Shear Experiments Research Articles

Experimental and numerical study on mechanical performance of single shear bolted connections with novel elliptical one-sided bolts

One-sided bolts, which typically employed for connecting components with closed cross section, often present complexities in both construction and installation. Addressing the limitations of conventional one-sided bolts, this study introduces a novel variant distinguished by its elliptical head, offering ease of installation without the need for specialized tools. Due to the special shape of the bolt head, the mechanical properties of the bolt need to be studied in depth. To investigate the shear properties of the novel elliptical one-sided bolts, three sets of single lap shear experiments were conducted. Subsequently, finite element numerical analyses were employed to simulate these experiments, facilitating the development of a reliable finite element model. Furthermore, parametric analyses were undertaken to examine the influence of various parameters on the ultimate shearing capacity and displacement of joints. The findings indicate that the shear capacity of the single lap joint employing novel elliptical one-sided bolts closely rivals that of ordinary hexagonal bolts with equivalent diameters. However, an enhancement in slip resistance capacity is observed in the novel elliptical one-sided bolt joints compared to hexagonal bolts. Notably, the parameters of the bolt exert a more pronounced impact on the ultimate shearing capacity and displacement of joints when contrasted with parameters associated with the plates. The recommended torque coefficient for the novel elliptical one-sided bolt is established as 0.2, and it is recommended to use appropriate torque to ensure the slip performance of the joint during practical application.

Hybrid effect on tensile, flexural, and quasi-static punch shear behavior of jute/ramie and jute/flax reinforced hybrid composites

Abstract The high specific properties and environmental durability of synthetic fibers make them a popular choice for reinforcing lightweight composites. Unfortunately, they are often limited by their poor biodegradability and high cost. Nevertheless, natural fibers are critical in industrial applications due to their environmental and economic benefits. This study investigated the tensile and flexural behavior of natural hybrid jute/ramie and jute/flax composites with different stacking sequences. A quasi-static punch shear test was also performed to understand their deformation behavior. Jute, ramie, and flax composites have also been fabricated for comparison. Tensile and flexural tests showed a positive hybrid effect in some samples, whereas flax–jute hybrid composites in two different stacking sequences exhibited a synergistic effect. While a maximum improvement of 37.99 % was achieved in the tensile test, this rate was 64.81 % in the flexural test with these hybrid composites. According to punch shear experiments, punch geometry and stacking sequence considerably impact punch shear strength, energy absorption capacity, and deformation.

Study on the particle breakage of coral sand in the ring shear experiment

Study on the particle breakage of coral sand in the ring shear experiment

Augmenting the quality and storage stability of soymilk by incorporation of untreated and ozonated oat 1,4-β-D-glucan

The study aimed to improve the quality and storage stability of novel plant-based soymilk with the incorporation of untreated (UtβG) and modified oat derived 1,4-β-D-glucan (OzβG) at varying concentrations (0, 1, and 2 % labelled as S0, S1 and S2). The treated soymilk was characterized for physical, chemical, nutritional, rheological, particle size, zeta potential, sensory and storage stability characteristics. The results revealed that 1, 4-β-D-glucan incorporation increased the acidity (0.67 to 0.73 %), viscosity (3.4 to 4.7 Cp) and ash content (0.74 to 0.92 %), however color remains natural. The frequency sweep and shear experiments showed that the 1,4-β-D-glucan modified the rheological parameters of the soymilk. The sensory analysis (n = 30) indicated that texture, mouthfeel and overall acceptability (8.38). Compared to OzβG-treated soymilk, UtβG soymilk, especially S2, exhibited superior thickening and rheological properties. The storage study indicated minimal phase separation in 1,4-β-D-glucan-incorporated samples, maintaining stability for 15 days under refrigerated conditions without compromising overall quality. Thus, this study provides valuable insights into the potential application of 1,4-β-D-glucan for improving the technological quality of soymilk that highlights possible implications for its commercialization potential.

Effect of nanosecond pulse laser power on welding interface and mechanical properties of AZ31B Mg/6061 Al

AZ31B magnesium alloy and 6061 aluminum alloy of 0.2 mm thickness were joined by nanosecond pulsed laser welding technology, and the effects of nanosecond pulsed laser power on the formation of weld seam, interface microstructure and mechanical properties were investigated, and numerical simulation of the temperature field during the welding process was carried out. The results show that when the laser power is 50 W, more defects such as cracks, pores and sags appeared in the joints due to the high heat input, and these defects resulted in a smaller effective joint area between the metals, which is very unfavorable to the strength of the joints. As the laser power decreases, at a laser power of 25 W, fewer defects are exhibited and the effective joint area becomes larger. As the laser power continues to decrease, the low heat input makes metal melting and joining very difficult. At low laser power, the Mg element intrudes backwards into the aluminum, causing the joint boundary interface to take on a reverse “V” shape. According to the results of the tensile shear experiments, the maximum tensile force of the joint was the highest at a laser power of 25 W, which reached 76.5 N. In addition, it was observed that the effective joint area, the number of oxides and their inclusions, and the degree of angular deformation had a very important effect on the mechanical properties of the joints. The results of temperature field numerical simulation experiments show that the heat is accumulated from outside to inside during the laser scanning process, and whether the temperature in the center of the molten pool reaches the melting point of the alloy can be used as an important basis for analyzing the degree of welding.

Development of a Stretchable and Removable Electrical Interconnection Solution for Ultra-Thin Electronic Components

Currently, the solutions for interconnecting electronic components with their active face facing on substrates are based on metallic soldering. The mechanical contacts are therefore rigid. In order to enhance the reliability of the bonding, underfill is usually used to redistribute the thermo-mechanical stress created by the Coefficient of Thermal Expansion (CTE) mismatch between the silicon chip and substrate. Underfill is done with epoxy resins containing silica fillers (SiO2). As a result, the removal of components is no longer possible. Moreover, this solution is not suitable for devices integrating ultra-thin silicon components (<100 μm) hybridized on flexible substrates that may be subject to deformation. This is the case, for example, of medical “patches” worn on the person and continuously solicited. Indeed, the rigid contact points are likely to break. To address this issue, we are developing a thin anisotropic conductive and stretchable adhesive film inspired by the adhesion of the gecko. Thanks to the microstructuration of its toes involving about 1 million setae, the gecko can develop a large contact surface and thus a large force of attraction by the multiplication of van der Waals interactions. In this work, this “dry adhesion” based on the principle of “contact splitting”, was implemented in order to improve the adhesion of a flexible interconnection. For this purpose, the surface of a polydimethylsiloxane (PDMS) film was structured with micrometric mushroom-shaped patterns known to be the most efficient form of contact. To this end, silicon molds with varying mushroom geometries were used to shape the PDMS (with different cap and pillar diameters) and the adhesion force microstructured films were assessed (shear and pull-off experiments). To make these films locally conductive through the thickness, a conductive composite was prepared and locally deposited in the mold. One approach we investigated, was using a screen-printing mask. This approach has been implemented and characterized using electrical tests (I-V measurements) in order to select the most suitable films to make a flexible interconnection.

Strength and creep characteristics of methane hydrate-bearing clayey silts of the South China Sea

Natural gas hydrates are abundantly detected in the clayey-silty deposits of the South China Sea (SCS). The long-term hydrate extraction process may trigger creep deformation and failure of the clayey-silty reservoir. Hence, it is essential to evaluate the creep properties of the clayey-silty hydrate reservoir for safe production. Current research mainly focused on rapid failure, while neglecting time-dependent creep deformation of the clayey-silty hydrate reservoir. In this study, a number of triaxial shear and creep experiments were carried out on methane hydrate-bearing clayey silts (HBCSs) in the SCS in order to investigate their strength and creep deformation characteristics. The results indicated that: (1) the increase of effective stress enhances the shear strength and deformation, and the presence of hydrates enhances the shear strength while reducing the deformation; (2) the creep strain and strain rate increase as the creep stress ratio and effective stress rise; (3) the accelerated creep stage only occurs at higher effective stress in HBCSs and not in hydrate-free clayey silts (HFCSs), and the creep strain and strain rate of the HBCSs are lower than those of the HFCSs. The experimental data will contribute to the construction and verification of creep constitutive models for HBCSs in the SCS.

Rheological and Micro-Rheological Properties of Chicory Inulin Gels.

As a soluble fiber, inulin is present in many plants and has many applications in food and non-food products. In this work, we investigated the rheological properties of inulin dispersions at seven concentrations. The linear viscoelastic properties of inulin were determined using a conventional mechanical rheometer. At 25 wt%, inulin exhibited fluid-like viscoelastic liquid behavior. However, when concentrations were ≥27.5 wt%, inulin exhibited gel-like viscoelastic properties. The viscoelastic properties (moduli and viscosities) increased with increasing inulin concentration. The high-frequency linear rheological properties of inulin were also investigated using the modern light scattering technique, diffusion wave spectroscopy (DWS). The diffusion wave spectroscopy (DWS) measurements showed the amplitude of complex moduli (|G*(ω)|) of inulin gels (≥27.5 wt%) to be proportional to ½ power law of the frequency, which suggests inulin gels behave similarly to flexible polymers. The non-linear steady shear experiments demonstrated that inulin exhibited shear-thinning behavior that was well fitted by a power law constitutive model. The trend of the power law exponent from the experiments indicated that the shear-thinning extent for inulin was greater as the inulin concentration increased. The results of this work indicated that the properties of inulin gel can be manipulated by altering its concentration. Therefore, the desired inulin product can be designed accordingly. These results can be used to direct further food and non-food applications, such as wound healing materials for inulin gels.

Determination of shear strength of additively manufactured poly lactic acid/flax fibre bio-composite via the iosipescu test

The need to reduce CO2 emissions is leading to the search for alternatives to the manufacture of products from petrochemical sources. One of these alternatives is polylactic acid a bio-sourced, and biodegradable material, which is expected to be one of the most widely used materials in the forthcoming years. Recently, the feasibility of enhancing the mechanical characteristics of the PLA, by adding the flax fibre was demonstrated. Flax fibers are becoming an ideal alternative in reinforced polymer composites, thanks to the energy-intensive processing required to elaborate synthetic fibers. Flax fibers are not only recyclable and bio-degradable but also have excellent mechanical characteristics. However, the mechanical properties of flax fibre-reinforced polylactic acid composites, obtained by additive manufacturing techniques, are not well known. In the first part of this study, the quality of the Iosipescu shear experiment is examined with full-field strain measurements. In the second part, the in-plane shear response of manufactured flax fibre reinforced polylactic acid composites notched with the machining process and additive manufacturing technique are compared. This last makes it possible to evaluate the influence of the printing conditions and in particular the shell layers (contour) on the mechanical characteristics. It was perceived that the fully 3D printed specimens had a greater shear strength (+50.47%) and shear modulus (+44.68 %) than machined notch specimens. The fully 3D printed specimens count with the presence of a contour that rounds the vertices of the notches, reducing the stress-concentration factor, whereas in machined notch specimens, such contour was removed.

An accurate forming model for capturing the nonlinear material behaviour of multilayered binder-stabilised fabrics and predicting fibre wrinkling

Prefabricated stacks of binder-stabilised dry fabrics are used to increase reinforcement deposition rates in the manufacturing of large composite structures such as wind turbine blades. To ensure optimal part quality, accurate simulation tools may be used to avoid costly trial-and-error experiments. This paper introduces a new modelling framework for predicting wrinkle defects that arise from forming thick binder-stabilised stacks of quasi-unidirectional non-crimp fabric. In this context, quasi-unidirectional non-crimp fabrics are unidirectional rovings stabilised with a backing layer. The non-constant bending stiffness of the fabric is modelled using an asymmetric compressive modulus, while a mixed-mode cohesive formulation with user-defined damage evolution is used for modelling the initial non-constant elastic binder interface stiffness and interface degradation. The model is verified against cantilever bending tests of single fabric layers and transverse shear experiments of bindered fabric layers. Comparison with experimental results on the forming of preforms shows that the model accurately predicts wrinkle location and geometry during the forming of thick binder-stabilised preforms. The error between the wrinkle geometry predicted by the new modelling approach and the experimentally measured wrinkle geometry is reduced by 35% to 94% compared to wrinkles predicted by conventional modelling approaches. The modelling framework is freely available at https://doi.org/10.5281/zenodo.10077428.

Experimental study on low cycle fatigue behavior of TWIP steel under cyclic shear loading condition

This study investigated the low-cycle fatigue (LCF) behavior of Twinning induced plasticity (TWIP) steel based on the twin bridge shear specimen and cyclic shear loading condition. The cyclic shear experiments were conducted with different strain amplitudes, and we compared their softening and hardening behaviors, cyclic stress-strain curves, and fatigue life. Through studying the crack morphology and the damage mechanism of shear specimens the role of cyclic shear stress on the damage evolution of TWIP under cyclic shear conditions was shown. The results indicate that the cyclic hardening and softening capacities of TWIP steel are highly affected by the strain amplitude. With increasing the load amplitude, the hardening rate increases, and its fatigue life is negatively correlated with the strain amplitude. Meanwhile, the hardening rate is positively correlated with the strain amplitude, and the softening rate is negatively correlated. The magnitude of strain amplitude affects the ratio of cyclic softening and cyclic hardening periods. Through analyzing the obtained microstructure characteristics, it is found that there is a high density of dislocations around the crack zone which causes the final failure of TWIP.

Determining the baryon impact on the matter power spectrum with galaxy clusters

ABSTRACT The redistribution of baryonic matter in massive haloes through processes like active galactic nuclei feedback and star formation leads to a suppression of the matter power spectrum on small scales. This redistribution can be measured empirically via the gas and stellar mass fractions in galaxy clusters, and leaves imprints on their electron density profiles. We constrain two semi-analytical baryon correction models with a compilation of recent Bayesian population studies of galaxy groups and clusters sampling a mass range above ∼3 × 1013 M⊙, and with cluster gas density profiles derived from deep, high-resolution X-ray observations. We are able to fit all the considered observational data, but highlight some anomalies in the observations. The constraints allow us to place precise, physically informed priors on the matter power spectrum suppression. At a scale of k = 1 h Mpc−1 we find a suppression of $0.042^{+0.012}_{-0.014}$ ($0.049^{+0.016}_{-0.012}$), while at k = 3 h Mpc−1 we find $0.184^{+0.026}_{-0.031}$ ($0.179^{+0.018}_{-0.020}$), depending on the model used. In our fiducial setting, we also predict at 97.5 per cent credibility, that at scales k < 0.37 h Mpc−1 baryon feedback impacts the matter power less than 1 per cent. This puts into question if baryon feedback is the driving factor for the discrepancy between cosmic shear and primary CMB results. We independently confirm results on this suppression from small-scale cosmic shear studies, while we exclude some hydro-dynamical simulations with too strong and too weak baryonic feedback. Our empirical prediction of the power spectrum suppression shows that studies of galaxy groups and clusters will be instrumental in unlocking the cosmological constraining power of future cosmic shear experiments like Euclid and Rubin-LSST, and invites further investigation of the baryon correction models.

In-situ EBSD observation of texture evolution and lattice rotation behavior in shear deformation of thin-walled aluminum alloy tubes

As shear stress plays a significant role in the deformation of tubular parts with complex shapes, investigation of the microstructue evolution of tubes under the shear stress state is beneficial to understanding the shear deformation mechanism and promoting the prediction accuracy of numerical simulation. In this paper, the shear experiments were conducted on thin-walled 5052 aluminum alloy tubes. The texture evolution and lattice rotation behavior of the tube during shear deformation were studied using in-situ electron back scatter diffraction (EBSD) technology. It is shown that the initial Cube texture remains stable, while a new Rot. Copper texture is formed in the shear deformation zone. The grains with the orientation of <100> parallel to the axial direction (AD) tend to stabilize, while several low-angle grain boundaries (LAGBs) are formed inside the grains with unstable initial orientations. Notably, the orientations of adjacent grains are more similar after shear deformation, and the high-angle grain boundaries (HAGBs) gradually transform to LAGBs showing the characteristics of polycrystalline cooperative deformation. By analyzing the lattice rotation mechanism under shear stress, it is found that the shear stress promotes the lattice rotation to a stable orientation parallel to the direction of the shear stress. This research provides theoretical guidance for predicting the forming of tubular parts with complex shapes.

Velocity Profile Geometries and Granular Temperature Distributions in Very Dense Granular Flows

AbstractUnderstanding the motion of particles in very dense granular flows is crucial for comprehending the dynamics of many geological phenomena, and advancing our knowledge of granular material physics. We conduct transparent ring shear experiments to directly observe the granular motion under relatively high‐pressure conditions, and find that the granular velocity non‐linearly decays, forming an approximately 7‐particle‐diameter‐thick localized shear band. A fitting curve underlying non‐local physics can be used to well predict velocity profile geometries that are almost independent of normal stress and shear velocity. Moreover, experimental results show monotonically decreasing granular kinetic temperature, which may be caused by energy dissipation due to more inelastic contacts under high confining pressures. The variation of granular temperature will significantly influence the local yield stress and rheological properties, which may lead to inhomogeneous fluidity of the material and thus to shear localization in very dense granular flows.

Multifactor optimization for induction welding of carbon fiber reinforced thermoplastic composites based on response surface methodology

AbstractInduction welding of thermoplastic (CFRP) composites is one of the most promising welding techniques due to its high efficiency, flexibility, and selectivity of the heat area. However, the nonuniformity of the temperature field in the welding area poses a challenge to welding quality. In this paper, a multifactor optimization method devoted to the quality and efficient bonding of carbon fiber‐reinforced polycarbonate (CF/PC) composites was presented. A transient three‐dimensional finite element model was developed and validated to analyze the heating characteristics during the welding process. The mapping relationship between process parameters—equilibrium temperature and relative effective area were established to optimize the weld quality applying the response surface method. The single lap shear experiment was carried out to evaluate the mechanical properties of the welded joints, focusing on micro appearances and welding defects. The results show that the optimal process parameters are a current of 100A and a coil distance from the surface of 3.6 mm. Under the process parameter, the effective welding area is 0.3823 with an error of 4.25%.Highlights The transient three‐dimensional finite element (FE) model was established. The evaluation indicators for welding quality were proposed. The multifactor optimization method for process parameters was developed. The mechanical property and welding defects of welded joints is evaluated.

Dynamic magnetic field magnetorheological finishing with constant load and variable gap

Magnetorheological finishing is limited by weak polishing forces and small polishing areas, resulting in a low polishing efficiency. This study formulates a method for dynamic magnetic field magnetorheological finishing in compression-shear mode with a constant load and variable gap, which can remodel the magnetic particle string using a dynamic magnetic field and enhance the polishing force by a constant load and variable gap. To investigate the impact of process parameters on macro and micro machining processes, as well as their effects, a series of experiments were conducted to investigate the polishing force, machining clearance, and machining effect of single-crystal silicon wafers under four different conditions: static magnetic field magnetorheological finishing (T1), dynamic magnetic field magnetorheological finishing (T2) at a constant gap, static magnetic field magnetorheological finishing (T3), and dynamic magnetic field magnetorheological finishing (T4) with a constant load and variable gap. The results indicated that the shearing force and processing quality significantly improved in the constant-load and variable-gap modes, and the process of machining clearance reduction involved two stages: fast and slow compression. The shearing force of T3 increased by 35 % compared to T1, and T4 increased by 20 % compared to T2. The material removal rate of T3 and T4 increased over time, in contrast to those of T1 and T2. The key parameters of the T4 single-factor shear and machining gap testing experiments show that the constant load variable gap compression process adaptively adjusts the machining gap such that the chain string structure is in a body-centered cubic structure (BCT), increasing the number of abrasive contacts and the depth of pressure into the workpiece to achieve a significant increase in the polishing shear constant load.

Influences of Graphene Oxide on Mechanical Properties and Mesoscopic Deformation and Failure Process of Concrete

In this research, graphene oxide (GO) was integrated into concrete to assess its effectiveness as an additive. Triaxial compression permeability experiments, variable‐angle (30°, 45°, and 60°) shear experiments, and dynamic compression experiments were conducted on graphene oxide concrete (GOC) and normal concrete (NC). The Holmquist–Johnson–Cook model and LS‐DYNA software were utilized to simulate the mesoscopic failure of NC and GOC under impact loading. The mechanism of GO was examined through scanning electron microscope (SEM) microscopic scanning and energy dispersive spectroscopy (EDS) energy spectrum testing. The findings demonstrate that the contain of GO significantly enhances the destruction resistance of concrete under triaxial compression. The permeability of both NC and GOC exhibits a negative exponential decrease with increasing confining pressure, and carbon fiber reduces concrete permeability by 17.79%–60.9%. Compared to NC, the cohesion and internal friction angle of GOC increased by 7.80% and 8.55%, respectively. GO also improves energy conversion and storage capacity during the elastic stage of concrete, reducing inelastic energy loss during shear processes. Although, both NC and GOC exhibit strain rate sensitivity, the DIF value of GOC surpasses that of NC and the disparity between the two intensifies with increasing impact pressure. Simulation results indicate that the number of crushing units in GOC is significantly lower than in NC, maintaining integrity. Analysis of SEM microscopic test results reveals that the distribution of cement hydration products in NC is uniform, whereas in GOC, it displays regional characteristics, a phenomenon corroborated by EDS energy spectrum test results.

A study of the shear strength properties of expansive soil treated with fly ash admixture

The behavior of clay minerals in expansive soils causes them to exhibit shrink-swell characteristics, making them unsuitable for engineering purposes in their natural state. To address this problem, researchers conducted direct shear experiments using fly ash as an admixture and black cotton soil as an expanding soil to explore the strength parameter. The experiments were conducted with varying amounts of fly ash ranging from 2% to 20%. Two arrangements of test series were made, and in the principal series, tests were made utilizing five unique densities and comparing dampness contents. The outcomes showed that the point of inside grating and union expanded directly up to the ideal dampness content and most significant dry thickness before diminishing. The subsequent series showed that the end of inward rubbing grew straightly with the expansion of fly debris admixture, yet attachment reduced after 10% admixture. The decrease in shear strength was because of the diminished passion, as the fly debris' cohesionless attributes took over as the admixture rate increased above 10%. Based on these findings, adding fly ash in small quantities to black cotton soil is recommended to avoid weakening it.

Evaluating Sand Particle Behavior in Liquefaction through Video Analysis of Ring Shear Experiments with a Transparent Shear Box.

Evaluating Sand Particle Behavior in Liquefaction through Video Analysis of Ring Shear Experiments with a Transparent Shear Box.

X-ray CT visualization of particle array structure in sandy soil using ring shear experiment

X-ray CT visualization of particle array structure in sandy soil using ring shear experiment