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Constitutive models constructed within the combined framework of kinematic hardening and bounding surface plasticity have proved to be successful in describing the rate-independent deformation of soils under non-monotonic histories of stress or strain. Most soils show some rate-dependence of their deformation characteristics, and it is important for the constitutive models to be able to reproduce rate- or time-dependent patterns of response. This paper explores a constitutive modelling approach that combines multiple viscoplastic mechanisms contributing to the overall rate-sensitive deformation of a soil. A simple viscoplastic extension of an inviscid kinematic hardening model incorporates two viscoplastic mechanisms applying an overstress formulation to a ‘consolidation surface’ and a ‘recent stress history surface’. Depending on the current stress state and the relative ‘strength’ of the two mechanisms, the viscoplastic mechanisms may collaborate or compete with each other. This modelling approach is shown to be able to reproduce many observed patterns of rate-dependent response of soils.

Excessive deformation has been observed during the construction of large-section (over 100 m2) tunnels in soft rock all over the world. A case study of deformation control for large-section tunnel construction in fractured carbonaceous slate was conducted. Xingzishan tunnel, China, was first excavated using the three-step reserved core soil excavation method (TRCSEM); however, this resulted in serious rockfalls at the tunnel arch and local collapse. To enhance the stability of the tunnel face, three different tunnel support systems with relatively stiff structures were proposed and tested along the tunnel chainage in the same rock condition, but all of them failed. The mechanism of the TRCSEM was revealed by field measurements, highlighting the significance of the stability of the upper bench of the tunnel face. In view of this, the three-step temporary inverted arch method (TTIAM) was employed and used with advance support. With this new method, the upper bench of the tunnel face was reinforced with fibreglass bolts to mitigate the deformation. Compared with the TRCSEM, the TTIAM effectively controlled large deformation at the tunnel face during the excavation in fractured carbonaceous slate with an acceptable construction cost.

The local deformation behavior and dynamic recrystallization of a shock compressed Mg-1 Zn alloy was investigated through EBSD and TEM. Since dislocation slipping and twinning were locally suppressed during high strain-rate deformation, a more flexible kinking deformation was activated to adjusted local orientation and facilitate slipping and twinning within the kinks. Meanwhile, due to the slow heat dissipation that resulted in a local temperature elevating, the kink bands were evolved into deformation bands with recrystallized nano-grains. Such a finding provides a new perspective for kinking-facilitated nanocrystallization in Mg alloys and other anisotropic metallic materials.

The deformation patterns and failure mechanisms of pressurised cavities at shallow depth are relevant to many geotechnical applications, including tunnelling and horizontal directional drilling. In this paper, an experimental study of a reduced-scale pressurised cavity under geostatic stress is presented, in order to measure the effect of cavity length, vertical stress and soil density on soil deformation and failure. X-ray computed tomography is used to acquire images of the system at key stages of the cavity inflation process. A closed-shaped failure region developed around the cavities, beyond which shear planes of elliptic paraboloid shape formed, extending from the bottom of the cavities all the way to the free surface. The plane-strain assumption did not hold beyond the central portion of the longest cavity tested (L = 6D). The volumetric strain and porosity changes inside the shear bands showed significant dilation in dense specimens, but contraction in loose specimens. The average orientation and the thickness of the shear bands were in agreement with those found in the literature for passive arching mechanisms (anchoring). The orientation of the principal strains around the cavity follows catenary shapes, similar to those displayed in active trapdoor mechanisms.

To investigate the overall damage characteristics and failure modes of a warship subjected to an underwater non-contact near-field explosion, a hull girder with a trapezoidal cross-section was designed, manufactured, and tested. The design criteria and parameters were determined according to the similarity criterion. Dynamic responses of the girder freely floating on water were obtained under varying conditions, including stand-off distance, charge mass, and position of attack. Damage morphologies of the girder model were obtained. Based on our analysis, basic conditions for sagging damage of the hull girder are proposed. The aim of this study was to determine an efficient method of attack resulting in the most severe damage to the ship hull. The experimental results show that the girder mainly exhibits a first-order response when the first wet frequency of the girder is close to the frequency of the explosion bubble pulsation. The largest deformation was observed when the underwater explosion occurred directly below the midspan of the girder compared to other explosions of the same intensity at different attack positions. When the ratio of stand-off to maximum bubble radius (λ) satisfies 0.7 ≤ λ＜2, the bubble mainly causes sagging damage instead of hogging. As λ decreases (1≤ λ＜2), the sagging damage increases under the same charge mass. However, as λ decreases further (0.7≤ λ＜1), the sagging deformation decreases. This is likely due to the impact of the liquid jet formed by the collapsing bubble, which causes the girder deformation to shift from sagging back to hogging deformation. The initial shock wave excites the high-frequency response of the girder structure but contributes very little to the overall velocity and displacement. However, bubble pulsation typically causes a low-frequency response, which will affect the velocity and displacement of the girder. The low-pressure region of the flow field formed by bubble pulsation and resonant coupling between the girder and the bubble are the predominant causes of damage to the overall girder structure.

Cement-grouted bituminous (CGB) mix is a semi-flexible type of pavement comprising an open-graded (porous) bituminous mix grouted with a cementitious mortar. CGB mixes have the advantages of both flexible and rigid pavements. This hybrid material of bituminous mix and cement grout offers better rut resistance and is more resistant to fuel and oil spillage compared to conventional bituminous mixes. This paper presents the details of different investigations carried out for the evaluation of the permanent deformation characteristics of different CGB mixes. A conventional bituminous concrete mix was also tested for comparison. The permanent deformation susceptibility of different CGB mixes was evaluated in a wheel tracking test facility. The rut depth developed after 20 000 load applications in the specimens conditioned at 60°C was correlated to different porous bituminous mix and CGB mix parameters. The empirical models presented in this paper will be useful for estimating the relative rutting performance of different CGB mixes in terms of their design parameters such as aggregate gradation, binder content and air voids in the mix.

A case study of the steel–concrete composite structure in the Pidie Jaya Regency Multipurpose Hall which experienced substantial permanent lateral deformation due to the effect of an earthquake is presented in this study. Therefore, it is important to assess the response of the structure to earthquake load and propose the strengthening strategies to make the buildings useful again. The purpose was to evaluate the causes of large deformations and the behavior of structure in resisting earthquake loads. The building structure model used in this study is a space frame with two-column base support conditions which are fixed and hinged supports after which a non-linear time history analysis was conducted. The time history analysis was conducted using five ground motion acceleration data recorded during earthquakes to determine the deformation and it was found that the large structure permanent deformation was due to the small structure stiffness in the direction of the deformation due to the use of only one column row in front of the building. Moreover, hinged support was observed to have caused a greater deformation than fixed support but was found not to be the main cause of large permanent deformation of the structure. The building structure was further strengthened by adding 4 columns while the oblique columns remained in a sloping condition. Meanwhile, the response spectrum analysis showed the strengthening structure was able to withstand earthquake loads with less deformation than the required standard.

The engineering characteristics of ocean sediments are significantly affected by fine particles such as diatoms. The objective of this study is to investigate experimentally the compressibility, small-strain stiffness and electrical resistivity of sand–diatom mixtures by way of oedometer tests. Sand–diatom mixtures are prepared at a fixed density with varying diatom contents ranging from 0 to 20% by weight. The vertical displacements are monitored during oedometer tests, and shear wave, compressional wave and electrical resistance are measured using bender elements, piezo-disc elements and an electrical resistance probe, respectively, at the end of each loading step. The test results show that the compression index increases, whereas the swelling index and shear and compressional wave velocities decrease with increasing diatom content because of the small and crushable diatom particles. The attenuation of shear and compressional waves increases continuously, while the shear and compressional wave velocities decrease with an increase in the diatom content due to weak inter-particle contact and a soft soil skeleton. In addition, the sand specimens with a lower compression index, Cc, a higher swelling index, Cs, a higher shear wave factor, α, and a lower shear wave exponent, β, gradually change to clay-like soils, which exhibit a higher Cc, a lower Cs, a lower α and a higher β as the diatom content increases. This study suggests that diatoms may affect the compressibility, small-strain stiffness and electrical resistivity of soil.

Deformation behavior as well as microstructural evolutions of a rolled AZ31 magnesium alloy with and without pre-existing extension twins were studied using compression tests which performed along different orientations at a temperature range of 25–350 °C. The results implied that the initial texture not only influence the evolution of flow stress, but also change the size and fraction of recrystallized grains. In contrast to samples parallel to rolling and transverse directions, compression along normal direction resulted in a respectful softening at 150 °C. The largest size and fraction of new grains at 250 °C were recorded after deformation along rolling direction, while the maximum flow softening was observed during deformation along normal direction. The anisotropy in microstructural evolutions was still retained at 350 °C. Pre-existing twins could reduce the anisotropy of material in respect of flow stress as well as DRX progression, where TD sample showed the lowest DRX fraction at 250 °C. Quaternion misorientation data obtained from EBSD analysis of pretwinned material implied that initial texture could not significantly influence final texture. A different misorientation distribution was realized after deformation of pretwinned material along ND and RD directions.

Ultra-high strain rate impact tests were conducted by Split-Hopkinson pressure bar to investigate the microstructure evolution and impact deformation mechanism of a solution treated casting AM80 Mg alloy at 25, 150 and 250 °C with a strain rate of 5000 s−1. The microcrack and dynamic recrystallization (DRX) preferentially nucleate at grain boundary (GB) and twin boundary (TB), especially at the intersections between GBs and TBs, and then propagate along twin direction. In contrast, the adiabatic shear bands preferentially occur at high-density twined regions. At 25 °C, the dominated deformation mechanisms are basal slip and twinning. As deformation temperature increases to 150 and 250 °C, the deformation gradually shifts to be dominated by a coordinated mechanism among non-basal slip, twinning and DRX. The flow stress behavior and deformation mechanism indicate that the degree of decrease in flow stress with temperature is associated with the change of deformation mode.

The horizontal strain in the vacuum preloading/dewatering of dredged slurry is significant to the apparent clogging effect and estimation of surface settlement around a drain; however, it has seldom been investigated in previous studies. In this study, a vacuum consolidation model test assisted by particle image velocimetry (PIV) technology was conducted. The displacement vector field was obtained through PIV analysis and image processing; it was used to visually observe the deformation features around a drain. Based on the displacement field, the vertical/horizontal strains at varied radial distances were calculated to explain the ‘soil pile’ and apparent clogging effect. From the strain distribution with radial distances, a significant lateral compression zone near the drain and an extension zone at farther areas were confirmed. Furthermore, a simple explicit model was established to evaluate the horizontal strain within a prefabricated vertical drain unit cell considering a horizontal attenuated vacuum and compression/extension zone. Finally, this method was applied to predict the horizontal displacement in the model test. The results showed that the proposed method can estimate the lateral displacement of soft clay slurry fairly well.

Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure (SRP). It is desirable to control the attitude through propellant-free means. This paper proposes a new method for attitude control of solar sails: A boom consisting of “smart” structural material can be deformed by the piezoelectric actuator, and Solar Radiation Pressure torque will be generated due to shape variation of sail membrane caused by boom deformation. The method has the advantages of simple structure, small disturbance and small additional load, and is not limited by the size of the solar sail. The case of rendezvous with the Asteroid 2000 SG344 is used to verify the attitude control around the pitch and yaw axes.

Spatially localized deformation components are very useful for shape analysis and synthesis in 3D geometry processing. Several methods have recently been developed, with an aim to extract intuitive and interpretable deformation components. However, these techniques suffer from fundamental limitations especially for meshes with noise or large-scale nonlinear deformations, and may not always be able to identify important deformation components. In this paper we propose a mesh-based variational autoencoder architecture that is able to cope with meshes with irregular connectivity and nonlinear deformations, assuming that the analyzed dataset contains meshes with the same vertex connectivity, which is common for deformation analysis. To help localize deformations, we introduce sparse regularization in this framework, along with spectral graph convolutional operations. Through modifying the regularization formulation and allowing dynamic change of sparsity ranges, we improve the visual quality and reconstruction ability of the extracted deformation components. Our system also provides a nonlinear approach to reconstruction of meshes using the extracted basis, which is more effective than the current linear combination approach. As an important application of localized deformation components and a novel approach on its own, we further develop a neural shape editing method, achieving shape editing and deformation component extraction in a unified framework, and ensuring plausibility of the edited shapes. Extensive experiments show that our method outperforms state-of-the-art methods in both qualitative and quantitative evaluations. We also demonstrate the effectiveness of our method for neural shape editing.

Large settlement and lateral deformation during construction of a rubble mound, such as a breakwater, over a soft clayey foundation are a challenge. Different mechanisms contribute to excessive settlement of marine clay, including consolidation, the size of the rubble particles, the penetration of individual rock particles and the flow of sludge through the rock pores. Placing a geotextile layer or sand mattress can restrict the amount of material loss caused by these mechanisms. To accurately assess the performance of a geotextile under a rubble mound, eight geotechnical centrifuge tests were conducted. The shear strength of the foundation and the type of the separator layer were the variables considered. The results indicate that the use of a geotextile as basal reinforcement reduced settlement at the breakwater crest and increased stability. In addition, the horizontal displacement of the rubble mound and the clayey foundation decreased remarkably.

This article describes a novel approach to achieve motion coordination in a multirobot system based on the concept of deformation. Our main novel contribution is to link these two elements (namely, coordination and deformation). In particular, the core idea of our approach is that the robots’ motions minimize a global measure of the deformation of their positions relative to a prescribed shape. Based on this idea, we propose a linear shape controller that also incorporates a term modeling an affine deformation. We show that the affine term is particularly useful when the deformation to be controlled is large. We also propose controls for the other variables (centroid, rotation, and size) that define the geometric configuration of the team. Importantly, these additional controls are completely decoupled from the shape control. The overall approach is simple and robust, and it creates closely coordinated robot motions. Being based on deformation, it is useful in several scenarios involving manipulation tasks, e.g., handling of a highly deformable object, control of an object’s shape, or regulation of the shape formed by the fingertips of a robotic hand. We present simulation and experimental results to validate the proposed approach.

With the increasing demand for transportation infrastructure, the construction of urban tunnel systems linking different areas is indispensable. The deformation and the failure process during a tunnel excavation are essential concerns for geotechnical engineers. However, few studies have systematically investigated the effect of the ground loss ratio on tunnel deformation and the inequality between the ground loss ratio and the volume of the settlement trough. An experimental study using the transparent soil testing technique is performed herein for better visualization and digitization purposes. The three dimensional vertical and horizontal deformation patterns of a single tunnel are investigated for both the surface and the stratum right below considering different ground loss ratios. The relationship among the empirical constant of the settlement trough width, buried depth, depth–diameter ratio, and ground loss ratio is presented.

The long-term settlement of calcareous sand foundations caused by daily periodic fluctuations has become a significant geological hazard, but effective monitoring tools to capture the deformation profiles are still rarely reported. In this study, a laboratory model test and an in situ monitoring test were conducted. An optical frequency domain reflectometer (OFDR) with high spatial resolution (1 mm) and high accuracy (±1 μe) was used to record the soil strain responses to groundwater table and varied loads. The results indicated that the fiber-optic measurements can accurately locate the swelling and compressive zones. During the loading process, the interlock between calcareous sand particles was detected, which increased the internal friction angle of soil. The foundation deformation above the sliding surface was dominated by compression, and the soil was continuously compressed beneath the sliding surface. After 26-48 h, calcareous sand swelling occurred gradually above the water table, which was primarily dependent on capillary water. The swelling of the soil beneath the groundwater table was completed rapidly within less than 2 h. When the groundwater table and load remain constant, the compression creep behavior can be described by the Yasong-Wang model with R2 = 0.993. The daily periodically varying in situ deformation of calcareous sand primarily occurs between the highest and lowest groundwater tables, i.e. 4.2–6.2 m deep. The tuff interlayers with poor water absorption capacity do not swell or compress, but they produce compressive strain under the influence of deformed calcareous sand layers.

The crystal orientation fabric (COF) of a polar ice sheet has a significant effect on the rheology of the ice sheet. With the aim of better understanding the deformation regime of ice sheets, the work presented here investigates the COF in the upper 80 % of the Dome Fuji Station ice core in East Antarctica. Dielectric anisotropy (Δε) data were acquired as a novel indicator of the vertical clustering of COF resulting from vertical compressional strain within the dome. The Δε values were found to exhibit a general increase with depth, but with fluctuations over distances in the order of 10–102 m. In addition, significant decreases in Δε were found to be associated with depths corresponding to three major glacial to interglacial transitions. These changes in Δε are ascribed to variations in the deformational history caused by dislocation motion occurring from near-surface depths to deeper layers. Fluctuations in Δε over distances of less than 0.5 m exhibited a strong inverse correlation with Δε at depths greater than approximately 1200 m, indicating that they were enhanced during the glacial-interglacial transitions. The Δε data also exhibited a positive correlation with the concentration of chloride ions and an inverse correlation with the amount of dust particles in the ice core at greater depths corresponding to decreases in the degree of c axis clustering. Finally, we found that fluctuations in Δε persisted to approximately 80 % of the total depth of the ice sheet. These data suggest that the factors determining the deformation of ice include the concentration of chloride ions and the amount of dust particles, and that the layered contrast associated with the COF is preserved all the way from the near-surface to a depth corresponding to approximately 80 % of the thickness of the ice sheet. These findings provide important implications regarding further development of the COF under the various stress-strain configurations that the ice will experience in the deepest region, approximately 20 % of the total depth from the ice/bed interface.

Nowadays, the mitigation of damage to a ship caused by the underwater explosion attracts more and more attention from the modern ship designers. In this study, two kinds of scale tests were conducted to investigate the effects of polyurea coatings on the blast resistance of hulls subjected to underwater explosion. Firstly, small-scale model tests with different polyurea coatings were carried out. Results indicate that polyurea has a better blast resistance performance when coated on the front face, which can effectively reduce the maximum deflection of the steel plate by more than 20% and reduce the deformation energy by 35.7%–45.4%. Next, a full-scale ship (approximately 50 m × 9 m) under loadings produced by the detonation of 33 kg of spherical TNT charges was tested, where a part of the ship was coated with polyurea on the front face (8 mm + 24 mm) and not on the contrast area. Damage characteristics on the bottom were statistically analyzed based on a 3D scanning technology, indicating that polyurea contributes to enhancing the blast protection of the ship. However, damage results of this test were different from those of the small-scale tests. Moreover, the deformation area of the bottom with polyurea was greatly increased by 40.1% to disperse explosion energy, a conclusion that cannot be drown from the small-scale tests.

Ultrasonic surface rolling process (USRP) is one of the effective mechanical surface enhancement techniques. During the USRP, unstable static force will easily do harm to the surface quality. In order to achieve a higher surface quality on the part with a curved surface, an active and passive compliant USRP system has been developed. The compliant USRP tool can produce the natural obedience deformation along the part surface. Force control based on the fuzzy Proportional-integral-derivative (PID) method is then designed to maintain the static force during the USRP. Experiments have been performed on a real aero-engine blade with curved surface. It is proved that the deigned active and passive compliant USRP system can significantly reduce the force variation from 42.2 N to 4.2 N, and achieve a uniform surface quality after processing.

Based on the two-arc profile assumption, the expansion deformation and energy absorption of circular tubes compressed by conical-cylindrical dies were reconsidered. First, the deformation of the two arcs was analyzed independently and an improved model denoted as Model-I was established. Then, by further involving the coupling between the bending moment and membrane forces, a more elaborate model, i.e., Model-II was developed. Afterwards, experiments and simulations were conducted to verify the models, which show that, compared with previous theoretical models, Model-II could not only capture the prominent features of the deformation, but also improve the prediction accuracy of the steady driving force significantly. By means of this model, it was found that the critical semi-conical angle, which makes the driving force minimum, increases with the increase of the friction coefficient, expansion ratio as well as the radius/thickness ratio of the tube. And, the energy dissipation due to stretching is always greater than that of bending, while the friction dissipation can account for the largest proportion at small semi-conical angle or large friction coefficient. At a certain friction and die conditions, the specific energy absorption of expanded tubes can be much higher than that under progressive collapse mode.

Both a conventional flow distributer and an improved one with a flow buffer were applied respectively during the high pressure die casting (HPDC) process, and samples of AZ91D magnesium alloy with different microstructure mainly consisting of α-Mg grains, β-phase and porosities were obtained. According to the grain orientation analysis, the predominant deformation behavior in α-Mg grains was dislocation slip, supplemented by deformation twinning. Dislocation slip was more difficult to occur in the samples with the improved flow distributer on account of the fact that the size of α-Mg grains in the microstructure was finer and more uniform. During the in situ tensile deformation test, cracks were observed to initiate from gas-shrinkage pore and island-shrinkage, and two main crack propagation mechanisms, porosity growth and coalescence were found accordingly. When the crack was in contact with the β-phase, it would pass through and fracture the network β-phase, whereas bypass the island β-phase by detaching it from the surrounding α-Mg grains. Mechanical property tests showed that the samples with relatively more homogeneous microstructure would perform higher mechanical properties, which was the combined effect of matrix α-Mg grains, β-phase, and porosities.

The stability of the surrounding rocks of large underground powerhouses is always emphasized during the construction process, especially in large-scale underground projects under construction, such as the Baihetan hydropower station in China. According to field investigations, numerical simulations and monitoring data analysis, we present a comparative analysis of the deformation and failure characteristics of the surrounding rocks of underground powerhouses on the left and right banks of the Baihetan hydropower station. The failure characteristics and deformation magnitude of the underground powerhouses on the left and right banks are quite different. Under the disadvantageous condition where the maximum principal stress intersects the axis of the powerhouse at a large angle, the left bank underground powerhouse shows prominent stress-controlled failure characteristics such as spalling, slack collapse and concrete cracking. Although the maximum principal stress is in the favorable condition which intersects the right bank powerhouse at a small angle, the relatively high intermediate principal stress with an angle subvertical to the right bank powerhouse plays an essential role in its deformation and failure, indicating that the influence of high intermediate principal stress cannot be ignored. In addition, structural plane-controlled failure and large deformation are also more evident on the right bank due to the extensive distribution of weak structural planes and complex surrounding rock properties.

Geosynthetic clay liners (GCLs) are used in landfill applications because of their high deformation resistance and excellent self-healing ability. In the present study, air and hydraulic flow characteristics of natural bentonite based GCL (GCL-N) and polymer amended bentonite based GCL (GCL-A) were assessed using air permeability and hydraulic conductivity measurements. The airflow characteristics of GCLs were studied at various apparent degrees of saturation (Sa) and corresponding suction using a custom-designed air permeability test setup. The effect of desiccation on the airflow characteristics of GCL-A was also examined. Further, hydraulic flow characteristics of virgin and desiccated-rehydrated GCLs were assessed using a flexible wall permeameter. The water absorption capacity of GCL-A is relatively higher than GCL-N, irrespective of the stress state. For any chosen Sa, air permeability of GCL-A is lower than GCL-N. Moreover, with the decrease in the suction from 2500 kPa to 1000 kPa, the air permeability of virgin GCL-A has reduced from 9 × 10−12 m2 to 3.57 × 10−16 m2 while the desiccated-rehydrated GCL-A has reduced from 8.86 × 10−11 m2 to 1.9 × 10−13 m2. The hydraulic conductivity of GCL-A is two orders of magnitude less than GCL-N, which shows the better performance of GCL made with amended bentonite.

Rock bolting technique is an important reinforcement measure in the geotechnical engineering practice. New rock bolts have been continuously emerging through the development of rock supporting technology. Complex conditions, such as high crustal stress, extremely soft rock, and strong mining disturbance often occur in the deep mining, resulting in large deformation of the surrounding rock masses. Since the deformation of traditional rock bolts is generally below 200 mm, failure often occurs to the rock bolts because of insufficient deformability. To effectively control the large deformation of surrounding rock masses caused by complex conditions, it is necessary to develop large deformation rock bolts with high constant resistance, also called energy-absorbing bolts. This paper systematically reviews the development of large deformation rock bolts and the structure, energy absorption mechanism, anchorage performance, and mechanical properties of several typical large deformation rock bolts. The advantages and disadvantages of existing large deformation rock bolts are compared and the concept of constant resistance large deformation support is introduced.

The conformability is yet a challenge for most soft robotic grippers due to the continuous motion and deformation of these machines under external force. Herein, inspired by the movement mechanism of human fingers, we propose a novel tendon-driven soft robotic finger with a preprogrammed bending configuration and a human finger like sequential motion that can be obtained by matching the stiffness gradient of the finger joints with three-dimensional (3D) printing technology. The contents of this article are organized as follows. First, the effect of the anisotropy caused by 3D printing filling direction on the mechanical property is investigated by tensile test. Then, kinematic, stiffness, and fingertip trajectory models are established to analyze the influence of the cross-section thickness and width on the bending and bearing capacity of the finger joint. Furthermore, several experiments are conducted on a self-built experimental platform to evaluate the advantages of sequential motion induced by stiffness gradients. Results reveal that soft robotic fingers with sequential motion show excellent conformability on the object surfaces with various curvatures and outperform nonsequential motion fingers with larger envelop range. Without changing motion trajectories of the fingertip, the deformability of the finger can be tuned by adjusting only the stiffness of the joint. Besides, a two-finger gripper is developed, which presents the capability of grasping objects with different shapes and weights in practical applications. The sequential motion mechanism proposed in this study shows promising potential in soft grippers and robotic design.

In this study, the effect of geocell confinement on strength, deformation, dynamic properties, and liquefaction characteristics of pond ash samples were investigated. Pond ash was collected from the Panki thermal power station, India. The geocells were handmade with high-density polyethylene sheets. Each geocell has three equal diameter circular cells. Consolidated undrained triaxial tests were conducted on both remolded and geocell-confined ash samples of size 100 × 200 mm under static and cyclic loading conditions. The confining pressures were chosen as 50, 75, and 100 kPa, cyclic strain rates were chosen as 0.2, 0.3, and 0.4% and the frequency of cyclic loading was 1 Hz. From this experimental study, it is observed that the increase in peak deviatoric stress of geocell-confined pond ash samples is about 21% to 32% higher than the unconfined samples. The liquefaction resistance of ash samples increases 51% to 87% due to geocell confinement. Result shows that ash samples exhibit better response in terms of cohesive strength, dynamic properties, and liquefaction resistance with geocell confinement, which proves the applicability of geocell-confined pond ash as a suitable material for construction of road embankments and slopes.

The force-generation mechanism of a dovelike flapping-wing micro air vehicle was studied by numerical simulation and experiment. To obtain the real deformation pattern of the flapping wing, the digital image correlation technology was used to measure the dynamic deformation of the wing. The dynamic deformation data were subsequently interpolated and embedded into the CFD solver to account for the aeroelastic effects. The dynamic deformation data were further used to calculate the inertial forces by regarding the wing as a system of particles to take into account the wing flexibility. The temporal variation of the forces produced by the flapping wing was measured by a miniature load cell. The numerical results provide more flow details of the unsteady aerodynamics of the flapping wing in terms of vortex formation and evolution. The calculated results of the inertial forces are analyzed and compared with the CFD results which represent the aerodynamic forces. In addition, the total forces, i.e., the sum of the CFD result and inertial result, are compared with the experimental results, and an overall good agreement is obtained.

To investigate the stability of gas-hydrate-bearing sediments under the seabed, many researchers have studied their mechanical behaviours, including strength and deformation characteristics. However, most researchers have focused on hydrate-bearing sand, and there are few publications on hydrate-bearing clay. In this paper, a series of experiments were conducted using remoulded gas-hydrate-bearing sediments drilled from the South China Sea whose host sediments primarily consisted of clay. The particle size, specific surface area, pore size distribution and scanning electron microscopy images of the host sediments were analysed, and triaxial tests were conducted to study their mechanical behaviours under different hydrate saturations and effective confining pressures. The results indicated that strength and stiffness increase with increasing hydrate saturation under the same effective confining pressure. The effective confining pressure could enhance the strength and stiffness at nearly the same hydrate saturation. The analysis of the Mohr circles and failure envelopes of the hydrate-bearing sediments under four different hydrate saturations revealed that the cohesion and internal friction angle increase with an increase in hydrate saturation.

The mining of extra-thick coal seams features severe deformation of the stoping roadway and section coal pillars due to the large mining thickness of the coal seams and the intense movement of the overlying strata. The adjacent goaf and secondary mining disturbance in the current working face further challenge the roadway deformation control. This study explores the effect of the overlying strata structural evolution in the fully mechanized caving face of the extra-thick seam on the failure of section roadway and coal pillars. Physical analog modeling was carried out. A MatchID non-contact full-field displacement- and strain-measuring system was used to determine the evolutionary characteristics of the overlying strata breakage in the extra-thick coal seam, including the displacement variation pattern and stress/strain distribution in coal pillars. The results indicated that following the primary mining disturbance in the adjacent working face, the section roadway and coal pillars underwent initial deformation due to the primary mining-induced stress. As the mining of the current working face continued, the section roadway and coal pillars were subjected to secondary mining disturbance to the effect that the structure of the broken overlying strata gradually formed a triangular support structure. Thus, the overlying strata tilted downwards and subsided, forming a layered hanging roof structure. The additional load was then imposed on the stoping roadway and upper part of the section coal pillars. Meanwhile, the overlying strata failure caused a significant increase in the stress within the section coal pillars. Following the secondary mining disturbance, the peak stress reached a maximum of 33.62 KPa, leading to deformation and instability failure of the section roadway and coal pillars. Finally, distinctive evolutionary features of the overlying strata structure in the extra-thick and ordinary coal seams were identified, and their effect on the deformation and failure of the section roadway and coal pillars were analyzed in detail. These findings are considered instrumental in substantiating the deformation control of the stoping roadway and coal pillars in the extra-thick coal seams.

The aim of the research reported in this paper was to evaluate the recommendations commonly used for limiting the deformations of segmental reinforced concrete tunnels built in soft soil. These traditional deformation limits are empirical and do not consider the slenderness ratio or soil-pressure distribution around tunnels. Furthermore, while they are generally assumed to relate to the serviceability limit state, this is not clear. Parametric analyses were therefore performed by means of finite-element models in which the non-linear behaviour of joints and materials was taken in account. The serviceability deformation was defined to prevent typical problems that could jeopardise the serviceability states of segmental linings. These serviceability deformations were then compared with traditional deformation limits. The results showed that the serviceability deformation depends on the slenderness ratio and the soil-pressure distribution. It was concluded that empirical recommendations are only suitable for certain slenderness ratios and soil-pressure distributions.

Steel–concrete composite shear wall offers a favourable lateral strength and deformation ductility for seismic applications while significantly shortening the project schedule through eliminating the use of formworks and taking advantage of modular construction methodology. This paper presents a fibre-based modelling technique for simulation of the cyclic nonlinear response of composite walls by taking advantage of existing reinforced concrete and steel plate shear wall models. The improved modelling technique for cyclic analysis of composite walls that benefits from the macro models available for steel and concrete shear walls is introduced. The model is validated using experimental test data from 20 wall specimens. A sensitivity analysis is performed to examine the influence of various geometrical and material properties using the proposed modelling technique. A step-by-step modelling recommendation is finally proposed. The results show that the proposed modelling technique can efficiently be used to reproduce the nonlinear cyclic response of composite walls.

This paper reports on the possibility of performing Friction Stir Welding (FSW) without the usual immanent shoulder to enable FS processing to deep welding of narrow and labile structures and applications where backing is not possible. Requirements and prerequisites, advantages and limitations for Shoulderless Friction Stir Welding (SLFSW) are discussed and an industrial application of the joining technology is presented. For leaving the shoulder out, its central functions in FSW have to be transferred to the pin. The resulting tool design of SLFSW is comparably small and slim and so reduces contact area and effective lever and in turn forces and heat input during processing. SLFSW allows welding paths almost at the edge of components and enables a complete and gap-free joining while a deformation of overhanging structures can be avoided. Compared to standard FSW processes, force reductions of about 80–85 % and power reductions of about 75-80 % were found in this study for a 6.5 mm deep weld opening up additional potential for integration with other spindle processes like milling. The locally very limited process impact of SLFSW resulted in comparably low distortion with a part precision reached of +/- 0.05 mm., Projekt DEAL

The morphing wing has a significant positive effect on the aerodynamic performance of the aircraft. This paper describes a leading-edge of variable camber wing with concentrated flexibility based on the geared five-bar mechanism. The driving points of morphing skin formed by the glass fibre composite sheet were optimized to make the skin deformation smooth. A geared five-bar kinematic mechanism rigidly connected to the skin was proposed to drive the leading-edge deformation. Besides, a new kind of concentrated flexure hinge was designed using the pseudo-rigid-body method and applied to the joint between the rigid mechanism and the skin. Finally, the leading-edge prototypes with traditional hinges and flexure hinges were produced, respectively. The feasibility of the concentrated flexibility leading-edge was verified through the comparative experiments of ground deformation. Simultaneously, aerodynamic analysis was carried out to compare the concentrated flexure leading-edge wing with the original airfoil.

The wheel tracking test (WTT) has been extensively used for laboratory characterization of permanent deformation of hot mix asphalt (HMA). However, the fully-confined setup of the device is unable to capture the tertiary zone where shear deformation takes place. This makes the permanent deformation resistance characteristics of HMA difficult to analyze. Hence, a modified wheel tracker (MWT), with unconfined lateral sides along the wheel tracking direction was utilized in this study, which can capture the tertiary flow (referred to as the flow number (FN)). The dynamic creep test, which yields FN, is a common laboratory test which has the ability to characterize permanent deformation considering the shear behavior. The study investigated the relationship of the MWT and the dynamic creep test utilizing the permanent deformation and permanent microstrain data from the respective tests. A novel parameter, FN-Index was explored. The permanent deformation parameters derived from the MWT were well correlated with the dynamic creep test. The MWT showed promising repeatability for the FNs.

The mechanical indices used to describe the anisotropy of layered rock mass are numerous and difficult to be measured. Take the medium - thick horizontal layered limestone rock mass as an example, rock mechanical tests, engineering geological survey, field tests, numerical back-analysis were done to obtain transverse isotropic deformation parameters and strength indices. Normal and transverse moduli of elasticity of rock mass could be preliminarily confirmed by rock uniaxial compression tests, RQD, and empirical formula. Then vertical compression testing of layered rock mass, vertical and horizontal plate bearing tests, and numerical back-analysis were conducted to determine the other deformation parameters. These parameters include normal and transverse moduli of elasticity, normal and transverse Poisson’s ratio, and shear modulus of the rock mass. The cohesion and internal friction angle of the rock mass were then confirmed by direct shear and shear testing. Test results of bidirectional elasticity modulus showed the obvious anisotropy of the layered rock mass. Engineering application indicated that vault settlement was the main deformation mode of the horizontally layered surrounding rock. This differed from the homogeneous rock. Rock falling and delamination readily occurred in the arch of the tunnel.

The face-centered cubic structure (fcc) and its deformation behaviors, as well as the distinctive role of fcc-Ti in nanocrystallization in TC17 subjected to high energy shot peening (HESP), were investigated by using comprehensive high-resolution transmission electron microscopy (HRTEM). The results showed that there was a stress-induced fcc-Ti in TC17 with a lattice constant of 0.420-0.433 nm and the B-type orientation relationship between the hcp-Ti and the fcc-Ti as [20]hcp//[10]fcc and (0001)hcp//(111)fcc, which was accomplished by the gliding of Shockley partial dislocations with Burgers vector of 1/3[010] on the basal plane. The deformation twinning dominated the subsequent deformation of fcc-Ti, producing two types of {111} twins with different characteristics. Among them, the I-type twin with complete structure was generated by successive gliding of Shockley partial dislocations with the same Burgers vector of 1/6[11]. In contrast, the cooperative slip of three Shockley partials, whose sum of Burgers vectors was equal to zero, produced the II-type twin with zero net macroscopic strain. And then, the emission of Shockley partial with the Burgers vector of 1/6[11] on every three (111)fcc planes resulted in the formation of a 9R structure. Due to the dissociation effect of lamellar fcc-Ti and the superior deformation ability of fcc structure, the occurrence of fcc-Ti effectively promoted surface nanocrystallization of TC17.

This paper presents a combination of experimental and numerical investigations on the dynamic response of scaling cabin structures under internal blast loading. The purpose of this study is to modify the similar relationship between the scaled-down model and the prototype of the cabin structures under internal blast loading. According to the Hopkinson’s scaling law, three sets of cabin structure models with different scaling factors combined with different explosive masses were designed for the experimental study. The dynamic deformation process of the models was recorded by a three-dimensional digital imaging correlation (DIC) method and a 3D scanning technology was used to reconstruct the deformation modes of the specimen. In addition, a finite element model was developed for the modification of the scaling law. The experimental results showed that the final deflection-to-thickness ratio was increased with the increase of the model size despite of the similar trend of their deformation processes. The reason for this inconsistency was discussed based on the traditional scaling law and a modified formula considering of the effects of size and strain-rate was provided.

The Westwood deposit (4.5 Moz Au) is hosted in the 2699–2695 Ma Bousquet Formation volcanic and intrusive rocks, in the eastern part of the Blake River Group, southern Abitibi greenstone belt. The Bousquet Formation is divided in two geochemically distinct members: a mafic to intermediate, tholeiitic to transitional lower member and an intermediate to felsic, transitional to calc-alkaline upper member. The Bousquet Formation is cut by the synvolcanic (2699–2696 Ma) polyphase Mooshla Intrusive Complex, which is cogenetic with the Bousquet Formation. The deposit contains three strongly deformed (D2 flattening and stretching), steeply S-dipping mineralized corridors that are stacked from north to south: Zone 2 Extension, North Corridor, and Westwood Corridor. The North and Westwood corridors are composed of Au-rich polymetallic sulfide veins and stratabound to stratiform disseminated to massive sulfide ore zones that are spatially and genetically associated with the calcalkaline, intermediate to felsic volcanic rocks of the upper Bousquet Formation. The formation of the disseminated to semimassive ore zones is interpreted as strongly controlled by the replacement of porous volcaniclastic rocks at the contact with more impermeable massive cap rocks that helped confine the upflow of mineralizing fluids. The massive sulfide lenses are spatially associated with dacitic to rhyolitic domes and are interpreted as being formed, at least in part, on the paleoseafloor. The epizonal, sulfide-quartz vein-type ore zones of the Zone 2 Extension are associated with the injection of subvolcanic, calc-alkaline felsic sills and dikes within the lower Bousquet Formation. These subvolcanic intrusive rocks, previously interpreted as lava flows, are cogenetic and coeval with the intermediate to felsic lava flows and domes of the upper Bousquet Formation. The change from fractional crystallization to assimilation- and fractional crystallization-dominated processes and transitional to calc-alkaline magmatism is interpreted to be responsible for the development of the auriferous ore-forming system. The Westwood deposit is similar to some Phanerozoic Au ± base metal-rich magmatic-hydrothermal systems, both in terms of local volcano-plutonic architecture and inferred petrogenetic context. The complex volcanic evolution of the host sequence at Westwood, combined with its proximity to a polyphase synvolcanic intrusive complex, led to the development of one of the few known large Archean subaqueous Au-rich magmatic-hydrothermal systems.

In the robotic belt grinding process, the elastic contact condition between the flexible tool and the workpiece is a critical issue which extremely influences the surface quality of the manufactured part. The existing analysis of elastic removal mechanism is based on the statistic contact condition but ignoring the dynamic removal phenomenon. In this paper, we discussed the dynamic contact pressure distribution caused by the non-unique removal depth in the grinding process. Based on the analysis of the equivalent removal depth of a single grit and the trajectories of grits in manufacturing procedure, an elastic grinding surface topography model was established with the consideration of the dynamic contact condition in the removing process. Robotic belt grinding experiments were accomplished to validate the precision of this model, while the result showed that the surface roughness prediction error could be confined to 11.6%, which meant this model provided higher accuracy than the traditional predicting methods.

Thermally hardened alloys based on iron (50 Cr – V – N type steel), titanium (VT-14), and aluminum (D16) were subjected to deformation by gas extrusion with local heating in the mode of deformation-thermal hardening with high degrees of deformation 90 % or more to obtain a thin wire at the output. Gas extrusion was performed at various combinations of processing parameters — gas pressure, deformation temperature, extrusion speed. The wire deformed under various combinations of processing parameters was cooled in air, subjected to tempering or aging and a tear test. The mechanical properties obtained as a result of the tests were compared with the data on the mechanical properties of the initial, undeformed alloys, heat-treated and non-heat-treated. On all gas-extruded alloys, the mechanical properties exceeded the initial ones both in strength and plasticity. The combination of gas extrusion parameters (gas pressure, deformation temperature, extrusion speed) has a decisive influence on the combination of strength and ductility of alloys treated by gas extrusion.

The unprecedented rate of metro construction has led to a highly complex network of metro lines. Tunnels are being overlapped to an ever-increasing degree. This paper investigates the deformation response of double-track overlapped tunnels in Tianjin, China using finite element analysis (FEA) and field monitoring, considering the attributes of different tunneling forms. With respect to the upper tunneling, the results of the FEA and field monitoring showed that the maximum vertical displacements of the ground surface during the tail passage were 2.06 mm, 2.25 mm and 2.39 mm obtained by the FEA, field monitoring and Peck calculation, respectively; the heaves on the vertical displacement curve were observed at 8 m (1.25D, where D is the diameter of the tunnel) away from the center of the tunnel and the curve at both sides was asymmetrical. Furthermore, the crown and bottom produce approximately 0.38 mm and 1.26 mm of contraction, respectively. The results of the FEA of the upper and lower sections demonstrated that the tunneling form has an obvious influence on the deformation response of the double-track overlapped tunnel. Compared with the upper tunneling, the lower tunneling exerted significantly less influence on the deformation response, which manifested as a smaller displacement of the strata and deformation of the existing tunnel. The results of this study on overlapped tunnels can provide a reference for similar projects in the future.

Combined loading–creep–wetting tests were performed to investigate the wetting deformation behaviours of rock-fill material by using a modified triaxial apparatus. Results show that the wetting deformation of rock-fill material can be classified into two components, namely, instantaneous wetting deformation and time-dependent wet-state creep deformation. The former occurs simultaneously with rock-fill wetting and possesses the characteristics of parallelism and non-hardening; the latter occurs over time after the rock-fill is wetted and exhibits features similar to those of general creep deformations in rock-fill material. Wetting deformation is induced by the physical-state weakening of the wetted rock-fill material; the wetting can be intuitively considered as a generalised load. Then, a new constitutive model of two-stage wetting deformation for rock-fill material is proposed. In the model, the instantaneous shear wetting strain is in a hyperbolic relationship with the stress level; the instantaneous volumetric wetting strain is described by the dilatancy equation of conventional triaxial loading; and the time-dependent wet-state creep strain is calculated using a general rock-fill creep model. The new model was also used to simulate triaxial wetting tests of rock-fill material, and its validity and practicability were further evaluated.