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The trend towards miniaturization of solder joints addresses the need for high-density interconnections in microelectronics. Excessive intermetallic compounds (IMC) and phase transformations cause internal stresses, leading to voiding and cracking in conventional microbumps. Therefore, advanced microbump design must focus on IMC suppression and phase stabilization. This study explores Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni microbumps, comparing them to conventional Cu/Sn-3.5Ag/Cu under various reflow times. High-field emission electron probe micro-analysis and transmission electron microscopy reveal improved microstructures. Electron backscatter diffraction confirms the (Cu,Ni) 6 (Sn,Zn) 5 grain size of several hundreds of nanometers. Fracture modes were established based on the correlation between shear testing and fracture surfaces. Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni microbumps enhanced shear strength (19.6 %–97.8 %) and failure toughness (10.6 %–132.1 %) compared to Cu/Sn-3.5Ag/Cu. The solid solution strengthened and refined (Cu,Ni) 6 (Sn,Zn) 5 combined with tough bulk (Cu,Ag) 5 (Sn,Zn) 8 in Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni microbumps, demonstrate a tough microstructure. These findings provide insights into the design of microbumps with a bonding height in sub-10micron scales. • The microstructure evolutions and phase identifications of Cu/Sn-3.5Ag/Cu and Cu–26Zn–18Ni/Sn-3.5Ag/Cu–26Zn–18Ni were investigated by EPMA and EBSD. • Complete inhibition of phase transformation to Cu 3 Sn and the formation of Kirkendall voids was achieved during reflow at 260 °C and isothermal aging at 150 °C in Zn/Ni-alloyed microbumps. • The grain size of Cu 6 Sn 5 was modified from several micrometers to hundreds of nanometers with highly random orientations by doping of Zn/Ni. • Mechanical reinforcement of Zn/Ni-alloyed microbumps was demonstrated and correlated with microstructures, grain structures, and fracture modes. [ABSTRACT FROM AUTHOR]

The utilization of the vegetal fabric-reinforced cementitious matrix (FRCM) represents an innovative approach to composite materials, offering distinct sustainable advantages when compared to traditional steel-reinforced concrete and conventional FRCM composites employing synthetic fibers. This article introduces a design for sandwich solutions based on a core of extruded polystyrene and composite skins combining mortar as a matrix and diverse vegetal fabrics as fabrics such as hemp and sisal. The structural behavior of the resulting sandwich panel is predominantly driven by the interaction between materials (mortar and polyurethane) and the influence of shear connectors penetrating the insulation layer. This study encompasses an experimental campaign involving double-shear tests, accompanied by heuristic bond-slip models for the potential design of sandwich solutions. The analysis extends to the examination of various connector types, including hemp, sisal, and steel, and their impact on the shear performance of the sandwich specimens. The results obtained emphasize the competitiveness of vegetal fabrics in achieving an effective composite strength comparable to other synthetic fabrics like glass fiber. Nevertheless, this study reveals that the stiffness of steel connectors outperforms vegetal connectors, contributing to an enhanced improvement in both stiffness and shear strength of the sandwich solutions.

Ice adhesion tests are widely used to assess the performance of potential icephobic surfaces and coatings. A great variety of test designs have been developed and used over the past decades due to the lack of formal standards for these types of tests. In many cases, the aim of the research was not only to determine ice adhesion values, but also to understand the key surface properties correlated to low ice adhesion surfaces. Data from different measurement techniques had low correspondence between the results: Values varied by orders of magnitude and showed different relative relationships to one another. This study sought to provide a broad comparison of ice adhesion testing approaches by conducting different ice adhesion tests with identical test surfaces. A total of 15 test facilities participated in this round-robin study, and the results of 13 partners are summarized in this paper. For the test series, ice types (impact and static) as well as test parameters were harmonized to minimize the deviations between the test setups. Our findings are presented in this paper, and the ice- and test-specific results are discussed. This study can improve our understanding of test results and support the standardization process for ice adhesion strength measurements.

The purpose of the experiment was to determine the distribution of shear stresses in the measurement area of a natural and modified wood sample. Previous wood shear tests conducted on a typical Iosipescu specimen have shown that a complex stress state exists at the bottom of the notch. With transverse loading of the samples, flexure occurs and normal stresses arise from the bending moment and thus fibers are deformed. For the investigations oriented on shear, shear with stretching, and shear with compression, a special specimen was prepared which differed by notch geometry from a typical Iosipescu specimen. A new test machine is described in the article, which is equipped with special specimen holders to perform investigations in complex stress conditions. Crack patterns recorded for natural and modified wood are presented. For all tests, numerical finite element model simulations were performed to obtain stress distributions inside the specimens. The calculated stress distributions were visualized as contour line projections for natural and modified wood. Transverse shear strength values for the modified Iosipescu sample were found to exceed the magnitude of previously published ASTM D1037-87 test results. The test results proved that the strength properties of anisotropic materials in a complex state of stress can be assessed with great accuracy. This is very important in engineering applications.

Mechanical characterizations of natural rubber filled with carbon-based nanomaterials were extensively studied in tensile and tear modes whereas fewer attempts have been conducted on a dynamic shear condition using a double-bonded shear test piece. This is of importance since natural rubbers are widely used as flexible membranes for wave energy harvesting devices. Therefore, this study was aimed to explore the microstructural, rheological, and dynamic viscoelastic characteristics of natural rubbers filled with different Multi-Walled Carbon Nanotubes (MWCNTs) contents. A combined compounding approach was employed to ensure a homogenous CNT dispersion was achieved. Transmission electron microscopy (TEM) was performed for the materials characterization while the processability and curing parameters of the compounds were investigated using the Mooney viscosity and rheometry test. Dynamic shear properties were compared using a cyclic test performed on a double-bonded shear test piece. TEM images showed that an optimum CNTs dispersion was reached at 3 phr MWCNTs loading whereas increasing CNT content resulted in further inhomogeneity. The addition of CNTs into the natural rubber not only improved the curing properties of the compound, i.e., low scorch and curing times, but it also increased the Mooney viscosity, the rheological properties, and the dynamic shear properties of the nanocomposite compared to the pristine rubber. The Payne and Mullins effects were also observed for all compounds manifesting dependency on the CNTs content and applied strain amplitude. Finally, MWCNT enhanced the dissipated energy of the nanocomposites with respect to the neat rubber in which an increase of 1040 % in energy dissipation for 10 phr MWCNTs compared to the control at a strain amplitude of 200 % was achieved.

The mechanical properties of the gravel soil-concrete structure interface are one of the important issues in academia and engineering. In this research, gravel soil samples were collected from the Three Gorges Reservoir region to carry out simple shear and direct shear tests of the gravel soil-structure interface. The shearing process was simulated with the numerical method. The strength and deformation characteristics of the interface, the applicability of the interface constitutive model, and the failure mechanism of the interface were analyzed. The results show that: 1) The direct shear test curve of the gravel soil-concrete interface shows strain softening with obvious stress peak, while the simple shear test curve shows strain hardening. The stress peak of the direct shear test is about 30% higher than that of the simple shear test. The shear contraction effect of the simple shear test is about 31% larger than that of the direct shear test. 2) The non-linear relationship of the gravel soil-concrete interface can be described by a hyperbola model, which has a good adaptability to the constitutive relationship of the interface in numerical analysis software. 3) The gravel soil-concrete interface gradually develops shear failure from the edge to the inside. The essence of soil-structure interaction is the movement of soil grains. The research results can provide a reference for the analysis of gravel soil-concrete interaction.

The large-scale model test bench frame is adopted to carry out shear test on the pre-stressed anchor block containing structural plane, and the characteristics of tensile, bending and shear failure of anchor cable are analyzed. Furthermore, the structural calculation software ABAQUS 2020 is utilized to construct the spiral structure model of composite steel wires and the anchor cable is simplified to be composed of bending inner and outer steel wires and central steel wire, so as to simulate accurately the interaction, failure mode and mechanical mechanism between anchor cable and grouting body, as well as between grouting body and concrete block. The results show that the anti-shearing process of pre-stressed anchor blocks can be divided into the anti-shearing stage of structural plane and the anti-shearing stage of anchor cable. Affected by the anti-shearing and deformation characteristics of the bending inner and outer steel wires, the shear stress of the anchor cable has experienced an alternate change process from strong to weak, then from weak to strong, and finally to weak. The axial force of the anchor cable continuously increases until the fracture of the anchor cable. Anchor cable fracture first appears at plastic hinge position of the inner bending steel wire, and then at the interface between the anchor cable and the structural plane, the central steel wire occurs tensile–shear fracture. Highlights: The interaction, failure mode, and mechanical mechanism of the internal components of anchor block have been simulated accurately. The tension, bend, and shear failure of anchor cable are analyzed based on the large-scale model test bench frame. The failure modes of the tension–bend–shear of the inner steel wires, the tension–shear of the outer steel wires, and tension of a single central steel wire of the anchor cable are significantly different. [ABSTRACT FROM AUTHOR]

The precision and reliability of test findings are closely related to the uniformity of remolded loess samples. Although many methods to evaluate the uniformity of remolded loess have been proposed, they have not been widely accepted, due to the many defects. Therefore, it is necessary to explore the evaluation method and index of the uniformity of remolded loess samples in laboratory tests. In this paper, variations in shear strength and microscopic properties along the sample height were examined using the direct shear test and scanning electron microscopy (SEM) test. The feasibility and reliability of employing shear strength as an indicator to assess the uniformity of remolded loess samples were confirmed based on the test results. The results showed that the shear strength and shear strength parameters decreased from top to bottom along the sample height, and that the difference in the shear strength and shear strength parameters between the top and the bottom of remolded loess samples increased with the increase in the sample height. The variation tendency of the shear strength and shear strength parameters altered when the height–diameter (H/D) ratio exceeded 0.97. The SEM test results revealed that as the sample height increased, the disparity in microstructure and pore distribution in various portions of remolded loess samples became more apparent. The effect of sample height on the uniformity of remolded loess samples was mostly attributable to the variation in coating thickness and the content of clay particles on the surface of coarse particles, induced by a reduction in compactness from the top to the bottom of samples. The coefficient for evaluating the uniformity of the remolded loess sample was defined as the ratio of the shear strength at the top to that at the bottom of the remolded sample, and 0.8 was chosen as the threshold value. The shear strength reflected the uniformity of remolded loess samples as accurately as the microscopic test parameters. Furthermore, the direct shear test is the most classic and widely used laboratory test, with a low cost, easy accessibility, short test cycle, simple data processing and low environmental requirements, which provides another feasible method to evaluate the uniformity of remolded loess. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Frozen soils are mixtures of ice and solid grains. Since the mechanical properties of ice and dry granular soils are completely different, the behaviour of the ice-soil mixture is highly dependent on the ice content. In this paper, a 3D model based on the distinct element method (DEM) is introduced and used for evaluating the resistance of frozen soil. In the DEM model, two groups of elements are used for representing soil particles and ice. The modelling of granular soils by DEM has been widely treated in the literature. However, few researches are available regarding DEM modelling of ice, and no DEM simulations have been published regarding soil-ice mixtures. For these reasons, preliminary simulations are performed to calibrate the DEM ice model and assess the relationship between the micromechanical parameters and the macroscopic behaviour. Then, several specimens are built by mixing different proportions of the two constituents to reproduce different ice contents, and appropriate parameters for the ice-soil interface are introduced. A series of triaxial compression and shear simulations are performed and analysed. The obtained macroscopic behaviour of the ice-soil mixtures is qualitatively and quantitatively described, and compared to existing experimental data in terms of resistance parameters. [ABSTRACT FROM AUTHOR]

The return to the Moon is an important short-term goal of NASA and other international space agencies. To minimize mission risks, technologies, such as rovers or regolith processing systems, must be developed and tested on Earth using lunar regolith simulants that closely resemble the properties of real lunar soil. So far, no singular lunar simulant can cover the multitude of use cases that lunar regolith involves, and most available materials are poorly characterized. To overcome this major gap, a unique modular system for flexible adaptable novel lunar regolith simulants was developed and chemically characterized in earlier works. To supplement this, the present study provides comprehensive investigations regarding geotechnical properties of the three base regolith simulant systems: TUBS-M, TUBS-T, and TUBS-I. To evaluate the engineering and flow properties of these heterogeneous materials under various conditions, shear tests, particle size analyses, scanning electron microscope observations, and density investigations were conducted. It was shown that small grains <25 µm (lunar dust) are highly compressive and cohesive even at low external stress. They are particularly important as a large amount of fine dust is present in lunar regolith and simulants (x50 = 76.7 to 96.0 µm). Further, ring shear and densification tests revealed correlations with damage mechanisms caused by local stress peaks for grains in the mm range. In addition, an explanation for the occurrence of considerable differences in the literature-based data for particle sizes was established by comparing various measurement procedures. The present study shows detailed geotechnical investigations of novel lunar regolith simulants, which can be used for the development of equipment for future lunar exploration missions and in situ resource utilization under realistic conditions. The results also provide evidence about possible correlations and causes of known soil-induced mission risks that so far have mostly been described phenomenologically. [ABSTRACT FROM AUTHOR]

The fatigue behavior of plain concrete has been studied for decades, usually under compressive or tensile loading. Shear loading (mode II) has been almost completely neglected in the past. In contrast to cylindrical compression tests, this type of loading offers the advantage of precise load determination and a small, well-defined fracture surface. This paper presents a comprehensive experimental campaign of 66 shear tests, which was conducted to systematically investigate the monotonic, cyclic, and fatigue response of high-strength concrete under mode II loading. Since the material behavior under shear stress is strongly dependent on the concurrent lateral compressive stress, a new test setup was developed which allows simultaneous control of compressive and shear loading. One potential utilization for these shear fatigue tests is the validation of a promising hypothesis that suggests that the development of fatigue damage in concrete at subcritical load levels is governed by a cumulative measure of shear sliding. The qualitative influence of the lateral compressive loading on the displacement and damage development, fracture behavior, and fatigue life is analyzed and discussed. The test results indicate that there is no influence of the lateral compressive load level on the shear fatigue life, as long as the increase in shear strength is considered. Furthermore, concrete under mode II loading seems to have a longer fatigue life than concrete in standard cylindrical specimens under compressive loading. [ABSTRACT FROM AUTHOR]

Determination of the shear properties of sandwich core materials A comparison of the core materials of sandwich panels has revealed inconsistent relationships between their stiffness moduli at different core thicknesses. Therefore, two test methods for determining the shear properties of the core material of sandwich panels were assessed theoretically and experimentally. The results show that for the shear beam test according to EN 14509 a more precise definition of the load distribution plates is necessary and that the usual neglect of the indentation at the support is only justified for thin and medium panel thicknesses. The investigations on the square shear test have shown the influence of the eccentricity between the joint plane and the top edge of the specimen and resulted in the development of a new test setup. The findings from the investigations provide the basis for more realistic modelling of the load‐bearing behavior of sandwich panels in the future. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of high-performance polypropylene fiber (HPPF) content, shear span to depth ratio, and stirrup ratio on the shear behavior of lightweight aggregate concrete (LWAC) beams were studied according to shear tests on eleven high-performance polypropylene fiber lightweight aggregate concrete (HPPLWC) beams and three LWAC beams under symmetrical concentrated load. The failure phenomenon, stirrup strain, shear capacity, and deflection of each specimen were analyzed, and it was determined that the failure patterns of the beams were classified as diagonal tensile failure, diagonal compression failure, shear compression failure, and bending shear failure, in which the beams without stirrups having the HPPF content of 0 kg/m3 and 3 kg/m3 were a diagonal tensile failure, the beam with the shear span to depth ratio of 1 was diagonal compression failure, the beams with the stirrup ratio of 0.38 % and the HPPF content of 6 kg/m3 and 9 kg/m3 were bending shear failure, and the rest of the specimens were shear compression failure. Adding HPPF to concrete could effectively improve its tensile strength, limit the growth of cracks, and further improve its initial cracking strength. By increasing the HPPF content and stirrup ratio, the shear capacity and ductility of the beams could be improved. Increasing the shear span to depth ratio of the beams could improve their deformability of the beams while simultaneously decreasing their shear capacity. Based on the experimental study, the contribution of each influencing factor to the shear capacity was analyzed, and the shear capacity model of the diagonal section of the HPPLWC beam was established. The model has great prediction accuracy as shown by error analysis.

Today, the post-harvest root stubble treatment of kale in Hunan mostly uses manual pulling and centralized treatments, which are inefficient and labor-intensive. In this study, to realize the direct mechanical crushing of kale root stubble and return it to the field after harvesting, we established an accurate simulation model of kale root stubble by creating a model of the root stubble of kale and calibrating the parameters of the simulation. This study took Jingfeng No. 1 kale stubble as the research object and used EDEM2021.2 simulation software to study the parameters of the kale stubble-crushing simulation model. The peak shear force of the sheared kale root stubble was used as the test data, and the most significant factors affecting the shear force were screened out through the Plackett–Burman test for the Design-Expert design. In addition, the steepest climb test and Box–Behnken test were used to accurately assess the factor data to obtain the best simulation value, which was 861.02 N. The relative error between the simulated and measured values was 0.61%. Finally, an accurate simulation stubble model was established by combining the best simulation parameters with the measured stubble length and diameter. This model provides a theoretical basis and technical support for more in-depth research on stubble simulation and mechanized stubble return.

Discrete element method (DEM) was used to evaluate the geometric characteristics of sandy pebble soil. The accuracy of the grain size distribution in the sandy pebble soil was ensured using the cutting ratio (ζ) and a gradation correction formula, which revised the normal vector of the polyhedron particle cutting surface for a single unit and the space volume of polyhedral particles. The modelling method was verified by conducting direct shear experiment on sandy pebble soil. The feasibility of polyhedral particles of sandy pebble soil for discrete element simulation was verified in comparison with that of the spherical particle model. [ABSTRACT FROM AUTHOR]

One of the most common applications of glass fiber composite materials (GFRP) is the manufacturing of the hulls of high-speed boats. During navigation, the hull of these boats is subjected to repetitive impacts against the free surface of the water (slamming effect), which can cause severe damage to the material. To better understand the behavior of the composite material under this effect, in the present work, an experimental test has been carried out to reproduce the slamming phenomenon in GFRP panels by means of a novel device that allows this cyclic impact to be obtained while the panels are always in contact with water. By means of non-destructive ultrasound inspection in immersion, it has been possible to establish the evolution of the damage according to the number of impacts received by each panel. Destructive tests in the affected zone, specifically shear tests (Iosipescu test), allow determination of the loss of mechanical properties experienced by the material after receiving a high number of impacts in the presence of water (up to 900,000 impact cycles in some panels). The behavior of the material was found to be very different in wet and dry conditions. Under dry conditions, the material loses stiffness as the damage density increases and its shear strength also decreases, as does displacement at maximum load. For wet conditions, the material shows higher displacements at maximum load, while the shear strength decreases with increasing stiffness. [ABSTRACT FROM AUTHOR]

In this study, seven one-third-scale bridge column specimens are tested via a quasi-static cyclic test to understand seismic performance differences between cast-in-place (CIP) and precast bridge columns with various shear span-to-depth ratios and connection design details. The columns are designed based on practical engineering application, which aims to provide design reference for the seismic behavior of real-world bridge structures with varying column heights, such as bridge ramps. Based on the test results, it was found that column height exceeding the plastic hinge region is of combined bending and shear failure and that the full development of the plastic hinge region of these columns yields the same damage progression. However, short columns that are lower than the height of the plastic hinge are subjected to pure shear failure, and they are also of the same level of seismic performance except for displacement-related indices. Though the strengthening effect of the grouted splice sleeve connections is observed and damage is more concentrated at the joint for precast bridge columns, the difference of overall seismic performance between CIP and precast bridge columns is less than 5% in terms of ductility and energy dissipation. The addition of shear keys or change of bond material help improve the structural integrity, while the increase of seismic performance is still limited. [ABSTRACT FROM AUTHOR]

The longitudinally connected ballastless track in natural environment is highly sensitive to temperature loads. Under the action of high temperature in summer, it is likely to cause such damages as relative deformation of the track slab and relative deformation between layers, which seriously affects the safety of train operation. Reinforcement of CRTSII slab ballastless track in service is the most important measure to control track damages at present. In order to study the feasibility of the anchoring plan of planting bars, the experiment and analysis of the change law of the bond performance between the track slab and the mortar layer with planted bars are conducted. Based on experiments, a finite element model for the anchorage restoration of the CRTSII slab ballastless track is established, and the optimal number and location of the reinforcement are determined. The results show that when the number of bars implanted in the track slab exceeds 8, there is no significant difference in the effect of suppressing track slab deformation at high temperature. It is recommended that the track maintenance department should pay more attention to the cracking and damage at the positions of the bar planting holes and joints after the planting bar is repaired. [ABSTRACT FROM AUTHOR]

3-Glycidyloxypropyltriethoxysilane and 3-Mercaptosilane were used to prepare a composite together with aluminum oxide. The compound is a potential candidate for being used as inorganic encapsulation. FTIR results paired with head-space analysis revealed a hardening of the composite at above 130 °C and degradation of the sol–gel-network above 150 °C. The adhesion of these compounds was tested via shear tests. It showed, that the addition of 3-Mercaptopropyltriethoxysilane enhanced the adhesion on silver significantly. This is attributed to the covalent nature of the Ag-S bond, which is forming as compared to the solely dispersive forces, when 3-Mercaptopropyltriethxysilane is not used. By conducting the shear test under temperature activation energies for the breakages were calculated. These coincide well with the binding energy of Ag-S in case silver surfaces are examined. In the case of a copper surface, a mixture of covalent and dipole–dipole interactions are found, since the activation energy for breakage is smaller as the Cu-O bond energy. Highlights: Novel encapsulation material using GLYEO and MTMO with Al2O3 fillers. Condensation reaction tracked with FTIR. Organic group of GLYEO degrades at elevated temperatures. High adhesion of composite at room temperature under thermal load. Adhesion mechanisms confirmed via shear strength evolution with temperature. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Landslides, which are predominantly caused by the rheological behavior of preexisting joints, occur frequently around the world and are among the most catastrophic disasters. However, most researchers have rarely considered the rheological characteristics of bolted rock joints. In this study, based on rock-like materials, rheological direct shear tests of joints with and without anchor bolts were carried out, and direct shear tests were conducted for comparison. The results showed that under direct shear conditions, with the presence of bolts, less spalling and failure of the rock mass occurs, and the shear strength of the joints was significantly enhanced. Under rheological direct shear conditions, joints with bolts have more total rheological shear displacement, but the effect of the bolt on the shear displacement of the steady creep stage was not obvious, and the shear stiffness of the rock mass was reduced by the coupling effect between the bolt and joint. Using the Mohr–Coulomb criterion for further analysis, we found that during the rheological process, the reinforcement of bolts mainly focuses on cohesion, while under direct shear conditions, the reinforcement of bolts is mainly reflected in the internal friction angle. This study is expected to provide theoretical guidance for landslide control and protection and to further reduce the occurrence frequency of geohazards. This research is expected to provide theoretical guidance for the prediction and prevention of geological disasters. [ABSTRACT FROM AUTHOR]

The egg yolk undergoes an irreversible gelation process when freezing to -6 °C or lower. In this experiment, liquid egg yolk (LEY) was frozen in liquid nitrogen and stored at -18 °C for 150 days. The measurement of pH and colour of LEY were performed. The examination of the rheological and calorimetric properties of samples was also carried out. The results indicated that the pH of LEY changed significantly during frozen storage, increasing from 6.37 ± 0.02 to 6.58 ± 0.03 over five months. The colour of the samples also showed a significant change compared to the fresh sample. The rheological properties of the LEY also changed significantly after 1 day of freezing and during frozen storage, with a clear increasing trend of the yield stress. The results of the calorimetric study showed that freezing and frozen storage did not affect the denaturation temperature, however, the denaturation enthalpy was reduced by about half after five months of frozen storage.

Introduction. To control the concrete strength of reinforce concrete structures the shear test based on the empirical proportional dependence of concrete strength and tear force of a special purpose anchor with an expanding cone is used. The absence of a physical model of a concrete deterioration when tearing strength is a sign of the defect of the method which hampers the search of the ways for accuracy increase and test validity. The purpose of this study is to develop a physical model of concrete deterioration to determine the calculated strength by the shear test.Materials and methods. The concrete strength model is a mechanism for local deterioration by tearing out a body of concrete in the form of an indicative cone when extracting it from a pre-fabricated anchor well. It is accepted that the deterioration occurs in two stages: from the melting of the concrete to the formation of cracks in the plane of the apex of the concrete cone in the first stage and the subsequent formation of cracks along the lateral surface of the cone during the extraction of the anchor. For transition to compression resistance, the average of the ratio of concrete resistance to compression and tensile or Fere formula shall be used. The model was verified by the calculation of 6 test measurements.Conclusions. It has been established that the empirical correlation between the resistance of concrete to compression and the force of extraction of the anchor in the concrete test is only possible if the resistance of concrete is linearly related to compression and extension. However, the actual ratio of concrete resistance to compression and tensile is non-linear, so for relatively weak concrete the possibility of overestimating the strength of concrete on compression empirical dependence is offset by a reduction factor, and for more durable concrete, measurements are underestimated.

Solid state recycling of aluminium chips is a promising technique to reduce environmental impacts of secondary production. As the recycling process induces a highly oriented microstructure, this study aims to quantify the mechanical properties of extrudates and identify the role of chip boundaries in the fracture behavior. Tensile and shear tests are performed on heat treated AA 6060 alloy and analyzed using digital image correlation. The tensile behavior of the chip-based material is similar to its cast-based counterpart, reaching a yield strength of 230 MPa. Shear properties are close for small deformations, although the chip-based material have lower ductility due to the early onset of damage at the chip boundary. These results confirm the industrial relevance of this process for large scale recycling of aluminium. [ABSTRACT FROM AUTHOR]

The formation mechanism of interfacial intermetallic compounds (IMCs) and the feature of β-Sn grains in different sized SAC305/Cu ball grid array (BGA) joints fabricated by laser jet solder ball bonding (LJSBB) were investigated. The effects of transient temperature distribution and temperature gradient (TG) on the microstructure of the joints were revealed. The BGA joint size (φ) showed a significant impact on the morphology and composition of the interfacial IMCs. Layered IMCs formed in small-sized joints (≤ 600 μm), while dendrite-like IMCs formed in large-sized joints (760 μm). The more abundant dissolution of Cu atoms and larger degree of composition undercooling in the larger joints were responsible for the significant IMC discrepancy. The formation mechanism of strong β-Sn <110> texture in the large-sized BGA joints was revealed based on the catalysis effect of the IMCs with narrower and deeper conical cavities on β-Sn nucleation. It was also found that the rapid growth of β-Sn along <110> direction was driven by the large TG. Furthermore, the anisotropy of the β-Sn grains contributed to the decreased average shear strength with increasing φ. The LJSBB process can be considered as an advanced soldering technology for improving the microstructure and mechanical property of BGA joints. [Display omitted] • Laminar Cu 6 Sn 5 +Cu 3 Sn formed in small-sized joints and dendrite-like Cu 3 Sn covered by Cu 6 Sn 5 formed in large-sized joints. • Changes in IMCs composition and morphology were due to adequate Cu dissolution and significant composition undercooling. • Compared with small-sized joints, large-sized joints exhibited stronger β-Sn <110> texture with θ close to 90°. • Narrower and deeper cavities and larger TG in large-sized joints worked together to form strong β-Sn <110> texture. • Large-sized joints with c-axis of β-Sn being nearly parallel with the substrate had a smaller shear resistance. [ABSTRACT FROM AUTHOR]

This study discusses the experimental assessment of the in-plane mechanical behavior of a multi-leaf stone masonry wall built from cut stone and reinforced with metal connectors (cramps and dowels). Inspired by conventional multi-leaf stone walls, the wall is meant for use in modern stone masonry buildings. The wall is constructed from two parallel load-bearing walls with a cavity between them, which aims to conceal the installation and insulation needed in modern buildings. The load-bearing walls are connected with cramps and dowels at certain intervals, so the wall works as a single section against horizontal and vertical loads. To characterize the in-plane behavior of the proposed wall, compressive, triplet, and diagonal compression tests were conducted to investigate the compressive strength, shear strength, modulus of elasticity, stiffness, ductility, and energy absorption of the wall. Compared with dry and mortar joint walls, dowels increased the wall’s initial shear capacity by 11 and 19 times, respectively. Applying cramps without curving channels inside the individual stone elements decreased the compressive strength by 18%. The energy absorption of the designed walls with metal connectors was substantially increased to that of the specimens representing conventional stone walls. The results show the wall’s applicability due to its higher shear strength and minimal drop in compressive strength, which is within acceptable limits.

Background. New surface treatments have been proposed to expand the clinical indications of zirconia prostheses. This study aimed to evaluate the effect of silica and fluorine nanofilms on zirconia ceramic on the resin cement bond strength. Methods. Zirconia blocks and discs underwent different surface treatments: untreated zirconia (CON), sandblasted, silica-coated alumina particles (30 µm) (SC), silica nanofilm (SN), and fluorine nanofilm (FN). Nanofilm deposition was performed through plasma enhanced chemical vapor deposition (PECVD). Zirconia surfaces were characterized on disks by morphology (atomic force microscopy, AFM), chemical analysis (x-ray photoelectron spectroscopy, XPS), and contact angle analysis. A silane coupling agent was applied on each treated surface, and a cylinder of resin cement was built up. Half of the specimens in each group were submitted to 6000 thermal cycles (TC). Bond strength was analyzed using the shear test, and the fractographic analysis was performed with stereomicroscopy and SEM/EDS. Statistical analysis was performed through one-way ANOVA and Tukey test in the non-aged and aged specimens. Results. Nanofilms modified the zirconia surface, which became more hydrophilic and chemically reactive. Chemical bonding between Si-O was found in SN, and FN promoted a fluorination process on the ceramic surface, converting zirconia into zirconium oxyfluoride. Specimens of the SN (TC) group failed on pre-testing. FN (TC) bond strength (3.8 MPa) was lower than SC (TC) and CON (TC) after shearing. Adhesive failure predominated in the experimental groups. Silica nanofilm failure occurred after aging. Conclusion. Silica and fluorine nanofilms deposited by PECVD did not promote effective bonding between zirconia and resin cement. [ABSTRACT FROM AUTHOR]

Fibre architecture of glass fibre (GF) reinforced polymer composites has a major impact on the mechanical properties for structural applications. In this study, a novel continuous glass fibre non-woven GF mat based on Spirograph art pattern is laid using a customized mechanical system. Spirograph-based continuous glass fibre non-woven (SNW) mat of different patterns was prepared and GF laminate epoxy composites were fabricated with the aim of achieving quasi-isotropic mechanical properties. The samples were cut to dimensions of test specimens from various identical locations symmetrically from a circular-shaped SNW composite laminates which were subjected to flexural, impact, shear and modified compression with anti-buckling tests. One particular SNW pattern composite laminate exhibited 40.82% better impact and 49.01% better shear resistance than commercial 0°/90° woven roving mat composite. The developed SNW laminate composite had quasi-isotropic fibre orientation and better mechanical properties without any stitching and interlacing as in case of woven fibre laminate composite. [ABSTRACT FROM AUTHOR]

The requirement of lightweight structures fabricated from polymer composite-based sandwich panels is ever rising in various industrial sectors. Still, the usage of polymer composites as fire-proofing structures is limited due to their low operating temperatures. In the current study, flame retardancy and mechanical properties of novel ultra-lightweight truss core-based structures with varying ammonium polyphosphate (APP) content, as a flame retardant additive, in the composites are explored. Sandwich composites are fabricated by using epoxy resin with 0%. 2.5%, 5%. 7.5% and 10% APP content. The influence of APP on flame retardancy of the fabricated sandwich composites is investigated through limiting oxygen index (LOI) and UL-94 vertical burning tests. The results reveal that formulation containing 10% APP achieved UL-94 V-1 rating and corresponding limiting oxygen index (LOI) value of 29%. The thermogravimetric analysis demonstrates the thermal stability for the modified epoxy compositions. Mechanical properties of flame retardant truss core sandwich composites are investigated through shear, flexural, and compression testing. A maximum of 872.5, 3814.0, and 152.3 MPa shear, flexural and compression moduli are observed for the fabricated sandwich composites, respectively, with 10% APP content in epoxy. These fabricated sandwich composites could potentially be used in civil infrastructures and marine industries with optimized flame-retardant and mechanical properties. [ABSTRACT FROM AUTHOR]

The adoption of full-field digital image correlation (DIC) strain measurement in recent years has fundamentally transformed conventional analysis procedures for the mechanical characterization of sheet metals. The wealth of local strain data that is now available until fracture has enabled experimentalists to propose new analysis techniques for tensile and shear tests to obtain the hardening response to large strain levels. Although the tests show great potential, significant gaps remain surrounding their applicability. The choice of test geometry and suitability of the analysis across a broad range of sheet metals with diverse hardening and anisotropic behaviour remain open questions. Critically, the assumptions within the tensile and shear methodologies in applying surface strain measurements to large strains while omitting through-thickness gradients have not been verified. The objective of the present study is to perform a critical evaluation of constitutive characterization techniques for sheet metals under quasi-static, ambient conditions. A series of virtual experiments were developed to numerically replicate the testing and analysis procedures followed in lab-scale experiments to extract the hardening response. A simple shear and two standard tensile test geometries were evaluated across a broad range of plasticity characteristics including different hardening rates and anisotropic behaviour. For each case, the input hardening curve in the virtual experiment is treated as the exact solution and compared to the hardening response obtained from each analysis method. The so-called area reduction method (ARM) used for tensile specimens was found to be relatively insensitive to the specimen geometry, yield exponent, and plastic anisotropy but overestimated the flow stress. The performance of the ARM method hinges upon the aspect ratio of the cross-section to avoid shear band formation and requires empirical correlations to improve its predictions at large strains. Despite their simplicity, tensile analysis methods that use small extensometers or local DIC point data are shown to systematically overestimate the hardening behaviour. Simple shear tests can provide accurate estimations of the hardening response, but the choice of geometry is material dependant. The study concludes by considering a strongly anisotropic mild steel to evaluate the tensile and shear characterization strategies with the results of a hydraulic bulge analysis.

This article presents various experimental studies on fatigue evaluation of wire bond interconnects and interfaces in electronic devices using an accelerated mechanical fatigue testing system. This dedicated experimental setup is designed to induce fatigue failure in the weak sites of the wire bond by reproducing the thermomechanical failure modes occurring during operation. An exceptional highly test acceleration is achieved by increasing the mechanical testing frequency into the kHz regimen enabling the determination of lifetime curves in a very short time. A comparison of this method to conventional testing methods such as power cycling, a shear testing exploits the potential of customized accelerated mechanical testing. Exemplary studies on the degradation and fatigue failure of heavy Al wire bonds typically used in power electronics and novel Cu wire bonds are presented and advantages and some restrictions of the proposed method are discussed. [ABSTRACT FROM AUTHOR]

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In the process of long-distance and large-diameter pipe jacking, thixotropic mud is generally injected into the outer surface of the pipe wall to reduce the frictional resistance between the pipe and the soil. The process of pipe jacking may be stopped due to various reasons such as pipe rupture and equipment damage. When the pipe is restarted after being stopped for a period of time, the interface mechanical properties usually change substantially, resulting in a substantial increase in frictional resistance compared to before the stop. However, the mechanical properties and shear mechanism of the pipe-soil interface after jacking is restarted have not been sufficiently investigated. In this paper, a series of gravelly sand-concrete direct shear tests are carried out, in which lubricant is injected into the interface between gravelly sand and concrete, and the effect of construction stagnation time is considered. The mechanical properties of the interface when the concrete pipe is restarted after stagnation is studied by the direct shear tests. The results show that the friction coefficient of pipe-soil interface increases with the stagnation time, which is determined by the thixotropic mud state and the content of gravelly sand involved in shear. In a short period of stagnation, the friction coefficient is determined by the cohesion caused by thixotropic mud and the friction angle produced by the gravelly sand involved in the shearing action. With the increase of stagnation time, the friction angle gradually becomes the decisive factor for the increase of friction coefficient. [ABSTRACT FROM AUTHOR]

This study assessed the validity of torsion test, by comparing it with shear test, in evaluating the bonding of resin composite core after different surface treatments to both zirconia and resin composite CAD/CAM blocks. In total, 108-resin composite core cylinders (3 mm × 3 mm) were prepared and stored in distilled water at 37 °C/48 h. The cylinders were subjected to no-treatment, sandblasting, or surface grinding. Cylinders from each treatment group were then bonded with either zirconia or resin composite CAD/CAM blocks using dual-cure resin cement and stored for 24 h. They were subjected to torsion (rotational speed, 0.25 rpm until failure) or shear (crosshead speed, 1.0 mm/min) tests (n = 9 for each core/block combination in each test). All fractured surfaces were observed by scanning electron microscopy, and the maximum principal stress (MPS) was assessed using finite element analysis (FEA). In the torsion test, the sandblasted composite core and resin CAD/CAM block showed significantly lower bond strength than the other groups (p < 0.05), but the shear test results showed no intergroup differences. While 39.89% of the specimens showed cohesion failures in the torsion test, 55.56% showed adhesion failures in the shear test. FEA demonstrated an even distribution of MPS from the outer edge to the center of the cement layer during the torsion test; however, MPS was unevenly concentrated at the bottom edge of the cement layer during the shear test. The torsion test was better than the shear test in bond testing because of the uniform tensile stress distribution and unidirectional displacement at the bond interface. [ABSTRACT FROM AUTHOR]

Polymer was carried by liquid in conventional polymer dispensing tank of polymer flooding in oilfield. Polymer particles often gather in the process of polymer blending, resulting in blockage of ground pipelines and formation. To reduce this phenomenon, finite element method was used. Optimization of polymer tank carrier based on venturi tube gas pulse injection. The polymer particles were carried into the liquid distribution tank by the injection method of pulse airflow to realize efficient carrying. Study on the effect of different pulse intensity and pulse waveform on cohesion. The results showed that the combined effect of strong pulse difference and pulse gap could make the airflow have strong carrying capacity for difficultly migrated polymer particles. Optimized the shortest pulse time and got the shortest time of triangle wave, sawtooth wave, square wave, and sine wave under simulated conditions. Time was 5.1 s, 6.3 s, 6.2 s, 6.2 s, respectively. The corresponding pulse frequencies were 20 times/s, 15 times/s, 10 times/s and 30 times/s, respectively. Properly increasing pulse intensity could enhance the carrying capacity of pulse airflow to polymer and reduced the carrying time of polymer. The optimal pulse parameters were triangular wave with pulse intensity of about 120 m/s and pulsed frequency of 20 times/s. Established the phenomenon and reason of indoor experiment. The viscosity of polymer solution after stirring was higher than that of liquid flow carried by gas phase pulse. This shows that the polymer system was more fully dissolved under the condition of gas phase pulse carrying. Pulsed airflow injection could effectively reduce polymer aggregation and shear action of agitator to protect polymer structure. Pulse airflow injection also plays an important role in safe operation of ground pipelines and stable seepage in porous media. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rock bolts have been widely used for stabilizing rock mass in geotechnical engineering. It is acknowledged that the bolt profiles have a sound influence on the support effect of the rock bolting system. Previous studies have proposed some optimal rib parameters (e.g. rib spacing); unfortunately, the interface shear behaviors are generally ignored. Therefore, determination of radial stress and radial displacement on the bolt-grout interface using traditional pull-out tests is not possible. The load-bearing capacity and deformation capacity vary as bolt profiles differ, suggesting that the support effect of the bolting system can be enhanced by optimizing bolt profiles. The aim of this study is to investigate the effects of bolt profiles (with/without ribs, rib spacing, and rib height) on the shear behaviors between the rock bolt and grout material using direct shear tests. Thereby, systematic interfacial shear tests with different bolt profiles were performed under both constant normal load (CNL) and constant normal stiffness (CNS) boundary conditions. The results suggested that rib spacing has a more marked influence on the interface shear behavior than rib height does, in particular at the post-yield stage. The results could facilitate our understanding of bolt-grout interface shear behavior under CNS conditions, and optimize selection of rock bolts under in situ rock conditions.

Energy consumption and the emission of harmful particles have increased significantly in recent decades. The constant development of transport poses an increasing threat to the environment. The search for alternative energy-saving solutions is closely linked to the development and improvement of new vehicles, reducing their negative impact on the environment. Fiberglass or carbon fiber are among the most promising materials that can reduce weight in all types of vehicles. They are also much easier to recycle than steel. Fiberglass or carbon fiber composite materials are widely used in a variety of applications: construction, ships, and trains. Vehicles and buses are no exception. These innovative materials are used not only for interior elements but also in constructional units for the production of light duty vehicles. Meanwhile in buses these material are not yet used in safety frame. Bus safety frames are made out of steel. Therefore, in this work the fiberglass composite material from which the tubes are made by pultrusion process would replace the steel tube in the safety frame construction of the bus. Such technology could reduce the weight of the bus safety frame by about 20%. Other parameters would also be affected by weight reduction: safety: bus would be less overloaded, the braking distance would be reduced, the center of gravity position would be closer to the ground; environmental: lower air pollution due to lower CO2 emissions; economic: lower fuel consumption. However, before using such technology, it is necessary to determine the properties of the composite material. Properties were determined by tensile and shear tests (ISO 527-2:2012 and ASTM D5379/D5379M-19). Comparison tests of different materials (tensile and crushing tests) were also performed. According to the experimental results, conclusions were drawn regarding the possibility of using fiberglass for the bus frame. First published online 1 July 2020

To improve the mechanical properties of calcareous sand, it is proposed that microbial induced calcium carbonate precipitation (MICP) technology be used. A series of solidification tests were conducted in natural seawater and freshwater environments. The standard stress path static triaxial apparatus was used to conduct shear tests on calcareous sand and solids under varying reinforcement conditions. The composite power-exponential (CPE) model is proposed to describe the stress–strain relationship curve of the solid, and the method for determining model parameters is presented. The experimental results showed that the strength of calcareous sand with solids increased with the increase in number of reinforcement times for both test environments. Owing to the high salinity of seawater, which inhibits the activity of urease in bacterial solutions, the reinforcement strength in the seawater environment was generally lower than that in the freshwater environment. The compactness had an evident effect on the strength of the added solids. With the increase in compactness, the strength of the sample also increased, but the rate of increase was reduced. The simulation results showed that the established constitutive model can accurately describe the stress–strain relationship of microbial-reinforced calcareous sand and verified the applicability of the model.