Keywords:2D-FGM Rules of mixture Volume fractions Elastic-plastic material model Temperature dependent material properties Thermal stresses Thermal and structure finite element analysis a b s t r a c tThe two-dimensional functionally graded materials, (2D-FGMs) have been recently introduced in order to significantly reduce the thermal stresses in machine elements that subjected to sever thermal loading. To the author's knowledge no work was found that investigates the elastic-plastic stress analysis for 2D-FGMs. In the current work, a 3D finite element model of 2D-FGM plates made of ZrO 2 , 6061-T6 and Ti6Al-4V with temperature dependent material properties has been proposed to perform such analysis. An elastic plastic stress-strain relation based on the rule of mixture of the 2D-FGM has been introduced in the model. Also, a 3D finite element model of conventional FGM plates, of ZrO 2 /Ti-6Al-4V and ZrO 2 / 6061-T6, with temperature dependent material properties has been proposed for the investigation of these plates too. Then, elastic-plastic stress analysis of the considered four plates (two conventional FGMs and two 2D-FGMs) under the same transient cyclic heating and cooling was carried out. It was found that heat conductivity of the metallic constituents of FGM has great effect on the temperature distributions that resulting from the thermal loads. Minimum temperatures variation and minimum stresses can be obtained using ZrO 2 /6061-T6/Ti-6Al-4V 2D-FGM. Also, the results indicate that only ZrO 2 /6061-T6/Ti-6Al-4V 2D-FGM can stand with the adopted sever thermal loading without fracture or plastic deformations.

Slippage of bolted joints is an important factor in the behavior of transmission towers. Field inspections of towers located in the northern regions of Canada show substantial frost-heave induced displacements. The conventional structural analysis software solutions for tower leg axial forces, based on idealized joint behavior under field-observed frost-heave induced displacements, are excessively large, implying tower failure in some cases. However, field inspections show structurally stable towers, and design engineers often consider joint slippage as the main reason for this discrepancy. In this paper, the experimental slippage behavior of transmission-tower bolted joints investigated by Ungkurupanian (2000) is incorporated into a non-linear joint finite element and applied to study the behavior of transmission towers under working loads by using the finite element method. The analysis shows that tower-leg joint slippage has a significant influence on tower behavior by either reducing the load carrying capacity or significantly increasing the deflections under working loads. On the other hand, joint slippage has a positive effect on towers subjected to frost-heave induced displacements, as the resulting member axial forces are much lower than those corresponding to rigid joints.

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This manuscript aims to study the effects of drilling factors on the thermal-mechanical properties and delamination experimentally during the drilling of glass fiber reinforced polymer (GFRP). Drilling studies were carried out using a CNC machine under dry cutting conditions by 6 mm diameter with different point angles of ∅ = 100°, 118°, and 140°. The drill spindle speed (400, 800, 1600 rpm), feed (0.025, 0.05, 0.1, 0.2 mm/r), and sample thickness (2.6, 5.3, and 7.7 mm) are considered in the analysis. Heat affected zone (HAZ) generated by drilling was measured using a thermal infrared camera and two K-thermocouples installed in the internal coolant holes of the drill. Therefore, two setups were used; the first is with a rotating drill and fixed specimen holder, and the second is with a rotating holder and fixed drill bit. To measure thrust force/torque through drilling, the Kistler dynamometer model 9272 was utilized. Pull-in and push-out delamination were evaluated based on the image analyzed by an AutoCAD technique. The regression models and multivariable regression analysis were developed to find relations between the drilling factors and responses. The results illustrate the significant relations between drilling factors and drilling responses such as thrust force, delamination, and heat affect zone. It was observed that the thrust force is more inspired by feed; however, the speed effect is more trivial and marginal on the thrust force. All machining parameters have a significant effect on the measured temperature, and the largest contribution is of the laminate thickness (33.14%), followed by speed and feed (29.00% and 15.10%, respectively), ended by the lowest contribution of the drill point angle (11.85%).

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In this paper the finite element simulation is exploited to investigate dynamical behaviors of perfect and defected Single Walled Carbon Nanotube (SWCNT). The natural frequencies, mode shapes and modal participation factors those not be considered elsewhere, are consider through this analysis. Energy equivalent model is adopted to find a linkage between the energy stored in chemical atomic bonds and potential energy stored in mechanical beam structure. Nanotube software modeler is used to generate a geometry of SWCNT structure by defining its chiral angle, length of nanotube and bond distance between two carbon atoms. The whole tube of SWCNT is simulated as cage and bonds between each two atoms are represented by beam (A BEAM 188) with circular cross section, and carbon atoms as nodes. Numerical results are presented to show the fundamental frequencies and modal participation factors of SWCNTs. The effect of vacancies on activation and deactivation of vibration modes are illustrated. During manufacturing of SWCNTs, atoms may be not perfectly bonded with adjacent and some vacancies may be found, so this defect is considered in this study.