Search

Background: The 2018 Hokkaido Eastern Iburi Earthquake triggered serious geodisasters, resulting in several landslides in volcanic soils depending on their geological features. However, there is limited investigation from the geotechnical viewpoint. Considering various volcanic soils are deposited in Hokkaido, Japan, it is crucial to ensure disaster prevention of infrastructures related to volcanic soils. Methods: To investigate the degree of weathering, water-retention characteristics, and mechanical properties of the volcanic soil, which triggered landslides during the earthquake, called Ta-d, this study conducted laboratory tests including X-ray diffraction, water-retention, and direct shear tests under various conditions related to a type of Ta-d, saturation condition, and stress dependency. Moreover, the pore pressure of the location where the landslides occurred was monitored for over a year to investigate the effect of rainfall on the previous day of the earthquake on the landslides. Results: The laboratory and field monitoring test results showed that Ta-d can be categorized into three types depending on the color and physical properties, which have different degrees of weathering and shear strengths. The water content of Ta-d was high (>100 %) throughout the year, whereas it exhibited a seasonal change due to snowfall, which covered the ground surface. Furthermore, fluctuations caused by the seasonal changes are more significant than those caused by rainfall, which indicated that the rainfall on the previous day of the earthquake was not a primary factor in the occurrence of the landslides Conclusions: This study reveals the geotechnical properties of Ta-d, which has not been well known, as comparing with those of other Hokkaido volcanic soils, and gives insights into the significant factors that can potentially cause the earthquake-induced geodisasters. [ABSTRACT FROM AUTHOR]

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.)

Mass timber composites (MTCs) generally require stiff glued connections to meet serviceability design criteria; however, achieving stiff glued connections without conventional pressing infrastructure can necessitate alternative gap filling adhesives. A readily available construction adhesive with potential for use with alternative pressing methods is investigated to develop the needed information for its commercial application in MTCs. The glue line thickness, surface coverage, three contact pressures, and how these parameters influence the load-slip curve of the connection when loaded in pure shear are investigated. The average glue line thickness ranged from 0.76 to 0.33 mm, with lower pressures having thicker glue lines and higher pressures having thinner glue lines. The planning precision was found to be more critical than clamping pressure for glue line thickness. Based on glue bond thickness testing and fabrication experience it is recommended to use 1.2–1.4 mm2 of adhesive per mm width to create full coverage glue bonds without excessive adhesive squeeze out. When tested under pure shear, specimens were observed to fail with a mixture of wood and glue, with more glue failure present as the pressure was increased. The initial stiffness of the connection tended to increase with clamping pressure, while the strength tended to decrease. Two bi-linear data fit models are applied to determine the yield point and simplify the load-slip behaviour for use in design analysis. Overall, the 75% max load method better fit the behaviour and was simpler to apply. The shear strength and stiffness achieved experimentally across all pressures were comparable to other glue connection literature results, and when applied in the design of a 10 m long MTC ribbed panel all pressures achieved near fully composite action. Overall, the adhesive has shown to be an easy to apply and structurally viable connection alternative for MTCs. [ABSTRACT FROM AUTHOR]

Under contemporary conditions, various soil reinforcement methods are employed, each possessing distinct characteristics and applications. These methods aim to improve the strength characteristics and stability of soil foundations. This study evaluates the effectiveness of combined soil reinforcement using a biopolymer (xanthan gum) and a geosynthetic (non-woven geotextile). The study included preparation of the modified soil, pH determination, and structural analysis using scanning electron microscopy to evaluate the physicochemical properties of soil, particle morphology, and interaction with the biopolymer. Unreinforced soil samples, as well as samples modified with biopolymer and combined reinforcement (biopolymer-geosynthetics), were shear tested to study their strength properties and resistance to deformation. The aim was to examine the effect of different reinforcement methods on the mechanical behavior of the soil. The test results showed that the combined reinforcement with biopolymer and nonwoven geosynthetics improved the shear strength. It was observed particularly at a low shear stress level. At the same time, soil cohesion increased significantly, while the impact on the friction angle was generally negligible. The friction angle of the soil after combined reinforcement increased by 14 %, and soil cohesion increased from 8 kPa to 23 kPa. Discussing the application of the combined reinforcement method, technological features, and advantages of the technique is important for understanding the overall effectiveness of soil stabilization. This method of soil modification has demonstrated effectiveness and represents a promising approach for enhancing soil properties. [ABSTRACT FROM AUTHOR]

Abstract Background The 2018 Hokkaido Eastern Iburi Earthquake triggered serious geodisasters, resulting in several landslides in volcanic soils depending on their geological features. However, there is limited investigation from the geotechnical viewpoint. Considering various volcanic soils are deposited in Hokkaido, Japan, it is crucial to ensure disaster prevention of infrastructures related to volcanic soils. Methods To investigate the degree of weathering, water-retention characteristics, and mechanical properties of the volcanic soil, which triggered landslides during the earthquake, called Ta-d, this study conducted laboratory tests including X-ray diffraction, water-retention, and direct shear tests under various conditions related to a type of Ta-d, saturation condition, and stress dependency. Moreover, the pore pressure of the location where the landslides occurred was monitored for over a year to investigate the effect of rainfall on the previous day of the earthquake on the landslides. Results The laboratory and field monitoring test results showed that Ta-d can be categorized into three types depending on the color and physical properties, which have different degrees of weathering and shear strengths. The water content of Ta-d was high (>100 %) throughout the year, whereas it exhibited a seasonal change due to snowfall, which covered the ground surface. Furthermore, fluctuations caused by the seasonal changes are more significant than those caused by rainfall, which indicated that the rainfall on the previous day of the earthquake was not a primary factor in the occurrence of the landslides Conclusions This study reveals the geotechnical properties of Ta-d, which has not been well known, as comparing with those of other Hokkaido volcanic soils, and gives insights into the significant factors that can potentially cause the earthquake-induced geodisasters.

Combination of experimental testing and numerical analysis is suggested to determine static mechanical properties of the auxetic honeycombs realized via material extrusion. Special specimens, which consist of two honeycombs plates and three steel plates, are used to analyze experimentally shear mechanical properties of honeycombs. Shear testing is simulated using the finite elements software ANSYS. The tests on tension of honeycombs are carried out. These tests are simulated by finite elements software. Plasticity of the honeycomb material and geometrically nonlinear deformations of the honeycomb walls are accounted in honeycomb model. The experimental data and calculations results are close. [ABSTRACT FROM AUTHOR]

In the process of resistance spot welding of advanced high-strength steel (AHSS), the development of heat-affected zones (HAZs) considerably modifies the mechanical properties of the weld region. However, the limited reporting in the study of shear behavior in the HAZ hinders the accurate prediction of joint fracture and failure behavior. This study focused on the shear fracture behavior of resistance spot-welded AHSS. Given the limited extent of the HAZ, a miniature shear test was designed and shear fracture tests were conducted on JSC590, JSC980, and JSC1180. These tests facilitated the acquisition and compilation of data regarding the shear mechanical properties of diverse steel grades and their respective HAZs. A hardness-based empirical model for the strength coefficient and the strain-hardening exponent in Hollomon's law was introduced, and this model was subsequently integrated into finite element method calculations. The accuracy of the model was validated by shear strength reproductions, exhibiting errors within the range of 5.4%–13.5% and the averaged error was less than 10%. Further analyses confirmed that stress triaxiality at critical positions varied from 0 to 0.33, indicative of shear-dominant stress conditions. Moreover, the evolution of stress states revealed a notable association between the fracture surfaces across different stress states and steel grades. These findings fill the gap regarding the shear behavior of localized HAZs and expand the understanding of their mechanical behavior under various stress states. It will contribute to accurate fracture prediction by stress triaxiality based fracture criteria, such as Modified Mohr-Coulomb (MMC) model, applied to AHSS.

The mechanical characteristics of anchor cable (AC) play a vital role in determining the design of prestressed support for roadways in deep coal mines. To investigate the shear mechanical properties of AC, a multifunctional testing device for AC was developed, which can conduct mechanical behavior tests such as anchoring, tensioning, and shearing on full-size AC. The research results showed that under shear stress, the AC presented a Z-shaped or S-shaped morphology, and the failure morphology of the rock surrounding the partial contact area with the AC was consistent with the shape of the AC. The initial tensioning force of the AC and the method used to anchor it greatly influenced the shear force, axial force, and shear deformation experienced by the AC. The analysis of the test results involved examining the shear force and deformation properties of the AC at various stages, and proposing the stress and deformation pattern of the AC when subjected to shear forces. The AC was analyzed to determine its bending deflection, rotation angle, bending moment, and shear force distribution pattern, which provided insights into the composite fracture mechanism involving bending, tensile, and shear stress. Highlights: The multifunctional testing device for anchor rods (cables) was developed, which can achieve mechanical behavior testing such as anchoring, tensioning, and shearing of full-size AC. The AC's shear force–displacement curve can be categorized into five stages, each characterized by distinct shear forces and deformation mechanisms. The influence of the initial pretightening force of the anchor cable and the anchoring method on the shear force, axial force, and shear deformation of the anchor cable is revealed. [ABSTRACT FROM AUTHOR]

The article discusses the possibility of analysing, in geomechanical terms, the applicability of the extension strain criterion to assessing the fracture and failure process of sandstone samples. The results of laboratory tests of indirect tension, as well as uniaxial and triaxial compression were used to identify various forms of the criterion. The criterion parameters for fracture initiation and advanced failure processes were presented, and the results in both cases are different. The possible ways of applying this criterion to assess crack initiation in a tension test and failure in a shear test were also presented. Digital image correlation (DIC) analyses were used to determine the deformations of sandstone samples in both test types. The results of these studies show the possibilities to use this condition, e.g., to assess the stability of large-diameter boreholes (for disposal of radioactive waste) and wellbore stability, and to monitor and track the behaviour of tunnels drilled in strong rocks. [ABSTRACT FROM AUTHOR]

The frictional capacity of pile–cemented soil interface is similar to the frictional capacity of pile–rock interface as the strength of cemented soil is close to the strength of soft rock. A series of pile–soil interface shear tests were carried out to study the frictional capacity of square pile–cemented soil interface. The shear test results show that the peak skin friction of square pile–cemented soil interface decreased with the increase in the side length of square pile; the failure mode of square pile–cemented soil interface was affected by the cemented soil thickness; the peak skin friction of square pile–cemented soil interface would increase with the roughness of square pile surface when the mean size of coated silica sand reached 0.94 mm, and the peak skin friction increased slightly with the density of coating sand. [ABSTRACT FROM AUTHOR]

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie 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 FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering 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.)

Shear tests are known to be quick tests for heavy wire bonds to evaluate the interconnect quality. The challenge is to interpret the results of such shear tests, in terms of shear strength and the shear code defined by the German Welding Society (DVS). In this study, we aim to get a better understanding of the shear process by studying the material behavior through the shear test of heavy wire bonds. We took two different aluminum wire materials, Al H11 and AlMg0.5, and ultrasonic bonded them on 99.95% copper sheets, resulting in a good bond quality according to the DVS standard. We performed shear tests on these samples, stopping them shortly before final failure. We investigated the resulting deformed state by cross-sections and further instrumental indentation patterns in the middle of the wedge. The indentation hardness patterns revealed that Al H11 and AlMg0.5 behave significantly differently in terms of hardening under deformation. Our experiments show that the different material behavior has an influence on the failure path of the shear tests. We conclude, when comparing different materials by means of shear test results, that the outcome is influenced by the different hardening behavior. [ABSTRACT FROM AUTHOR]

A rework of electronic assemblies and the reuse of electronic components are the most effective ways to reduce electronic waste. Since neither components nor substrates were developed with the intention of multiple usage, the question of how the integrity of lead-free solder joints is affected by multiple reflow operations is crucial for the implementation of any reuse strategy. Therefore, various types of 1206 multilayer ceramic capacitors (MLCCs) differing in their capacitance value and dielectric type (X5R, X7R, Y5V, NP0) were soldered on test printed circuit boards (PCBs) having a pure Cu-metallization surface in order to investigate the intermetallic reactions during multiple reflows. The metallization system on the MLCC-component side consisted of a thick film of Ni covered by galvanic-deposited Sn. The reflow experiments were conducted using a hypoeutectic SnAgCu solder. The results show the formation of a Cu6Sn5 intermetallic phase on both metallizations, which grows homogeneously with the number of reflows. Moreover, an ongoing decomposition of the solder into Ag-enriched and depleted zones was observed. The effect of these microstructural changes on the functionality of the solder joint was investigated by mechanical shear experiments and electrical four-point capacitance measurements. [ABSTRACT FROM AUTHOR]

Rock slope landslides and underground construction destabilization are frequently attributed to shear impairment by intermittent joints, and the support by bolts represents an indispensable technique for reinforcing jointed rocks. Therefore, we conducted laboratory experiments on intermittently jointed rock-like materials that were anchored, employing various anchoring inclination angles and methods, to investigate the influence of bolt anchoring on the shear properties and acoustic emission characteristics of intermittently jointed rock-like materials. Experimental results revealed that the peak shear strength of the anchored intermittently jointed rock-like materials is proportional to the bolt inclination angle. The strain on the joint is inversely related to the peak shear strength and the bolt inclination angle. The full-length anchorage and end anchorage can drastically enhance the mechanical traits of intermittently jointed rock-like materials, effectively impeding the proliferation of shear cracks after reaching the peak shear strength. The anchorage inclination exhibits a positive correlation with the accumulative acoustic emission (AE) energy and, conversely, a negative correlation with the peak AE count. In geotechnical engineering, the anchoring effect of anchor bolts can enhance the integrity of fractured rock masses and improve overall stability. [ABSTRACT FROM AUTHOR]

Manufacturers of adhesives for industrial use determine the strength of adhesive joints during shear tests. Most often, components made of the same material are joined. In contrast, the roughness of the surfaces to be joined results from the use of a specific surface treatment technology. In adhesive manufacturers' recommendations for metal-to-metal joints, surface technologies can be found without specifying numerical requirements for roughness. Modern techniques for shaping the geometric accuracy of components allow the formation of determined irregularities on the surface, which are characterised by their height and mutual distribution. Furthermore, regular irregularities can be obtained by using the appropriate tool and technological machining parameters. In this way, surfaces with similar load-bearing capacity, core volume, texture or expected hydrophobic properties can be produced by various methods. However, a basic prerequisite is the careful definition of the numerical requirements, both for the basic roughness indices and those of a complementary nature. As a rule, the strength of the adhesive joint is also lower than the strength of the adhesive itself. The strength of an adhesive joint depends on the 'mechanical anchorage' of the adhesive and the adhesion phenomenon on the surface. The research assumes that it is possible to induce an interaction between the geometric state of the surface and the properties of the adhesive, so as to guarantee the maximum strength of the adhesive joint. To verify this, a series of experimental tests were developed and carried out for two different adhesives characterised by different viscosities and offered bond strength. Based on the tests carried out, recommendations were made to the designers of adhesive joints, where, in addition to the height of the surface irregularities, the properties related to fluid retention and the shape of the irregularities in the valleys should be determined. [ABSTRACT FROM AUTHOR]

This paper presents experimental studies to investigate the compressive and shear behaviors of cold-formed thin-walled steel-foam concrete composite walls. Three compressive walls and three shear walls were tested. The failure mode and load-displacement curve of the specimen were obtained from the compressive experiment. The compressive wall infilled with foam concrete mainly experienced distortion buckling of the end stud and local crushing failure of the concrete. The stud openings had a limited effect on the compressive bearing capacity of the composite wall. The failure mode and load-deformation curve were obtained in shear tests. The ductility index, shear stiffness, yield load, peak load, energy dissipation, and stiffness degradation were analyzed. The shear composite wall filled with foam concrete mainly occurred concrete crushing failure, local or distortional buckling failure of the end stud, and cracking failure of the calcium silicate board. The shear stiffness, shear capacity, ductility, and energy dissipation of the composite wall could be significantly improved after filling with foam concrete. [ABSTRACT FROM AUTHOR]

Glacier collapses can occur due to shear failure at the ice-rich debris–rock interface (IDRI). To examine the shear behavior of IDRI, shear tests were conducted on artificial IDRI specimens with varying ice contents (40%, 65%, and 90%), normal stresses (150, 250, 350, 450, and 550 kPa), and temperatures (−1, −3, −5, −7, and −9 °C). Our findings reveal that temperature has the most significant impact on both peak and residual shear strength, followed by normal stress and ice content. As the temperature increases from −9 to −1 °C, the peak and residual shear stress decreased by 62.5%–78%. Notably, for IDRI with the lowest ice content (40%), the residual shear stress is highly influenced by normal stress. We have developed an improved Mohr–Coulomb strength criterion of IDRI in which the cohesion and internal friction angle are determined by ice content and temperature. Furthermore, we propose a novel constitutive model, based on the disturbed state concept, to describe the shear behavior of IDRI. This model combines a spring model and a hyperbolic model. We also discuss the mechanisms through which ice content and temperature influence the shear deformation modes and shear strength of IDRI. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica 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.)

ABSTRACT Under the conservation tillage model, corn stubble with a complex structure has become the main obstacle for the operation of tillage tools. To better design relevant tillage tools as a reference, this study established a discrete element model of corn stubble. The intrinsic parameters and partial contact parameters of corn single root (CSR) were obtained through physical experiments, and the maximum shear force (Fmax) of CSR was tested. Fmax was used as the response value, Plackett-Burman test, steepest climbing test, and Box-Behnken test were used to determine the optimal parameters of the discrete element model. The results showed that the coefficient of friction of CSR-CSR, the coefficient of friction of CSR-steel, and the bonded disk radius all had significant effects on Fmax (P

Iran is among the earthquake-prone countries in the world. Since infill-wall materials have a brittle behavior, they result in considerable damage under large displacements. Therefore, it seems essential to modify the behavior of infill-wall’s materials. The present article seeks to correct this drawback by using a kind of ductile lightweight concrete (DLC) with a soft behavior. To this end, lightweight concrete was produced from cement, polypropylene, filler, and fine fibers. In order to obtain the modeling and design parameters in buildings, the compressive strength, stress-strain curve, material ductility, Poisson’s ratio, and shear strength of the mortar were evaluated. According to the results, on average, the compressive strength, Poisson’s ratio, and elastic modulus equaled 6 Mpa, 0. 14, and 800 Mpa, respectively. By using machine learning method the stress-strain graph of DLC has been showed and maximum compressive strength and friction angle of the mortar obtained from the designed setup and regression were 0.633 Mpa and 23°, respectively.

Abstract Rock bolts are extensively utilized in underground engineering as a means of offering support and stability to rock masses in tunnels, mines, and other underground structures. In environments of high ground stress, faults or weak zones can frequently arise in rock formations, presenting a significant challenge for engineering and potentially leading to underground engineering collapse. Rock bolts serve as a crucial structural element for the transmission of tensile stress and are capable of withstanding shear loads to prevent sliding of weak zones within rock mass. Therefore, a complete understanding of the behavior of rock bolts subjected to shear loads is essential. This paper presents a state-of-the-art review of the research progress of rock bolts subjected to shear load in three categories: experiment, numerical simulation, and analytical model. The review focuses on the research studies and developments in this area since the 1970s, providing a comprehensive overview of numerous factors that influence the anchorage performance of rock bolts. These factors include the diameter and angle of the rock bolt installation, rock strength, grouting material, bolt material, borehole diameter, rock bolt preload, normal stress, joint surface roughness and joint expansion angle. The paper reviews the improvement of mechanical parameter setting in numerical simulation of rock bolt shear. Furthermore, it delves into the optimization of the analytical model concerning rock bolt shear theory, approached from the perspectives of both Elastic foundation beam theory coupled with Elastoplasticity theory and Structural mechanic methods. The significance of this review lies in its ability to provide insights into the mechanical behavior of rock bolts. The paper also highlights the limitations of current research and guidelines for further research of rock bolts.

The study of mechanical properties of soft crushed coal is of great significance for roadway support and prediction of coal and gas outburst, but there is a lack of effective equipment for sampling, sample preparation and mechanical properties analysis of soft crushed coal. Therefore, a set of sample preparation and shear test system for soft crushed coal was developed, which was mainly composed of sampling device, sample preparation device and mechanical property parameter test system. The main functions and characteristics of each part was as following. ① The single-action three-tube coring device in the sampling device was comprised of 3 parts of head assembly, outer tube assembly and inner tube assembly. A stability ring was arranged between the inner and outer tube to ensure that the inner tube and the outer tube were concentric. A liner was arranged inside the inner tube assembly cavity to store coal cores, and the inner tube does not rotate with the outer tube during coring and drilling. When the drilled coal core was full of liner, then the coring device was withdrawn. The liner was disassembled and taken out, and the coal cores and liner were taken out and packaged together. The sampling device was flexible, portable and easy to disassemble and carry. ② The sample preparation device was comprised of 4 prats of stripping instrument, cutting machine, refrigerator and hot fan. The stripping instrument was used to strip the outer lining pipe of coal core. Cutting machine, refrigerator and hot fan was used to cut, freeze and heat shrink coal core. The production of the standard coal core sample is divided into 3 steps of punching and wetting, freezing and cutting, heat shrinking and stripping. Adopting the technology of partial freezing and cutting at the end, and synchronizing the demolding and heat shrinkage uniformly to achieve the sample preparation with various standard size, with perfect sample making method and high success rate. ③ The mechanical property parameter test system was comprised of 3 parts of main structure servo oil source control device and software system, which can realize restrictive and non-restrictive straight shear test function. It was mainly used to carry out straight shear test under different normal stress and triaxial compression test under different confining pressure of soft crushed coal standard specimen. The overall design structure was simple and convenient to operate. A single action three-tube corer was used to obtain soft crushed coal, and a sample preparation device such as a demolding instrument was used to prepare them into standard specimen in this study. Then the straight shear test and triaxial compression test of soft crushed coal standard specimen by using the mechanical property parameter test system were conducted under normal stress of 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 MPa and confining pressure of 0.2, 0.3, 0.4 MPa, respectively. The shear strength parameters such as cohesion and internal friction angle of soft crushed coal was obtained under the two test conditions. The cohesion and internal friction angle obtained from straight shear test were 0.125 kPa and 37.2°, and those obtained from triaxial compression test were 0.121 kPa and 36.4°, respectively. The results show that the system has great practicability and reliability, and provides a better test platform and method for studying the mechanical characteristics of soft crushed coal.

Fiber-reinforced elastomeric isolators (FREIs) are composite devices consisting of an alternation of elastomer layers and fiber reinforcement layers. They have mechanical properties comparable to those of conventional Steel-Reinforced Elastomeric Isolators (SREIs). The mechanical and construction characteristics of FREIs, together with their lower cost, make them potentially usable on a large scale. However, for their actual use, it is necessary to take into account the current regulations regarding seismic isolation. The application of FREIs provides the absence of anchoring to the structure, but the European Technical Standard UNI EN 15129 requires that the isolators are attached to the structure by mechanical fastening only. In this research work, a constraint device that fulfills this requirement but, at the same time, does not significantly alter the mechanical behavior of FREIs is investigated. The properties of the selected device and its installation method are presented. The results of both a simple compression test and a combined compression and shear test performed on two isolators reinforced by quadri-directional carbon fiber fabrics and two isolators reinforced by bi-directional fabrics are presented. The tests were performed in the absence and presence of the constraint device in order to investigate the modifications produced by the device. [ABSTRACT FROM AUTHOR]

Understanding the biomechanical properties of safflowers is essential for appropriately designing harvesting machinery and optimizing the harvesting process. Safflower is a flexible crop that lacks a basis for relevant simulation parameters, which causes difficulties in designing harvesting machinery. In this study, a calibration method for safflowers was proposed. First, a discrete element model was established by measuring the intrinsic parameters of a safflower, such as its geometric parameters, density, Poisson's ratio, and modulus of elasticity. Second, the contact and bonding parameters were calibrated using a combination of physical and simulation tests. In the contact parameter tests, the Hertz-Mindlin (no-slip) model was implemented for the stacking angle tests conducted regarding the safflower filament. A regular two-level factorial design was used to determine the important factors and perform the steepest climb test. Moreover, the Box-Behnken design was adopted to obtain the optimal contact parameters. In the bonding parameter tests, the Hertz-Mindlin model with bonding contact was applied for the safflower shear simulation tests; moreover, the optimum bonding parameters were obtained through the central composite design test. The results demonstrated that the relative errors between the simulated and measured stacking angles and maximum shear were 3.19% and 5.29%, respectively. As a result, the safflower simulation parameters were accurately calibrated, providing a reference for appropriately setting the simulation parameters and designing key mechanical components. [ABSTRACT FROM AUTHOR]

The study on the mechanical properties of soil-structure interface is the basis to solve the problem of soil-structure interaction, which involves many aspects of practical engineering. By modifying the conventional unsaturated direct shear apparatus and using the modified unsaturated direct shear apparatus, the shear tests of unsaturated sand-structure interface were carried out, and the effects of the matrix suction, the structural interface type and the net normal stress on the shear strength of the interface were studied. The experimental results show that the influence of matrix suction on the interface cohesion of unsaturated sand-structure interface is great, while that on the interface friction angle is small. With the increase of matrix suction, the shear strength of unsaturated sand-concrete interface increases first and then decreases, indicating a peak effect. The shear strength of unsaturated sand-steel interface was less affected by matrix suction. Under the condition of constant matrix suction, the shear strength of sand-steel interface increases nonlinearly with the increase of net normal stress. The influence of net normal stress on the friction angle (δb) corresponding to matrix suction is little. Finally, a shear strength formula of unsaturated sand-concrete interface was established based on peak effect. [ABSTRACT FROM AUTHOR]

Rock bolts are extensively utilized in underground engineering as a means of offering support and stability to rock masses in tunnels, mines, and other underground structures. In environments of high ground stress, faults or weak zones can frequently arise in rock formations, presenting a significant challenge for engineering and potentially leading to underground engineering collapse. Rock bolts serve as a crucial structural element for the transmission of tensile stress and are capable of withstanding shear loads to prevent sliding of weak zones within rock mass. Therefore, a complete understanding of the behavior of rock bolts subjected to shear loads is essential. This paper presents a state-of-the-art review of the research progress of rock bolts subjected to shear load in three categories: experiment, numerical simulation, and analytical model. The review focuses on the research studies and developments in this area since the 1970s, providing a comprehensive overview of numerous factors that influence the anchorage performance of rock bolts. These factors include the diameter and angle of the rock bolt installation, rock strength, grouting material, bolt material, borehole diameter, rock bolt preload, normal stress, joint surface roughness and joint expansion angle. The paper reviews the improvement of mechanical parameter setting in numerical simulation of rock bolt shear. Furthermore, it delves into the optimization of the analytical model concerning rock bolt shear theory, approached from the perspectives of both Elastic foundation beam theory coupled with Elastoplasticity theory and Structural mechanic methods. The significance of this review lies in its ability to provide insights into the mechanical behavior of rock bolts. The paper also highlights the limitations of current research and guidelines for further research of rock bolts. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society 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 Coal Science & Technology (0253-2336) is the property of Coal Science & 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 shear stress–shear displacement relationship and shear strength parameters of the interface between the pipe and the surrounding soil are important for designing the jacking force. One most commonly used method to measure the shear strength of the pipe–soil interface is the direct shear test. This paper presents the results of a series of direct shear tests conducted in the laboratory on the pipe–soil interfaces for different moisture contents. Simultaneously, digital image correlation is used to supplement the research of the horizontal displacement field of the interface. The results show that the increase of normal stress will makes the interface more prone to strain hardening during the shearing process, and the influence of the change of specimen moisture content on the interface strain characteristics gradually weakens. The shearing process of the specimen mainly involved shearing contraction, and slight shear dilation occurs only when the moisture content is small. We proposed a unified model for describing the shear volumetric change caused by the combined action of moisture content and normal stress. The shear displacement field presents a layered distribution, which is related to the shear displacement corresponding to the shear stress. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

For high-power modules with wire bonding as the interconnection method, fatigue damage and cracking at the bond interface are important forms of module failure. However, the currently used numerical models of the bond interface neglect the influence of microdefects and damage evolution of the interface material and cannot accurately describe the degradation process of the mechanical properties of the bond interface. In this work, the shear strength of the Al-bonded wire-Al metallization layer bond interface of an insulated-gate bipolar transistor (IGBT) module after different numbers of power cycles was measured via shear tests, and force-displacement (F– $\delta $ ) curves and fracture surface morphologies were obtained. The experimental results indicate that the bond interface strength decreases significantly as the number of power cycles increases. To describe this phenomenon, the cohesive zone model-based finite discrete element method (CZM-based FDEM) is introduced in the bonding zone; that is, the bonding zone is discretized via triangular elements, and cohesive elements are inserted between adjacent triangular elements to describe the cracking process of the bond interface. By randomly assigning different material property parameters to the cohesive elements, the microdefects can be characterized, and by adjusting the proportions of cohesive elements with different strengths, the phenomenon whereby the bond interface strength decreases during power cycling can be better demonstrated. Finally, a comparison with the results of shear tests validated that this method can effectively predict fracture processes at the bond interface and is able to describe the degradation of the interfacial mechanical properties observed in the experiments.

The rapid development of computer technology provides an opportunity for researchers dealing with discrete element modeling to develop more accurate particle models. The sphero-polygonal particle model can follow the shape of the grains to be modeled much more finely. However, it is important to examine the model sensitivity to the different micromechanical parameters if we switch to the use of the sphero-polygonal model.Shear testing measurements and simulations were performed by applying the discrete element method (DEM) to find this. A geometrically more accurate sphero-polygonal particle model was applied instead of the usual sphere-clumpapproach to simulate the particle assembly's mechanical behavior during shear testing to calibrate the micromechanical parameters ofwheat grains by reproducing the shear failure curve obtained fromexperiments. Hopefully, the results will contributeto the practical applicability of the sphero-polygonal grain modeling in the discrete-elementmethod.

The waste blast furnace slag generated during the steelmaking process is used as the basic material, and an appropriate amount of fly ash is added to conduct shear tests to obtain the shear mechanical indicators of the fly ash blast furnace slag mixture, thereby obtaining the strength mechanical properties of the mixture. The test results show that there are few fine particles in the mixture, which is not enough to affect its shear mechanical properties, so the water content has little effect on the shear strength of the mixture, and the mixture has good water stability; In the shear test, it can be found that the greater the normal stress, the greater the initial shear shrinkage, and the smaller the later shear expansion. After the normal stress exceeds 150 kPa, the shear expansion significantly decreases.

[Objective] The effects of soil moisture content and root area ratio on the soil consolidation effect of Medicago sativa and Euphorbia hypericifolia root systems and the interaction mechanism of root-soil were studied in order to provide scientific basis for selecting plant species and controlling soil moisture content in ecological restoration of mines. [Methods] Wild M. sativa and E. hypericifolia were observed on a Haizhou open pit mine slope in Burin City, Liaoning Pvocince. Tests were conducted to determine the tensile properties of the root systems. The root-soil complex shear test was used to determine the optimum moisture content of the root systems of the two plants. The root-soil composite shear optimization test was conducted based on the optimal moisture content to determine the optimal root area ratio for soil consolidation efficiency. [Results] ① The tensile resistance of the root systems of the two species increased as a power function of root diameter. The tensile strength of the root systems decreased as a power function of root diameter. ② The cohesive force of the vegetative soil and the two root-soil complexes tended to increase and then decrease with increasing moisture content, and the angle of internal friction tended to decrease with increasing moisture content. ③ The M. sativa and E. hypericifolia root systems had the greatest soil consolidation effect when the moisture content was 25% and 21%, respectively. ④ At the optimal moisture content, the greatest soil consolidation efficiency was achieved when the root area ratios of the M. sativa and E. hypericifolia root systems were 0.04% and 0.08%, respectively. [Conclusion] The morphological and mechanical effects of the E. hypericifolia root system made it the superior species because of its greater soil consolidation than the M. sativa root system.