this paper. Two possible designs (Type I and Type II) have been investigated. By using mathematic models, Finite Element Method (FEM) and experimental results, Type I design of a double-sided linear permanent magnet Halbach array is selected. Compared with the other design, Type I design can provide a much larger braking force. Moreover, the analysis also shows that the mathematic models can well capture the characteristic of Type I design. Thus these models are used to design a set of optimal design parameters such as the length and thickness of permanent magnet block to maximize flux density and braking force per unit mass of permanent magnets. The optimal performance is validated by using FEM.