Material Flow Behavior Research Articles

Shear rate dependency on flowing granular biomass material

The commercialization of bioenergy has been significantly limited by various material handling issues due to the poor flowability of granular biomass materials. Addressing these issues demands a fundamental understanding of flow physics and robust models to predict the multi-regime flow behavior of biomass particles. In this study, we investigated the multi-regime flow behavior of loblolly pine chips, a widely used bioenergy feedstock, through combined experiments and simulations. A quasi-static hypoplastic model and a cross-regime Drucker–Prager (DP)-μ(I) model were utilized and validated against inclined plane flow experiments to understand the quasi-static and dense flow behavior of milled pine chips. The results show that along the inclined plane, loblolly pine chips mainly present in heap flow (varying thickness along the plane), and in plane flow (iso-thickness along the plane) only when the inclination closes to the material’s critical state internal friction angle. The results also show that the multi-regime DP-μ(I) model predicts a completely different velocity profile from the hypoplastic model. DP-μ(I) model can capture the flow behavior of pine chips in both flow regimes well but at the cost of extra parameter determination, and the shear-rate dependent rheology model can successfully capture the flow of elongated high-frictional particles. These findings advance the scientific understanding of the multi-regime flow behavior of granular biomass materials and shed light on formulating novel constitutive models to assist granular biomass handling in the bioenergy industry.

Visualization of vertical transfer of material through high-velocity rotating flow zone during friction stir welding

In this letter, combined experimental and computational analysis has allowed new understanding of the vertical material flow behaviors during friction stir welding. It is found that a high-velocity rotating flow zone exists near the welding tool, where horizontal and vertical flow are both significant. Material entering the high-velocity rotating flow zone migrates to the lower location of the workpiece after multiple rotations. Material outside the high-velocity rotating flow zone bypasses the tool and migrates towards the upper locations. The findings of this research offer insights into the regulation of microstructures and the formation of defects in FSW.

Robotic wire-based friction stir additive manufacturing

High axial force requirement for existing friction stir additive manufacturing technologies is a substantial obstacle to manufacturing of complex reliable components by high-freedom robots. Here, we proposed a new robotic wire-based friction stir additive manufacturing (R-WFSAM) method, characterized by paraxial feeding wires and pre-plasticization process, to enable the formation of deposited layers with significantly low force. The spiral groove design on the screw tool facilitates the pre-plasticization of materials prior to deposition and the continuous extrusion of the material, reducing axial force and diminishing the reliance on high-stiffness equipment for solid-state relevant technologies. Fully dense aluminum alloy components on the 2D plane and 3D curved surface by hybrid position/force control were successfully manufactured. The sufficient material flow and material mixing behavior during deposition on the plane induced by the multi-pin design strengthened the interfacial bonding. Homogeneous and fine grains were also achieved due to severe plastic deformation. The R-WFSAM Al-Si alloy component possessed an ultimate tensile strength of 230±5 MPa and an uniform elongation of 28.1±1.0 %, exhibiting excellent isotropic mechanical properties. This method provides a novel approach for manufacturing large-size complex structural components with high flexibility and field re-manufacturing.

Deep drawing simulation of dual phase steel using hardening curves and anisotropic parameters from uniaxial and biaxial tensile tests

Among the various factors, the accuracy of the predictions from the numerical simulation of sheet metal forming processes depends on the material model used to define the mechanical behavior of the blank material. The coefficients of the hardening model to define the flow curve and the plastic strain ratios are commonly determined using the uniaxial tensile tests. The advanced anisotropic yield criteria incorporate material flow behaviour and plastic strain ratio in equi-biaxial tension. In this work, deep drawing of a flat bottom cylindrical cup has been simulated using dual-phase steel (DP600) sheets. The biaxial material properties obtained by conducting hydraulic bulge test and cruciform specimen test are used in the anisotropic yield criteria in the simulations. The hardening curves are extrapolated using different hardening laws in which the coefficients are determined from the stress-strain curves obtained from both uniaxial tensile and hydraulic bulge tests. The predicted peak drawing load and thickness variation in the drawn cups are compared with the experimental results of deep drawing.

Continuous Anode Slurry Production in Twin-Screw Extruders: Effects of the Process Setup on the Dispersion

Screw design in the extrusion process has an important effect on the distribution of material through the extruder, resulting in partially filled sections in the processing zone. Accordingly, the local accumulation of material in the extruder leads to variations in material strain conditions and also influences the local residence time of the material in a given screw section. This work evaluates particle dispersion in anode slurry considering three different screw arrangements. The particle size distribution is considered as a quality parameter representing the microstructure of the battery slurry components and their distribution. Numerical simulation of the material flow behavior through a laboratory extruder was performed to investigate the filling ratios and resulting shear rates for different screw designs and process conditions. The importance of process parameters and a suitable screw configuration to achieve specific particle sizes in battery slurry is discussed.

Effect of feeding material shape on microstructures and mechanical properties in friction rolling additive manufacturing

Friction rolling additive manufacturing (FRAM) is a solid-state additive manufacturing method capable of accommodating a wide range of material forms. However, there is a lack of comprehensive research on the optimal feedstock form. Thus, this study investigated the influence of feedstock shape on material formation, microstructure, and mechanical properties. The results revealed that irrespective of whether a strip or wire was used, the plasticized material flowed through a thin plastic flow channel (approximately 112 μm) between the tool head and the feedstock. Wire feedstock resulted in greater deformation and more significant grain refinement than strip feedstock, with grain refinements of 95 % and 81 %, respectively. Additionally, gaps between multiple wires were filled with plasticized material, forming a dense and defect-free mixing zone. Moreover, the tensile performances of the deposited samples obtained from wire and strip feedstocks exhibited no significant differences, measuring 143.9 MPa and 144.5 MPa, respectively. Numerical simulations were employed to elucidate the underlying mechanism of the temperature field and material flow behavior when strips and wires were used as feed materials. The findings of this study are anticipated to serve as a reference for selecting feedstock forms for FRAM.

Large deformation response of a novel triply periodic minimal surface skeletal-based lattice metamaterial with high stiffness and energy absorption

Triply periodic minimal surface (TPMS) lattice metamaterials present superior mechanical performance over traditional strut-based lattice metamaterials due to their unique structural characteristics. However, the high stiffness–stable plastic response trade-off dilemma is still the major challenge for skeletal-based metamaterials. Herein, a novel TPMS skeletal lattice metamaterial is proposed. Finite element simulations are conducted to reveal its elastic properties and plastic response under compression. Afterwards, validation experiments are performed on the lattice specimens fabricated by the most common Fused Deposition Modeling (FDM) process. The nominal stress–strain curves and collapse mode of the lattice materials are obtained accordingly. Both the numerical simulations and experiments demonstrate that the proposed TPMS lattice metamaterial exhibits high specific modulus, strength and energy absorption, together with a smooth and elongated stress plateau, thereby overcoming the strength-efficiency trade-off. Different from the rigid nodal region in traditional strut-based lattices, the strut connection parts in the novel TPMS lattices experience shear and twisting, which avoids the catastrophic failure of the struts and enhances the loading efficiency of the structure under compression. Meanwhile, the numerical results indicate that the stable plastic response of the designed architecture is insensitive to the plastic flow behavior of the bulk material, which is also supported by the experimental results. It is also demonstrated that the novel TPMS lattice metamaterial presents several times higher stiffness as well as energy absorption simultaneously than the current strut-based lattice materials, which can be potentially applied as load-bearing components and impact energy absorbers.

Study the Physical Properties of Fertilizers and Plant Basin Parameters to Design the Tractor Operated Round Basin Maker cum Fertilizer Applicator for Orchard Crop

The physical form of fertilizer production is of extremely importance, both agronomically and in regard to satisfactory handling, transport, storage, and finally application to the field. The improvement of equipment for handling, storage, and application of granular fertilizer require a proper understanding of material properties and flow behavior. The most common problems encountered in fertilizers were caking, poor flow ability, segregation, dustiness and excessive hygroscopicity due to differences of physical properties. The physical properties such as moisture content, angle of repose and bulk density as important in designing the hopper and metering roller of fertilizer plays an important role in the storage, transport and application of fertilizer. The urea, Ammonium phosphate Sulphate, complex fertilizers and fertilizer ratio (10 26 26) per one orchard tree should be applied yearly trice based on crop requirement. The angle of repose value ranges 28° -37° the hopper angle was decided. For that, to flow the fertilizer freely from the hopper, the inclined angle of the hopper should be greater than 40° respectively. The lowest bulk density and tapped density observed 0.648 kg cm-3 and 0.708 kg cm-3 respectively. Coefficient friction for galvanized Iron (GI) material is very high So, based on the obtained results, a fertilizer applicator for orchard crops has been designed. The basin diameter of orchard palm varies from 1500 mm to 1750 mm the mean of 1650 mm. The root zone depth of orchard crop varies from 150 to 180 mm at radius of 1800 mm from the base of palm. The mean 171.66 mm hence depth of operation of machine was selected as 150 mm such that the machine does not interfere with root zone of orchard trees.

Investigating micro-cutting mechanism of glow discharge polymer based on material properties and removal behaviors analysis

Glow discharge polymer (GDP) is the unique artificial material for the target balls in Inertial Confinement Fusion tests, while its practical micromachining such as the fabrication of microstructure on material surfaces keeps challenging due to its unclear micro-cutting mechanism. Hence, this paper seeks to investigate the micro-cutting mechanism of GDP from the perspective of the material flow and cutting energy. To achieve it, the energy conservation equation of three cutting modes triggered by different ratios of uncut chip thickness to the tool cutting edge radius (RTS) was established based on cutting deformation behaviors. Meanwhile, the diamond cutting tests and the FEM simulation at different RTS were developed. The experimental observation of cutting forces and specific cutting forces verified the evolution of three cutting modes, including shearing, shearing-ploughing and ploughing in the micro-cutting of GDP with the decrease of RTS. Next, from the change of the node displacement vector observed from the simulated results, it can be seen that the real-time material flow behavior during micro-cutting of GDP varies obviously with the evolution of cutting modes. Besides, the fracture toughness Gc, and the energy dissipation of different cutting modes were analyzed. The proportion of the energy spent on material fracture (Gc=9.95 N/mm) is the largest one in shearing and shearing-ploughing modes, while in ploughing mode, the material plastic deformation consumed the most energy. The above results reveal the specific material properties and removal behaviors of GDP and contribute to optimizing the machining strategies for the practical micromachining of microstructures on material surfaces.

Effect of tool probe geometry on the material flow and mechanical behaviour of dissimilar AA2024/AA7075 friction stir welded joints

Effect of tool probe geometry on the material flow and mechanical behaviour of dissimilar AA2024/AA7075 friction stir welded joints

Material flow behavior and microstructural refinement of AA6061 alloy during friction extrusion

In this work we used friction extrusion (FE), a solid phase processing technique, to produce dense, fully consolidated 5 mm rods of aluminum alloy 6061 (AA6061). The combination of large shear stresses and high temperatures at the tool-billet interface during extrusion produced equiaxed, dynamically recrystallized grains and finely distributed precipitates. Texture and microstructure evolution during extrusion was investigated in detail using scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. Smoothed particle hydrodynamics simulation was performed to study complex material flow during extrusion. Simulation results suggest spiral material flow during extrusion which corroborated experimental results. Advantages of friction extruded microstructure over conventionally extruded counterparts are also explored using flash annealing for solution treatment followed by artificial aging. Mechanical properties of the as-friction extruded, and the artificially aged specimens were evaluated using tensile testing and compared with conventional extruded material properties.

Characterization Approach for Compression Molded Discontinuous Fiber Thermoplastic Composites

Thermoplastic composites show potential in increasing the manufacturing production rate of composite aerospace structures. This is largely due to their ability to be consolidated quickly using automated processes. A variety of reinforced thermoplastic material forms are offered that can be processed multiple ways in order to meet structural performance requirements at the necessary production volumes without substantial compromise. Intrinsically, this requires generating a significant amount of statistically-based material property data for each unique material and process combination. Currently, the National Institute for Aviation Research (NIAR) and the Federal Aviation Administration (FAA) are developing a material qualification framework for compression molded discontinuous fiber thermoplastic composites in consensus with industry experts. To aid in the development of the qualification framework, a screening test matrix was formed to identify the key processing parameters and evaluate the appropriate test methods and specimen sizes. Three main variables were considered in the trial testing: reinforcement size, material flow behavior and panel thickness. The effect of these key processing parameters on the mechanical properties are discussed along with guidelines for testing and characterization.

Material flow and heat transfer characteristics in flat-top laser composite arc-based directed energy deposition

In this study, a novel flat-top laser composite arc-based directed energy deposition process is proposed, and the material flow and heat transfer behaviors are investigated for both arc-only and hybrid flat-top laser modes. Transient CFD models are developed to simulate the energy of the laser and arc using the surface heat source and double-ellipsoid body heat source models, respectively, and validated through experimentation. The results show that the high-temperature metal fluid flows outward from the center of the molten pool and then backward in the front part. The flat-top laser does not alter the flow field pattern but allows for the spread of more hot liquid metal towards the lateral edges. Furthermore, it is discovered that the flat-top laser reduces the contact angle and promotes a stable molten pool temperature.

Effects of toolhead size on the heat generation and material flow behaviors in solid state friction rolling additive manufacturing

As a key part of solid-state friction rolling additive Manufacturing (FRAM), the toolhead is used to generate heat and deformation through friction with the feed material to form a deposit, and its geometric size directly affects the formation of the FRAM plastic zone; however, to date, no in-depth studies have been conducted. In this study, the effects of toolhead diameters (25, 50, and 100 mm) on the temperature history, material flow, and mechanical properties of the deposited samples are investigated via thermocouple measurements, optical microscopy, and mechanical property tests. The results indicate that, with the increase in toolhead diameter from 25 mm to 100 mm, the area of the interaction zone between toolhead and strip increases from 138 mm2 to 274 mm2, peak temperature increases from 522.3 °C to 559.8 °C, the material flow distance in the plastic zone increases from 7.03 mm to 16.6 mm, and the deposition height decreases from 2.4 mm to 1.2 mm. Regardless of the chosen toolhead size, defect-free and high-performance deposited materials can be obtained by optimizing the process parameters. The mechanical properties of deposited 6061 via a 100-mm toolhead are optimal, and the microhardness, tensile strength, and elongation of the deposited material are 66 HV, 234.7 MP, and 28.3 %, respectively. This study provides a basis for the selection and optimization of toolhead size in the FRAM process.

A machine‐learning supported multi‐scale LBM‐TPM model of unsaturated, anisotropic, and deformable porous materials

AbstractThe purpose of this paper is to investigate the utilization of artificial neural networks (ANNs) in learning models that address the nonlinear anisotropic flow and hysteresis retention behavior of deformable porous materials. Herein, the micro‐geometries of various networks of porous Bentheimer Sandstones subjected to several degrees of strain from the literature are considered. For the generation of the database required for the training, validation, and testing of the machine learning (ML) models, single‐phase and biphasic lattice Boltzmann (LB) simulations are performed. The anisotropic nature of the intrinsic permeability is investigated for the single‐phase LB simulations. Thereafter, the database contains the computed average fluid velocities versus the pressure gradients. In this database, the range of applied fluid pressure gradients includes Darcy as well as non‐Darcy flows. The generated output from the single‐phase flow simulations is implemented in a feed‐forward neural network, representing a path‐independent informed graph‐based model. Concerning the two‐phase LB simulations, the Shan‐Chen multiphase LB model is used to generate the retention curves of the cyclic drying/wetting processes in the deformed porous networks. Consequently, two different ML path‐dependent approaches, that is, 1D convolutional neural network and the recurrent neural network, are used to model the biphasic flow through the deformable porous materials. A comparison in terms of accuracy and speed of training between the two approaches is presented. Conclusively, the outcomes of the papers show the capability of the ML models in representing constitutive relations for permeability and hysteretic retention curves accurately and efficiently.

Elucidation of solid-state metal flow behaviors during friction stir welding: Numerical and experimental investigation

During the process of friction stir welding, the behavior of interfacial friction holds a pivotal role in shaping both the heat generation and material flow within the workpiece. However, a quantifiable comprehension of how the friction between the tool and the workpiece (T/W) precisely influences the interface contact state and the heat generation, and the material flow remains elusive. This paper strives to address this gap by introducing a mathematical model that couples interface friction and material flow through the utilization of a shear stress boundary condition at the T/W interface, which is able to present sliding and sticking condition, in our computational fluid dynamics simulation. Notably, the simulation underscore a non-uniform distribution characterizing the friction interface contact state. It is found that augmenting the coefficient of friction (CoF) induces a transition from sliding to sticking both locally and averagely at the T/W interface. When the friction interface becomes predominantly characterized by a sticking state, the CoF exerts a nominal influence over the overall heat generation, yet maintains a discernible impact on material flow patterns. This foundation enables the elucidation of the mechanism through which the friction interface contact state impacts material flow behavior. The simulated material flow trajectory also highlight that under a sliding-dominated friction interface, materials simply flow around the tool. The material flow trajectories on the advancing side (AS) and the retreating side (RS) are approximately symmetrical. The materials driven by the shoulder and the pin are converged at the center of the weld behind the tool. Simulation and experimental results demonstrate that under a sticking-dominated friction interface, materials tend to undertake multiple circulations around the tool and migrate downward to the AS. Other materials are observed to migrate upward to the RS. The entrance point for this circular behavior resides in the AS situated beneath the shoulder.

Application of novel constrained friction processing method to produce fine grained biomedical Mg-Zn-Ca alloy

In order to obtain Mg alloys with fine microstructures and high mechanical performances, a novel friction-based processing method, name as “constrained friction processing (CFP)”, was investigated. Via CFP, defect-free Mg-Zn-Ca rods with greatly refined grains and high mechanical properties were produced. Compared to the previous as-cast microstructure, the grain size was reduced from more than 1 mm to around 4 µm within 3 s by a single process cycle. The compressive yield strength was increased by 350% while the ultimate compressive strength by 53%. According to the established material flow behaviors by “tracer material”, the plastic material was transported by shear deformation. From the base material to the rod, the material experienced three stages, i.e. deformation by the tool, upward flow with additional tilt, followed by upward transportation. The microstructural evolution was revealed by “stop-action” technique. The microstructural development at regions adjacent to the rod is mainly controlled by twinning, dynamic recrystallization (DRX) as well as particle stimulated nucleation, while that within the rod is related to DRX combined with grain growth.

A New Regression Model for the Prediction of the Stress-Strain Relations of Different Materials.

Experimental flow stress-strain data under different stress states are often used to calibrate the plastic constitutive model of anisotropic metal materials or identify the appropriate model that is able to reproduce their plastic deformation behavior. Since the experimental stress-strain data are discrete, they need to be mathematically returned to a continuous function to be used to describe an equivalent hardening increment. However, the regression results obtained using existing regression models are not always accurate, especially for stress-strain curves under biaxial stress loading conditions. Therefore, a new regression model is proposed in this paper. The highest-order term in the recommended form of the new model is quadratic, so the functional relationships between stress-strain components can be organized into explicit expressions. All the experimental data of the uniform deformation stage can be substituted into the new model to reasonably reproduce the biaxial experimental stress-strain data. The regression results of experimental data show that the regression accuracy of the new model is greatly improved, and the residual square sum SSE of the regression curves of the new model reduced to less than 50% of the existing three models. The regression results of stress-strain curves show significant differences in describing the yield and plastic flow characteristics of anisotropic metal materials, indicating that accurate regression results are crucial for accurately describing the anisotropic yielding and plastic flow behaviors of anisotropic metal materials.

On material flow behavior, strain energy, and improved surface integrity ratio in subsequent burnishing after turning

On material flow behavior, strain energy, and improved surface integrity ratio in subsequent burnishing after turning

Compression properties and constitutive model of short glass fiber reinforced poly-ether-ether-ketone (PEEK)

To analyze the deformation behavior of short glass fiber-reinforced poly-ether-ether-ketone (SGFR-PEEK) under various conditions through numerical simulations, it is crucial to construct a constitutive model that can describe its stress–strain behavior over a wide range of strain rates and temperatures. In this study, quasi-static compression tests were conducted on SGFR-PEEK composites with varying mass fractions, and dynamic tests were performed using a Split Hopkinson Pressure Bar to acquire the material's compressive stress–strain response under quasi-static and dynamic conditions. The results indicate that, under compression, the yield stress of SGFR-PEEK composites increases with an augmentation in glass fiber content, rises with increasing strain rate, and decreases with elevated temperature. Based on experimental findings, a modified Johnson–Cook constitutive model was established to characterize the mechanical performance of SGFR-PEEK. In comparison to the traditional Johnson–Cook intrinsic structure model, the modified model takes into account the glass fiber mass fraction as comprehensively as possible and better predicts the material's flow behavior at high strain rates. Finally, this modified constitutive model was implemented in the ABAQUS software using the user-defined subroutine VUMAT to simulate the compression behavior of SGFR-PEEK composites under different loading conditions, and the model was validated. This research provides valuable insights for the practical application of SGFR-PEEK composites in engineering.