Shear Angle Research Articles

Juno Magnetometer Observations at Ganymede: Comparisons With a Global Hybrid Simulation and Indications of Magnetopause Reconnection

AbstractJuno's flyby of Ganymede on 7 June 2021, provides a unique opportunity to explore the moon's magnetosphere. By means of Magnetometer (MAG) observations and a hybrid numerical simulation, we provide a global description of this environment and analyze the upstream magnetopause in detail. In particular, LATMOS Hybrid Simulation results suggest Juno observed open (one foot‐point connected to Ganymede, the other to Jupiter) and closed magnetic field lines along its trajectory. Additionally, we determine that the upstream magnetopause location and orientation seen by Juno MAG are consistent with previous Galileo observations. We observe a non‐zero normal component of the magnetic field across the magnetopause, along with flux rope structures embedded within the boundary's current sheet. Both signatures are strong indicators that magnetic reconnection was occurring along Ganymede's magnetopause. Based on this crossing, we calculate a shear angle of ∼78° across the magnetopause, with a dimensionless reconnection rate of ∼0.12.

Shear Strength and Re-Failure Characteristics of Intact Red Sandstone and Grouting-Reinforced Body of Fractured Red Sandstone under Different Shear Angles

To reveal the strengthening mechanism and re-failure mechanism of grouting on fractured rock, the variable-angle shear tests, real-time acoustic emission (AE) tests and VIC-3D (non-contact full field strain measurement system) tests were carried out on intact red sandstone (IRS) and grouting-reinforced body of fractured red sandstone (GRBFRS). The results show that the peak shear strength of IRS and GRBFRS decreases with the increase of shear angle. Grouting reinforcement mainly increases the cohesion of GRBFRS to improve its shear strength, but its reconstructability decreases with the increase of shear angle. In the whole process of shear deformation, the shear micro damage and shear fracture of GRBFRS are more than those of IRS. Although the shear re-failure before and after the peak stress stage is the most notable, its intensity or degree is reduced. When the shear angle is 45°, both IRS and GRBFRS undergo shear-splitting failure. However, when the shear angle is large, the IRS and GRBFRS only occurs shear failure. Moreover, the larger the shear angle, the more likely IRS and GRBFRS is to produce secondary shear cracks. The low strength of the rock–grout interface in GRBFRS is the main inducer of shear re-failure.

Experimental Study of Interfacial Bond Properties between CGM and Existing Concrete

To ensure that the cementitious grouting material (CGM) layer and existing concrete work together, the interfacial bond strength between CGM and normal concrete substrate was experimentally investigated by conducting direct and slant shear tests. The effects of connection interface form, concrete strength, interface shear key, and shear angle on the bond strength of CGM and normal concrete were discussed in detail. The results showed that for composite specimens, the interfacial bond strength was the highest for the triangular interface form, followed by the trapezoidal interface and smooth interface, which had the lowest. The interfacial bond strength increased as the existing concrete’s strength increased; the interfacial bond strength could be greatly improved under shear load in the slant section or when the shear key was set at the interface. Moreover, the interfacial bond strength increased with the increase in the shear angle. The interfacial bond–slip curves were analyzed, and a bond–slip model of the interface between CGM and concrete was proposed. A certain value of interfacial bond stiffness was also recommended.

Computational and experimental study of structural fuses optimized to resist buckling

The concept of structural fuses, i.e., replaceable hysteretic dampers that limit the forces that can be transferred to the surrounding structure, has been used in research and practice to improve the seismic performance of structural systems. A recent study used topology optimization to develop new structural fuse shapes that discourage buckling and promote stable yielding of shear-acting structural fuses. The objective of the current study is to further validate and develop the optimized shapes to allow the design and application of these optimized structural fuse shapes in practice. First, the pixelated optimized topology was interpreted as a collection of geometric shapes, parameterized to make it accessible for design, and plastic mechanism analysis was used to develop a generalized equation for shear strength. An experimental study was conducted on three specimens that were 711 mm by 762 mm by 25 mm thick, to evaluate strength, stiffness and hysteretic behavior. Finite element models were then validated against the experimental results, and used to conduct a computational parametric study to evaluate the effect of varying key design parameters on strength, stiffness, out-of-plane buckling, effective plastic strain, and energy dissipation. The experimental study showed that one of the optimized geometries possessed a good balance between buckling resistance and fracture resistance reaching approximately 11% shear angle without either. Design guidance is provided for this topology including a parameterized method for reproducing the shape, design equations, and recommendations for proportioning.

The relationship between adhesion morphology and cutting force in orthogonal cutting of 6061-T6 aluminum alloy

Due to the sticky and soft characteristics of aluminum alloy, it is easy to form adhesion on the tool rake face during cutting process. In this work, the orthogonal cutting tests for 6061-T6 aluminum were carried out at cutting speeds of 20–300 m/min and feed rates of 0.05–0.3 mm, and the relationship between adhesion and cutting force has been explored. A slip-line model was used to separate the edge force of cutting edge to obtain the pure friction force of tool rake face, thereby obtaining the average friction coefficient. Adhesion morphologies were observed under the scanning electron microscope (SEM) and compared with the average friction coefficients. It was found that different adhesion morphologies correspond to different friction coefficient ranges. Simultaneously, the relationship between the temperature and normal stress on the tool rake face and the adhesion morphology and friction coefficient was investigated. The results showed that the temperature is the major factor of adhesion evolution and friction coefficient change. Combining the tool rake face temperature and the adhesion morphology, it was noted that the reduction of the friction coefficient is not only owing to the self-lubrication caused by thermal softening, but also due to the decrease of the total shear force caused by the incomplete contact. Finally, the relationship between the friction coefficient of tool rake face and the cutting force and specific cutting energy was discussed, with the conclusion that the friction coefficient has an impact on the cutting force and specific cutting energy by changing the shear angle.

Shear Strength Characteristics of Stabilized Sedimentary Soil with Bacillus Subtilis Bacteria

Sedimentary soils are formed from deposits resulting from weathering of rocks through natural processes. One way to increase the bearing capacity of sedimentary soil is by stabilizing it. The purpose of this study was to determine the effect of variations in the mixture of Bacillus Subtilis bacteria on the characteristics of sedimentary soils and to determine the effect of the curing period on the shear strength of the sediment stabilized by Bacillus subtilis bacteria. Based on the results of physical properties testing, the original soil was classified as ML, which is silt with low plasticity based on the USCS classification system, and classified as soil group A-4, namely silty soil according to the AASHTO classification system. The addition of Bacillus Subtilis bacteria mixed with urea and CaCl2 was proven to increase the value of shear stress, cohesion, and shear angle of the soil. The addition of Bacillus Subtilis with a mixture of urea and CaCl2 to the sedimentary soil accompanied by a curing period was shown to increase the shear stress at the percentage of adding stabilizing agent 8% from 1.25 kg/cm2, 1.45 kg/cm2, and 1.77 kg/cm2 at the beginning to 1.73 kg/cm2, 2.09 kg/cm2, and 2.39 kg/cm2 at 28 days of curing, with an average increase of 35 percent. The cohesion value continued to increase from the initial value of 0.72 kg/cm2 to 1.57 kg/cm2 at 28 days of curing, resulting in an increase in cohesion value of 118 percent. For the value of the shear angle in the soil, there was an increase from the original soil shear angle value of 22° to 31° in a mixture of 8% bacteria with a curing period of 28 days so that there was an increase in the value of the shear angle by 40 percent.

Shear Strength Behaviour of Sedimentary Soil Stabilized by Fly Ash

Sedimentary soil is made up of deposits that are the consequence of the weathering of rocks that have already been deposited elsewhere by various natural processes, including water, wind, and others. A location with sedimentary soil is the Bili-bili Dam in the South Sulawesi Province's Gowa Regency. Sedimentary soil at this location is quite abundant and has not been used in general, so it can be investigated for its use, namely stability against the influence of external forces on the carrying capacity of the sedimentary soil. Stabilizing the soil is one approach to boost its bearing capacity, particularly for sedimentary soil. The original soil is categorized as group A-4, or silty soil, according to the AASHTO classification system and as ML, or silt with low plasticity, according to the USCS classification system, based on the findings of physical characteristics testing. It has been demonstrated that the soil's cohesiveness and shear angle increase with the addition of fly ash. It has been demonstrated that adding fly ash stabilizing material to the sedimentary soil of the Bili-bili Dam and allowing it to cure increased the cohesion value from the initial soil cohesion value of 0.72 kg/cm2 to 1.70 kg/cm2 after 28 days. With a 20% fly ash mixture and a curing period of 28 days, the shear angle value increased from the initial soil shear angle value of 22 to 31; this is a 40% increase in the shear angle value.

Experience in obtaining laminated aluminum composites by asymmetric accumulative roll bonding

The issue of asymmetric processing of long products in the range of speed ratios of work rolls from 2 to 5 has not been widely studied and is of interest from the point of view of increasing both the strength and ductility of metal products. An area of severe plastic deformation was found, showing the relationship between shear strain and shear angle, at which large compressive strains and ultra-high shear strains occur. An analysis was made of the values of equivalent deformations of laminated aluminum composites obtained both after the first and second processing cycles, modeled in the DEFORM and QForm software systems. The paper defines a rational range of the speed ratios of work rolls, which makes it possible to obtain not only the rectilinear movement of the metal at the exit from the deformation zone, but also the maximum elongation, the ratio of tensile strength to the yield strength for laminated aluminum composites. A regularity has been deduced showing that with an increase in the speed ratio of work rolls, the rolling forces decrease, the value of the relative reduction at a constant roll gap increases. At the maximum speed ratio of the rolls (5), melting of the samples occurs.

Experimental and numerical studies on two-point incremental forming of woven fabric composite sheet

Stamping of fiber reinforced plastic (FRP) composite sheet, especially the woven fabrics and their prepregs, has been extensively researched. However, for small-batch production, high cost and long cycle due to design of complicated molds are still critical issues in composite manufacturing. In this paper, a novel hybrid process is proposed to reduce manufacturing costs and cycles of composite parts in small-batch production with the combination of incremental sheet forming and autoclave process. To verify the process feasibility, two-point incremental sheet forming of a typical pyramid part using plain fabric prepreg was preliminarily studied through experimental and numerical methods. A metal-fiber-metal (MFM) sandwich panel configuration consisting of two dummy sheets and core fabric prepreg layer was used to prevent the woven fabric from directly contacting the forming tool and support die, which can avoid viscous friction and guarantee the practicability of the ISF process. Based on the mechanical properties of the plain weave obtained from uniaxial tension and bias extension tests, a continuous approach-based finite element model (FEM) was established in PAM-FORM. Next, cross section profiles, peripheral outlines and shear angle distributions were extracted from experimental and simulation results. The corresponding comparison results were used to evaluate prediction accuracy of the established FE model. Finally, the influence of fabric layer on dummy sheets, fabric deformation history and the influence of friction coefficient on simulation results were analyzed.

Improving dry machining performance of surface modified cutting tools through combined effect of texture and TiN-WS2 coating

In this research work, investigation on different surface modification techniques on cutting tools such as TiN-WS2 coating (T2), textured cutting tool (T3) and TiN-WS2 coated textured tool (T4) in dry machining of Ti-6Al-4V has been carried out and compared with commercial tool (T1). The presence of (002) orientation corresponding WS2 was observed in the diffraction pattern and this in turn was said to provide lubricity properties to the coatings. The cutting force generated during machining was reduced by 14 % for T4 tool when compared to T1. The T4 tool showed an increase in the shear angle by 7.5 % and decrease in coefficient of friction by 47 %. The prime mechanism attributed to the better performance of cutting tool was reduced tool-chip contact length. The T4 tools showed a 13 % reduction in tool-chip contact length when compared to commercial tools. The tool life of the T2, T3 and T4 tools was improved by 35 %, 29 % and 43 % respectively in comparison to commercial tools. The TiN-WS2 coatings, through its effective lubricity properties have said to nullify the effect of coating affinity between the tool and workpiece as evidenced by the absence of built-up edge on the tool rake face while machining using TiN-WS2 coated tool. The combined effect of TiN-WS2 coatings and surface textures have resulted in better machining characteristics, suggesting it as a suitable surface modification for dry machining of Ti-6Al-4V.

Mathematical Model for Estimation of Shear Parameters of Alluvial Soils of Kamrup Metro District (Assam, India) from Index Properties

ABSTRACT Projects related to Geotechnical Engineering require thorough ground study to know the soil behaviour thus making it necessary to determine the strength and stability parameters of soil. The soils of Assam are primarily of four types viz., Alluvial (old and new), Piedmont, Hill and Lateritic soils with the alluvium abundantly available in the state. The most important soil parameters are the shear strength parameters, namely, cohesion (c) and angle of internal friction (Φ) which can be obtained using triaxial tests with different drainage conditions. But one triaxial test may take weeks to complete and are very expensive. Moreover, for large projects it is practically preposterous to conduct large number of triaxial tests. Hence, an alternate way is to develop a relation between different parameters which enable us to determine others. The main objective of this study is establishing prediction models that allow the shear parameters to be predicted from soil index properties. For this, three prediction models are developed by combining various soil parameters viz., Liquid Limit (LL), Plastic Limit (PL), Specific Gravity (G) and Optimum Moisture Content (OMC) using Multivariate Regression Analysis (MRA) and Artificial Neural Network (ANN). The results show better performance for ANN than MRA.

Comparison of Machining Simulations of Aerospace Alloy Al6061-T6 Using Lagrangian and Smoothed Particle Hydrodynamics Techniques

This research focuses on the study of the simulation capabilities of the lagrangian (LAG) model and Smoothed Particle Hydrodynamics (SPH) model for the orthogonal dry machining of aluminum alloy Al6061-T6. A three-dimensional finite element model was developed and verified using experimental data from the published literature. The numerical models were developed using lagrangian boundary conditions via finite element modeling in ABAQUS/Explicit 6.14. The cutting simulations were carried out at low and medium cutting speeds. Johnson–Cook material constitutive law and Johnson–Cook damage law were used in both models. The numerical methodologies are compared based on cutting forces, chip morphology, shear angle, chip separation criterion, and chip thickness. The findings of the present work show that the LAG model is good for predictions regarding cutting forces and chip morphology, while the SPH model is good for predictions regarding the shear angle and chip thickness. The difference between results generated by both models mainly occurred due to the friction coefficient. The comparative study shown here offers a guidance approach for various numerical models for appropriate parameter analysis.

Study on the Mechanical Performance of H-Shaped Steel-Concrete Laminated Plate Composite Beams under Negative Bending Moment

To make the construction of assembled steel-reinforced truss concrete laminated plate composite structure faster, safer, and more efficient, this paper proposes an H-shaped steel-reinforced truss concrete laminated plate composite structure with new angle connectors embedded in the precast bottom panel. Through experimental studies on the H-shaped steel-concrete laminated plate composite beams with precast bottom panels protruding from the bent-up bars, precast bottom panels with embedded new angle connectors and laminated whole cast slab, the similarities and differences of load-deflection, deflection distribution, interface slip, crack distribution and cross-section strain distribution of three groups of composite beams under negative bending moment were analyzed and compared. Using ABAQUS finite element software, we established a finite element model and found the numerical simulation results were in good agreement with the experimental results. Based on this, five groups of finite element models were established for parametric analysis to investigate the effect of concrete strength on the flexural load capacity and flexural stiffness of the steel-laminated plate composite beams with embedded angle connectors. The results of the study show that the combined performance of the H-shaped steel-concrete laminated plate composite beams with the new angle connection embedded in the precast bottom panel was better and the flexural stiffness was greater. The slippage of the H-shaped steel-concrete laminated plate composite beams with embedded new angle connectors in the precast bottom panel was less than the slippage of the precast bottom slab bent-up bars protruding and the laminated cast plate, with the maximum slippage being only 1/2 of the precast bottom panel bent-up bars protruding. In the composite structure of H-shaped steel-concrete composite slabs under negative bending moment, shear angle connectors can replace the bent-up bars protruding from the laminated bottom panel to achieve without extending the reinforcement of the laminated bottom panel.

Cutting Force in Peripheral Milling of Additively Manufactured Maraging Steel

Additively manufactured parts have recently been applied to products in aerospace, automobile, and tool industries in terms of design flexibility and material consumption with mechanical strength. Because the surfaces of additively manufactured parts are coarse, milling is conducted as a post-process to achieve fine surfaces within the specified tolerance. However, the microstructures and the mechanical properties of additively manufactured metals differ from those of wrought metals. Therefore, the cutting characteristics should be understood to determine the appropriate cutting parameters. The paper studies the cutting process in peripheral milling of additively manufactured maraging steel in a cutting model. The cutting force, the surface finish, the chip morphology, and the tool wear were evaluated through cutting tests. Although the hardness of the additively manufactured workpiece was higher than that of the wrought workpiece, the maximum cutting forces were approximately the same. An energy-based force model was applied to discuss the cutting force characteristics in terms of the shear area and the shear stress on the shear plane. In milling of additively manufactured workpiece, the shear stress on the shear plane becomes larger than that of the wrought workpiece. However, the shear plane length is short at a large shear angle. Therefore, the cutting force does not significantly increase. The typical change in the cutting force of the additively manufactured workpiece is also compared with that of the wrought workpiece in terms of the cutting model. The chip flow directions, then, are analyzed in the cutting force model. The chips of the additively manufactured workpiece flow more in the radial direction than those of the wrought workpiece.

Simulation of the hemispherical forming process of a woven fabric with two different material models

The anisotropic hyperelastic model (MAT_249) and Non-Orthogonal Model (MAT_293) are the material models developed recently to simulate the forming process of dry fabric and fabric-reinforced thermoplastic prepregs. In this study, the prediction capabilities of these two models in terms of shear angle distribution and boundary profile of the deformed fabric are compared over a hemispherical forming simulation of a plain weave E-glass fabric reinforcement. According to the results, in the simulation performed with MAT_293, it is seen that excessive distortions occur in the meshes at the advanced stages of the deformation in the fabric. In addition, after a certain punch stroke, the shear angle distribution obtained with MAT_293 starts to deviate rapidly from realistic results. MAT_249 produces consistent results even in large deformations.

Utilization of bagasse ash plus cement to increase the shear strenght of clay soil

Soil shear strength is one of the parameters for assessing the bearing capacity of the soil. Clay soil is a type of soil with poor bearing capacity. To improve the bearing capacity of clay, a mixture of materials can be used as a stabilizing agent. In this study, the mixed material used as a stabilizing agent was bagasse ash plus cement with a percentage of bagasse ash at 5%, 10%, and 15% of the dry weight of the soil. The percentage of cement used is 5% of the dry weight of the soil. Tests were carried out in the form of laboratory tests, sieve analysis, limits of consistency, specific gravity, compaction, and direct shear test. The testing standard uses the Indonesian National Standard (SNI). Soil classification using the Unified Soil Classification System (USCS) method. The results showed that the cohesion and shear angle in the soil increased with the increase in the percentage of bagasse ash plus 5% cement so that the shear strength of the clay also increased from 48.558 kN/m2 for clay without mixture to 71.217kN/m2 with variations of clay mixed with bagasse ash 15% plus cement 5%.

Geostability of Dewatered Sludge as Landfill Cover Material

<p>Dewatered sludge is the main by-product from wastewater treatment and it contains various types of hazardous substances which can cause environmental pollution. The alternative utilization of sludge waste is for covering the landfill or as liner for the landfill. Landfill cover is a critical component to protect the surrounding environment from leachate contamination produced by landfills and it has specific characteristics. This study analyzes the optimum water content, permeability coefficient, and stability of the material consisting of a mixture of dewatered sludge, bentonite, and quicklime. The test results show that the optimum water content in the three composite variables meet the requirements; the highest optimum value was 28%, a mixture with a ratio of 84% sludge, 15% bentonite, and 1% quicklime. The results also show that mixing sewage sludge with bentonite significantly reduces the permeability value with a ratio of 80% sludge, and 20% bentonite produces the lowest permeability coefficient of 1.979 x 10-7 and this has reached the hydraulic conductivity limit of 1 x 10-7. The shear strength and safety factor results test show that V3 had the best results, with a cohesion value of 22.40 kPa, a shear angle of 31.97°, and a safety factor of 5.297. The addition of bentonite tends to reduce the value of the safety factor. This safety factor can reach a high value because of the ratio of the total shear resistance to the working soil shear stress.</p>

Determination of the Shear Angle in the Orthogonal Cutting Process

Determination of the shear angle by experimental and analytical methods, as well as by numerical simulation, is presented. Experimental determination of the shear angle was performed by analyzing the chip roots obtained by the method of cutting process quick stop through purposeful fracture of the workpiece in the area surrounding the primary cutting zone. The analytical determination of the shear angle was carried out using the chip compression ratio and was based on the principle of a potential energy minimum. Measurement of the shear angle in the numerical simulation of orthogonal cutting was performed using the strain rate pattern of the machined material at the selected simulation moment. It was analyzed how the parameters of the Johnson–Cook constitutive equation and the friction model affect the shear angle value. The parameters with a predominant effect on the shear angle were determined. Then the generalized values of these parameters were established with a software algorithm based on identifying the intersection of the constitutive equation parameter sets. The use of generalized parameters provided the largest deviation between experimental and simulated shear angle values from 9% to 18% and between simulated and analytically calculated shear angle values from 7% to 12%.

An Analytical and Experimental Study on Cutting Characteristics and Transient Cutting Force Modeling in Feed Directional Ultrasonic Vibration-Assisted Cutting of High Strength Alloys.

Ultrasonic vibration-assisted cutting (UVC) is progressively being used in machining as it can significantly promote the fabrication process. However, the ultrasonic vibration affecting the cutting process is still controversial. The full-transient cutting process is proposed in this study to analyze the affecting mechanism induced by ultrasonic vibration in the cutting process. This novel model is the first developed based on the fact that ultrasonic vibration would change mechanical behaviors and the cutting process. For example, the reduction of shear flowing stress in the primary shear zone and alteration of the shear angle in the UVC process. Then, considering those coupled effects, a novel model is proposed to determine the average and transient cutting forces. Here, insight and understanding into the physical phenomenon in UVC are provided. The effectiveness of the proposed model is verified by comparison with experimental results and analytical models available in the literature, with cutting parameters varying from macro to micro-scale. The results show that the ultrasonic vibration affects the cutting process in a complicated way, which is determined by transient characteristics, acoustic softening, thermal softening, plowing, and friction. Those effects on cutting performances in the UVC process under various cutting scenarios are investigated and discussed systematically. The average deviation of cutting forces between experiments and values predicted by the proposed model for Ti6Al4V, AISI 1045, and Al6063 is about 7%, 10.2%, and 11%, respectively. The deviation decreases with the increase of cutting speed in the machining of Ti6Al4V, which is different from the machining of other materials. This is contributed by the varied effect of ultrasonic vibration on the cutting process.

Thermo-stamping shear characteristics of thermoplastics based on X-ray micro-CT

ABSTRACT Understanding the thermo-stamping shear characteristics is not only essential to improve the forming quality of the glass fiber reinforced polypropylene (GFRPP) products but also critical to ensure their structure design reliability. Most previous studies primarily focused on the fiber yarn shear characteristics in the outer surface of the composite product, and omitted the shear angle variations of the inner layers, which might increase the failure risk to the product design. In this study, the U-shaped GFRPP rail was manufactured by the thermo-stamping process and scanned layer-by-layer through the X-ray micro-CT technology. Based on the scanning results, the differences in the shear angle variations of different layers at the same position, and within the same layer but different zones were analyzed, respectively. Finally, the effect of the temperature variation on the shear angle variation was analyzed by the simulation method. Results indicate that the interlaminar shear forces and slippages lead to the differences in shear angle variations among different layers. Intralaminar fiber yarn slippages and bending deformations caused the differences in shear angle variations within the same layer. The heat loss of the stamping molds resulted in a lower stamping temperature and further led to shear angle variation reduction.