جستجوی مقالات مرتبط با کلیدواژه « خاک رس » در نشریات گروه « مکانیک »

Intermittent drying is an effective strategy for improving the drying kinetics, energy consumption as well as, the quality of the dried products. The aim of this study is to investigate the effect of the period of intermittent drying on the drying kinetics and the induced stresses. To this end, a clay like material is used and by changing the air relative humidity periodically, the stresses induced were determined. Parameters variation with moisture and temperature are considered in modeling. Good agreement between experimental and simulation variables results reveals that the model developed is valid and accurate. Simulation results suggest that the drying rate should be kept at its minimum at the stage of disruption of hydraulic continuity. Due to the gradual disruption of capillary tubes in transition period, the part is affected gradually, and this necessitates the possible crack deformation points of the part to be sought simultaneously. Also, the current work studied the magnitude of each of stresses induced by non-uniform moisture distribution and stresses induced by non-uniform temperature distribution. It is shown that the thermal stresses are negligible compared to the moisture stresses and can be neglected in drying modeling.

In the present paper, to determine the pressure-dependent yield surface of polypropylene/nanoclay nanocomposites, the extended Drucker-Prager yield criterion is used and its parameters are derived by a combined experimental/numerical/optimization approach. In this method, the difference between the experimental and numerical results obtained from three-point bending test is minimized. In order to alleviate the burdensome numerical simulation, a surrogate model based on Kriging method is used to estimate the cost function. The optimum of this function is obtained by maximizing expected improvement method. Afterward, the results are verified by tension and compression tests. The results show that this method can substitute the complicated experimental tests which are normally employed to identify the extended Drucker-Prager parameters. Also, this method can be used to determine the mechanical properties of thermoplastic material such as tensile and compressive yield stresses and elastic modulus using only a three-point bending test. In addition, it is found that the volumetric change of thermoplastic during plastic deformation is significant and the non-associative, compared with the associative, plastic flow assumption is more proper for this material for the extended Drucker-Prager criterion.

In this study، various amounts of clay nanoparticles and titan nanoparticles (1، 3 and 5% wt.) were introduced into a vinyl ester resin matrix by high shear mixer. The influence of these nanoparticles on the mechanical properties (tensile strength، tensile modulus، flexural strength، flexural strength and fracture toughness) is investigated. To investigate the structure of nanocomposites، X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests are done. The XRD test shows that the structure of clay-vinyl ester nanocomposites is exfoliated. The results of tensile، flexural and fracture toughness experiments show that clay is better than titan in the improvement of the mechanical properties. Clay- vinyl ester nanocomposite with 1% wt. of clay has the better mechanical properties than others samples.

Abstract-In this study,nanocomposites based on polypropylene and polyethylene containing 0 to 7phr of nanoclay and 3phr of maleated polypropylene (PP-g-MA) and maleated polyethylene (PE-g-MA) as compatibilizer were prepared by melt compounding followed by injection molding.Morphology of the mixtures was carried out through Field Emission Scanning Electron Microscopy (FESEM). Mechanical properties of different samples were examined empirically by tension and izodimpact tests.Test results show that the addition of clay particles to the PP and LLDPE, increases the tensile strength, yield strength, tensile modulus and decreases impact strength and elongation at break compared to pure polymer.Themixture design method and Minitab16 software were utilized for designing the tests, statistical analyses, and optimization the mechanical properties of the mixtures.Results showed that the in compounds based on polypropylene and polyethylene, respectively, compounds includes 3.96 and 2.12percent clay has the best mechanical properties.blends base on PP have better tensile modulus and LLDPE blends have better impact strength.