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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.

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.

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.

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.

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.

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 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.

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 mechanical properties of crystalline materials can be efficiently optimized using a hierarchical twinned structure. Conventional deformation mechanisms for coherent Σ3 boundaries generally involve three basic models: cross-slip, partial dislocation step, and full dislocation step. In this study, we report a novel deformation mechanism that allows the co-existence of twin-separation, phase transformations, grain rotation, and cracking, around a triple junction of twin boundaries in a hierarchical twinned high-entropy alloy. The deformation mechanisms in the reference high-entropy alloy (Fe-30Mn-10Co-10Cr at.%) were investigated using LAADF-STEM. The triple junction of the hierarchical twinned structure gradually deformed during in-situ strain and showed mechanisms significantly different from that observed in the purely twinned structures. These new mechanisms are referred to as “novel synergetic deformation mechanisms of hierarchical twin boundaries.” Understanding the fundamental mechanisms of the hierarchical twin boundaries under deformation could assist the design of strong and ductile bulk materials with hierarchical twinned structure.

Seismic assessment of reinforced concrete (RC) buildings heavily relies on the deformation capacity predictions of members. Similarly, the prediction of the deformation capacity of retrofitted RC columns has the utmost importance for seismic retrofit design. In this paper, a new unified drift model is proposed in order to estimate the rotation capacity of RC columns retrofitted with concrete jacketing, steel jacketing and fibre-reinforced polymer (FRP) wrapping. In order to generate the model, an extensive database was compiled consisting of 269 columns composed of 39 concrete-jacketed, 91 steel-jacketed and 139 FRP-wrapped RC columns failing in flexure mode. In the proposed drift model, the key model parameters are the confinement stress ratio, the axial load ratio and the lap splice length. The accuracy and scatter of the estimations with regard to the previous models were studied. For all of the column retrofitting options, the proposed unified model was observed to have rotation predictions better than the previous models in terms of the mean of the predicted to experimental rotation capacity ratios and with a reduced standard deviation.

Reinforcement of earth retaining walls dates back to antiquity, although a considerable evolution has occurred over the past decades. Reinforcement materials have evolved from natural to metal and finally to geosynthetic materials. These materials are extensible and the reinforcement effect develops through the soil–reinforcement interface, which is dependent on the deformation of the wall, the soil and the reinforcing elements. It is important to control deformation in order to avoid functional and structural problems. This paper contributes to the accurate prediction of the deformation of retaining walls reinforced with geosynthetics using data from laboratory-scale physical models. The feasibility of a simple method to calculate the deformation of the face and earth pressures is evaluated from the data of reduced-scale model walls previously tested in a laboratory: a brick-faced wall and a more flexible geotextile-wrapped wall. The calculated horizontal deformation of the face compares well with the physical measurements and, therefore, the proposed method can be taken as a valid and expedited tool to predict the deformation of retaining walls reinforced with geosynthetics.

Owing to the unique advantages in flight altitude, dwelling time and wide coverage area, stratospheric airships provide permanent monitoring and surveillance for both civil and military applications. Here we propose a semi-rigid stratosphere airship design with circumferential high-pressure inflatable rings and a longitudinal carbon fiber skeleton supported inside. We perform numerical simulations to analyze the deformation characteristics during the whole ascending and descending process. An equivalent internal gradient pressure model of helium is established based on the capsule shape and buoyancy-weight equilibrium conditions. The implicit dynamic method is used to deal with the large deformation of the airship capsule under a low negative pressure condition. Deformation and load-bearing performance of the airship capsule, inflatable ring, skeleton, and suspension line are obtained under different working conditions. The results show that the airship, supported with the inflatable rings and the suspension lines, effectively maintains the shape and ensures the stiffness during the ascending, dwelling, and descending stages, especially suffering from negative pressure.

In this study, a free energy model of the Lattice Boltzmann Method (LBM) is performed to simulate the motion, deformation, and decomposition of a droplet in the presence of electrohydrodynamic flow in porous media. To simulate the multi-phase flow in the presence of dielectric current by using the LBM, three distribution functions are used. To implement the free energy mode of HCZ, two equilibrium distribution functions are considered, one for solving the Navier-Stokes equation and the other for solving the Cahn-Hillard equation. Initially, the ability of the code to apply surface tension is tested by using the Laplace law and the droplet release test. Results show that there is a linear relation is between surface tension and κ which is a parameter in the HCZ model. The results show that the present numerical program is capable of modeling the regulated surface tension force as well. Then, the Rayleigh–Taylor instability simulation is used to evaluate the code's ability to apply volume forces. Also, the obtained results of the written numerical program are in good agreement with the numerical results of other valid references. Obtained results show that the difference between droplet deformation measured by numerical method and Taylor function is less than 2%. After modeling the droplet motions to investigate the droplet deformation, two electric fields are inserted into the droplet with reverse directions of each other. Then, by various tests, it is shown that at a given potential difference the droplet breaks down after much deformation and is divided into smaller droplets. The decomposition of droplets in a pre-mixed emulsion is a common technique to produce the monodisperse droplets. The presence of monodisperse droplets in an emulsion improves the physical properties of polymer from the science expert's perspective. The results of this study are used to improve the quality of polymer components.

Correlation between mechanical properties and texture characteristics was investigated in a hot-rolled Ti-7333 alloy. After rolling deformation, two strong fiber-textures with 〈100〉 parallel to rolling direction (RD) and 〈110〉 parallel to RD were determined. The mechanism of stress-induced boundary migration mainly controls the nucleation of recrystallized grains holding the similar orientation with the adjacent deformed grains on the bulged grain boundaries. It was revealed that the 〈110〉 fiber-texture with higher Schmid factor (SF) possesses the high deformation ability along RD.

Revealing the mesoscale deformation mechanisms of titanium alloy with tri-modal microstructure is of great significance to improve its mechanical properties. In this work, the collective behavior and mechanisms of slip activities, slip transfer, and grain boundary sliding of tri-modal microstructure were investigated by the combination of quasi-in-situ tensile test, SEM, EBSD and quantitative slip trace analyses. It is found that the slip behavior presents different characteristics in the equiaxed α (αp) and lamellar α (αl) grains. Under a low level of deformation, almost all the slip deformation is governed by single basal and prismatic slips for both of αp and αl, despite small amount of -pyramidal slip exists in αl grains. As deformation proceeds, -pyramidal and -pyramidal slip systems with high Schmid factors were activated in quantities. Specially, certain coarse prismatic slip bands were produced across both of single and colony αl grains whose major axes tilting about 40 °–70 ° from the tensile axis. Slip transfer occurs at the boundaries of αp/αp and αl/β under the condition that there exists perfect alignment between two slip systems and high Schmid factors of outgoing slip system. The slip transfer across αl/β boundary can be divided into two types: straight slip transfer and deflect slip transfer with a deviation angle of 5 °–12 °, depending on the alignment of slip planes of two slip systems. The grain boundary sliding along boundaries of αl/β and αp/β was captured by covering micro-grid on tensile sample. It is found that the crystallographic orientation and the geometrical orientation related to loading axis play great roles in the occurrence of grain boundary sliding.

In this study, the investigation of effective stresses of Titanium Grade 5 feedstock material during the continuous forming process has been carried out. The numerical simulation has been carried out through a finite element tool DEFORM-3D. The experimental plan and design have been carried out by using Response Surface Methodology (RSM) on MINTAB platform by considering extrusion wheel velocity and feedstock temperature as main extrusion parameters. Effective-stresses of Ti-6Al-4 V alloy have been investigated to understand the deformation behavior for further more applicability of feedstock material in the modern industrial sector and to keep the shoe and other components of the CONFORM machine safe. It has been found that the effective-stress of feedstock material is high in the biting - deformation region and then gradually decreases towards the flowing direction of the material. It has been observed that as the feedstock temperature increases, the value of effective stresses which occur in other region decreases to some extent. So, the result concludes that increasing extrusion wheel velocity and feedstock temperature of alloy will reduce the shear strength of feedstock material during the continuous forming process. Therefore, the load requirement for deformation can be reduced. Moreover, the wear of extrusion shoe which is one of the most important elements can also be minimized thereby enhancing the life of extrusion shoe material.

This study incorporates European Space Agency (ESA) C-band Sentinel-1a data to evaluate and identify land deformation in natural and reclaimed land of coastal city Karachi, Pakistan on a multi-temp...

International audience; This paper aims to establish an intelligent procedure that combines the observational method with the existing deep learning technique for updating deformation of braced excavation in clay. The gated recurrent unit (GRU) neural network is adopted to formulate the forecast model and learn the potential rules in the field observations using the Nesterov-accelerated Adam (Nadam) algorithm. In the proposed procedure, the GRU-based forecast model is first trained based on the field data of previous and current stages. Then, the field data of the current stage are used as input to predict the deformation response of the next stage via the previously trained GRU-based forecast model. This updating process will loop up till the end of the excavation. This procedure has the advantage of directly predicting the deformation response of unexcavated stages based on the monitoring data. The proposed intelligent procedure is verified on two well-documented cases in terms of accuracy and reliability. The results indicate that both wall deflection and ground settlement are accurately predicted as the excavation proceeds. Furthermore, the advantages of the proposed intelligent procedure compared with the Bayesian/optimization updating are illustrated.

The volume change behaviour of fine-grained soils under repeated freeze–thaw cycles was investigated in context of artificial ground freezing, in which relatively quick freezing is achieved under confinement. Laboratory cyclic freeze–thaw tests with large freezing rates were performed on two clays in two different laboratory set-ups, either with isotropic pressure or with one-dimensional configuration. After freeze–thaw cycles, soils appear to reach residual states unique to each stress level, and the freeze–thaw residual line (FTRL) is defined to represent them. The current soil state's distance to the FTRL, defined as the freeze–thaw state parameter, is well correlated to subsequent volume changes. The one-dimensional freezing set-up provides a correlation more representative of the net effect of freeze–thaw, as all-around freezing under isotropic pressure subjects the specimen to unnatural shear straining. The different nature of freeze–thaw-induced volume changes was observed for high-plasticity Kasaoka clay and low-plasticity kaolin, as characterised by different configurations of the FTRL to the normal compression line. X-ray computed tomography confirmed largely uniform deformation in most of the adopted test conditions, while lower stress and slower freezing led to partial vertical cracking. This type of non-uniformity is shown not to be a main cause of the observed overall freeze–thaw-induced volume changes.

A force controlled nanocutting system based on a flexible mechanism was developed. Instead of utilizing force sensors, the force sensing and control in the developed system is realized by sensing and controlling the deformation of the flexible mechanism. With force feedback control for controlling the cutting force in real time, this system could achieve adaptive cutting along non-planar surfaces without prior knowledge about the surface shape. The finite element method was used to model the flexible mechanism and a Pareto-based multi-objective optimization algorithm with the goals of high force resolution and stability was used to obtain the geometric parameters of the flexible mechanism. During the cutting processing, a capacitive displacement sensor was used to detect the deformation of the flexible mechanism to measure the force in real time, and a piezoelectric ceramic actuator was used to adjust the feed position of the tool to control the cutting force. Nanocutting experiments of microstructures were successfully carried out on inclined and curved surfaces of ductile as well as brittle materials without prior knowledge of their surface forms.

The aim of this work is a control scheme implementation to deform a nonrigid object in which deformation dynamics are modeled by the finite element method. The deformation of a soft object is highly difficult to model because of its non-linearity, time-dependency, and material-response characteristics. Thus, the control implementation for Differential Drive Mobile Robots (DDMR) to deform an elastic object, is a challenge. The proposed steps to solve it are: Position-control designed over DDMR kinematics. Alignment-control applied for DDMRs orientation. The desired shape of the object is achieved using two contact points as the control nodes. A centralized vision algorithm was employed in each stage to obtain positions. To show the usefulness of the proposed scheme, numerical simulation, and real-time implementation were carried out.

In order to avoid the damage of piezoelectric vibrator due to excessive deformation during resonance, an amplitude-limiting rotational piezoelectric energy harvester excited by a radially dragged magnetic force was presented in this paper. The amplitude-limiting device consisted of two springs and a wedge cam to limit deformation of the piezoelectric vibrator. Simulation analysis and tests were carried out to obtain the influence of system parameters on the response characteristics of the piezoelectric vibrator. The results showed that the amplitude-limiting device could effectively limit the maximal deformation and output voltage of the piezoelectric vibrator. The maximum generated voltage increases with the increases of the wedge cam lift, but the optimum speed range decreases. The effective speed range increased with the decreasing number ratio of exciting magnets and the rising spring stiffness. Moreover, a combination of a high-stiffness return spring and a low-stiffness buffer spring is helpful to enhance the effective speed range and to decrease the fluctuation of output voltage. Therefore, the energy generation capability and bandwidth of the energy harvester could be effectively improved through reasonable parameter matching. Under the load resistance of 40 kΩ, the maximal output power of 2.3424 mW is achieved at the rotating speed of 183.7 rpm.

There is a lack of knowledge regarding the parameters needed for the effective seismic performance assessment of historical stone masonry buildings. The paper presents the results of an extensive experimental campaign consisting of four compression and fifteen in-plane cyclic shear tests on three-leaf ashlar stone masonry walls and its constituents. The morphology, level of vertical load, and testing boundary conditions were systematically varied, and their influence on the load-bearing and deformation capacities, stiffness, ductility and energy dissipation was analysed. Good consolidation of the inner core enables in-plane failure mechanism of the walls to occur without decisive out-of-plane damage. The boundary conditions applied significantly influence the failure modes and large deformation capacities obtained, whereas transverse connections in the case of a shear failure mechanism do not significantly influence the overall lateral in-plane response of walls.

Chamfered inserts have found broader applications in metal cutting process especially in high-performance machining of hard-to-cut materials for their excellent edge resistance and cutting toughness. However, excessive heat generation and resulting high cutting temperature eventually cause severe tool wear and poor surface integrity, which simultaneously limits the optimal selection of machining parameters. In the present study, an analytical thermal–mechanical model is proposed for the prediction of the three-dimensional (3-D) temperature field in cylindrical turning with chamfered round insert based on a modified slip-line field approach. First, an innovative discretization method is introduced in a general 3-D coordinate system to provide a comprehensive demonstration of the irregular cutting geometry and heat generation zones. Then, a plasticity-theory-based slip-line field model is developed and employed to determine the intensities and geometries of every elementary heat sources in Primary Deformation Zones (PDZ), Secondary Deformation Zones (SDZ) and Dead Metal Zones (DMZ). At last, a 3-D analytical model is suggested to calculate the temperature increases caused by the entire heat sources and associated images. The maximum cutting temperature region predicted is found existing upon the chip-tool contact area rather than the tool edge. Moreover, the rationalities of cutting parameters employed are analyzed along with theoretical material removal rates and ensuing maximum cutting temperatures. The results indicate that the cutting conditions with large depth of cut and high cutting speed are more desirable than those with high feed rates. The proposed models are respectively verified through a series of 3-D Finite Element (FE) simulations and dry cutting experiments of Inconel 718 with chamfered round insert. Satisfactory agreement has been reached between the predictions and simulations as well as the measurements, which confirms the correctness and effectiveness of the presented analytical model.

There are several algorithms for determining control forces of active devices in civil engineering structures. Uniform distribution of deformations theory is a structural concept which mainly focuses on equalizing deformations in order to promote the utilization of ductility capacity of structural elements thereby mitigating damages to a structure. In common active control algorithms, deformation uniformity and reducing damages are barely noted. In this research, a new active control algorithm regarding uniform deformation theory will be proposed. Uniform distribution of Deformation Control (UDC) algorithm consists of a massless optimized Virtual Added linear structure with Pinned connections (VAP) which is added to a desired original structure. This VAP can be treated as an added stiffness matrix. Once the parameters of the VAP were optimized in a manner that the desired responses were obtained from the new integrated structure, then, the new integrated structure is developed and analyzed in each time step. Finally, the VAP beams axial forces are extracted and applied to the original structure as control forces via active control devices such as active tendons. This proposed control algorithm is simple and effective in reducing responses especially drifts, making more uniform thereby reducing structural damages as well as decreasing the required capacity of actuators and the power consumption eventually. High potential and promising performance of the proposed UDC algorithm will be represented through numerical investigation in an office building example. The results are compared with Nonlinear Instantaneous Optimal Control (NIOC) algorithm as a very common active control algorithm for linear and nonlinear structures.

The accurate calculation of the mesh stiffness for a plastic gear pair is significant for analyzing its transmission performance. During the meshing process, factors such as gear tooth meshing deformation and thermal effect will cause variations of the meshing position and tooth load particularly for plastic gears. These increase the difficulty for the accurate calculation of the gear mesh stiffness for plastic gear pair. To address this issue, the instantaneous gear tooth meshing deformation is obtained based on the potential energy method. Then, the effects of the above factors on the contact condition of a meshing tooth pair are analyzed, based on which the actual mesh position is accurately obtained via an iterative algorithm. Under the commonly-used elastic contact assumption, the contact stiffness at the new meshing position is calculated based on the Hertzian contact theory, and the algorithm of the mesh stiffness calculation for a plastic gear pair is derived by analyzing the influence of the elastic approach of meshing tooth on load distribution mechanism of gear pair. Compared with previous analytical methods, the proposed algorithm for mesh stiffness calculation shows higher accuracy, and it can also properly analyze the effect of load and other parameters on the mesh behavior of plastic gear pair, which can provide a theoretical basis for the performance analysis of plastic gear transmission system.

A reinforced concrete column and steel beam (RCS) hybrid frame structure with replaceable members was proposed in this paper. Non-linear pushover analyses were conducted to investigate the overall mechanical performance of the proposed structural system. Based on the residual deformation of replaceable links after an earthquake, a method for evaluating the replaceability of members of the RCS hybrid frame was proposed. The acceptable residual inter-storey drift and residual rotation drift at the end of the link were adopted as the two indices in this method. Numerical models and full-scale experiments were performed to systematically investigate the stress and deformation of the entire section of the replaceable steel links. The residual deformation was shown to increase with an increase in the inter-storey drift (θ) and decrease with an increase in the length ratio. Then the control values of the acceptable residual deformation indices were determined through a statistical analysis of the residual deformation of links with different length ratios and link-column connection modes: when the residual inter-storey drift was less than 0.0048 rad and the residual rotation drift at the end of the links was less than 0.0074 rad, the link could be easily replaced. These findings can provide reference for similar structural designs.

The dry sliding wear behavior of A7075 based composites strengthened with particulates of ZrB2 was examined using the pin-on-disc device. The composites were synthesized by reinforcing different weight % (5, 10, and 15) of the ZrB2 using a stir casting technique followed by hot extrusion. The dry sliding wear resistance is optimized under varying conditions of sliding velocity, sliding time, and load. The sample's worn-out surfaces were examined using scanning electron micrographs to obtain the composites' wear mechanism. Delamination, abrasion adhesive modes of deformation were observed. The wear parameters were optimized with Grey relational analysis (G.R.A.) and ANOVA techniques and obtained the optimal combination of input parameters.

Grain growth and shrinkage are essential to the thermal and mechanical stability of nanocrystalline metals, which are assumed to be governed by the coordinated deformation between neighboring grain boundaries (GBs) in the nanosized grains. However, the dynamics of such coordination has rarely been reported, especially in experiments. In this work, we systematically investigate the atomistic mechanism of coordinated GB deformation during grain shrinkage in an Au nanocrystal film through combined state-of-the-art in situ shear testing and atomistic simulations. We demonstrate that an embedded nanograin experiences shrinkage and eventually annihilation during a typical shear loading cycle. The continuous grain shrinkage is accommodated by the coordinated evolution of the surrounding GB network via dislocation-mediated migration, while the final grain annihilation proceeds through the sequential dislocation-annihilation-induced grain rotation and merging of opposite GBs. Both experiments and simulations show that stress distribution and GB structure play important roles in the coordinated deformation of different GBs and control the grain shrinkage/annihilation under shear loading. Our findings establish a mechanistic relation between coordinated GB deformation and grain shrinkage, which reveals a general deformation phenomenon in nanocrystalline metals and enriches our understanding on the atomistic origin of structural stability in nanocrystalline metals under mechanical loading.

Dam deformation monitoring and prediction are crucial for evaluating the safety of reservoirs. There are several elements that influence dam deformation. However, the mixed effects of these elements are not always linear. Oppose to a single-kernel extreme learning machine, which suffers from poor generalization performance and instability, in this study, we proposed an improved bat algorithm for dam deformation prediction based on a hybrid-kernel extreme learning machine. To improve the learning ability of the global kernel and the generalization ability of the local kernel, we combined the global kernel function (polynomial kernel function) and local kernel function (Gaussian kernel function). Moreover, a Lévy flight bat optimization algorithm (LBA) was proposed to overcome the shortages of bat algorithms. The results showed that our model outperformed other models. This proves that our proposed algorithm and methods can be used in dam deformation monitoring and prediction in different projects and regions. HIGHLIGHTS The Lévy flight was improved bat algorithm to overcome the shortcoming about speed and effectiveness of bat algorithm.; We integrated the advantage of Gaussian and polynomial functions as the kernel function of KELM (PGKELM).; The LBA-PGKELM at the top of LBA-SVM and BPNN which based on gradient descent method.

Numerical calculations were carried out in order to investigate the delay of transition to turbulence on a wing section by means of local dynamic surface deformation. Physically, the deformation ma...

Based on the traditional two-layer accumulative roll bonding (TARB), the geometrical variations and mathematical relationship during the four-layer accumulative roll bonding (FARB) were derived and summarized. Furthermore, the multi-layer accumulative roll bonding (MARB) technology was proposed and the geometrical variations and mathematical relationship of MARB were simultaneously derived and summarized. Experimentally, Mg-14Li-3Al-2Gd (LAGd1432) sheets were fabricated by TARB and FARB, respectively. Compared with the TARB, the FARB has a higher accumulative efficiency in terms of accumulative layers, total number of interfaces, interface spacing, total deformation and equivalent strain. Therefore, the FARB-processed sheets in lower cycles have the similar microstructure and mechanical properties of the TARB-processed sheets in higher cycles. In addition, FARB process can further break through the deformation limit of TARB process in a single cycle through adopting two-step rolling in one cycle with 50% deformation in one pass and 75% accumulative deformation in one cycle, which can effectively solve the problem of poor interface bonding of the latest interface brought by the last cycle, and thus significantly improve the phenomenon of unstable performance of the ARB-processed sheets.

The machinability of hard brittle polycrystalline ceramic has a strong correlation with internal microstructures and their accommodated deformation behavior. In the present work, we investigate the mechanisms governing the brittle-to-ductile transition behavior of polycrystalline 3C–SiC in diamond cutting by means of molecular dynamics simulations. Simulation results reveal the co-existence of dislocation slip and amorphization-dominated ductile deformation and cracking along grain boundaries-mediated brittle fracture, as well as the correlation of individual deformation modes with machining force variation and machined surface morphology. In addition, inter-granular fracture, grain boundary sliding and grain pull-up are also operating brittle deformation modes of polycrystalline 3C–SiC. The strong competition between above heterogeneous deformation modes determines the brittle-to-ductile transition behavior in grooving of polycrystalline 3C–SiC. Simulation results also demonstrate that grain size has a strong impact on the brittle-to-ductile transition and material deformation behavior of polycrystalline 3C–SiC under diamond cutting.

Hot deformation characteristics of a 25Cr–6Mn–3Ni–1Mo–3W lean duplex stainless steel containing high C and N contents were elucidated. Hot compression tests were performed at temperatures of 600–1100 °C and strain rates of 0.01–10 s−1. Using the stress–strain curves from the hot compression tests, processing maps were established based on the dynamic material model. The hot working domains for the temperature range of 700–900 °C were found to be unstable, regardless of the strain rate. Transmission electron microscopy and electron backscatter diffraction analyses revealed that cracking occurred along the ferrite (α)/austenite (γ) phase boundaries during hot deformation in this unstable hot working regime, where coarse Cr23C6 carbide precipitated along the α/γ interphase. To further understand the hot deformation behavior, hot tension tests were carried out, which indicated that a ductility dip occurred at 700–900 °C due to the interphase precipitation of Cr23C6 carbide; this result was in accordance with the hot compression tests. Finally, the change in the precipitation behavior of Cr23C6 carbide upon deformation temperature and its effect on the hot workability were discussed through a time–temperature-precipitation diagram of Cr23C6 carbide.

A kind of novel suspended nano thin films that exhibit excellent thermoacoustic effects is introduced as a promising candidate and a new approach for acoustic wave generation without mechanical vibration. Although several analytical models have been established in the past to determine thermoacoustic fields and to aid design optimization, there still show many limitations. In particular, those analyses in the past are mostly only available for one-dimensional problems. In this paper, a new numerical approach based on the boundary element method (BEM) is developed for predicting acoustic fields excited from a suspended thermoacoustic (TA) nano thin film with an arbitrary three-dimensional configuration. To substantiate the numerical model, experimental studies on the thermoacoustic emission of carbon nanotube (CNT) thin films are performed to verify the proposed method and excellent agreement is observed. By using the numerical approach, the accuracy and applicability of two recently developed analytical models for suspended CNT thin films are evaluated and discussed in detail. Furthermore, the influence of irregular deformation of CNT thin films on the acoustic field is investigated.

This study investigates the influence of ground motion duration on the dynamic deformation capacity of a suite of 10 modern reinforced concrete moment frame buildings. A robust numerical algorithm is proposed to estimate the dynamic deformation capacity of a structure by conducting incremental dynamic analysis. The geometric mean dynamic deformation capacity of the considered buildings was, on average, found to be 26% lower under long duration ground motions, compared to spectrally equivalent short duration ground motions. A consistent effect of duration on dynamic deformation capacity was observed over a broad range of structural periods considered in this study. Response spectral shape, however, was found to not significantly influence dynamic deformation capacity. These results indicate that the effect of duration could be explicitly considered in seismic design codes by modifying the deformation capacities of structures.

The deformation behaviour of a powder and, thus, of the individual particles is a crucial parameter in powder compaction and affects powder compressibility and compactibility. The classical approach for the characterization of the deformation behaviour is the performance of powder compression experiments combined with the application of mathematical models, such as the Heckel-Model, for the derivation of characteristic compression parameters. However, the correlation of these parameters with the deformation behaviour is physically often not well understood. Single particle compression and nanoindentation enables the in-depth investigation of the deformation behaviour of particulate materials. In this study, single particle compression experiments were performed for the characterization of the deformation behaviour of common pharmaceutical excipients and active pharmaceutical ingredients (APIs) with various, irregular particle morphologies of industrial relevance and the findings are compared with the results from powder compression. The technique was found useful for the characterization and clarification of the qualitative deformation behaviour. However, the derivation of a quantitative functional relationship between single particle deformation behavior and powder compression is limited. Nanoindentation was performed as complementary technique for the characterization of the micromechanical behavior of the APIs. A linear relationship between median indentation hardness and material densification strength as characteristic parameter derived by in-die powder compression analysis is found.

Content-aware medical image adaptation can make medical images be well presented on different display devices. The existing adaption algorithms mainly consider the visual effect of salient regions, such as specific organ areas of the patient body, but either ignore the quality of unimportant areas or execute more slowly. In order to enhance the effect of adaption and accelerate the speed of adaptation, we propose an efficient medical image adaptation method via axis-aligned mesh deformation. With this method, importance map is firstly produced by combing the weighted edge map and saliency map. Then, integer programming is used to initialize and deform the axis-aligned mesh based on importance map. Finally, image adaptation is operated rapidly by bi-linear interpolation. With the proposed method, the real-time image adaptation can be realized, and not only the visual effect of the significant areas but also the contour integrity and continuity of the non significant areas can be maintained. Experiments on open data-sets show that the proposed method has high efficiency, better effect and strong stability, and is suitable for real-time image adaptation.

The excavation of a foundation pit considerably affects the adjacent structures and underground pipelines owing to the change in the stress state of the surrounding soil, resulting in deformation. The study of an actual engineering case was conducted to examine the influence of excavation on the deformation of adjacent subway tunnels. The finite element analysis software PLAXIS 3D was used to simulate the entire excavation process. The structural design of the foundation pit was optimized based on the simulation results to ensure the stability of the foundation pit and the safety of the existing subway tunnel structure. Finally, the safety evaluation of the excavation of the foundation pit that caused the deformation of the adjacent subway tunnel was performed. The influence of the excavation and unloading of the foundation pit on the subway tunnel is closely related to the distance between the subway and the foundation pit, the amount of earthwork excavated at one time, and the engineering geological conditions. The results of this paper can provide useful reference for the design optimization and safety assessment of similar projects.

The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971. To calibrate the numerical model, the experiments of square plates with pre-formed circle holes were modeled and the numerical results have a good agreement with the experiment data. The calibrated numerical model was used to study the deformation and failure mechanism of cylindrical shells with pre-formed circle holes subjected to blast loading. The structure response and stress field changing process has been divided into four specific stages and the deformation mechanism has been discussed systematically. The local and global deformation curves, degree of damage, change of stress status and failure modes of cylindrical shell and square plate with pre-formed circular holes are obtained, compared and analyzed, it can be concluded as: (1) The transition of tensile stress fields is due to the geometrical characteristic of pre-formed holes and cylindrical shell with arch configuration; (2) The existence of pre-formed holes not only lead to the increasing of stress concentration around the holes, but also release the stress concentration during whole response process; (3) There are three and two kinds of failure modes for square plate and cylindrical shell with pre-formed holes, respectively. and the standoff distance has a key influence on the forming location of the crack initiating point and the locus of crack propagation; (4) The square plate with pre-formed holes has a better performance than cylindrical shell on blast-resistant capability at a smaller standoff distance, while the influence of pre-formed holes on the reduction of blast-resistant capability of square plate is bigger than that of cylindrical shell.

A millimeter-wave planar resonator sensor for the detection of deformation and crack in metal device with high precision and sensitivity is presented in this article. The deformation and crack directly imply great damage in the industrial metal structures, which made the detection crucial in structural health monitoring. The main structure of the proposed sensor is based on the concept of multiband electromagnetic induced transparency (EIT) effect. EIT effect is an interference quantum phenomenon, which can be realized in microwave band by electromagnetic resonate structures. Multiband EIT is actualized using a series of split-ring resonators (SRR) coupling with each other to produce one wide stopband and four narrow passbands. The resonance frequencies of the SRRs are affected by the variation of coupling amount between the SRRs and the part of metal device under test that places close to the specific SRR. The orientation of metal deformation and crack is achieved by different frequency shifts of the four independent group delay peaks induced by multiband EIT. Thus, the proposed sensor can orientate the deformation on the metal device with the precision of 1.3 MHz/μm.

The evolution of deformation mechanisms with increasing depth of cut (DOC) in micro-grooving of Zr-based metallic glass was deeply investigated in this study for the first time. The micro-grooving characteristics of metallic glass were initially studied by nanoscratch test, which verified that the material removal mode abruptly changes from extrusion mode to cutting mode with increase of DOC. Based on the free-volume theory, a dynamic model coupling stress, temperature and free volume concentration was used to simulate the change of deformation characteristics with DOC. The results showed that the deformation mechanism of metallic glass is closely related to free volume flow, which is significantly affected by average strain rate and free volume flow coefficient in deformation zone and can be tuned with different DOC. Considering that free volume flow is determined by its flow coefficient and concentration, we proposed to control the deformation characteristics of metallic glass in micro-grooving by heat treatment and verified its effectiveness experimentally.

The propagation of hydrogen/air premixed flame in channels were investigated, giving particular focus on the effect of aspect ratio through both experimental and numerical investigations. The schlieren system and pressure sensor were used to capture flame shapes and pressure changes, respectively in a channel with aspect ratio of 12. The phenomena of flame shape evolutions, including classic tulip inversion, featured T-shape flame, elongated tulip flame and tulip distortion captured in the experiments, were well reproduced by the numerical simulation. The predicted flame front speed, pressure build-up and their fluctuations are also in reasonably good agreement with the measurements. The validated numerical modelling approach was then applied to investigate the effect of channel aspect ratio on flame shape change, flame propagation and overpressure dynamics. It was found that with increasing aspect ratio, the flame shape changes become more vigorous accompanied by the amplified flame and pressured dynamics due to the enhanced pressure waves, flame-pressure wave interaction and flame instability. The Bychkov's analytical model was used to give predictions on the characteristic times of flame deformation in the channels. By comparison, the analytical model performs better for channel with lower aspect ratio.

Radial forging (RF) is an economical manufacturing forging process, in which four dies arranged radially around the workpiece simultaneously act on the workpiece with high-frequency radial movement. In this study, a ZK60 magnesium alloy step-shaft bar was processed under different accumulated strains by RF at 350 °C. The deformation behavior, microstructure evolution, and mechanical responses of this bar were systematically investigated via numerical simulations and experiments. At the early deformation stage of forging, the material undergoes pronounced grain refinement but an inhomogeneous grain structure is formed due to the strain gradient along the radial direction. The grains in different radial parts were gradually refined by increasing the RF pass, resulting in a bimodal grained structure comprising coarse (∼14.1 μm) and fine (∼2.3 μm) grains. With the RF pass increased, the initial micro-size β-phases were gradually crushed and dissolved into the matrix mostly, eventually evolving to form a higher area fraction of nano-sized Zn2Zr spheroidal particles uniformly distributed through the grain interior. The texture changed as the RF strain increased, with the c-axes of most of the deformed grains rotating in the RD. Additionally, excellent mechanical properties including higher values of tensile strengths and ductility were attained after the three RFed passes, compared to the as-received sample.

Based on the self-deforming blade model and the related wind tunnel test platform, the experiments with synchronous deformation and pitch of the blade were carried out to simulate the operating condition of the blade on the vertical axis wind turbine (VAWT). Taking NACA0012 as the reference blade, the unsteady aerodynamic characteristics of the blade deformation at different deformation frequencies and amplitudes were investigated at low Reynolds number of 2.5 × 105. It is found that the maximum lift force of the blade with deformation amplitude of 0.06c is raised by nearly 60% compared with that of the rigid blade. Secondly, by applying the same deceleration frequency, same pitch amplitude and different initial angles of attack to the blade, it is observed that the flow hysteresis phenomena are obviously different from that of applying various synchronous pitch and deformation amplitudes, and the special aerodynamic characteristic curves are obtained. The lift force increases significantly with the rise of deformation amplitude and drag force, while the lift-drag ratio increases in one cycle. The study in this paper proves the applicability of the blade with this deformation law in the VAWT, and provides a reference for its application on the design of VAWT.

Laser polishing has been considered as a promising process in which the smoothing surfaces can be obtained at the additive manufacturing (AM) metallic components by localized ablation and melting. Here, a laser polishing optimization system for selective laser melting (SLM) Ti-6Al-4 V alloy is developed based on supervised machine learning by applying the Python programming language and the TensorFlow 2.0 library. With this optimization system, the creation of ultrafine microstructures in the laser-polished surface leads to superior smooth surface with the enhanced micro-hardness and deformation resistance, which is much better than that of additive manufactured surface. The present study provides a promising method for SLM titanium (Ti) alloy with high surface properties and smooth finish.

Deformation behavior of soft pneumatic actuators (SPAs) can mechanically be preprogrammed into their architecture during design. To date, the majority of SPAs rely on a unimodal bending design. This paper develops a method of including a bimodal design into the deformed state by means of a bilinear material that replaces the conventional strain limiter. With a simple increase in pneumatic pressure, it is possible to have distinctly different deformation directions in one actuator. While inflating at low pressures, the actuator has a preferential deformation direction. As the pressure continues to increase, this preferential deformation direction changes due to a change in the stiffness of the strain limiter. An example of this behavior is demonstrated by an actuator that initially bends in one direction, but then gradually changes direction in plane as the pressure continues to increase. Three different physical actuators were manufactured, tested, and correlated with preliminary numerical models. The physical and numerical models exhibited the desired bimodal behavior, although at different pressures. Furthermore, it was possible to alter the pressure at which this transition occurs by changing the crimp ratio of the embedded bilinear material.