Explore the vast range of titles available.

Wide stiffened aluminium panels are extensively used in aerospace, marine, and civil industries due to their light-weight structure and high stiffness. In this paper, a wide stiffened aluminium panel was manufactured using the principle of the multi-container extrusion, and a comparative study was conducted using two different die designs at the same extrusion condition, in which metal flow behaviour, extrusion force, welding quality, and billet material utilisation have been investigated numerically. Additionally, the effect of extrusion speed on the extrusion process was evaluated with the modified design. It was shown that, compared with the initial design, better metal flow behaviour can be obtained in the modified design. Multi-container extrusion greatly reduces the extrusion force, and the modified design results in a more uniform extrusion force for each extrusion container. The total extrusion force for the modified design is slightly higher compared with the initial die design, due to the increased friction in the upper die channels and the second-step welding chamber. Besides, the modified design of the multi-container extrusion can obtain better welding quality evaluated by different welding criteria, and the extrusion speed has a minor effect on the welding quality. The most notable feature is that the modified design greatly improves the material utilisation, which could save 39.5% material compared to the initial design.

Currently, the extrusion process with traditional conical die or elliptic die will cause the problems of high energy consumption and stress concentration. In order to address these problems, a novel streamline die characterized by the Gaussian function is designed first. The corresponding velocity field is constructed on the basis of the condition of equal flow per second. By using the newly constructed velocity field, the energy analysis of the extrusion is conducted, and the concrete internal work rate of plastic deformation, shearing work rate, and work rate of friction are obtained by a new method, called the feature-fitting substituting method. Then, the analytical expressions of extrusion force and stress state coefficient are obtained by the upper bound method. Simultaneously, the finite element (FE) simulation is conducted to verify the accuracy of the analytical expression of extrusion force and to disclose the advantages of the present die over the existing dies. The results show that the extrusion forces obtained from the present die match well with the simulation results, and the maximum deviation is no more than 1.73%. Above all, it is proved that the present Gaussian die can consume less energy and reduce the possibility of die loss evidently.

Wire hot extrusion was investigated to produce thin wires of metals and metallic matrix nanocomposites, including aluminum (Al), copper (Cu), and copper/carbon nanotube composites (Cu/CNT, 1%wt). A new energy-based analytical solution was developed to predict extrusion force, where friction effect between die and sample was considered. This analytical solution achieved a much better result than the classical slip line theory and other existing analytical solutions, where friction effect was usually not considered. Finite element (FE) models using ALE method were built to validate the analytical solution under different extrusion conditions. A series of FE simulations were run for different die angles (30°, 45°, and 60°) and two different area extrusion ratios (4:1 and 16:1). The comparison results showed a very good correlation between the analytical solution and FE results. Four wire extrusion tests of metals and Cu/CNT composite were conducted under elevated temperatures (about 300 to 700 ℃). Test results further proved the excellent accuracy of the analytical solution and the necessity of considering friction effect. Trade-off between high temperature oxidation and material fracture during wire extrusion for less ductile materials was also briefly discussed.

Extrusion of AlZnMgCu alloys is associated with a very high plastic resistance of the materials at forming temperatures and significant friction resistance, particularly at the contact surface between the ingots and the container. In technological practice, this translates into high maximum extrusion forces, often close to the capacity of hydraulic presses, and the occurrence of surface cracking of extruded profiles, resulting in a reduction in metal exit speed (production process efficiency). The accuracy of mathematical material models describing changes in the plastic stress of a material as a function of deformation, depending on the forming temperature and deformation speed, plays a very important role in the numerical modelling of extrusion processes using the finite element method (FEM). Therefore, three mathematical material models of the tested aluminium alloy were analysed in this study. In order to use the results of plastometric tests determined on the Gleeble device, they were approximated with varying degrees of accuracy using the Hnsel–Spittel equation and then implemented into the material database of the QForm-Extrusion® programme. A series of numerical FEM calculations were performed for the extrusion of Ø50 × 3 mm tubes made of 7075 aluminium alloy using chamber dies for two different billet heating temperatures, 480 °C and 510 °C, and for three different material models. The metal flow was analysed in terms of geometric stability and dimensional deviations in the wall thickness of the extruded tube and its surface quality, as well as the maximum force in the extrusion process. Experimental studies of the industrial extrusion process of the tubes, using a press with a maximum force of 28 MN and a container diameter of 7 inches, confirmed the significant impact of the accuracy of the material model used on the results of the FEM numerical calculations. It was found that the developed material model of aluminium alloy 7075 number 1 allows for the most accurate representation of the actual conditions of deformation and quality of extruded tubes. Moreover, the material data obtained on the Gleeble simulator made it possible to determine the limit temperature of the extruded alloy, above which the material loses its cohesion and cracks appear on the surface of the extruded profiles.

The application of titanium alloy micro-gears in microelectromechanical systems has been severely restricted, as the graphite mold is prone to abrasion or even to crack at high temperatures, mainly due to the forming load. We aimed to manufacture Ti-6Al-4V alloy micro-gears through hot extrusion under an electric field and to clarify the influence of holding time on the extrusion force. The results suggest that the formed gears had a complete filling and clear tooth profile. Moreover, the contact resistance and current density caused a gradient temperature distribution inside the billet, resulting in a carburized layer and inhomogeneous β grains. The extrusion force increased with an increased holding time, which can be ascribed to the increase in the thickness of the carburized layer and the β grain size. Among these two factors, β grain size played a leading role in the extrusion force. Continuous dynamic recrystallization dominated the deformation in a single β phase, and the misorientation of the transformed α laths from β grains followed the Burgers orientation relationship. This study may pave the way for the extrusion forming of other titanium alloy micro-components.

Raw and ripe banana (Musa Cavendish) peel slices were dried by application of ultrasonication (U) and carbonation-ultrasonication (CU) as pre-treatments for tray drying (T) at 60 °C. Lesser drying time and higher diffusivity was noticed in CU + T dried samples followed by U + T and T dried samples. Model ‘Wang and Singh’ was identified as the excellently fitting model to experimental data. SEM images of dried samples revealed the microchannels formation due to U treatment, which were more couloir after CU treatment. Water and oil holding capacity (WHC and OHC) for raw peel powders was higher than ripened peel powders at 40, 60 and 80 °C. WHC and OHC increased significantly after U + T drying or CU + T drying as compared to T drying for ripe and raw peel powder samples. Back extrusion force (BEF) varied from 67.42 to 69.22 N and from 84.6 to 86.02 N for ripe and raw peel samples respectively. Given treatments resulted in lesser colour change and Browning Index. But U + T or CU + T treatment did not affect BEF significantly. CU + T was deemed to be the appropriate drying technique for ripe and raw banana peel drying.

ObjectivePre-filled syringes (PFSs) have become popular as a convenient and cost-effective container closure system for delivering biotherapeutics. However, standard siliconized PFSs may compromise the stability of therapeutic proteins due to their exposure to the silicone oil–water interface. To address this concern, silicone oil-free (SOF) glass syringes coupled with silicone-oil free plunger stoppers have been developed. This study aims to compare the impact of silicone oil-free (SOF) and siliconized syringes as primary container on protein stability and device functionality of the combination products.MethodsThe stability of proteins with different modalities was assessed in SOF and siliconized 1 mL glass syringes for up to 6 months at 5℃, 25℃, and 40℃ with levels of subvisible particles and soluble aggregate determined by micro-flow imaging (MFI) and ultra performance size-exclusion chromatography (UP-SEC). The functionality of SOF glass syringes, including break loose force, extrusion force and delivery time in autoinjectors, was evaluated at different time points during the stability study. Additionally, SOF glass syringes were filled with viscosity surrogate ranging from 1 to 90 cP to understand the impact of solution viscosity on break loose force, extrusion force, and autoinjector delivery time.ResultsSOF demonstrates compatibility with proteins and exhibited significantly low particle counts compared to siliconized PFS. SOF syringes show significantly higher break-loose and extrusion forces. However, unlike siliconized syringes where silicone oil migration increases extrusion force, no significant change in functionality was observed in SOF glass syringe during stability testing. Overall, SOF glass syringes showed great potential as an alternative package for biologics with comparable performance on functionality as siliconized PFS.ConclusionsThe combination of SOF glass and its PTFE coated stopper presents a new primary container closure system with both adequate protein stability and desired functionality features.

The leaves of spinach are delicate and easily injured during harvesting. To reduce the spinach damage rate and increase the conveyance success rate, an orderly harvester was designed and manufactured, and the key conveying parameters of the harvester were optimized by simulation and experiments. The compression damage stress of spinach was determined by compression tests. Then, a finite element simulation model for spinach clamping was established, and the influence of different clamping heights on the spinach deformation and equivalent stress were simulated and analyzed. Finally, response surface Box–Behnken experiments were conducted to optimize the combinations of the twisting angle, clamping distance, and height difference. The results of the compression tests showed that the compression damage stresses of spinach leaves, stems, and their connection points were 8.04 × 10−2 MPa, 7.85 × 10−2 MPa, and 11.63 × 10−2 MPa, respectively. The optimal clamping height of spinach for orderly conveyance was obtained to be 20 mm according to the finite element simulation. The response surface experimental results indicated that the significance order of factors affecting the extrusion force was the clamping distance, the height difference, and the twisting angle. The significance order of factors affecting the conveyance success rate was the clamping distance, the twisting angle, and the height difference. The optimal parameter combination was ae twisting angle of 60°, clamping distance of 24 mm, and a height difference of 20 cm. The experimental validation of the optimization results from the finite element simulation and response surface tests demonstrated that the extrusion force and conveyance success rate were 2.37 N and 94%, respectively, with a conveying damage rate of 3% for spinach, meeting the requirements for the low-damage and orderly harvesting of spinach.

Torsion extrusion (TE) method as a severe plastic deformation (SPD) process can effectively refine the microstructures and improve the mechanical properties of materials. Accurate and rapid prediction of the extrusion force in the process of TE is an important problem in industry. This paper proposed an analytical model using upper bound method (UBM) for predicting the extrusion force in the TE process. The kinematically admissible velocity field is established based on a continuous spherical extrusion velocity field coupled with a torsional velocity field constrained in a conical die. The torsional angular velocities along the radial and axial directions are assumed with quadratic and cubic function, respectively, due to the radial and axial nonlinearity of torsional velocity in the deformation zone. In addition, considering its complexity, the shape of the deformation zone is mapped to a rectangular zone. By establishing the torsional velocity field in the mapped zone, the torsional velocity field of the deformation zone is obtained according to the mapping relation. The UBM model is validated by comparing the predicted extrusion force with the simulation results obtained from the finite-element method (FEM). Moreover, the influences of the friction factor, reduction ratio and die angle on the extrusion force were investigated as well.

In recent years, the interest in modeling extrusion processes has resulted in the development of several analytical and numerical methodologies. The present work optimizes cold extrusion process variables (Die angle (DA), Ram speed (RS), Coefficient of friction (CoF)) on extrusion force, displacement, damage and time for the Aluminum AA 2024 alloy material. DEFORMTM-3D software is used to carry out numerical simulations and to study the behavior of the Aluminum AA 2024 billet during the plastic deformation over the conical die. The die/ container and ram (top die) are considered as rigid bodies and the room temperature is maintained during the extrusion process. The simulations are conducted as per L27 Taguchi orthogonal array. The obtained results are analyzed in ANOVA. An optimization using multiple variables is performed by grey relational analysis (GRA). The highest grey relational grade (GRG) is obtained for experiments conducted at DA level 2, RS level 2, and CoF level 3 (minimum extrusion force, damage and time) and (maximum displacement) is achieved by GRA. Systematically, the influence of the ram speed, coefficient of friction, and die angle are examined. The damage factor is considerable at 30° DA under the ram speed of 3mm/min.