Papers by Salman Ebrahimi-Nejad
Materials Research Express
Mechanics & Industry
In this paper, first, the vibrational governing equations for the suspension system of a selected... more In this paper, first, the vibrational governing equations for the suspension system of a selected sports car were derived using Lagrange's Equations. Then, numerical solutions of the equations were obtained to find the characteristic roots of the oscillating system, and the natural frequencies, mode shapes, and mass and stiffness matrices were obtained and verified. Next, the responses to unit step and unit impulse inputs were obtained. The paper compares the effects of various values of the damping coefficient and spring stiffness in order to identify which combination causes better suspension system performance. In this regard, we obtained and compared the time histories and the overshoot values of vehicle unsprung and sprung mass velocities, unsprung mass displacement, and suspension travel for various values of suspension stiffness (KS ) and damping (CS ) in a quarter-car model. Results indicate that the impulse imparted to the wheel is not affected by the values of CS and K...
Journal of Intelligent Material Systems and Structures
This article investigates quasiperiodic energy harvesting in a nonlinear vibration-based harveste... more This article investigates quasiperiodic energy harvesting in a nonlinear vibration-based harvester, consisting of delayed nonlinear vibrations from magnetic levitation subjected to harmonic base acceleration, in which time-delay is introduced. For energy harvesting, a coil made up of seven layers of 36 gauges wound around the outer casing is utilized. The first- and second-order perturbation approximations are used to obtain the frequency responses of the power and vibration amplitudes in the vicinity of primary resonance. Numerical results are presented to verify the correctness of the analytical solutions. The results show that there is a good agreement between the second approximation and the numerical method; thus, we used the second-order perturbation to present the results. The impact of several parameters on the power and vibration amplitudes in the absence and presence of delay is studied. It was observed that using the nonlinear vibrations due to magnetic levitation in the ...
Materials Research Express
Automation in Construction
Journal of Construction Engineering and Management
The European Physical Journal Plus
Chaos, Solitons & Fractals
Acta Acustica united with Acustica
Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering
In accordance with the worldwide trend for developing energy-efficient vehicles and meeting envir... more In accordance with the worldwide trend for developing energy-efficient vehicles and meeting environmental regulations, there exists a large potential for decreasing energy losses due to tyre rolling resistance and significantly reduce fuel consumption and greenhouse gas emissions and also improve tyre tread durability. To achieve a quantitative estimate of tyre rolling resistance force, in the present paper, we carry out rolling resistance modelling in order to introduce a comprehensive relation for predicting rolling resistance force variations with speed taking into account the most influential parameters. To accomplish this goal, full three-dimensional finite element modelling of a visco-hyperelastic inflated rubber tyre under the deformation of vertical loading is performed and validated by making use of available test data. Free rolling simulations are performed and rolling resistance diagrams at various vehicle speeds and inflation pressures are extracted by analysing the resu...
International Journal of Vehicle Noise and Vibration
Materials Research Express
Materials Research Express
Materials Research Express
Physics, Chemistry and Applications of Nanostructures - Reviews and Short Notes - Proceedings of International Conference Nanomeeting – 2011, 2011
Polymer Testing, 2012
A predictive creep model is developed which uses the properties of matrix and reinforcement to pr... more A predictive creep model is developed which uses the properties of matrix and reinforcement to predict the creep of polymer/layered silicate nanocomposites. Up to this point, primarily empirical creep models such as Findley and Burgers models have been used for creep of polymer/clay nanocomposites. The proposed creep model is based on the elastic-viscoelastic correspondence principle and a stiffness model of these nanocomposites. Also, the added stiffness of polymeric matrix due to the constraining effect of layered silicates on polymer chains in the nanocomposite is considered by a parameter termed constraint factor. The results of the proposed model show good agreement with experimental creep data for different clay contents, stresses and temperatures. Comparing the model predictions with experimental data, a logical relationship between the method of processing and the constraint factor is discovered which shows that in-situ polymerization can be more efficient for improving creep resistance of polymer/layered silicate nanocomposites relative to melt processing.
physica status solidi (a), 2012
A. Shokuhfar et al.: Effect of temperature on the compressive buckling of boron nitride nanotubes... more A. Shokuhfar et al.: Effect of temperature on the compressive buckling of boron nitride nanotubes physica s s p status solidi a
Physica E: Low-dimensional Systems and Nanostructures, 2013
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Papers by Salman Ebrahimi-Nejad