فهرست مقالات Elastic modulus

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  1 - Influence of argon gas flow on mechanical and electrical properties of sputtered titanium nitride thin films
  Kaykhosrow Khojier Hadi Savaloni Ebrahim Shokrai Zohreh Dehghani Naser Zare Dehnavi
  10.1186/2251-7235-7-37
  AbstractTitanium nitrides have good mechanical, tribological, electrical, biomedical, and optical properties; therefore, they are used to harden and protect cutting and sliding surfaces, as semiconductor devices, and as a nontoxic exterior for biomedical applications. T چکیده کامل

  AbstractTitanium nitrides have good mechanical, tribological, electrical, biomedical, and optical properties; therefore, they are used to harden and protect cutting and sliding surfaces, as semiconductor devices, and as a nontoxic exterior for biomedical applications. The dependence of the mechanical and electrical properties of titanium nitride thin films deposited on silicon substrates by direct-current reactive magnetron sputtering technique on argon gas flow (in the range of 8 to 20 sccm) was investigated. The crystallographic structure of the films was studied by X-ray diffraction (XRD), while surface morphology was studied using atomic force microscopy (AFM). Mechanical and electrical properties of these films were investigated by nanoindentation test and a four-point probe instrument, respectively. The XRD patterns showed titanium nitride (TiN) formation with a face-centered cubic structure for all samples. It was also observed that (111) crystallographic direction was the preferred orientation for TiN thin films which became more pronounced with increasing argon gas flow. The AFM images showed a granular structure for TiN layers. The hardness, crystallite/grain size (obtained from XRD and AFM), and surface roughness increased with the flow of argon gas, while elastic modulus and dislocation density in the films decreased. The study on electrical properties showed that the dependence of voltage with current for all samples was linear, and film resistivity was increased with argon gas flow. پرونده مقاله
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  2 - Semi Analytical Analysis of FGM Thick-Walled Cylindrical Pressure Vessel with Longitudinal Variation of Elastic Modulus under Internal Pressure
  M Shariati H Sadeghi M Ghannad H Gharooni
  In this paper, a numerical analysis of stresses and displacements in FGM thick-walled cylindrical pressure vessel under internal pressure has been presented. The elastic modulus is assumed to be varying along the longitude of the pressure vessel with an exponential func چکیده کامل

  In this paper, a numerical analysis of stresses and displacements in FGM thick-walled cylindrical pressure vessel under internal pressure has been presented. The elastic modulus is assumed to be varying along the longitude of the pressure vessel with an exponential function continuously. The Poisson’s ratio is assumed to be constant. Whereas most of the previous studies about FGM thick-walled pressure vessels are on the basis of changing material properties along the radial direction, in this research, elastic analysis of cylindrical pressure vessel with exponential variations of elastic modulus along the longitudinal direction, under internal pressure, have been investigated. For the analysis of the vessel, the stiffness matrix of the cylindrical pressure vessel has been extracted by the usage of Galerkin Method and the numerical solution for axisymmetric cylindrical pressure vessel under internal pressure have been presented. Following that, displacements and stress distributions depending on inhomogeneity constant of FGM vessel along the longitudinal direction of elastic modulus, are illustrated and compared with those of the homogeneous case. The values which have been used in this study are arbitrary chosen to demonstrate the effect of inhomogeneity on displacements and stress distributions. Finally, the results are compared with the findings of finite element method (FEM). پرونده مقاله
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  3 - A Study on the Quasi-static Compression Behavior of 5056 Aluminum Alloy Foams
  Sadegh Soltani Hamed Deilami Azodi Seyed Hossein Elahi
  In this paper, 5056 aluminum alloy foams with different percentages of calcium carbonate as foaming agents have been produced, and the physical and mechanical properties of the foams have been studied. Quasi-static compression tests have been carried out to determine th چکیده کامل

  In this paper, 5056 aluminum alloy foams with different percentages of calcium carbonate as foaming agents have been produced, and the physical and mechanical properties of the foams have been studied. Quasi-static compression tests have been carried out to determine the mechanical properties of foamed material. The effects of the amount of calcium carbonate on the size of the pores, the minimum thickness of the walls, density, compressive strength and energy absorption capacity of foams have been investigated. The uniform structure of the pores has been observed in foam specimens with 1.5, 1.8 and 2.1 wt% CaCO3. Increasing the amount of CaCO3 foaming agent from 1.5% to 2.1% has increased the average size of the pores by more than 180% and reduced the thickness of cell walls by 90%. So, the density and the relative density of the aluminum foams have been reduced by 28.6%. The results also show that increasing the amount of CaCO3 foaming agent decreases compressive strength, the absorbed energy and the elastic modulus of 5056 aluminum foams. By increasing the amount of foaming agent from 1.5% to 2.1%, the elastic modulus has reduced by about 16%, and a decrease of 21% has been seen in the energy absorbed by the foam at the strain of 0.4. پرونده مقاله
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  4 - Molecular simulation for prediction of mechanical properties of polylactic acid polymer for biotechnology applications
  Amin Mansouri Ali Heidari Fatemeh Karimian Amir Mohammad Gholami Mehran Latifi Sheyda Shahriari
  Development of materials for use in medicine and industries is one of the biggest challenges in research in materials science. Today, absorbable, biocompatible and biodegradable polymers have been identified to be used as alternative materials for biomedical application چکیده کامل

  Development of materials for use in medicine and industries is one of the biggest challenges in research in materials science. Today, absorbable, biocompatible and biodegradable polymers have been identified to be used as alternative materials for biomedical applications. Among the biomaterials used in medical fields, polylactic acid (PLA) have been considered widely. This polymer obtained from completely renewable sources and due to their good physicochemical properties in various industries it is highly recommended. The purpose of this study was to introduce PLA mechanical properties using molecular dynamics (MDs) simulation. The special advantage of PLA over other polymers is its biodegradation, which is generally degraded by a single-step process involving a bacterial attack on the polymer itself. It is easily degraded in atmospheres with high humidity and temperatures of 50-70°C. However, at lower temperatures or lower humidity, the stability of PLA products is higher. The MD analysis indicates that the density value corresponds well to the experimental values. Based on the molecular model, the elastic modulus properties of the model were investigated. In this study, the average elastic modulus of the molecular PLA model was calculated to be about 2.2 GPa. پرونده مقاله
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  5 - Neural network in predicting the mechanical strength of Al6061/SiC composites used in aerospace industries
  سید رحیم کیاحسینی
  In this research, the effect of three parameters, the percentage and type of SiC reinforcing material and the type of thermal cycle of composite manufacturing on the elastic modulus, yield strength and ultimate strength of Al/SiC composite have been investigated. For th چکیده کامل

  In this research, the effect of three parameters, the percentage and type of SiC reinforcing material and the type of thermal cycle of composite manufacturing on the elastic modulus, yield strength and ultimate strength of Al/SiC composite have been investigated. For this purpose, the information related to composite with Al6061alloy reinforced with SiC particles was extracted. After normalizing the input and output information, the perceptron recurrent network was designed and it was tried to extract the optimal parameters by changing different parameters of the network such as the frequency of network training, changing the learning coefficient of the network and weight and bias coefficients and comparing the sum of squared errors in different conditions. Finally, by defining the adaptive learning coefficient in the network, it was tried to improve the speed and accuracy of the network. The results showed that by repeating the network training 10000000 times, the sum of squares of error was reduced to the range of 7-10. Also, the lowest error sum of squares is related to the learning coefficient α=0.002. The results related to the definition of the adaptive learning coefficient showed that if the network is trained 100,000 times, the training speed decreases to 60,000 times with the same error for the adaptive learning coefficient and the constant learning coefficient. In other words, if the adaptive learning coefficient is used, the training speed and error reduction will be higher than using the constant learning coefficient. پرونده مقاله