نشریه مکانیک مواد پیشرفته و هوشمند
سال سوم شماره 4 (پیاپی 10، زمستان 1402)

The development of the use of reinforced composites, as well as the increasing progress of technology in various industries, such as aerospace, biomedicine, and structures, has increased the investigation of production processes. Reinforcement of polypropylene composites with natural jute fibers is a suggested solution to protect the environment and also improve the quality of the composite. On this basis, it is necessary to study the effect of the influencing parameters on the manufacturing process of composites reinforced with jute fibers. In this research, by using existing linear regression equations, the sensitivity analysis of various parameters affecting tensile strength, flexural strength, and impact strength has been investigated. The effect of molding temperature parameters, compression pressure and compression time has been investigated using the E-fast sensitivity analysis method. Molding temperature is determined as the most influential variable in the compression molding process with the greatest impact compared to other variables. Compression pressure parameter and compression time are known as the second and third influential parameters after the mentioned parameter. The importance and influence of defined variables in the compression molding process will be considered in creating the desired quality and mechanical properties.

Due to the increasing use of new materials, such as auxetic structures, it is necessary to investigate mechanical phenomena, such as vibration, in structures made of these types of materials. This paper examines the forced vibrations of a three-layer cylindrical shell containing inviscid fluid under shock load. All three layers are made of aluminum, and the central layer is made of a re-entrant honeycomb cell structure. Using high-order shear deformation theories (HSDT) and Hamilton’s principle, the governing equations of the system have been extracted and solved by the Galerkin weighted residual method. The outputs of the Abaqus finite element software are used to validate the results. The system is investigated with both simple and clamped support conditions. Finally, this study investigates the influence of the geometrical parameters of the shell and the auxetic structure, as well as the type, intensity, duration, and location of the load, and the effect of the fluid on the dynamic and time responses.

In this research, aluminum reinforced continuous carbon fibre composite, was produced with A356 aluminum alloy and PAN base carbon fibre and carbon felt and then flexural and tensile strength properties has been investigated. For this purpose, at the first carbon fibre were coated with a different thickness of nickel layers by electroless method, and the effect of nickel layer thickness on surface condition and tensile strength of the carbon fibre were investigated. Composite samples with0.3 volume fraction of felt and fiber, were produced using nickel coated and uncoated carbon fibre by squeeze casting method. Samples were made at 30 Mpa applied pressure and the microstructure and flexural and tensile strength of them were investigated. The study of coated carbon fibre’s surface condition, showed that the minimum thickness required to form a continuous coating of nickel on carbon fibre is about 0.5µm. The increment of the thickness of coating layer, decreased the overall strength of the fibre. The study of tensile strength of composite samples made using nickel coated and uncoated carbon felt and fibre, showed that the nickel coating has a strong effect on tensile strength of the composite and causes increment in tensile strength as many as three times. For composite samples made with 0.3 volume fraction of nickel coated carbon fibre and felt, the maximum tensile strength was achieved in 30 Mpa applied pressure in amount of 463 Mpa Which is related to carbon felt.

This research examines the elastic property as one of the mechanical properties and antibacterial properties of cellulose nanoparticles and rosemary plant extract and their effect on the overall performance of epoxy biocomposites based on cellulose nanoparticle and rosemary extract. In this article, rosemary plant is used to determine the antimicrobial activity. At first, the samples were made for uniform distribution with four weight percents (pure, 0.5%, 1%, 1.5%, 2%) of rosemary extract, nano cellulose and the combination of extract and nano cellulose.Then the samples were subjected to tensile test and the results indicate that the Young's modulus started to increase from 0.5% by weight and the highest Young's modulus is obtained at 1.5% by weight of the reinforcements. Also, the mechanical properties of the samples started to decrease at 2% by weight, which can be due to the clumping or agglomeration of non-reinforcers in the epoxy, which reduces its mechanical properties. In the antibacterial test, based on the results, Escherichia coli bacteria did not show sensitivity to rosemary extract and no lack of growth was observed. This is while Staphylococcus aureus bacteria showed sensitivity to rosemary extract and recorded a 20 mm diameter halo. Finally, Staphylococcus bacteria is sensitive to the manufactured biocomposites and the best antibacterial performance was observed in the hybrid biocomposite at 2% by weight.

he engine, which is under to various mechanical and thermal loads. In this study, thermoelastic analysis has been performed on a rotating disk with variable thickness and made of functionally graded materials using the generalized quadratic differential method. First, by expanding the displacement differential equation and then by applying the thermal strain caused by the thermal gradient, the radial and circumferential stress-strain relations in the elastic state and from the combination of these equations, the stress relations in terms of strain are obtained. Finally, by placing the strain-displacement relationships in the stress-strain equations and placing the resulting equation in the disk equilibrium relationship, the thermo-elastic equation of this disk is obtained. This general equilibrium equation is related to a disk with variable thickness and properties that is under symmetrical thermal loading and centrifugal. Changes in the thickness, temperature and properties of the disc as a function of the radius have been investigated and the results have been compared. In this study, the validation was done with the variable material theory method and at the end, the stress, strain and displacement in the state of temperature-dependent properties was checked. The results show that the maximum error is 5% and this method can be effective in the analysis of rotating disks under mechanical and thermal loading in turbine engines.