Significant Local Deformation Research Articles

Mapping vertical and horizonal deformation of the newly reclaimed third runway at Hong Kong International Airport with PAZ, COSMO-SkyMed, and Sentinel-1 SAR images

In order to meet long-term air transportation needs, Hong Kong International Airport (HKIA) has been constructing the third runway system (3RS) through land reclamation projects since 2016. However, the third runway and taxiway, which were paved in September 2021, suffered from severe surface settlement. Therefore, we attempted to reveal the settlement pattern within the 3RS and analyze the factors contributing to this displacement. Employing the multi-temporal interferometric synthetic aperture radar (MT-InSAR) technique, we utilized PAZ, COSMO-SkyMed, and Sentinel-1 satellite images to extract ground displacements along the radar line of sight. The results show that, compared with COSMO-SkyMed and Sentinel-1 images, PAZ demonstrates superior performance in the deformation monitoring of the HKIA, with more deformation details and larger displacements. The maximum settlement rate derived by PAZ on the 3RS exceeds 110 mm/year. To ensure the reliability of the derived displacements along the LOS, we validated them through cross-validation, comparing the outcomes from different SAR data with data from GPS stations. In order to gain a detailed deformation information, we derived the vertical and horizontal (ground range direction) displacements by utilizing deformation measurements along the LOS of multiple SAR satellites and the geometric information, and the maximum values recorded for vertical and E-W displacements reached 88.31 mm/y and 41.91 mm/y, respectively. Furthermore, our investigation revealed that the significant local deformation observed on the taxiway and third runway was predominantly attributed to various factors including the creep of soft soil, consolidation of filling materials, characteristics of road surface materials, and distinct stages of construction.

Impact force identification for composite structures using adaptive wavelet-regularised deconvolution

Impact force identification (IFI) through deconvolution methods from measured structural responses poses a challenge due to the ill-posed nature of the inversion problem. Regularisation techniques, such as Tikhonov, sparse, and wavelet regularisation, offer potential solutions to mitigate the ill-posedness. However, determining suitable regularisation parameters is time-consuming. This study presents an adaptive wavelet-regularised time-domain deconvolution method for efficient IFI, based on wavelet transform and multi-resolution analysis. By analysing impact sensor signals using wavelets, adaptive impact windows covering the entire impact duration are generated, reducing signal length for deconvolution. Multi-resolution analysis of sensor signals enables identification of wavelet bases for the multi-resolution representation of impact force history. Regularisation is achieved by filtering out insignificant wavelet bases based on their energy contributions. Validation is performed through experiments involving small-mass hammer and large-mass drop tower impacts, comparing against various deconvolution methods. Results demonstrate the superior computational efficiency and comparable accuracy of the proposed adaptive method in IFI across different time windows. Notably, accurate force deconvolution for large-mass impacts confirms the effectiveness of the deconvolution methods for IFI, particularly when the structure undergoes significant local deformation.

Earth Observation Capacity of the National Geoinformation Center of Bulgaria as Part of the Tools for Geo- and Anthropogenic-Hazard Management in EPOS

Exploring the nature of the Earth system and its multi-scale architecture requires an integrated symbiotic approach not only to understand our planet but also to reveal the hazards and footprints of their events on human life. Following the conceptual model of the European Plate Observing System (EPOS) we integrate a variety of research to obtain a multilateral use of geoinformation for scientific and practical purposes. In 2018, we started building a Bulgarian distributed scientific infrastructure called the National Geoinformation Center, aiming to provide data, products, and expertise to predict and prevent natural and anthropogenic risks and disasters, as well as environmental changes. The present paper demonstrates the capabilities of seismological, Global Navigation Satellite System (GNSS), geomagnetic and multi-scale laboratories (MSL) in Bulgaria that participate to the respective thematic core services of EPOS. More than 40 seismological stations register and transmit data in real time through the operational center of the Bulgarian Seismological Network. Data from 18 GNSS stations, part of the National GNSS network, are officially registered in the EPOS GNSS Data Gateway. Data and products are available via the EPOS GNSS Product Portal for interested users. Panagjurishte geomagnetic observatory (PAG) provides real time variations and long-period data series for the Earth’s magnetic field. The Palaeomagnetic Laboratory at the National Institute of Geophysics, Geodesy and Geography (NIGGG) participates in MSL with its unique facilities for paleo-, archeo- and environmental magnetism studies. Four case studies are presented to illustrate best practices for utilizing the data collected. The analysis of seismicity in a region of a long-time exploited salt deposit is upgraded with GNSS data to reveal the reason for crustal movements in the region. The results show that the majority of the seismic events took place in the upper part of the Earth’s crust at a depth of up to 5 km, where the salt body is buried. The observed significant local deformations of the Earth’s surface are very likely related to the technological process of deposit exploitation. A recent model of the geomagnetic declination over the Bulgarian territory is also presented. It tracks the variation of the regional magnetic field from 2015 to 2020 and adds short-wavelength signals from the secular network observations. Last but not least, the application of a mineral magnetic laboratory analysis along the depth of a Holocene soil profile is demonstrated. Results reveal the soil evolution in response to environmental changes adding a new magnetic proxy parameter for more precise identification and characterization of the soil formation processes.

Research on the Water Entry of the Fuselage Cylindrical Structure Based on the Improved SPH Model

During aircraft landing on water, the intense impact load may lead to significant local deformation of the fuselage skin. Ensuring the aircraft’s integrity and reliability is of paramount importance. This paper investigates the fuselage skin’s dynamic response during water entry. In the simulation of complex water entry problems, the smoothed particle hydrodynamics (SPH) method can fully leverage the advantages of the particle method. However, the traditional SPH method still suffers from the drawbacks of tensile instability, significantly affecting the computational accuracy. Therefore, this paper first introduces the improved SPH model addressing fluid and solid tensile instability issues. Furthermore, the Riemann-based contact algorithm at the fluid–solid interface is also demonstrated. Based on the above improved SPH model, the simulation of water entry of the elastic cylinder is performed to validate the efficacy of the improved SPH model. Then, the dynamic response characteristics of elastic fuselage skin and the skin–stringer–floor–column structure when it enters the water are analyzed, including the deformation features and slamming force. Lastly, based on the presented damage model, a study is conducted on the water entry of the metallic elastic–plastic skin–stringer–floor–column structure, analyzing the locations of failure and providing guidance for the structural safety design of engineering.

Model of Angular Object Positioning Process by a System of Oblique Friction Force Fields on Parallel Planes

Abstract The primary contribution of the paper is a proposal of a method to minimize the angular positioning error in the process of transferring cuboidal objects between oblique friction force fields generated by two conveyors located on parallel planes. The research included infeed conveyors with two variants of inputs: angular and straight. It was assumed that the object, while moving between oblique conveyors at different heights, performs a 3D movement. The object is treated as a rigid body with a soft base, edges, and corners that can be subjected to significant local deformations. A modified nonlinear Kelvin model was used to describe the normal reaction forces at the contact points of the object with the bearing surfaces of the conveyors, and the modified static Bengisu–Akay friction model represents the tangential forces. Research shows that the use of a slight offset between the bearing surfaces of the conveyors and the highest possible proportion between the motion velocities of the infeed and outfeed conveyors have positive effect on improving the angular precision of the positioned objects. This conclusion applies to both variants of the infeed conveyor inputs. The results of the research have practical application in the design of high-performance conveyor transport systems, used in the processes of picking cuboidal objects, requiring a strictly defined angular orientation.

Coseismic deformation of the 2022 Luding <italic>M</italic><sub>S</sub>6.8 earthquake and seismic potential along adjacent major faults

<p indent="0mm">The 2022 Luding (Sichuan) <italic>M</italic>6.8 earthquake occurred on the Moxi segment of the Xianshuihe fault, one of the most seismically active faults in mainland China. Since 1900, six moderate to strong earthquakes (&gt; <italic>M</italic>6.5) have ruptured different sections of the Xianshuihe fault. This Moxi segment has a complex tectonic setting as it forms an intersection zone of the Anninghe, Daliangshan, Xiaojin, and Longmenshan faults. In this study, we investigated the distribution of coseismic deformation of the 2022 Luding earthquake in order to improve understanding of the seismogenic fault and gain insight into the kinematic behaviors of regional faults and seismogeneity of future strong earthquakes. We collected continuous global positioning system (GPS) and strong motion data within 200 and <sc>50 km</sc> from the epicenter, respectively, and performed high-precision processing to extract the coseismic deformation field of this earthquake. We also collected Sentinel-1 and Advanced Land Observing Satellite-2 (ALOS-2) ScanSAR model descending data covering the epicenter area, and processed these data using differential interferometric synthetic aperture radar (D-InSAR) technology. The GPS measurements confirm that deformation from this earthquake occurred as far as <sc>200 km</sc> from the fault. This coseismic deformation was distributed in four quadrants, indicating that the focal mechanism of the Luding earthquake was left-lateral strike-slip. A strong motion station <sc>16 km</sc> from the epicenter recorded a significant displacement waveform; peak ground displacement was <sc>14 cm</sc> and the permanent coseismic displacement was <sc>12 cm.</sc> InSAR deformation maps show significant coseismic deformation in a 30 km×<sc>30 km</sc> area along the fault. The maximum line-of-sight displacement reached <sc>15 cm</sc> to the west of the fault. In addition, significant local deformation (&gt; <sc>15 cm)</sc> was observed near the Wajiao township. Field investigations suggest that surface ruptures developed along the fault segment between Ertaizi and Aiguocun. However, it is difficult to identify rupture information from the InSAR maps owing to a loss of coherence in the near-field of the seismogenic fault. Detailed field investigations are needed to determine if coseismic slip reached the surface. Finally, we inverted interseismic coupling along the northeastern boundary faults of the Sichuan–Yunnan block, and quantitatively calculated the seismic moment budget on these faults. Based on the historical earthquake distribution of the past <sc>300 years</sc> and present-day fault locking conditions along the Xianshuihe fault, the Luding earthquake accommodated clockwise vertical-axis rotation of the expanding Qinghai-Tibetan Plateau relative to the South China Block. The earthquake fully released the strain accumulated on the Moxi segment since the 1786 Moxi <italic>M</italic>7³/₄ earthquake; as such, it is unlikely that large earthquakes will occur on the Moxi segment in the near future. However, we also performed a comprehensive investigation of seismic hazard along the Xianshuihe-Xiaojiang fault system based on the mapped seismic gap, asperity distribution, seismic moment deficit, and Coulomb failure stress caused by surrounding earthquakes. We found that the seismic moment accumulated on the Anninghe, Zemuhe, Daliangshan, and southern Longmenshan faults can be balanced by <italic>M</italic>_w7.0–7.7 earthquake. The Luding earthquake caused significant Coulomb stress loading (&gt; <sc>0.01 MPa)</sc> on the Daliangshan, Anninghe, and southern Longmenshan faults, bringing those faults closer to failure. In particular, Coulomb stress loading at the northern end of the Anninghe fault exceeded the conventional triggering threshold <sc>(0.1 MPa)</sc> for earthquakes; therefore, the risk of future strong earthquakes on the Anninghe fault deserves special attention.

Standards and methods for dent assessment and failure prediction of pipelines: A critical review

Dent, a common mechanical damage on pipelines, is associated with a significant local plastic deformation. Dents can cause pipeline failures, especially when they are combined with other types of defects such as gouges, fatigue, corrosion, and cracks. In this work, a systematic review of various assessment methods and standards for pipeline dents, including the combination of a dent with other defects, is conducted. Generally, the methods available today are not sufficiently accurate and reliable to assess pipeline dents, especially the dent-defect combinations. For plain dents on pipelines, both the depth-based criterion and the strain-based criterion are commonly used in engineering. Their main problems include inaccuracy and conservatism. For a dent combined with other defects, the existing assessment techniques are not mature enough to give reliable results. Both experimental testing and numerical modeling through finite element (FE) analysis are capable of investigating the influence of dents and dent-defect combinations on burst failure pressure of the pipelines, although an approximation to the reality is still the main difficulty existing in the experimental testing and FE analysis. Nowadays, relevant studies on assessment techniques for plain dents, a dent with fatigue and a dent with a single gouge have been common in literature. The combinations of a dent with corrosion or cracks have been rarely assessed due to complicated mechanisms involving a multi-physics coupling effect. Development of novel assessment methods by integrating mechanical stress and strain, electrochemical reactions and steel metallurgy will be a key topic to accurately assess the dent-defect combinations for improved pipeline integrity.

Dynamic response of fully-clamped steel plate under laboratory-simulated sequential fragment impact and blast loading

Composite projectile (CP) impact, as a new in-laboratory experimental technique, was further developed to simulate sequential fragment impact and blast loading generated by cased charge explosion. New developments include modification of the equivalent relationships between main loading characteristics from the explosion and the CP impact and the improvement of the experimental setup. Then, it was used to study the dynamic response of a fully-clamped steel plate under simulated sequential fragment impact and blast loading. For comparison, a widely used traditional technique, which decoupled the two load types by generating pressure pulse on the structure with pre-formed holes to simulate the sequential loading, was also employed. Deformation processes, deformation/failure modes, and central deflections of the plates tested using the two different techniques were compared and analyzed. It was found that the traditional technique underestimated the damage caused by sequential fragment impact and pressure pulse: the plate subjected to the CP impact was found to be more susceptible to tearing fractures at high impact velocities. Finite element simulations were subsequently performed and the simulation results were validated against experimental data. The validated FE model was then employed to further evaluate the synergetic effects of sequential fragment simulating projectile (FSP) impact and impulsive loading on the ballistic performance and deformation behavior of the fully-clamped steel plate. Results indicate that while pressure pulse in the sequential loading leads to an enhanced ballistic limit of the plate, FSP impact in the sequential loading causes significant local shear and tensile deformation around the perforation, resulting in plate tearing at a lower impact velocity.

Ultrasonic additive manufacturing of zirconium: Pilot results

Ultrasonic additive manufacturing (UAM) was successfully applied to the Zirconium material system to create a three-dimensional component prototype. The UAM process resulted in grain size refinement and significant localized deformation. Electron backscatter diffraction analysis revealed activated slip systems only applicable at high deformation temperatures, while texture analysis showed a decrease in measurable texture of the UAM build in comparison to the initial Zr-foil. Average tensile strengths in the X (sonotrode travel), Y (vibration), and Z (build) directions averaged 435 MPa, 458 MPa, and 359 MPa, respectively, demonstrating the viability of UAM for Zr-based materials. The delamination of some Z specimens along foil boundaries during loading suggests an interplay between interfacial Ti impurities introduced during welding and the spatial dependence of weld quality for this material system.

Fire Performance of Continuous Steel-Concrete Composite Bridge Girders

This paper presents a detailed investigation in to fire resistance along with failure mode in continuous steel-concrete composite twin I-shaped bridge girders under different localized fire through considering fire severity and fire exposure positions namely; mid-span zone in one of the two span, hogging moment zone and side-support zone. A 3-D finite element (FE) model, built utilizing the computer program ANSYS, is used to track structural fire performance in a typical two span of continuous composite twin I-shaped bridge girders (fabricated with twin I-shaped plates supporting a concrete slab) dependent on thermomechanical coupled analysis. The model validation is undertook through comparison of temperature and deflection response attained from a scaled composite single I-shaped girder tested exposed to ISO834 fire. The numerical analysis results show that the developed model can be favorably used to analyze the behavior and failure mode of continuous steel-concrete composite twin I-shaped bridge girders during entire range of fire exposure. Fire severity and fire exposure positions present critical influence in to the fire resistance of continuous composite bridge girders. Fire exposure prevention on hogging moment zone can significantly extend failure time of continuous girders, and further hold back progressive structural collapse. Web buckling based failure criterion can be applicable to calculate fire resistance of realistic continuous girders under simultaneous structural loading together with localized fire. Continuous composite bridge girders subjected to localized fire present highly significant local deformation response in the fire exposed bridge girder span.

Spatial-Temporal Evolution of Land Subsidence and Rebound over Xi’an in Western China Revealed by SBAS-InSAR Analysis

Land subsidence is one of the major urban geological hazards, which seriously restricts the development of many cities in the world. As one of the major cities in China, Xi’an has also been experiencing a large area of land subsidence due to excessive exploitation of groundwater. Since the Heihe Water Transfer Project (HWTP) became fully operational in late 2003, the problem of subsidence has been restrained, but other issues, such as ground rebounds, have appeared, and the effect of the underground space utilization on land subsidence remains unsolved. The spatial-temporal pattern of land subsidence and rebound in Xi’an after HWTP and their possible cause have so far not been well understood. In this study, the evolutionary characteristics of land subsidence and rebound in Xi’an city from 2007–2019 was investigated using Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-SAR) technology to process the Advanced Land Observing Satellite (ALOS) and Sentinel-1A SAR datasets, and their cause and the correlation with groundwater level changes and the underground space utilization were discussed. We found that the land subsidence rate in the study area slowed from 2007–2019, and the subsidence area shrank and gradually developed into three relatively independent and isolated subsidence areas primarily. Significant local rebound deformation up to 22 mm/y commenced in the groundwater recharge region during 2015–2019. The magnitude of local rebound was dominated by the rise in groundwater level due to HWTP, whereas tectonic faults and ground fissures control the range of subsidence and the uplift area. The influence of building load on surface deformation became increasingly evident and primarily manifested by slowing the subsidence reduction trend. Additionally, land subsidence caused by the disturbances during the subway construction period was stronger than that in the operational stage. Future land subsidence in Xi’an is predicted to be alleviated overall, and the areas of rebound deformation will continue increasing for a limited time. However, uneven settlement range may extend to the Qujiang and Xixian New District due to the rapid urban construction. Our results could provide a scientific basis for land subsidence hazard mitigation, underground space planning, and groundwater management in Xi’an or similar regions where severe ground subsidence was induced by rapid urbanization.

Model of positioning objects by the system of oblique friction force fields on horizontal and vertically offset planes

The paper presents a model of the process of angular positioning of cuboidal objects using a system of two oblique friction force fields produced by the conveyor belts located on parallel planes a and b, offset vertically by value H. It has been assumed that, while moving from friction force field a to lower placed field b, the object performs a 3D motion and comes into contact with the friction force fields at the corners, edges or the base surface. The object is treated as a rigid body with a soft surface of the bottom, which can be subjected to significant local deformations when interacting with obstacles. Two continuous collision models were used to describe the normal reaction forces at the contact points of the object with the bearing surfaces of the conveyors: the nonlinear MSC Adams model and the modified nonlinear Kelvin model. In addition, three friction models were included, i.e. two static Bengisu-Akay and MSC Adams models and one dynamic LuGre model. Numerical and experimental research demonstrate that the use of friction force fields with vertical offset of a short distance (e.g. H = 0.005 m) enhances the rotation angle Φ minimization of the object positioned.

Multiscale mechanical performance and corrosion behaviour of plasma sprayed AlCoCrFeNi high-entropy alloy coatings

The combination of technical advantages of high entropy alloys (HEAs) and manufacturing capabilities of thermal spray (TS) offer potential towards new protective coatings to address extreme engineering environments. In this research, equi-atomic AlCoCrFeNi HEA coatings were synthesized via atmospheric plasma spray (APS) using mechanically alloyed feedstock, and a correlation between microstructure and mechanical properties in terms of both hardness and wear were established at multiscale levels. In addition, electrochemical performance in sea water and the overall residual stress distribution in the HEA coatings were also assessed. Superimposition of scanning electron micrographs and statistically analysed heat and contour maps using nanoindentation datasets revealed deviations in localized properties within and across individual phases; which were supported by Weibull plots of individual phases. Scanning wear tests revealed superior nanowear resistance of oxide phases developed by in-flight oxidation during APS process. In comparison, the HEA phases in the coating exhibited significant localized plastic deformation. The outcome of macroscale wear testing postulated that plasma sprayed AlCoCrFeNi HEA coatings exhibited superior wear resistance at high temperature (500 °C) than at room temperature, signifying high thermal stability of the coating. Residual stress generated due to plasma spray was measured using neutron diffraction and was tensile in nature. The corrosion resistance of the coating was slightly lower than that of SS316L, however, the anodic and cathodic polarization behaviour of HEA coating were identical to that of SS316L, indicating that the AlCoCrFeNi-based HEAs have prospects as corrosion resistant materials.

Lithium doping and vacancy effects on the structural, electronic and magnetic properties of hexagonal boron nitride sheet: A first-principles calculation

The first-principles calculations based on spin-polarized density functional theory is carried out to investigate the structural, electronic and magnetic properties of a hexagonal boron nitride sheet (h-BNS) doped by one or two lithium atom(s). Moreover, a vacancy in the neighborhood of one Li-substituted atom is introduced into the system. All optimized structures indicate significant local deformations with Li atom(s) protruded to the exterior of the sheet. The defects considered at N site are energetically more favorable than their counterpart structures at B site. The spin-polarized impurity states appear within the bandgap region of the pristine h-BNS, which lead to a spontaneous magnetization with the largest magnetic moments of about 2 μB in where a single or two B atom(s) are replaced by Li atom(s). Furthermore, the Li substitution for a single B atom increases the density of holes compared to that of electrons forming a p-type semiconductor. More interestingly, the structure in which two Li are substituted two neighboring B atoms appears to show desired half-metallic behavior that may be applicable in spintronic. The results provide a way to enhance the conductivity and magnetism of the pristine h-BNS for potential applications in BN-based nanoscale devices.

First-principles investigation of the structural and electronic properties of self-assemblies of functional molecules on graphene

Graphene-based two-dimensional materials have attracted an increasing attention these last years. Among them, the system formed by molecular adsorption on, aim of modifying the conductivity of graphene and make it semiconducting, is of particular interest. We use here hierarchical first-principles simulations to investigate the energetic and electronic properties of an electron-donor, melamine, and an acceptor, NaphtaleneTetraCarboxylic DiImide (NTCDI), and the assembly of their complexes on graphene surface. In particular, the van der Waals-corrected density functional theory (DFT) method is used to compute the interaction and adsorption energies during assembly. The effect of dispersion interactions on both geometries and energies is investigated. Depending on the surface coverage and the molecular organization, there is a significant local deformation of the graphene surface. Self-assembly is driven by the competition between hydrogen bonds in the building blocks and their adsorption on the surface. The dispersion contribution accounts significantly in both intermolecular and adsorption energies. The electron transfer mechanism and density of states (DOS) calculations show the electron-donor and acceptor characters of melamine and NTCDI, respectively. Molecular adsorption affects differently the energy levels around the Fermi level differently, leading to band gap opening. These results provide information about the new materials obtained by controlling molecular assembly on graphene.

Study of Insertion of Dengue E into Lipid Bilayers by Neutron Reflectivity and Molecular Dynamics Simulations

The envelope (E) protein of Dengue virus rearranges to a trimeric hairpin to mediate fusion of the viral and host membranes. Insertion of E into host membranes is essential to the process, serving to anchor E into the target membrane and possibly also to disrupt local order within the membrane. Both aspects are likely to be affected by the depth of insertion, the orientation of the trimer with respect to the membrane normal, and the interactions that form between the trimer and the membrane. In the present work, we resolved the depth of insertion, the tilt angle, and the fundamental interactions for the soluble portion of Dengue E trimers (sE) associated with planar lipid bilayer membranes of various combinations of POPC with POPG, POPE, and cholesterol by neutron reflectivity (NR) and by molecular dynamics (MD) simulations. The tip of E containing the fusion loop (FL) is located at the interface of the headgroups and acyl chains of the outer leaflet of the lipid bilayers, in good agreement with prior predictions. The NR measurements and the MD simulations both indicate that E tilts with respect to the membrane normal upon insertion, promoted by either the anionic lipid POPG or cholesterol. The simulations show that tilting of the protein correlates with hydrogen bond formation between lysines located on the sides of the trimer close to the tip (K246 and K247) and nearby lipid headgroups. These hydrogen bonds provide the majority of the interaction energy whereas interactions involving the FL are a minor contribution. POPG promotes formation of these hydrogen bonds through direct interactions with K246, K247, and other polar residues whereas cholesterol indirectly facilitates formation of these hydrogen bonds as a result of a greater hydrated volume in the headgroups. Simulations in which the protein was held in a vertical orientation with respect to the membrane show that these strong hydrogen bonding interactions of K246 and K247 with lipid headgroups causes significant local membrane deformation of a 70:30 POPC:POPG bilayer as the lipids wrap around the periphery of the E trimer. We propose that these interactions play the dominant role in membrane anchoring and may also play a role in initiating mixing of the outer leaflets during the fusion process.

Interwire wear and its influence on contact behavior of wire rope strand subjected to cyclic bending load

The present study establishes a solving model for analyzing the interwire wear evolution of a wire rope strand subjected to cyclic bending load, in which the frictional contact and sliding between the wires are considered simultaneously. A wear experiment between the wires is conducted to study the wear behavior of the wires. Meanwhile, the proposed model is verified experimentally. Then the interwire wear and its effect on the contact behavior of the strand are analyzed. The results show that the interwire wear only happens on the side further from the curvature center of the bended strand than its neutral layer, and no wear happens when the wires are apart from each other or the interwire slippage is zero. As the wear process goes on, the wear region extends only along the normal direction of the core-wire contact line, and the maximum wear depth occurs at the middle position between the neutral layer and the furthest location from the curvature center. The contact pressure is distributed uniformly along the normal direction of contact line, but a significant stress concentration and local deformation happen at the position furthest from the curvature center of the bended strand.

Zero-flow: a novel approach to continuous ultrasonic welding of CF/PPS thermoplastic composite plates

Continuous ultrasonic welding of plastic films, fabrics, and even thermoplastic composite prepreg tape is a common industrial practice. However, continuous ultrasonic welding of stiff thermoplastic composite plates is challenging due to squeeze flow of resin at the welding interface, and significant local deformation of the welding stack, that are generally needed to achieve strong welds. This paper presents a novel approach to continuous ultrasonic welding of thermoplastic composite plates based on zero-flow welding. The proposed technique can create strong welds before any squeeze flow takes place at the interface. It is enabled by the use of very thin flat energy directors, owing to simultaneous melting of both energy director and adherends’ matrix. The results prove the feasibility and indicate the potential for high-strength welds between thermoplastic composite plates at very high speed.

Pushing the Envelope: Dengue Viral Membrane Coaxed into Shape by Molecular Simulations

Dengue virus is a flavivirus responsible for millions of infections per year. Its surface contains a phospholipid bilayer, within which are embedded the envelope (E) and membrane (M) proteins, arranged with icosahedral geometry. Exposure to low pH triggers the E proteins to undergo conformational changes, which precede fusion with the host cell membrane and release of the viral genome. The flavivirus membrane exhibits significant local curvature and deformation, as revealed by cryoelectron microscopy (cryo-EM), but its precise structure and interactions with envelope components remain unclear. We now report simulations of the dengue viral particle that refine its envelope structure in unprecedented detail. Our final models are morphologically consistent withcryo-EM data, and reveal the structural basis for membrane curvature. Electrostatic interactions increased envelope complex stability; this coupling has potential functional significance in the context of the viral fusion mechanism and infective states.

Coherence between geodetic and seismic deformation in a context of slow tectonic activity (SW Alps, France)

A dense, local network of 30 geodetic markers covering a 50×60km2 area in the southwestern European Alps (Briançon region) has been temporarily surveyed in 1996, 2006 and 2011 by GPS. The aim is to measure the current deformation in this seismically active area. The study zone is characterized by a majority of extensional and dextral focal mechanisms, along north–south to N160 oriented faults. The combined analysis of the three measurement campaigns over 15 years and up to 16 years of permanent GPS data from the French RENAG network now enables to assess horizontal velocities below 1mm/year within the local network. The long observation interval and the redundancy of the dense campaign network measurement help to constrain a significant local deformation pattern in the Briançon region, yielding an average E–W extension of 16±11nanostrain/year. We compare the geodetic deformation field to the seismic deformation rate cumulated over 37 years, and obtain good coherencies both in amplitude and direction. Moreover, the horizontal deformation localized in the Briançon region represents a major part of the Adriatic-European relative plate motion. However, the average uplift of the network in an extensional setting needs the presence of buoyancy forces in addition to plate tectonics.