Extrusion Force Research Articles

The Elucidation of the Molecular Mechanism of the Extrusion Process.

Extrusion is a popular method for producing homogenous population of unilamellar liposomes. The technique relies on forcing a lipid suspension through cylindrical pores in a polycarbonate membrane. The quantification of the extrusion and/or recalibration processes make possible the acquisition of experimental data, which can be correlated with the mechanical properties of the lipid bilayer. In this work, the force needed for the extrusion process was correlated with the mechanical properties of a lipid bilayer derived from other experiments. Measurements were performed using a home-made dedicated device capable of maintaining a stable volumetric flux of a liposome suspension through well-defined pores and to continuously measure the extrusion force. Based on the obtained results, the correlation between the lipid bilayer bending rigidity and extrusion force was derived. Specifically, it was found that the bending rigidity of liposomes formed from well-defined lipid mixtures agrees with data obtained by others using flicker-noise spectroscopy or micromanipulation. The other issue addressed in the presented studies was the identification of molecular mechanisms leading to the formation of unilamellar vesicles in the extrusion process. Finally, it was demonstrated that during the extrusion, lipids are not exchanged between vesicles, i.e., vesicles can divide but no membrane fusion or lipid exchange between bilayers was detected.

The Role of Alpha-1-Acid Glycoprotein in the Diagnosis and Treatment of Crush Syndrome-Induced Acute Kidney Injury.

Crush syndrome (CS) is the most common cause of deaths following earthquakes and other disasters. The pathogenesis of CS has yet to be fully elucidated. Thus, clinical choice of ideal drug treatments for CS remains deficient. In this study, we first evaluated the relation between extrusion force and the severities of CS. Rats were exposed to different extrusion forces: 1 kg, 3 kg, 5 kg, and 8 kg, respectively. Survival rates, crushed muscle tissue edema, serum biochemical parameters, and histopathological staining were used to assess severity. Our results showed that there were no statistical differences in survival rate or changes in thigh circumference among the different extrusion forces groups. However, serum levels of potassium, creatine kinase, blood urea nitrogen, creatinine, and myoglobin were elevated at 12- and 24-h post-decompression in 5 kg and 8 kg groups, compared with 1 kg and 3 kg groups. Histopathological staining demonstrated that the degree of organ damage to kidney, muscle, and lung tissues correlated with increasing extrusion force. We next analyzed changes in serum protein profiles in 3 kg or 5 kg extrusion pressure groups. A total of 76 proteins (20 upregulated, 56 downregulated) were found to be altered at all three time points (0, 12, and 72 h) post-decompression, compared with the control group. Three common upregulated proteins alpha-1-acid glycoprotein (α1-AGP), neutrophil gelatinase-associated lipocalin (NGAL), and Haptoglobin were selected for validation of increased expression. α1-AGP was explored as a treatment for CS-induced acute kidney injury (AKI). Intraperitoneal injection of α1-AGP protected kidneys from CS-induced AKI by regulating TNF-α and IL-6 production, attenuating neutrophil recruitment, and reducing renal cell apoptosis. Our findings demonstrated that the severity of crush injury is causally related to extrusion pressure and increase in blood serum markers. Our identification of the biomarker and treatment candidate, α1-AGP, suggests its implication in predicting the severity of CS and its use as a mediator of CS-induced AKI, respectively.

Electrostatic model of dielectric elastomer generator based on finite element

When dielectric elastomer materials are used for power generation, bias voltage is applied at both ends of dielectric elastomer film, and there are equal amounts of heterogeneous charges on both sides of the film, so Maxwell electrostatic force is always coupled in the process of power generation. In order to investigate the distribution of Maxwell stress in dielectric elastomer material under electric field, the electrostatic model of dielectric elastomer generator is established in COMSOL finite element simulation software environment in this paper. The distribution of electrostatic force is studied from two aspects of theoretical derivation and simulation, and the magnitude and direction of electrostatic force are determined. The simulation results show that the Maxwell electrostatic force can be equivalent to the tensile force along the film plane and the extrusion force perpendicular to the plane, and they are the same.

A comparative study on deformation mechanisms, microstructures and mechanical properties of wide thin-ribbed sections formed by sideways and forward extrusion

Extruded profiles/sections are increasingly used in the transport industry for lightweight structures. In this paper, a wide thin-ribbed aluminium profile with asymmetric Z-shape, was manufactured by a novel sideways extrusion process proposed by the authors. A comparative study was conducted by utilising the direct/forward extrusion process at the same extrusion temperature and speed, in which the different process mechanics, resulting microstructures and mechanical properties of profiles have been investigated by experiments and finite element modelling. It was revealed that, compared with sideways extrusion, although the design of a die pocket in forward extrusion induces preform and avoids the use of the large-diameter billet and extrusion container/press needed for extruding wide profiles, it requires a greater extrusion force due to work-piece upsetting necessary to fill the die pocket and leads to a lower effective strain in the profile rib. EBSD characterisation of the regions with an equal effective strain indicated that an increased shear strain is more efficient for obtaining fine grains with a higher average misorientation angle. In the same region of the profile rib made from the two different processes, sideways extrusion results in greater grain refinement due to greater effective strains, and a slightly greater texture intensity was found due to the intensive shear deformation. Tensile tests on formed profiles revealed that sideways extrusion leads to a higher yield strength (YS) and ultimate tensile strength (UTS) but a relatively lower elongation to failure, due to the combined effects of grain refinement, GND and texture intensity enhancement. Compared with the billet, the profile formed by forward and sideways extrusion has a YS increased by about 60% and 79% respectively, and an UTS increased by about 74% and 80% respectively in the extrusion direction, demonstrating an advantage of the sideways extrusion process in improving material strength under the same extrusion condition.

Finite Element Model of Equal Channel Angular Extrusion of Ultra High Molecular Weight Polyethylene

Abstract Ultra-high molecular weight polyethylene (UHMWPE) used in biomedical applications, e.g., as a bearing surface in total joint arthroplasty, has to possess superior tribological properties, high mechanical strength, and toughness. Recently, equal channel angular extrusion (ECAE) was proposed as a processing method to introduce large shear strains to achieve higher molecular entanglement and superior mechanical properties of this material. Finite element analysis (FEA) can be utilized to evaluate the influence of important manufacturing parameters such as the extrusion rate, temperature, geometry of the die, back pressure, and friction effects. In this paper, we present efficient FEA models of ECAE for UHMWPE. Our studies demonstrate that the choice of the constitutive model is extremely important for the accuracy of numerical modeling predictions. Three considered material models (J2-Plasticity, Bergstrom-Boyce, and the three-network model) predict different extrusion loads, deformed shapes, and accumulated shear strain distributions. The work has also shown that the friction coefficient significantly influences the punch force and that the two-dimensional (2D) plane strain assumption can become inaccurate in the presence of friction between the billet and the extrusion channel. Additionally, a sharp corner in the die can lead to the formation of the so-called “dead zone” due to a portion of the material lodging into the corner and separating from the billet. Our study shows that the presence of this material in the corner substantially affects the extrusion force and the resulting distribution of accumulated shear strain within the billet.

Stamping of Nonuniform Channels. 3. Forces and Shape Changes in Channel Extrusion. 3.2. Determining the Extrusion Force, Maximum Wall Pressure, and Wall Height

Stamping of Nonuniform Channels. 3. Forces and Shape Changes in Channel Extrusion. 3.2. Determining the Extrusion Force, Maximum Wall Pressure, and Wall Height

Experimental Study on Shear Behavior and Failure Mechanism of Bolted Heterogeneous Rock Joints under Different Anchorage Conditions

Despite their frequent natural occurrence and engineering encounter, heterogeneous rock joints (rock joints with different lithological characters on both sides of the joint surface) have been studied much less systematically. To study the shear behavior and failure mechanism of bolted heterogeneous rock joints, laboratory tests were performed on the heterogeneous rock joints having different joint roughness coefficients (JRC) under different anchorage conditions. The results indicate that shear strength increases with the increase of JRC, showing exponential growth. Under the same roughness, the shear strengths of rock joints from large to small are fully grouted, end anchorage, and without anchorage. The mechanical characteristics of the bolt and joint are poorly matched under the end anchorage condition, which is easy to cause these two to be broken one by one. Under fully grouted, the extrusion force caused by the rock bolt will diffuse around the anchorage agent and will not cause partial continuous damage. The surface damage of heterogeneous rock joints increases with the increase of JRC and presents obvious heterogeneous characteristics. The shear dislocation between the blocks under shear load results in the interaction between the bolt and surrounding media. Under the action of shear force, the bolt body produced both axial and transverse deformation, which leads to breakage of anchorage agent and rock mass. Rock bolt has a significant impact on the shear behavior of the anchorage system, and the damage of the rock bolt to rock mass should be considered in rock engineering reinforcement design.

Effect of dispensing rate on internal void formation in restorations built with sonically activated resin composite

AbstractInternal void formation in sonically activated resin composite (SonicFill 2, Kavo Kerr, Orange, CA, USA) applied at three different extrusion force magnitudes was evaluated. Forty SonicFill 2 composite compules were divided into four groups according to dispensing method and magnitude of extrusion force as follows: No sonic energy/manual dispensing (FM) (control), sonic energy with low extrusion force (F1), sonic energy with medium extrusion force (F3), and sonic energy with high extrusion force (F5) (n = 10). For F1, F3, and F5, sonic energy was delivered using a SonicFill handpiece. For the control, no sonic energy was applied. Composites were placed into the molds and polymerized. Micro‐computed tomography scanning for intrarestoration void assessment was performed and intrarestoration void rates (%) were calculated. Data were statistically analyzed (α = 0.05). Sonic energy yielded lower intrarestoration void rates than that of the control (10.58% ± 1.74%) (p < 0.05). Intrarestoration void rates between F1 (8.11% ± 0.99%) and F3 (7.00% ± 0.95%) were similar (p > 0.05), whereas F5 (5.14 ± 0.91%) led to significantly lower void rates compared to F1 and F3 (p < 0.05). The highest extrusion force (F5) setting of the SonicFill handpiece caused the lowest internal void rates in SonicFill 2 resin composite restorations compared to those of the medium (F3) and lowest (F1) settings.

Investigations on Roller-Based Filament Drives

The filament drive is a key part of the extrusion assembly of a Fused Filament Fabrication printer. This investigation examines the maximum feed force and the slip of different driving rollers using a filament made of polylactic-acid (PLA) on a test stand. The test stand systematically varies the main feed process parameters: feed velocity, pinch force between the rollers, and feed force. The maximum feed force has a characteristic dependency on the pinch force combined with a feed-velocity-dependency, which is influenced by the outer diameter of the driving roller. The slip was found to increase linearly with the feed force. The slip decreases with increasing pinch force and is nearly constant for pinch forces above 77 N—172 N, depending on the driving roller tooth geometry and outer diameter. A model derived from contact mechanics was used for phenomenological modeling of the slip in relation to pinch force and feed velocity. An exponential ansatz provided good modeling of the slip at a constant pinch force. The model of the slip combined with the extrusion forces in the liquefier can be used to estimate the material flow in the future, thus leading to increased precision of the parts in a magnitude of systems.

Study on in-situ material flow behaviour during friction stir welding via a novel material tracing technology

• The proper tracer materials were used to reflect the real material flow rule in friction stir welding process. • The material flow characteristics in different positions of stir zone has been extensively studied in terms of displacement,flow path, rotation angle and driving force. • The material flow model in different horizontal planes of the welds were established. A novel material tracing technology was proposed using ER2319 aluminium alloy welding wire as the tracer material to study the material flow behaviour at different positions of friction stir welded 6061-T6 aluminium alloy joint. Having been influenced by temperature and driving force of the tool, the displacement of all the tracer materials deposited behind the original position during welding decreased gradually from top to bottom of the stir zone (SZ). The advancing side (AS) and the retreating side (RS) of the SZ are dominated by the shear action and the extrusion action, respectively. The extrusion force and friction force are the driving forces for material flow during friction stir welding. The material flowed downward at the AS and upward at the RS in the vertical plane of the joint, while the material of the SZ flowed to the back of the tool through the RS in all the horizontal planes of the joint. The flow path of tracer material in most positions of the SZ is arc shaped, however, it is a complex curve in the SZ bottom at the AS due to the poor material flowability. The rotation angle of the tracer material decreased from AS to RS of the SZ and from top to bottom of the SZ.

Physicochemical Properties of Injectable Hyaluronic Acid: Skin Quality Boosters

AbstractIn addition to clinical research on the efficacy and compatibility of injectable hyaluronic acid (HA) based fillers, ample in vitro research on the physicochemical properties of these materials is published. Different HA‐based product ranges are also available as skin quality boosters (SQBs) to improve skin quality. The aim of this study is to investigate the physicochemical properties of specific HAs for improving skin quality, as, to the best of the authors' knowledge, no data is published on this topic to date. This paper may provide a better understanding of clinical performance and differentiation between these SQBs. Five HA injectable hydrogels (Belotero Revive, Juvederm Volite, Restylane Skinbooster Vital, Viscoderm Hydrobooster, and Profilho) from the SQB product ranges of different companies and manufacturing technologies are investigated for their extrusion force, swelling degree, rheological performance, and cohesivity. There are significant differences in extrusion force, swelling degree, rheological performance, and cohesivity between the assessed SQBs. HA concentration (mg mL−1) exhibits statistically significant positive correlations with extrusion force, swelling degree, tan delta, and cohesivity. This study provides a physicochemical characterization of different SQBs and information to improve understanding of this type of product.

Influence of Rheological Properties and Needle Size on Extrusion Forces of Hyaluronic Acid Based Soft Tissue Fillers.

To date no precise data are available for extrusion forces related to the G-prime and G-double-prime of fillers in combination with different 27G and 30G needles. Therefore, the objective of this study was to analyze extrusion forces of various product-needle-combinations containing two different 27G and two different 30G needles in combination with fillers of a wide range of elastic moduli starting from 2.0 – 166.0 Pa. Four different fillers with the following elastic moduli 1.87, 11.65, 61.80, 165.50 Pa were combined with four different needles: 27G ½”, internal diameter: 0.300 μm; 27G ½”, internal diameter: 0.241 μm; 30G ½”, internal diameter: 0.241 μm and 30G ½“, internal diameter: 0.240 μm. Product-needle-combination were subjected to uni-axial mechanical testing and the respective extrusion force was measured. The results of this study revealed that the G-prime and the G-double-prime of a product are statistically significantly related to their extrusion force, with higher G-prime/G-double-prime products requiring higher extrusion forces. The results additionally revealed that whether the size of the needle was described as 27G or 30G by the respective manufacturer statistically significant differences between the measured extrusion forces were detected. Injectors need to be aware that not every 27G/30G needle has the same extrusion force even though the external diameter is similar (27G or 30G); this might additionally influence the ability to withdraw blood during a pre-injection aspiration manoeuvre. J Drugs Dermatol. 20(5): doi:10.36849/JDD.5237.

Analytical and Numerical Analysis of Extrusion Force, Stress and Strain Development During Extrusion Al6063-SiC Composite

Nowadays composite material are highly interesting in different areas like, aerospace, thermal management, automotive application, and electronic products etc. Aluminium based metal matrix with silicon carbide as particle reinforcements called discontinuous reinforced metal matrix composite materials. It has excellent mechanical properties like high yield strength, wear resistance, corrosion resistance and vibration resistance. During the development of discontinuous reinforcement metal matrix composites compression process like, extrusion is an advisable secondary process for homogenous distribution of the reinforcement’s materials through the metal matrix. This research was investigated the metal flow behavior of extrusion load, stress and strain distribution of Al6063/Sic based discontinuous reinforcement metal matrix composite. The billets extruded from round billet to square shape and are used for different applications. Third order polynomial and cosine die profiles were used as extrusion dies for this research by taking 30%, 60% and 90% area reductions. Depends on these three different area reductions upper bound and DEFORM 3D finite element analysis method were used to analyze analytically and numerically respectively. Due to these different area reductions, the extrusion load was minimum in cosine die profiles both analytical and numerical results. In 30% of area reduction cosine die profile has optimum load (878.59N) and it used to extrude Al6063/20%SiC composite billet materials from 20mm input diameter to 14.8x14.8mm output square sides. Therefore, 30% area reduction cosine die profile has minimum extrusion load as compare other area reduction of cosine die and 3rd order polynomial dies. It is used as extrusion die for Al6063/SiC composite materials to optimum extrusion loads in different % of area reduction of square shape extruded.

Development of a finite element lumbar spine model to predict intervertebral disc herniation risk factors

The objective of the current study was to develop a lumbar motion segment FE model that predicts disc herniation risk. The posterolateral nucleus extrusion force and disc pressure increased as the amount of flexion and magnitude of compression was increased in all loading scenarios. The nucleus extrusion force and posterior stress in the annulus both increased when exposed to a combination of compression and flexion. Results of the current study confirmed the authors hypothesis that the model would accurately predict herniation risk when exposed to a biomechanical environment known to cause herniations.

Solid state processing of titanium chips by an unconventional plastic working

Abstract The aim of this paper is to demonstrate how various titanium chips can be processed into solid bulk materials in the form of rods. In this work, an alternative technology for recycling chips without re-melting is presented. In order to transform chips into a new material, an unconventional plastic working method was applied that involved upsetting, heating and extrusion with a rotating die. Two purities of pure titanium were investigated: Ti Grade4 (the lowest possible purity) and high-purity Ti 99.99 (the highest possible purity). For each of these materials, four geometries of chips were processed, i.e. chips after turning (thin and coarse) and chips after milling (thin and coarse). In this paper, the influence of chip purity and chip geometry on the course and effects of the processing were investigated. In addition, technological aspects such as extrusion force and die wear were analyzed. Independent of the type of chips, the results obtained have proved the efficiency and utility of the applied method. As a result of this processing, solid, bulk products in the form of rods O8 mm in diameter were successfully obtained. The rods were nearly fully consolidated, and their density was practically the same as the density of commercial titanium. The materials obtained exhibited conventional, grained structures. It was also shown that the materials obtained were free from significant structural defects such as porosity and impurities. Additional confirmation of their proper structure and purity was provided by the correct results of hardness (~200 HV10, Ti Gr4, and, ~100 HV10, Ti hp).

3D Printing of In Vitro Hydrogel Microcarriers by Alternating Viscous-Inertial Force Jetting.

Microcarriers are beads with a diameter of 60-250 µm and a large specific surface area, which are commonly used as carriers for large-scale cell cultures. Microcarrier culture technology has become one of the main techniques in cytological research and is commonly used in the field of large-scale cell expansion. Microcarriers have also been shown to play an increasingly important role in in vitro tissue engineering construction and clinical drug screening. Current methods for preparing microcarriers include microfluidic chips and inkjet printing, which often rely on complex flow channel design, an incompatible two-phase interface, and a fixed nozzle shape. These methods face the challenges of complex nozzle processing, inconvenient nozzle changes, and excessive extrusion forces when applied to multiple bioink. In this study, a 3D printing technique, called alternating viscous-inertial force jetting, was applied to enable the construction of hydrogel microcarriers with a diameter of 100-300 µm. Cells were subsequently seeded on microcarriers to form tissue engineering modules. Compared to existing methods, this method offers a free nozzle tip diameter, flexible nozzle switching, free control of printing parameters, and mild printing conditions for a wide range of bioactive materials.

Synthesis and Characterization of Biocompatible Methacrylated Kefiran Hydrogels: Towards Tissue Engineering Applications.

Hydrogel application feasibility is still limited mainly due to their low mechanical strength and fragile nature. Therefore, several physical and chemical cross-linking modifications are being used to improve their properties. In this research, methacrylated Kefiran was synthesized by reacting Kefiran with methacrylic anhydride (MA). The developed MA-Kefiran was physicochemically characterized, and its biological properties evaluated by different techniques. Chemical modification of MA-Kefiran was confirmed by 1H-NMR and FTIR and GPC-SEC showed an average Mw of 793 kDa (PDI 1.3). The mechanical data obtained revealed MA-Kefiran to be a pseudoplastic fluid with an extrusion force of 11.21 ± 2.87 N. Moreover, MA-Kefiran 3D cryogels were successfully developed and fully characterized. Through micro-CT and SEM, the scaffolds revealed high porosity (85.53 ± 0.15%) and pore size (33.67 ± 3.13 μm), thick pore walls (11.92 ± 0.44 μm) and a homogeneous structure. Finally, MA-Kefiran revealed to be biocompatible by presenting no hemolytic activity and an improved cellular function of L929 cells observed through the AlamarBlue® assay. By incorporating methacrylate groups in the Kefiran polysaccharide chain, a MA-Kefiran product was developed with remarkable physical, mechanical, and biological properties, resulting in a promising hydrogel to be used in tissue engineering and regenerative medicine applications.

Study of the External Inverting Process of the Mild Steel Thin-walled Tube

The invertube is an ideal energy absorber to improve the crashworthiness of the vehicle skeleton body structure, but the low cost mild steel thin-walled tube often suffers some serious tearing phenomena in the external inverting process on the forming die. In order to investigate the interference factors of external inverting deformation, the optimum parameter of die structure design and the axial resistance force level of thin-walled tube in the external inverting process, a nonlinear finite element explicit dynamic codes were adapted to simulate the plastic inverting process of a mild steel thin-walled tube. The tube has the outer diameter of 60mm and the wall thickness of 2.0mm. The external inverting processes were conducted upon two kinds of round corner dies. Based on the results of previous theoretical analysis, the radius range of the corresponding die were obtained by theoretical calculation. The two die section forms and a series of dies with different round corner radii were also designed to build finite element simulation models. The inverting simulation results show that the optimal induced radii of the dies are within the range of 10.5-11.0mm. Meanwhile, it can be seen that the mild steel thin-walled tube has good formability in the early stage, which is convenient for the subsequent fine shaping of the invertube end. Moreover, the die bears less axial extrusion force, which is conducive to the improvement of the working life of the die. In the last, an ideal alloy steel die with the optimal rounded radius of 10.7mm was manufactured and used to verify the feasibility to finish the invertube manufacturing using mild steel thin-walled tubes. It provides a good simulation technology reference for the die structure design to realize the external inverting of the mild steel thin-walled tube.

Research of stamping of unequal channel bars. Part 3. Force parameters and shape change of the billet when extruding channels. 2. Determination of the extrusion force, maximum pressure on the matrix wall and the heights of the walls, taking into account the elastic deformation jf the matrix

On the basis of the system of equations of the theory of plastic flow, the forces, the maximum pressure on the wall of the matrix and the heights of the obtained walls when extruding channels are determined, taking into account the elastic deformation of the matrix. Keywords: die forging, extrusion, misalignment, punch, matrix, plane deformation, stresses. mt13@bmstu.ru

Application of physical simulation at study of pipe production processes

Physical experiments allow to obtain maximum information on a studied process at minimal cost, ensuring its higher accuracy comparing with data, obtained by mathematical simulation and avoiding risks, which can occur at industrial testing of new technological modes. Results of studies of deformation in the process of pipes production by extrusion presented. The studies were accomplished at laboratory test units, developed by specialists of the laboratory of drawing and extrusion of JSC “RusNITI”. One of the basic problems at pipes production by extrusion is ensuring minimal possible wall non-uniform thickness. It was noted that the relation between plunger die moving speeds during sleeve pressing-out and immediate pipe extrusion has a significant effect on pipe wall non-uniform thickness. Computer simulation of the pipe extrusion process, accomplished by application QForm program shown that minimal values of wall non-uniform thickness corresponded to relation abovementioned speeds as 0.5–0.8. To check the data, a physical simulation of extrusion process of lead cylinder samples, having outside diameter of 18.94 mm and wall thickness 5.19–5.32 mm was accomplished. For the extrusion, a universal servohydraulic system of dynamic test Shimadzu Servopulser was used. Within the physical experiment a dependence was established between pipe wall non-uniform thickness on relation between speeds of pressing-out and extrusion. The revealed regularity was confirmed during pilot production of a pipe lot at the 55 MN force extrusion line. Another physical simulation of extrusion of 10.0×2.0 mm pipe-samples made of C1 grade lead was accomplished with one- and twothread helical ribbing of internal surface. For its accomplishment an experimental module was designed and manufactured. It was established that rotation speed of the extrusion mandrel had no significant effect on extrusion force. Metallographic studies shown that the extrusion mandrel rotation speed contributes to considerable increase of pipes surface hardness and obtaining finer grain comparing with the classic extrusion method. The technical ability of pipes production with internal helical ribbing by hot extrusion method was confirmed. The results of the study became a base for elaboration of a technology of pipes production at Volzhsky pipe plant according to ТУ 14-3Р-157–2018 “Steel seamless hot-extruded pipes with helical ribbing of internal surface for steam boilers”. Results of physical simulation of pipe drawing process at self-adjusting mandrel with application of lubricant materials of various viscosity. The data obtained were used for elaboration of a technology for production of cold-deformed pipes with internal diameter of 6.0–12.0 mm at Sinarsky pipe plant.