Iranian Journal of Mechanical Engineering Transactions of ISME
Volume:20 Issue: 2, Sep 2019

The various industrial and engineering applications of flow of fluid between parallel plates have continued to generate renewed interests. In this work, a comparative study of approximate analytical methods is carried out using differential transformation,homotopy perturbation, Adomian decomposition, variation of parameter and variational iteration methods for the analysis of a steady two-dimensional axisymmetric flow of an incompressible viscous fluid under the influence of a uniform transverse magnetic field with slip boundary condition. From the results, it is established that, the result of DTM and VPM shows to be more convenient for engineering calculations compared to the HPM as it appears more appealing than the HPM.  Also, effects of pertinent flow, magnetic field and slip parameters are studied. By comparing the results of approximate analytical methods in this work with the numerical method using Runge-Kutta coupled with shooting method, the validity and the accuracy of approximate analytical solutions are established.

Rotating machinery support design with the aim of reducing the force transmitted to the foundation has significant importance regarding the various applications of these machineries. In this paper presents a rapid approximate method for calculating the optimum support flexibility and damping of flexible rotors to minimize force transmissibility in the vicinity of the rotor first critical speed. First, the governing equations for the Jeffcott rotor model mounted on flexible supports are derived and the optimal parameters for the supports have been analytically achieved. Next with consideration of the complexity and tedious of the analytic equations, a numerical algorithm for determination of the optimal support design parameters is introduced which may be applied to any rotor model regardless of the model complexity and number of degrees of freedom. The simulation results show the effect of optimal parameters on the considerable reduction of the force transmitted to the foundation. The method has the advantage of being quickly and easily applied and can reduce analysis time by eliminating a time consuming search for the approximate optimum damping using more exact methods.

The main purpose of this study is to estimate the step heat fluxes applied to the wall of a two-dimensional symmetric channel with turbulent flow. For inverse analysis, conjugate gradient method with adjoint problem is used. In order to calculate the flow field,   two equation model is used. In this study, adjoint problem is developed to conduct an inverse analysis of heat transfer in a channel turbulent fluid flow. The primary purpose is to find suitable number of sensors at each half of the channel’s wall and an appropriate space on the wall for locating the sensors. The innovate aspect of the study is to find out ideal length of the channel’s wall on which sensors are located.

This work presents the effects of strain rate on the tensile properties and fracture morphologies of AHSS-DP 350/600 subjected to LSP. Fatigue crack growth test was performed to evaluate fatigue behavior in the metallic plate of AHSS-DP350/600. However, this material is used in automobile industry and enhancing it fatigue resistance is a challenge in material engineering. In order to evaluate and compare the influence of the microstructure on their mechanical and chemical properties, tensile and hardness test were performed and analysis. This revealed that the LSPed specimens have higher values of yield stress, maximal stress, Young’s modulus than non-LSP specimens, the elongation and hardness as a result of their porosity and pore size influenced. It was observed that the macroscopic (tensile tests) and microscopic (microhardness tests) properties of the non-LSP are sensitive to these defects generated during the material machining process and LSP specimens could prolong the material working life.

This paper presents an analytical solution for an orthotropic circular cross section bar with a magnetic coating weakened by multiple arbitrary oriented cracks under Saint-Venant torsion by means of the distributed dislocation technique. At first, the solution of the orthotropic bar with a magnetic coating weakened by a Volterra-type screw dislocation is achieved with the aid of the finite Fourier sine transform. Next, the problem is then reduced to a set of singular integral equations with a Cauchy type singularity. Unknown dislocation density is achieved by numerical solution of these integral equations. Finally, several examples are solved and numerical results are discussed to reveal the effect of the magnetic layer on the reduction of the mechanical stress intensity factor in the bar.

In this research, effect of opening on the buckling of FMLs (Fiber Metal Laminate) is studied. Samples are made of a laminate, epoxy resin reinforced with four layers of woven basalt fibers, inserted between two Al plates. Different samples are prepared, tested and studied; one group without opening and the other two groups with circular openings of radii 10 and 20 mm. In all samples buckling is associated with de-bonding. Post-buckling behavior is studied. Plasticity in Al plates and damage in composite laminate are detected in samples with opening which make their repair challenging and risky. Nevertheless, repair of samples without opening are straightforward because of the fact that neither of the above phenomena are spotted in these samples.

Design of a new intelligent driver assistance system based on traffic sign detection with Persian context is concerned in this paper. The primary aim of this system is to increase the precision of drivers in choosing their path with regard to traffic signs. To achieve this goal, a new framework that implements fuzzy logic was used to detect traffic signs in videos captured along a highway from a vehicle. Implementing fuzzy logic in smart systems increases its inference and intelligent capabilities that results in better decision making in real-time conditions. In order to detect road sign’s texts, the combination of Canny Edge Detector Algorithms and Maximally Stable Extremal Regions (MSER) is used. Regions of an image that vary in properties, such as color or brightness, with respect to surrounding regions, are detected with the help of MSER algorithm. By using a multi-stage algorithm, Canny edge detector detects a wide range of edges in the acquired images. In order to join the individual characters for the final stage of detection of texts in traffic signs, a morphological mask operator is used. Finally, the recognition of the detected texts is carried out by employing MATLAB Optical Character Recognition (OCR). The overall accuracy of this new framework in detecting and recognizing texts is 90.6%.