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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.

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.

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.

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.

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.

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.

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.

This work investigated the dependence of deformation mechanisms and mechanical properties on cold rolling reductions of the metastable TB8 titanium alloy. Results shown that the crystal orientation of the matrix changes with the increasing level of reduction, leading to the activation of complex deformation mechanisms in the matrix. When the rolling reduction is 10%, the deformation mechanisms are dominated by dislocations and {332} deformation twins. As the reductions increase to 20%-50%, the secondary deformation twinning (SDT) is triggered in primary deformation twins besides the primary kink band is activated. Meanwhile, the secondary kink bands and {332} twins have be observed in the primary kink bands. When the reduction reaches to 60%, the deformation mechanisms are dominated by dislocations and deformation twins. Furthermore, the matrix refined by crisscrossing among the twins, kink bands and other deformation mechanisms during cold rolling, which shortens the dislocation mean free path and then affects the strength and shape of the alloy. The dynamic Hall-Petch effect and the interaction between multi-scale deformed structures control the work hardening behavior of the alloy.

The increase in solid fraction (SF) of a packed granule bed with pressure applied during the in-die compression process results in an evolution of the tablet's matrix and mechanical strength. In this case study, the tensile strength (TS) of a dry granulated microcrystalline cellulose (MCC)/mannitol (MNT)-based formulation was modeled in light of the deformation potential, ∆ (tablet SF – initial granule bed SF). Results showed that the TS of tablets linearly decreased as SF of granules (produced as mini-tablets of an ibuprofen formulation) increased. The formulated granules achieved a measurable tablet strength at a slightly lower critical deformation potential (∆c) than the pure MCC granules. Beyond ∆c, tablet TS increased almost linearly as the deformation potential increased, and the rate was higher for tablets with higher SF. Compared to the simple MCC system, the granules of the MCC/MNT-based formulation were weaker, and TS of tablets increased with deformation potential at a lower rate.

A novel hot extrusion method to fabricate anisotropic nanocrystalline SmCo5 magnet was investigated. The results indicate that the hot-extruded (HE) SmCo5 magnet obtains a strong c-axis texture in perpendicular to the extrusion direction, but the texture strength is clearly different in different regions. The deformation degree plays a key role in the formation of c-axis crystallographic texture and magnetic anisotropy. In surface region of the HE magnet, the deformation degree of grains is the biggest, and the c-axis texture and remanence are the strongest. Furthermore, deformation mechanism of the HE SmCo5 magnet was preliminarily discussed.

Hollow porcelain insulators in substations are frequently confronted with rain flashovers under extreme rainfall. This study aims to investigate the spatial and temporal variation of electric fields between hollow porcelain insulator sheds affected by dynamic deformation of pendant water drops and effects of the dimensionless number of fluids, the Weber number (We) and the electric Bond number (BoE), on it for influencing factors' analysis. Flow‐electric field coupling simulations were carried out to compute the magnitude and the position of AC electric fields between the sheds. The results show that the maximum electric field at a point in time (Etmax) increases significantly after the breakup of the pendant water drop, and its position alters accordingly. For low We and BoE, the global maximum electric field (Egmax) increases with increasing We and BoE, respectively. It is much closer to the adjacent sheds and occurs later than Etmax at the breakup of the pendant water drop (Ebmax). By contrast, Egmax decreases in different degrees at high We and BoE, respectively. There is little difference between Egmax and Ebmax in the position and the occurring time. The influence mechanism on the maximum electric field and discharges and the relationship between discharges induced by the pendant water drop and rain flashover are discussed.

The results of studies of the process of obtaining wire for the manufacture of jewelry chains from new nickel-free 585 gold fineness alloys are presented.New 585 gold fineness alloys, alloyed with palladium, silver and other elements, and as modifiers - with rhodium and ruthenium in the stated quantities have been proposed.By modeling the process of section rolling of rods in octagonal calibers using the variation method of minimum total power, the broadening of the metal and the energy-power parameters of rolling rods from the investigated alloys have been determined. The regularities of their change have been found. Software has been developed for designing processes for the production of longish deformed semi-finished products and technological modes of rolling and drawing of new gold alloys.With the help of experimental studies, the adequacy of the results of calculations and modeling was checked and new data were obtained on the mechanical properties of the metal and its structure.It has been found that the proposed alloys and the modes of their processing using the processes of section rolling and drawing make it possible in industrial conditions to obtain jewelry wire with a diameter of up to 0.25 mm with the level of mechanical and operational properties required for chain tying.

In this paper we study numerically and experimentally non-reversible deformation of anisotropic, semi-flexible fibre networks. We formulate a Discrete Element Model (DEM) with bonded particles to simulate uniaxial compression of such networks and use this model to describe and quantify the effect of elasto-plastic fibre contacts and fibre-fibre adhesion on non-reversible deformation. Our results show that inter-fibre adhesion plays a role for compression in a low solid volume fraction range where adhesive forces can overcome fibre deformation forces and moments. Also, elasto-plastic contacts between fibres become important at higher solid volume fractions when the yield criterion is exceeded. The combined case of fibres having elasto-plastic contacts and adhesion shows a significant synergetic effect leading to a degree of non-reversible deformation of the network far beyond that of networks with only elasto-plastic fibre contacts or inter-fibre adhesion.

The internal inhomogeneous deformation and re-breaking characteristics of broken rock and coal during compaction are the basis for understanding porous structure evolution of the caved zone and then affect the enrichment of coalbed methane (CBM) in mining gob. In this paper, compression-AE experiments on limestone are carried out using a self-developed AE testing system. An AE location method, which is especially suitable for broken porous media is proposed. The results show that 1) the compression process of broken limestone can be divided into three stages: initial compression, linear compression, and plastic compression. There is a good correspondence between AE counts, energy and compression stages. 2) Broken limestone has layered re-breaking characteristics: the particle re-breaking firstly occurs in the middle layer and gradually moves toward the upper and lower layers as compression degree increases. The ultimate re-breaking degree in upper and middle layers is larger than that in lower layer. 3) The final screened results when strain rate reaches 0.24 show that the reduction of porosity is larger in upper and middle layers than that in lower layer under loading. The lower layer owns the largest porosity due to relative smaller compression degree.

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.

A reasonable method is proposed to calculate the active earth pressure of finite soils based on the drum deformation mode of the flexible retaining wall close to the basement’s outer wall. The flexible retaining wall with cohesionless sand is studied, and the ultimate failure angle of finite soils close to the basement’s outer wall is obtained using the Coulomb theory. Soil arch theory is led to get the earth pressure coefficient in the subarea using the trace line of minor principal stress of circular arc after stress deflection. The soil layers at the top and bottom part of the retaining wall are restrained when the drum deformation occurs, and the soil layers are in a non-limit state. The linear relationship between the wall movement’s magnitude and the mobilization of the internal friction angle and the wall friction anger is presented. The level layer analysis method is modified to propose the resultant force of active earth pressure, the action point’s height, and the pressure distribution. Model tests are carried out to emulate the process of drum deformation and soil rupture with limited width. Through image analysis, it is found that the failure angle of soil within the limited width is larger than that of infinite soil. With the increase of the aspect ratio, the failure angle gradually reduces and tends to be constant. Compared with the test results, it is showed that the horizontal earth pressure reduces with the reduction of the aspect ratio within critical width, and the resultant force decreases with the increase of the limit state region under the same ratio. The middle part of the distribution curve is concave. The active earth pressure strength decreases less than Coulomb’s value, the upper and lower soil layers are in the non-limit state, and the active earth pressure strength is more than Coulomb’s value.

In the present article, a detailed numerical deformation and failure analysis of sandwiched structures with different face sheet materials and core design has been carried out. Different face sheets materials ranging from aluminium alloys to composites such as carbon/epoxy and kevlar/epoxy fixed on different types of core were analyzed. Sandwiched structure with aluminium alloy face sheet showed minimum deformation of the impacting point, large impactor recoil and least strain energy absorption. Whereas carbon/epoxy face sheet showed large deformation of the impacting point for all the core designs. Employing the carbon/epoxy face sheet, the impactor recoiled only with square and hexagonal core design while the strain energy absorption was minimum for square and maximum for circular core designs. Kevlar/epoxy face sheet also showed large deformation of the impacting point for all the types of honeycomb core designs. The impactor recoiled very minimally for square core design and there was no recoil for the hexagonal and circular core. Kevlar/epoxy face sheet showed maximum displacement of the impacting point and strain energy absorption for the circular core. Thus, it can be said that sandwiched structure with a carbon/epoxy face sheet appeared to be the best choice in terms of energy absorption during the impact. The present study showed improvement in ballistic behaviour of sandwich structure with composite face sheet as compared to metallic face sheet in terms of energy absorption.

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.

Natural gas hydrate is regarded as a potential clean energy source. However, hydrate phase transition during gas production leads to significant hydrate‐bearing sedimentary layer deformation, which is one of the main obstacles for safe hydrate exploitation. In this study, distributed optical fiber sensors were used to examine the porous medium deformation induced by phase change and verify its feasibility for application in hydrate research. Experiments on ice formation in a porous medium were conducted to mimic the hydrate formation in sediments. Optical fiber sensors were used to record and analyze the strain characteristics caused by the deformation of porous medium during the phase change process. The frequency shift during the cooling process shows that the fiber segment sensitivity is influenced by its initial length and tightness. In experiments with porous medium, the strain caused by the phase change exhibited a linear trend. In a comparative experiment using pure water, the strain caused by the phase change showed a nonlinear trend. The results indicate that the porous medium deformation induced by phase change can be accurately evaluated using strain data from distributed optical fiber sensors. The strain results also reflect the rate of the phase change. This study proves that the distributed optical fiber sensor has the potential to clarify the deformation characteristics of porous medium caused by hydrate phase change.

In this paper, a THMC multi-field coupling triaxial cell was used to systematically study the evolution of gas permeability and the deformation characteristics of sandstone. The effects of confining pressure, axial pressure and air pressure on gas permeability characteristics were fully considered in the test. The gas permeability of sandstone decreases with increasing confining pressure. When the confining pressure is low, the variation of gas permeability is greater than the variation of gas permeability at high confining pressure. The gas injection pressure has a significant effect on the gas permeability evolution of sandstone. As the gas injection pressure increases, the gas permeability of sandstone tends to decrease. At the same confining pressure, the gas permeability of the sample during the unloading path is less than the gas permeability of the sample in the loading path. When axial pressure is applied, the axial stress has a significant influence on the permeability evolution of sandstone. When the axial pressure is less than 30 MPa, the gas permeability of the sandstone increases as the axial pressure increases. At axial pressures greater than 30 MPa, the permeability decreases as the axial pressure increases. Finally, the micro-pore/fracture structure of the sample after the gas permeability test was observed using 3D X-ray CT imaging.

This fundamental research aims to analyse the effect of heat transfer coefficients, plasticity model of evolved material properties and simplified meshing strategy on substrate deformation induced by wire arc additive manufacturing (WAAM) process with dissimilar materials based on experiment and numerical simulation. Throughout the experiment, stainless steel wire SS316L was used as feedstock to build a five-layer and three-string component on an 8-mm-thick low carbon steel S235 as substrate plate by means of a robotic GMAW system with pure argon as shielding gas and diagonal clamping. In order to define heat transfer coefficients by adjusting simulation to experimental results, the transient thermal distribution was to be measured at specific points located in the component layer using Type K thermocouple inserted during the process and on the substrate implanted beforehand. For modelling and simulation, a non-linear thermo-mechanical method was applied in which the component was modelled using rectangular element shape with optimized hexagonal mesh size obtained through sensitivity analysis in accordance to actual specimen geometry and clamping condition. Non-linear isotropic hardening rule with von Mises yield criterion and temperature-dependent material properties was implemented into the simulation which were generated by means of advanced material modelling software based on elemental composition of evolved component characterized using SEM/EDX. For numerical and experimental validation purpose, substrate deformation was measured using coordinate measurement machine before and after the process. It can be concluded that the result of the computed substrate deformation showed an acceptable agreement compared to experiment within the range of error between 0.5 and 27.5% at each specific measurement points and 10.1% as average single error. This basic investigation can be enhanced in the case where cost-effective WAAM application with dissimilar materials towards single-piece substrate component is concerned.

Aims The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs). Methods At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE. Regression modelling was used to identify variables related to the amount of cement cover on the retrieved trays. Results A total of 114 explanted fixed-bearing TKAs were examined. This included 76 used with contemporary PE inserts which were compared with 15 used with older generation PEs. The Attune and NexGen (central locking) trays were found to have significantly less cement cover than Triathlon and PFC trays (peripheral locking group) (p = 0.001). The median planicity values of the PE inserts used with central locking trays were significantly greater than of those with peripheral locking inserts (205 vs 85 microns; p < 0.001). Attune and NexGen inserts had a characteristic pattern of backside deformation, with the outer edges of the PE deviating inferiorly, leaving the PE margins as the primary areas of articulation. Conclusion Explanted TKAs with central locking mechanisms were significantly more likely to debond from the cement mantle. The PE inserts of these designs showed characteristic patterns of deformation, which appeared to relate to the manufacturing process and may be exacerbated in vivo. This pattern of deformation was associated with PE wear occurring at the outer edges of the articulation, potentially increasing the frictional torque generated at this interface. Cite this article: Bone Joint J 2021;103-B(12):1791–1801.

The forming defects such as the cross-sectional distortion and axial instability often occur during the free bending process of thin-walled tube. To eliminate or suppress the above-mentioned forming defects, the method of inserting the mandrel inside tube was employed in this paper. First, the principle of free bending with mandrel was theoretically deduced, which was used to explain the mechanism of the supporting force provided by the mandrel on the deformation behavior of tube. Then the influence of the mandrel position, the number of core balls in mandrel and the clearance between the mandrel and tube on the free bending forming quality of thin-walled tube was analyzed and summarized by the numerical simulation method. Finally, the free bending experiment of thin-walled tube with optimized mandrel parameters was conducted to verify the reliability of the numerical simulation method and the rationality of the mandrel parameters. All of these findings advance the insight into the deformation behavior of thin-walled tube influenced by mandrel and help to improve the forming quality of thin-walled tube and facilitate the application of free bending technology in thin-walled tube.

A novel aluminium foam-filled circular-triangular nested tube (AFCTNT) energy absorber was developed in this study, and its energy absorption behaviour under impact loading was experimentally and numerically studied. Drop-weight impact tests on the AFCTNT energy absorbers with different volumes of aluminium foam filler were first conducted to obtain their energy absorption parameters, force–displacement responses, and deformation modes. In addition, numerical studies on AFCTNT energy absorbers were also carried out, and the specific energy absorption of nested tubes and aluminium foam were obtained to further reveal their energy absorption performances. Experimental results indicated that the deformation modes of AFCTNT energy absorbers were evidently affected by the volume of aluminium foam filler. Moreover, the energy absorption performances of AFCTNT energy absorbers were found to be significantly improved by filling aluminium foam in terms of higher energy absorption, specific energy absorption, mean crushing force, and crushing force efficiency. Both experimental and numerical results demonstrated that the AFCTNT energy absorber with fully-filled aluminium foam outperformed the other AFCTNT energy absorbers owing to more significant interaction effect between the nested tubes and aluminium foam.

Background: The porous SHS–TiNi alloy is a widely used material for repairing defects in bone tissues. Objective: The objective of the study is to comprehensively investigate porous SHS–TiNi alloy samples for fatigue strength under cyclic bending, to study deformation characteristics under quasistatic tension and bending, and to carry out the fractographic analysis of fracture features. Methods: The study employed the electrospark method for cutting plates from a porous isotropic SHS– TiNi rod 30 mm in diameter and 300 mm in length. Results: Deformation behaviour under tension and three-point bending of porous plates showed that porous samples undergo viscoelastic deformation due to the austenite–martensite (A→M) phase transformation. The fracture surfaces of elastic porous samples were studied by SEM. Microscopic studies of fracture surfaces revealed zones of quasi-brittle fracture of martensite and viscous fracture of austenite. The porous framework of intermetallic alloy exhibits a continuous brittle layer and numerous brittle non-metallic inclusions. However, successful fatigue tests showed that brittle phases and inclusions do not significantly affect deformation and fatigue characteristics of porous titanium nickelide. It was found that 70% of porous samples sustain 106 cycles of deformation without fracture due to reversible A→M→A phase transformations in the TiNi phase, which is one of the components of multiphase porous alloy. Conclusion: Viscoelastic behavior of the porous sample and its high fatigue strength under cyclic loading is due to reversible deformation of the TiNi phase. The corrosion-resistant layer of the porous framework allows an effective use of SHS–TiNi.

Nowadays, in the aerospace industry, additive manufacturing and repairing damaged metallic components like Ti6Al4V samples have grabbed attention. Among repairing techniques, solid-state additive manufacturing processes like cold spray are promising because of their unique benefits such as high deposition rate with almost no oxidation in the deposited materials. However, its main drawback is the level of porosity of as-sprayed samples. To increase density and inter-particle bonding, deposited particles must go through more degrees of deformation by increasing particle velocity and particle temperature. In order to increase these two parameters simultaneously, high-velocity air fuel (HVAF) can be utilized. For understanding the effect of using HVAF on particle deformation, a proper elastic-plastic finite-element-based simulation is required. The obtained outcomes show that enhancing particle velocity and providing more kinetic energy will increase particle deformation and sample density. Importantly, increasing particle temperature will seize particle deformation by thermal softening effect, i.e., enhancing as-sprayed sample density, while rising substrate temperature by preheating will soften the substrate resulting in a decrease in particle deformation.

Introduction of mechanical twinnability is one of the most useful strategies to enhance deformability of crystalline materials by giving them an ability of reversible deformation over the elastic l...

Structural evolution of impact-resistant polypropylene copolymers (IPCs), having different compositions of segmental ethylene–propylene (sEP) copolymers, under tensile deformation was investigated ...

For investigating effectiveness of laser-arc hybrid welding for fabrication of steel bridge members, a series of experiments were conducted. One-pass full-penetration butt-joints with steels for bridge high performance structures (SBHS400) with a thickness of 15 mm were joined by the laser-arc hybrid welding. Six passes were required for fabricating the same dimensional full-penetration joints by the arc welding. The time for fabrication by the hybrid welding was around 2% of that of the arc welding. Welding processes by the hybrid welding and the arc welding were simulated by a thermal elastic–plastic analysis. The magnitude of out-of-plane deformation by the hybrid welding was around 5% of that of the arc welding. The width of tensile residual stress region by the hybrid welding was around 50% of that of the arc welding. The hybrid welding might show the higher effectiveness compared to the conventional arc welding from the viewpoints of controlling the welding distortion, residual stress, and welding time.

In this work, the effect of microstructure on hot deformation behavior of ATI 718Plus (hereinafter refers to 718Plus) alloy was studied by isothermal compression test. The results showed that when the strain rate was 0.01–0.1 s−1 with deformation temperature of 980 and 1030 °C, hot deformation behavior was mainly affected by dislocation density. Dislocation density of the air-cooling alloy was larger than that of the furnace-cooling alloy, which makes its critical strain smaller and peak stress higher than that of the furnace-cooling alloy. When the strain rate was 1 s−1, hot deformation behavior of the alloy was mainly affected by twins and γ′ phase, and high-density deformation twins in air-cooling alloys resulted in higher critical strain. γ′ phase exists in furnace-cooling alloy, which makes its peak stress higher than that of air-cooling alloy. 718Plus alloy is sensitive to cooling rate; dislocation and γ′ phase have obvious effects on its hot deformation behavior.

The dynamic recrystallization (DRX) behaviors and their transformation process during hot deformation with various Zener–Hollomon (Z) values were investigated in nuclear grade 316H stainless steel, and the factors influencing DRX transformation, especially adiabatic heating, were evaluated in depth. During hot deformation, with the increase of the Z value, the degree of flow softening (DFS) showed a tendency to decrease first and then increase gradually. The analysis of the microstructure revealed that at low Z value (not exceeding 3.9 × 1019 s–1) deformation conditions, DRX was massively activated and the recrystallization mechanism had a transition from continuous DRX (CDRX) to discontinuous DRX (DDRX) with the increasing Z values, leading to the transition of homogeneous grains to heterogeneous grains. Furthermore, with the reactivation of DRX at high Z value deformation conditions, the discontinuous DRX becomes the primary recrystallization mode. Adiabatic heating plays an important role in facilitating the reactivation of DRX and flow softening during hot deformation with low temperature or high strain rate (high Z values, above 6.1 × 1021 s–1).

The reasons for obtaining the unloading curves of the indentation diagrams of topocomposites coated with aluminum nitride with a nonlinear section of the end of the unloading curve are investigated. The influence of the plasticity of the base and the structure of the coating of aluminum nitride of coatings deposited by the magnetron method on the base made of aluminum alloy D16T on the mechanism of deformation and destruction of the topocomposite was evaluated. The assessment of these characteristics was carried out based on the results of the analysis of model and experimental indentation diagrams of topocomposites with coatings of aluminum nitride and titanium nitride, as well as using the results of materials science studies of the behavior of materials of topocomposite components at high specific loads known in the literature. It was found that the nonlinear shape of the end of the unloading curves is associated with solid-phase structural changes in the coating material. The level of solid-phase structural changes in the coating can be estimated from the width of the hysteresis loops during repeated indentation cycles.

The results of computation and experimental studies of changes in the regularities of the strain resistance and damage accumulation in conditions of the irregular low cycle loading are presented and compared with similar data for a regular cyclic elastoplastic deformation at the same loading. The irregular mode of low cycle loading implemented in the study is adopted in the form of an equiprobable distribution of changes in the stress amplitudes within a given range between maximum and minimum levels at the symmetric form of the cycles. This mode was reproduced on test equipment through introduction of the corresponding functional dependence of changes in the stress amplitude in the cycles into the control program. The data on a cycle-by-cycle kinetics of both cyclic and unilaterally accumulated strains obtained under irregular mode of loading were recorded in a databank and then compared with the data for a regular loading. This provided the possibility of their analytical description by the corresponding equations of state with the correction of the parameters of the diagrams of cyclic elastoplastic deformation taking into account the conditions of irregularity of loading modes. The results of the experiments are presented in the form of diagrams of the tests modes, curves of a low cycle fatigue of the studied material at the soft and hard loading modes, diagrams of a cycle-by-cycle kinetics of the cyclic and accumulated strains at the regular and irregular modes, and also as kinetic diagrams of damages accumulation for these conditions. Using the summation criteria expressed through the deformation characteristics of accumulated damage, it is shown that taking into account change in the character of the strain development under irregular low-cycle loading, the criterion dependences can be used to assess the durability and compare it with the similar data under regular modes when accepting the condition of attaining the limiting state.

Dicaesium octaiodide is composed of layers of zigzag polyiodide units (I8 2−) intercalated with caesium cations. Each I8 2− unit is built of two triiodides bridged with one diiodine molecules. This system was subjected to compression up to 5.9 GPa under hydrostatic conditions. Pressure alters the supramolecular architecture around I8 2−, leading to bending of the triiodide units away from their energetically preferred geometry (D ∞h). Short I2...I3 − contacts compress significantly, reaching lengths typical for the covalently bonded polyiodides. Unlike in reported structures at ambient conditions, pressure-induced catenation proceeds without symmetrization of the polyiodides, pointing to a different electron-transfer mechanism. The structure is shown to be half as compressible [B0 = 12.9 (4) GPa] than the similar CsI3 structure. The high bulk modulus is associated with higher I—I connectivity and a more compact cationic net, than in CsI3. The small discontinuity in the compressibility trend around 3 GPa suggests formation of more covalent I—I bonds. The potential sources of this discontinuity and its implication on the electronic properties of Cs2I8 are discussed.

A heat-reflective coating can be used to solve various problems, including rutting and deformation caused by the excessively high asphalt pavement temperatures during summer. However, the durabilit...

The influence of the severe plastic deformation via high-speed high-pressure torsion (HSHPT) on the structural and magnetic properties of the Zr13Co87 alloys is investigated. Moderate applied deformation promotes the growth of the rhombohedral hard magnetic phase leading to the increase of the sample’s hardness and magnetic coercivity. A higher degree of deformation affects the samples morphology leading to a critical value of the grain size under which the exchange coupling of the soft phase is less effective. Additionally, it produces a random alignment of the anisotropy axes, which are both detrimental to the hard magnetic properties.