Deformation Trend Research Articles

Changing pictures of molecular faces and depths of potential acting on an electron in molecule for intramolecular proton transfer reactions of formic acid and malonaldehyde

Proton transfer plays a critical role in many chemical and biological processes. MF theory is used to investigate intramolecular proton transfer reactions of formic acid and malonaldehyde. A MELD package with our in-house program is employed to calculate potential acting on an electron within a molecule (PAEM), molecular face (MF), molecular intrinsic characteristic contour (MICC) parameters, molecular face surface area (MFSA), as well as molecular face volume (MFV) of the two proton transfer reactions along the IRC routes. Vivid MF graphs are drawn. Then we found the following features: Firstly, the difference of frontier electron density (MICCED) distribution of formic acid is larger than malonaldehyde. Secondly, for formic acid, the trends of polarization and deformation of O atomic region are the same as another O, whereas opposite for malonaldehyde. Thirdly, the electron density uniformity of the formic acid reaction has minimum value at the transition state, whereas maximum with wave-like shape for malonaldehyde. Finally, the change tendencies of MFSA and MFV for formic acid are opposite to those for malonaldehyde. The uniformity of TS is a maximum from our PAEM method, Bader QTAIM and Gilli structure of views for malonaldehyde. In brief, although the both intramolecular proton transfers look similar, the changing features of both shape and frontier electron density along IRC routes are quite distinct, even opposite.

Computational and analytical investigations of shape effects in the experimental characterization of magnetorheological elastomers

Magnetorheological elastomers (MRE) are composite solids consisting of an elastomeric matrix and dispersed magnetic inclusions. Due to the composite nature of MREs, there is a demand for accurate techniques that allow for the determination of their effective properties. This task is complicated by the fact that the response of an MRE specimen is not only influenced by the properties of its constituents and the respective microscopic morphology, but also dependent on its shape. This is due to the fact that every MRE sample interacts with the magnetic fields it is exposed to and thus experiences shape-dependent boundary conditions. This makes it difficult to find adequate experimental procedures for material characterization. In the present contribution we analyze the effective response of several MRE specimens with respect to the individual impact of microscopic morphology and macroscopic shape. To closely link our investigations to experimental measurements we perform multiscale simulations of typical experimental scenarios in a two-dimensional setting. The underlying approach thereby fully resolves the magneto-mechanical problem on the specimen scale and accounts for the microscopic behavior via homogenization. In this way the approach allows for the multiscale computational characterization of magnetorheological elastomers with arbitrary shapes and microstructures. As prototype examples we analyze two-dimensional specimens with rectangular and elliptical shapes. Furthermore, we present a generic analytical approach to shape effects, which is based on magneto-mechanical tractions acting on the surface of MRE specimens. We show that the analytical approach is able to predict fundamental stress states and deformation trends, which were also observed in our numerical simulations.

An inertial measurement method of ship deformation based on IMM filtering

Matching filtering algorithm based on inertial measurement unit is the development trend of deformation of ship hull. Kalman filter requires that the system model parameters are known accurately, however the parameters of the actual ship hull deformation model are unknown or uncertain. According to the above problem, this paper introduces interacting multiple models (IMM) Kalman filtering method based on the “velocity plus angular velocity” model matching. The estimated residuals of each model are used to calculate the probability of the corresponding model. Finally, simulation results show fast convergence, good stability and high accuracy of the proposed algorithm. Then, we use the Monte Carlo simulation. The results show that the IMM can increase 5%–10% accuracy than the Kalman filter. The IMM algorithm can improve the estimation accuracy of the deformation angle and the environmental adaptability compared with the traditional Kalman filter.

Computational Modeling for Fluid–Structure Interaction of Bioprosthetic Heart Valve with Different Suture Density: Comparison with Dynamic Structure Simulation

In this paper, a parametric geometry model based on elliptic and conic surfaces was developed for bioprosthetic heart valve (BHV) simulation. The valve material was modeled by a hyperelastic nonlinear anisotropic solid model. Different suture densities could be substituted by various bonded points between artery vessel and the leaflets as boundary conditions in the computational modeling. Besides these two assumptions that dynamic structure (DS) and fluid–structure interaction (FSI) both shared, the latter need incompressible viscous Newton fluid model to depict bloodstream passing through the BHV. Immersed boundary (IB) method was introduced to solve the FSI simulation. In addition, the DS analysis applied transvalvular pressure on the valve while FSI had left ventricular pressure on fluid inlet as initials. There was inconsistency between the moments of the maximum deformation and the maximum loading in both simulations. Although a similar trend of deformation lagging the load was viewed, the extent of delay in FSI was much smaller compared with that in DS simulation. The deformed profiles in cross-sectional views were shown in one picture to illustrate different dynamic responses caused by distinct assumptions. Percent of open area at the moments when the maximum deformation occurred was defined to show which calculation achieved better approximation for precise hemodynamics. Fixed point was given as boundaries between BHV and artery in the modeling part. Calculations showed that the more the fixed points in this bonded contact, the lower the principal stress was. The maximum shear stress showed a different trend. It had a different trend. Stress concentration in the conjunction area made it high-risk to be teared. Different suture densities had significant impaction in FSI simulations. With that analysis our work achieved a more comprehensive simulation to describe true hemodynamics of a BHV implanted in artery. The artery vessel had particular dynamic response under such assumptions, gradient existed in the maximum principal stress distribution diagram, from inner wall through which blood passing to the outer wall. Results showed a large suture density was suggested in BHV implantation.

Integrated Multi-Level Control Value and Variation Trend Early-Warning Approach for Deformation Safety of Arch Dam

Appropriate early-warning index of dam deformation can be used to identify the structural behavior in real time. It is an important measures to monitor the service safety of dam engineering. This paper focuses on the approach determining the early-warning index of arch dam deformation by analyzing the prototypical observations of dam safety and implementing the numerical simulation of dam structure. First, according to the long-term deformation process of arch dam, an early-warning criterion, which combines the multi-level control value and variation trend of dam deformation, is presented. Second, the numerical analysis for structural failure is implemented to calculate the global safety factor of arch dam. A method determining the global safety factor-based control value of dam deformation is developed. Third, the multi-resolution analysis of wavelet is introduced to identify the variation trend of dam deformation from the measured data. The variation trend rule is given to judge the deformation status of arch dam. Finally, the deformation behavior of one actual arch dam is taken as an example. The multi-level control value formula of dam deformation is given. It is combined with the variation trend of dam deformation to fulfill the comprehensive evaluation of deformation safety. It is indicated that the proposed approach is suitable to be used to determine the early-warning index of arch dam deformation, can help with identifying the service safety and potential risk of dam engineering.

Reactivation versus reworking of the active continental margin during the Zagros collision: Mahallat–Muteh–Laybid complexes, Sanandaj–Sirjan zone, Iran

Reactivation of long-lived basement faults has significant influences on further deformation of collision zones. Three major inherited pre-collisional NW-, N- and NE-trending basement discontinuities have played important roles on the structural and tectono-sedimentary evolution of the Iranian micro-continent in the northeastern part of the Gondwana super-continent. Sanandaj–Sirjan zone (SSZ), known as the metamorphic belt of the Zagros orogeny, marks the SW margin of the Central Iran. SSZ is formed as a result of the Arabia–Eurasia collision and its general trend of deformation coincides with the NW structural trend of the collision. The NE-trending Mahallat, Muteh and Laybid complexes in the middle part of the NW-trending SSZ are the exception and have a trend almost normal to the NW-trending Zagros. A combined methodology of remote sensing, geometric and kinematics analyses complemented by field work was used to reconstruct the history of deformation in the Zagros hinterland since the earlier stages of collision to the present-day. Our results reveal the key role of the preexisting discontinuities of the Iranian basement in both the kinematics and structural pattern of the middle part of the SSZ. These basement faults have acted as main boundary conditions changing the collisional fabric perpendicular to its overall trend. Progressive deformation and the related changes during collision have caused drastic changes in the kinematics of the boundary faults. The establishment of dextral transtension in the SSZ has had secondary influences on the pattern of deformation by local clockwise rotation and localized dextral shear in the southern parts of the area of interest. This study highlights the significance of long-lived pre-existing structures in the deformation of collision zones. Such basement faults are capable to change both the pattern and kinematics of deformation of the adjacent areas involved in a continental collision.

InSAR time-series monitoring of ground displacement trends in an industrial area (Oreokastro—Thessaloniki, Greece): detection of natural surface rebound and new tectonic insights

The industrial area of Oreokastro, NW of the city of Thessaloniki, is monitored using radar interferometry to determine the spatial evolution of the underlying ground deformation trends. Previous studies, using SAR data acquired between 1992 and 1999, have revealed subsidence; however, the driving mechanism has not been, so far, solidly explained. Here, SAR satellite data from ERS 1, 2 and ENVISAT missions, acquired between 1992 and 2010, are analysed to enhance our understanding of the ground displacement trends and provide a thorough interpretation of the phenomena. The analysis confirms a subsiding displacement pattern from 1992 to 1999, whereas the recent data indicate that after 2003 the motion direction has changed to uplift. This whole monitoring of subsidence and the subsequent uplift is a rarely documented phenomenon, and in the case of Oreokastro is not reflecting a natural process; on the contrary, the driver is anthropogenic, related to the regional aquifer activity. Our study also highlights the fact that the local faults act as groundwater barriers and captures the existence of a possible previously unknown tectonic structure.

Statistical Modeling Applied to Deformation-Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field

This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling. Image enhancement and then image segmentation (Gaussian mixture modeling) processes were applied to extract features with reliable information of droplets dimensions from optical micrographs. The droplets deformation and relaxation trends were accurately adjusted by the Kohlrausch-Williams-Watts (KWW) function and a mean relaxation time was obtained by fitting the time evolution of geometry parameters. It was found to be proportional to the initial radius of the spherical droplets and was associated to interfacial tension.

Application of Distributed Optical Fiber Sensing Technique in Monitoring the Ground Deformation

The monitoring of ground deformation is important for the prevention and control of geological disaster including land subsidence, ground fissure, surface collapse, and landslides. In this study, a distributed optical fiber sensing technique based on Brillouin Optical Time-Domain Analysis (BOTDA) was used to monitor the ground deformation. The principle behind the BOTDA is first introduced, and then laboratory calibration test and physical model test were carried out. Finally, BOTDA-based monitoring of ground fissure was carried out in a test site. Experimental results show that the distributed optical fiber can measure the soil strain during ground deformation process, and the strain curve responded to the soil compression and tension region clearly. During field test in Wuxi City, China, the ground fissures deformation area was monitored accurately and the trend of deformation can also be achieved to forecast and warn against the ground fissure hazards.

Deformation and Dynamic Load Amplification Trends at Railroad Bridge Approaches

Railroad track transitions such as bridge approaches may experience differential movements due to variations in track stiffness; impact loads due to train speed and excessive vibration; ballast settlement from fouling, degradation, or both; tie–ballast contact condition and gap; and settlement of fill, subgrade, and foundation layers. A research study completed recently at the University of Illinois focused on identifying the major causes of this differential movement and implementing suitable rehabilitation measures to mitigate recurrent problems with settlement and geometry. Transient and permanent deformation trends were observed in track substructure layers at two instrumented bridge approaches along the Amtrak Northeast Corridor. Multidepth deflectometer systems installed through crossties successfully recorded both permanent (plastic) and transient deformations of individual track substructure layers. Strain gauges mounted on the rail effectively measured vertical wheel loads applied during train passage and monitored the support conditions under the instrumented crossties. Track settlement (or permanent deformation) data revealed that the ballast layer was the primary source of differential movement contributing to recurrent settlement and geometry problems. Transient layer deformations recorded under train passage were higher in the ballast than in any other substructure layer. Transient displacement and wheel load data were consistently higher at near-bridge locations than at open-track locations. Rail-mounted strain gauges indicated that load amplification levels were significantly higher at near-bridge locations than at open-track locations.

Pre-Alarm System Based on Real-Time Monitoring and Numerical Simulation Using Internet of Things and Cloud Computing for Tailings Dam in Mines

The tailings dam, a necessary facility to maintain the normal operation of mining enterprises, is a hazard source of human-caused debris flow with high potential energy. The real-time pre-alarm for the instability of tailings dam is vital to ensure the normal mining and safety of human lives and properties. Based on the Internet of Things and wireless networks, the multiple and the key information system of tailings dam is constructed using the sensor data, which include the stability indexes like phreatic line, reservoir water level, internal and external deformation of the tailings dam. The cloud platform is applied to predict the future state of the phreatic line based on real-time monitoring data, where the equation of phreatic line can be obtained. The numerical simulation model is established by considering the predicted equation of phreatic line, limit equilibrium state parameters, reservoir water level, and rainfall. Then, the safety factor, random reliability, and interval non-probabilistic reliability can be solved out through the cloud platform. Combined with the trend of real-time monitoring deformation, as well as calculated dynamic safety factor, random reliability, and interval non-probabilistic reliability, the stable or dangerous warning signals of tailings dam can be obtained by the remote real-time pre-alarm system. The main solved method for the key parameters and pre-alarm process are presented through a case study. It is proved that the pre-alarm system is an efficient and real-time platform for the tailings dam stability with the integration and mutual validation of key information.

Multi-objective optimization of flexure hinge mechanism considering thermal–mechanical coupling deformation and natural frequency

Flexure hinge mechanism plays a key part in realization of terminal nano-positioning. The performance of flexure hinge mechanism is determined by its positioning design. Based on the actual working conditions, its finite element model is built and calculated in ANSYS. Moreover, change trends of deformation and natural frequency with positioning design parameters are revealed. And sensitivity analysis is performed for exploration response to these parameters. These parameters are used to build four objective functions. To solve it conveniently, the multi-objective optimization problem is transferred to the form of single-objective function with constraints. An optimal mechanism is obtained by an optimization method combining ANSYS with MATLAB. Finite element numerical simulation has been carried out to demonstrate the superiority of the optimal flexure hinge mechanism, and the superiority can be further verified by experiment. Measurements and tests have been conducted at varying accelerations, velocities, and displacements, to quantify and characterize the amount of acceleration responses obtained from flexure hinge mechanism before and after optimization. Both time- and frequency-domain analyses of experimental data show that the optimal flexure hinge mechanism has superior effectiveness. It will provide a basic for realizing high acceleration and high precision positioning of macro–micro motion platform.

Bridge Displacements Monitoring Using Space-Borne X-Band SAR Interferometry

The development of interferometric methodologies for deformation monitoring that are able to deal with long time series of synthetic aperture radar (SAR) images made the detection of seasonal effects possible by decomposing the differential SAR phase. In the case of monitoring of man-made structures, particularly bridges, the use of high-resolution X-band SAR data allows the determination of three major components with significant influence on the SAR phase: the linear deformation trend, the height of structures over terrain, and the thermal expansion. In the case of stable metallic or (reinforced) concrete structures, this last effect can reach a magnitude comparable to or even exceeding the other phase components. In this review, we present two case studies that confirm the feasibility of InSAR techniques for bridge deformation monitoring and our original approach to refine the thermal expansion component.

Study on Stress Analysis and Welding Deformation of the Loader Boom

This paper takes the 5T loader boom as the research object. Firstly, the static analysis of the boom loader is carried out under the typical working conditions. The weak part of the welding seam is found, and then the welding deformation of the boom is analyzed for the weak welding part. Further, the deformation trends of the welding arm are studied. It is found that the weak part of the welding seam is at the welding arc of the boom plate and the beam. Besides, the deformation of the arm plate is about 30mm inward in the welding process due to the welding stress, and the residual stress of the boom. This work can provide theoretical and data support for the processing and deformation correction of the boom.

Modeling of tool-chip contact length for orthogonal cutting of Ti-6Al-4V alloy considering segmented chip formation

In this work, the orthogonal cutting experiments on Ti-6Al-4V alloy were conducted at different cutting speeds(10—160 m/min)and feed rates(20—160 μm/rev). The tool-chip contact length was measured by the track of tool rake face; meanwhile, the chip morphology caused by the localized and overall chip deformation was characterized by the degree of segmentation and the chip compression ratio, respectively. These parameters were analyzed and calculated according to the segmented chip morphology. In addition, three modified models considering the overall chip deformation and the localized deformation of adiabatic shear band were proposed, and the constants of the models were calculated by the genetic algorithm optimization. Considering the overall and localized chip deformation, the value and variation trend of the tool-contact length predicted by these three models agreed well with the experimental results.

Numerical investigation of micro- and nanochannel deformation due to discontinuous electroosmotic flow

Large pressures can induce detrimental deformation in micro- and nanofluidic channels. Although this has been extensively studied for systems driven by pressure and/or capillary forces, deflection in electrokinetic systems due to internal pressure gradients caused by non-uniform electric fields has not been widely explored. For example, applying an axial electric field in a channel with a step change in conductivity and/or surface charge can lead to internally generated pressures large enough to cause cavitation, debonding, and/or channel collapse. Finite electric double layers within nanofluidic channels can further complicate the physics involved in the deformation process. In order to design devices and experimental procedures that avoid issues resulting from such deformation, it is imperative to be able to predict deformation for given system parameters. In this work, we numerically investigate pressures resulting from a step change in conductivity and/or surface charge in micro- and nanofluidic channels with both thin and thick double layers. We show an explicit relation of pressure dependence on concentration ratio and electric double layer thickness. Furthermore, we develop a numerical model to predict deformation in such systems and use the model to unearth trends in deformation for various electric double layer thicknesses and both glass and PDMS on glass channels. Our work is particularly impactful for the development and design of micro- and nanofluidic-based devices with gradients in surface charge and/or conductivity, fundamental study of electrokinetic-based cavitation, and other systems that exploit non-uniform electric fields.

ON DYNAMIC RESPONSES OF GANHAIZI LANDSLIDE IN RESERVOIR ZONE DURING XILUODU PROJECT OPERATION

Ganhaizi landslide is a large-scale landslide nearest to Xiluodu dam site in Reservoir zone. And with the water level fluctuation a certain deformation and partial collapse occurred in this landslide body. Because of its big volume and the distance to dam site less than 14km, disastrous consequences will be result in the event of large-scale instability. In this paper based on the systematic analyses about the macro deformation signs and the deformation monitoring data during the operation period, the dynamic response rules of Ganhaizi to reservoir water level fluctuation were studied in detail, including the slope deformation trend, failure mode, potential failure range and influence degree. Some technical supports for project operation management, disaster prevention and mitigation were provided.

Discussion of “Experimental characterization of deformation, coefficient of earth pressure at rest, stiffness, and contact force distributions of sand during secondary compression and rebound”

This paper aims to provide a comprehensive picture of the sand responses during secondary compression and rebound based on experimental characterizations. The experiment was carried out on dry Leighton Buzzard sand using a modified direct shear box equipped with tactile pressure sensors for the stress measurements and bender elements for stiffness (i.e., Ghv and Ghh) monitoring. It was found that secondary compression and rebound followed the same deformation trends as primary compression and rebound to continuously contract and expand, respectively. The deformation characteristics determined the changes in the associated soil properties; therefore, the opposite soil behavior during secondary compression and rebound was observed. During secondary compression, the corresponding void change, deviatoric strains eq, and the deviatoric strain rate e˙q increased with increasing vertical stress σv′ or deviatoric stress q because the sample crept more easily under a higher σv′ or q. The compression deformation ga...

Comparative Experimental Study and FE Analysis of Corrugated Steel Pipe Culverts with Different Stiffness

This paper describes comparative experiment on corrugated steel pipe culverts with different stiffness. The two culverts both with 1.2m span and 4m backfill height but with different corrugation pattern and plate thickness were constructed side by side. Displacement, strain and soil pressure at critical points were tested during construction. Two-dimensional (2D) finite element (FE) models were established and the computed values were compared with measured values to verify the effectiveness of FE models and the reasonability of the test. The study shows that the deformation trend is the same but the deformations of the flexible pipe were much larger. Only after the backfill finished and the soil-structure bear the load together the FE simulation could basically reflect the stress state of the structure due to the nonlinearity of soil and the complexity of soil-structure interaction. The larger deformation of the flexible pipe makes the soil-structure interaction obvious, which reduces the pressure of backfill soil on the structure. Therefore realities should be considered when choosing corrugation pattern and thickness of corrugated plates to optimize design and save construction cost.

Rutting prediction in airport pavement granular base/subbase: A stress history based approach

Abstract Test data from full-scale aircraft gear loading conducted at the National Airport Pavement Test Facility (NAPTF) by the US Federal Aviation Administration (FAA) were analyzed to investigate the effects of wander (offset loads) and channelized traffic loadings on the deformation behavior of unbound aggregate layers in asphalt pavement test sections. Insights were drawn on the complex rebound (recovered) and residual (unrecovered) deformation trends of granular materials due to passing of each of the 6-wheel Boeing 777 (B777) and the 4-wheel Boeing 747 (B747) gears for various combinations of loading (stress history effects), wander positions, and wander sequences. Measured field layer deformations and the accumulation rates could only be achieved when the magnitudes and variations of stress states in the granular layers, number of load applications, gear load wander patterns, previous loading stress history effects, trafficking speed or loading rate effects, and finally, principal stress rotation effects due to moving wheel loads were properly accounted for. Accordingly, measured transverse profiles and multi-depth deflectometer data were used to create individual pass residual deformation transverse profiles. The created transverse profiles were then combined with stress history effects to predict the residual transverse profiles for the test sections with P209/P154 granular base/subbase layers. The proposed method emphasizes the use of the previous load location and stress history of the pavement element to develop the residual deformation in that element. Calculation of the residual deformation in each element across the pavement surface results in the development of the complete permanent deformation transverse profile. This technique can be applied to estimate the transverse rutting profile of the pavement after trafficking based on any combination of applied wander and traffic direction.