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Strain hardening, elongation, and shearing speed effects of flow behaviors on coil-rod shearing during automatic multi-stage cold forging (AMSCF) are experimentally investigated. AMSCF machines and an experimental apparatus with a universal testing machine are utilized. Various coil materials are tested, including A6061-T6, SWCH10A, SCM435, and SCM415. The former is used to investigate the elongation and shearing speed effects on the sheared surface features. The latter is used to reveal the dependence of shearing phenomena on strain hardening and elongation. The new findings show the strong dependence of coil-rod shearing phenomena and surface features on flow behaviors and shearing speed. They will lead the engineers to the optimized shearing process design.

The increasing demand for sustainable and cost-effective manufacturing solutions has led to the development of innovative approaches to enhance the durability and reliability of cutting tools. This study presents a novel method for manufacturing shearing tools utilizing interchangeable modular elements loaded by deposition welding with covered electrodes. Using Weibull distribution modeling, a comparative reliability analysis between conventionally manufactured shear tools and the proposed modular design demonstrates a significant increase in the mean time to failure (MTTF). The least squares method (LSM) estimation was used in order to determine the shearing tools’ lifetime, expressed by reliability indices. Experimental results confirm that the modular tools achieve more than double the lifetime of traditional counterparts, with improved resistance to wear and mechanical stress. These findings highlight the potential for widespread industrial application, optimizing tool performance and sustainability in manufacturing processes.

With consumer electronics transitioning toward flexible products, there is a growing need for high-performance, mechanically robust, and inexpensive transparent conductors (TCs) for optoelectronic device integration. Herein, we report the scalable fabrication of highly conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films via solution shearing. Specific control over deposition conditions allows for tunable phase separation and preferential PEDOT backbone alignment, resulting in record-high electrical conductivities of 4,600 ± 100 S/cm while maintaining high optical transparency. High-performance solution-sheared TC PEDOT:PSS films were used as patterned electrodes in capacitive touch sensors and organic photovoltaics to demonstrate practical viability in optoelectronic applications.

Zwitterionic hydrogels exhibit eminent nonfouling and hemocompatibility. Several key challenges hinder their application as coating materials for blood-contacting biomedical devices, including weak mechanical strength and low adhesion to the substrate. Here, we report a poly(carboxybetaine) microgel reinforced poly(sulfobetaine) (pCBM/pSB) pure zwitterionic hydrogel with excellent mechanical robustness and anti-swelling properties. The pCBM/pSB hydrogel coating was bonded to the PVC substrate via the entanglement network between the pSB and PVC chain. Moreover, the pCBM/pSB hydrogel coating can maintain favorable stability even after 21 d PBS shearing, 0.5 h strong water flushing, 1000 underwater bends, and 100 sandpaper abrasions. Notably, the pCBM/pSB hydrogel coated PVC tubing can not only mitigate the foreign body response but also prevent thrombus formation ex vivo in rats and rabbits blood circulation without anticoagulants. This work provides new insights to guide the design of pure zwitterionic hydrogel coatings for biomedical devices. Zwitterionic hydrogels are nonfouling and hemocompatibility but several key challenges such as weak mechanical strength and low adhesion hamper their application as coating materials for devices. Here, the authors report a microgel reinforced zwitterionic hydrogel with excellent mechanical robustness and anti-swelling properties.

Despite decades of technological advancements in blood-contacting medical devices, complications related to shear flow-induced blood trauma are still frequently observed in clinic. Blood trauma includes haemolysis, platelet activation, and degradation of High Molecular Weight von Willebrand Factor (HMW vWF) multimers, all of which are dependent on the exposure time and magnitude of shear stress. Specifically, accumulating evidence supports that when blood is exposed to shear stresses above a certain threshold, blood trauma ensues; however, it remains unclear how various constituents of blood are affected by discrete shears experimentally. The aim of this study was to expose blood to discrete shear stresses and evaluate blood trauma indices that reflect red cell, platelet, and vWF structure. Citrated human whole blood (n = 6) was collected and its haematocrit was adjusted to 30 ± 2% by adding either phosphate buffered saline (PBS) or polyvinylpyrrolidone (PVP). Viscosity of whole blood was adjusted to 3.0, 12.5, 22.5 and 37.5 mPa·s to yield stresses of 3, 6, 9, 12, 50, 90 and 150 Pa in a custom-developed shearing system. Blood samples were exposed to shear for 0, 300, 600 and 900 s. Haemolysis was measured using spectrophotometry, platelet activation using flow cytometry, and HMW vWF multimer degradation was quantified with gel electrophoresis and immunoblotting. For tolerance to 300, 600 and 900 s of exposure time, the critical threshold of haemolysis was reached after blood was exposed to 90 Pa for 600 s (P < 0.05), platelet activation and HMW vWF multimer degradation were 50 Pa for 600 s and 12 Pa for 300 s respectively (P < 0.05). Our experimental results provide simultaneous comparison of blood trauma indices and thus also the relation between shear duration and magnitude required to induce damage to red cells, platelets, and vWF. Our results also demonstrate that near-physiological shear stress (<12 Pa) is needed in order to completely avoid any form of blood trauma. Therefore, there is an urgent need to design low shear-flow medical devices in order to avoid blood trauma in this blood-contacting medical device field.

When granular assemblies are subject to external loads or displacements, particles interact with each other through contact and may exhibit translations and rotations. From a micromechanical perspective, particle rotations are an essential mechanism influencing the macroscopic behavior of granular materials. In this study, biaxial shearing tests were conducted on assemblies of dual-sized circular particles at different confining pressures. A high-precision image analysis method was developed to extract the particle-level motion of all the particles, including the rotational behavior. Experimental results showed that most of the particles exhibited rotations. Particles within the shear band exhibited more significant rotations and were characterized by low connectivity (number of contacts per particle). In contrast, the particles outside the shear band rotated lesser, only in the beginning stage of shearing. Every rotation in either direction is accompanied by an opposite rotation of almost the same magnitude in the neighboring region, and rotation clusters have been observed. Rotations in both directions are normally distributed within the assembly, and the average particle rotation is zero. The average rotations in both directions evolve symmetrically with major principal strain. Generally, the rotation rate (degrees per incremental strain) is observed to be maximum at the start of the shearing, and gradually it becomes constant toward the end of the shearing. The average value of the absolute cumulative rotation observed for whole particles is 18.6° at the end of shearing, i.e., 20% deviatoric strain. Smaller size particles tend to exhibit 67% higher rotations than bigger particles. Confining pressures have no significant effect on the rotational behavior of circular particles.

Wax deposition during crude oil transmission can cause a series of negative effects and lead to problems associated with pipeline safety. A considerable number of previous works have investigated the wax deposition mechanism, inhibition technology, and remediation methods. However, studies on the shearing mechanism of wax deposition have focused largely on the characterization of this phenomena. The role of the shearing mechanism on wax deposition has not been completely clarified. This mechanism can be divided into the shearing dispersion effect caused by radial migration of wax particles and the shearing stripping effect caused by hydrodynamic scouring. From the perspective of energy analysis, a novel wax deposition model was proposed that considered the flow parameters of waxy crude oil in pipelines instead of its rheological parameters. Considering the two effects of shearing dispersion and shearing stripping coexist, with either one of them being the dominant mechanism, a shearing dispersion flux model and a shearing stripping model were established. Furthermore, a quantitative method to distinguish between the roles of shearing dispersion and shearing stripping in wax deposition was developed. The results indicated that the shearing mechanism can contribute an average of approximately 10% and a maximum of nearly 30% to the wax deposition process. With an increase in the oil flow rate, the effect of the shearing mechanism on wax deposition is enhanced, and its contribution was demonstrated to be negative; shear stripping was observed to be the dominant mechanism. A critical flow rate was observed when the dominant effect changes. When the oil flow rate is lower than the critical flow rate, the shearing dispersion effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. When the oil flow rate is higher than the critical flow rate, the shearing stripping effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. This understanding can be used to design operational parameters of the actual crude oil pipelines and address the potential flow assurance problems. The results of this study are of great significance for understanding the wax deposition theory of crude oil and accelerating the development of petroleum industry pipelines.

The changes in the magnetization properties of high-strength steel and ultra-high-strength steel sheets are investigated, and then the sheared edges and the scattering behavior of slivers in shearing of the ultra-high-strength steel sheets are observed. The maximum magnetic flux density of the magnetized sheet is increased with the increasing tensile strength of the sheet. The maximum magnetic flux density in the magnetized blanks decreases, whereas the density in the demagnetized blanks increases. In the sheared edges, the ratio of the fracture surface becomes larger with the increasing tensile strength of the steel sheet. In shearing, the shearing slivers are observed at the time of crack penetration and at the time of punch rise. The mass of the slivers generated from the blank in shearing increases with the increasing tensile strength of the steel sheet. Two-thirds of the generated shearing slivers stick to the blank in the magnetized blank, whereas two-thirds of the slivers in the blank without magnetization scatter to the outside of the die.

Lyotropic chromonic liquid crystals are water-based materials composed of self-assembled cylindrical aggregates. Their behavior under flow is poorly understood, and quantitatively resolving the optical retardance of the flowing liquid crystal has so far been limited by the imaging speed of current polarization-resolved imaging techniques. Here, we employ a single-shot quantitative polarization imaging method, termed polarized shearing interference microscopy, to quantify the spatial distribution and the dynamics of the structures emerging in nematic disodium cromoglycate solutions in a microfluidic channel. We show that pure-twist disclination loops nucleate in the bulk flow over a range of shear rates. These loops are elongated in the flow direction and exhibit a constant aspect ratio that is governed by the nonnegligible splay-bend anisotropy at the loop boundary. The size of the loops is set by the balance between nucleation forces and annihilation forces acting on the disclination. The fluctuations of the pure-twist disclination loops reflect the tumbling character of nematic disodium cromoglycate. Our study, including experiment, simulation, and scaling analysis, provides a comprehensive understanding of the structure and dynamics of pressure-driven lyotropic chromonic liquid crystals and might open new routes for using these materials to control assembly and flow of biological systems or particles in microfluidic devices.

Materials that exhibit yielding behavior are used in many applications, from spreadable foods and cosmetics to direct write three-dimensional printing inks and filled rubbers. Their key design feature is the ability to transition behaviorally from solid to fluid under sufficient load or deformation. Despite its widespread applications, little is known about the dynamics of yielding in real processes, as the nonequilibrium nature of the transition impedes understanding. We demonstrate an iteratively punctuated rheological protocol that combines strain-controlled oscillatory shear with stress-controlled recovery tests. This technique provides an experimental decomposition of recoverable and unrecoverable strains, allowing for solid-like and fluid-like contributions to a yield stress material’s behavior to be separated in a time-resolved manner. Using this protocol, we investigate the overshoot in loss modulus seen in materials that yield. We show that this phenomenon is caused by the transition from primarily solid-like, viscoelastic dissipation in the linear regime to primarily fluid-like, plastic flow at larger amplitudes. We compare and contrast this with a viscoelastic liquidwith no yielding behavior, where the contribution to energy dissipation from viscous flow dominates over the entire range of amplitudes tested.