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Todays, numerous researchers have focused on proposing severe plastic deformation (SPD) methods due to the superior mechanical and physical properties of achieved ultra-fine grain material. In all SPD methods a large strain is implied without any substantial dimensional change of work piece to generate UFG and even nanograin (NG) materials. Equal Channel Angular Pressing (ECAP) is one of the most successful techniques for industrial applications. Using long and thin rod is limited in ECAP process. In the present study, a combined process composed of ECAP and Extrusion processes is used on Titanium of grade 2. Titanium is extensively used in aviation and other industries because of high strength to weight value. Using combined process leads to produce high length and thin nanostructured rod. The main goal of this process is evaluation of the temperature in Extrusion process on nanostructures Titanium rods. At first, Titanium rods were processed to 4 passes by ECAP process at 400°C Then they were processed by Extrusion process in 5 different temperatures included 300, 350, 400, 450 and 500°C. The result showed that the best mechanical properties were achieved for the specimen was extruded at 300°C. Strength and hardness were severely improved. Also, the microstructure was really homogenous and refine. The mechanical properties of titanium grade 2 after combined process were equivalent to titanium grade 5 which is used in medical applications and it is expensive.

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In this paper, employing a thermomechanical constitutive model for shape memory polymers (SMP), a beam element made of SMPs is presented based on the kinematic assumptions of Timoshenko beam theory. Considering the low stiffness of SMPs, the necessity for developing a Timoshenko beam element becomes more prominent. This is due to the fact that relatively thicker beams are required in the design procedure of smart structures. Furthermore, in the design and optimization process of these structures which involves a large number of simulations, we cannot rely only on the time consuming 3D finite element (FE) analyses. In order to properly validate the developed formulations, the numeric results of the present work are compared with those of 3D finite element results of the same authors, previously available in the literature. The parametric study on the material parameters e.g., hard segment volume fraction, viscosity coefficient of different phases, and the external force applied on the structure (during the recovery stage) are conducted on the thermomechanical response of a short I-shape SMP beam. For instance, the maximum beam deflection error in one of the studied examples for the Euler-Bernoulli beam theory is 7.3%, while for the Timoshenko beam theory, is 1.5% with respect to the 3D FE solution. It is noted that for thicker or shorter beams, the error of the Euler-Bernoulli beam theory even more increases. The proposed beam element in this work, could be a fast and reliable tool for modeling 3D computationally expensive simulations.

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In this research, processing and 3D printing of PETG-ABS- Fe 3 O 4  nanocomposites reinforced with iron oxide nanoparticles in three different weight percentages of iron oxide nanoparticles with PETG70-ABS30 polymer matrix was done. This research was carried out with the aim of strengthening the shape memory properties, thermal properties, mechanical properties and adding the ability to indirectly stimulate the background matrix through the addition of iron oxide nanoparticles. SEM images confirmed that the mixture of PETG-ABS is immiscible and adding nanoparticles does not change the compatibility and miscibility of the base polymer, and this result is consistent with the DMTA analysis was also checked and confirmed. With increasing amount of iron oxide, the tensile strength and elongation decrease, and this decrease in mechanical properties is more pronounced in the sample of 20% by weight of iron oxide compared to the sample of 10% by weight. Nevertheless, the final strength of the samples is around 25 to 32 MPa, which indicates a suitable and acceptable distribution of nanoparticles up to 15% by weight in the polymer field. By increasing the amount of iron oxide nanoparticles, the amount of shape recovery increases and the nanocomposites containing 10, 15 and 20% by weight show shape recovery of 63.77%, 88.48 and 93.33%, respectively.

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Smart materials can react to environmental changes like living organisms and adapt themselves to environmental conditions and changes such as changes in temperature, electric current, magnetic field, light, humidity, etc. Using 3D printing to process smart materials is a new approach known as 4D printing. In this research, processing, manufacturing and 3D printing of PETG-ABS in three weight percentages of 70/30, 50/50 and 30/70 were done. The results of SEM also confirmed the compatibility of these two polymers. In all PETG-ABS mixtures, a combination of sea-island and drop-matrix morphology was observed, and for the 30/70 and 30/70 blends, phase droplets dispersed in the matrix were clearly observed. The results of mechanical properties also showed that as the percentage of ABS in the mixture increases, the tensile strength increases and the elongation decreases. The results obtained from the shape memory test indicate the existence of the ability to program the shape memory property in 4D printing mixtures. As expected, the increase in the weight percentage of ABS was associated with the disorder in the recovery of the mixtures, so the mixture with 70% by weight of PETG and 30% by weight of ABS showed the most favorable shape memory properties.