The unrestrained torsional analysis of bars is an important theme in elasticity theory, first solved by Saint-Venant using semi-inverse methods. It has been considered and solved by several others using analytical methods and numerical procedures due to the importance in the design of machine parts under torsional moments. In this paper, the Saint Venant torsion problem is solved for rectangular prismatic bars using Galerkin-Kantorovich variational method (GKVM). The work presents a detailed theoretical framework of the problem, deriving using first principles considerations the stress compatibility equation in terms of the Prandtl stress function ϕ(x,y). The derived domain equation which is required to be satisfied over the rectangular cross-sectional domain is a partial differential equation of the Poisson type. GKVM is adopted as the solution method for finding the solution to the domain equation. The unknown Prandtl stress function ϕ(x,y) is assumed, following Kantorovich method to be a product of an unknown function for fx sought to minimize the Galerkin-Kantorovich variational functional (integral) (GKVF) and a known function (y2-b2) which satisfies the boundary conditions at all boundary points in the y-direction, that is, at y=±b. The resulting GKVF is a simplified functional whose integral is a second order inhomogeneous ordinary differential equation (ODE) in fx. The integrand is solved to find fx leading in a full determination of the Prandtl stress function. The expression for stresses, torsional moments and torsional parameters are then found and they satisfy the boundary conditions and the domain equation. The results for the torsional moments and torsional parameters are identical to previous results obtained using double finite sine transform method (DFSTM), and analytical methods. The merit of GKVM is that it has led to the exact solution of the unrestrained torsion problems.

The performance of vehicle body vibration and ride comfort of active or semi-active suspension with proper control is better than that with passive suspension. It is important to use simple, reliable, effective and low-cost optimal control methods to control the vehicle suspension. An important issue in the optimal control of vehicle semi-active suspension is to determine the weighting coefficient reasonably. This paper established a whole-car model of semi-active suspension systems with 7 degrees of freedom in Matlab, built optimum control system with system function, and then optimized the weight of control system by Particle Swarm Optimization (PSO) [1]. The results show that under different road input, the seven-degree-of-freedom control model for the whole vehicle controlled by particle swarm optimization algorithm can obtain better control effect, and effectively improve the comprehensive performance of the semi-active suspension system, both the vehicle's ride comfort and handling stability.

The dynamic characteristic of the timing system has a significant impact on the performance of the engine's NVH. With low contact stress and strong anti-interference ability, the arc tooth synchronous belt was adopted by engine timing transmission system. The multi-body dynamics model of the in-line four cylinder engine timing system was established. We explored the influence of crankshaft speed and initial tension on the dynamic performance of the engine timing system. The result shows when the crankshaft speed V= 2000 r/min and the initial tension of the synchronous belt F= 300 N, the load distribution of the RU type synchronous belt teeth root is more uniform. The stress is 0.2474 N/mm2 lower than the average value, and the transverse vibration amplitude decreases by 0.3067 mm. Under this circumstance, the fluctuation amplitude of camshaft angular velocity is 6.5312 rad/s lower than the maximum average amplitude, so the transmission error is reduced by 37.95 %. The fluctuation amplitude of interference value decreases by 0.3413 mm, and the fluctuation amplitude of interference velocity decreases by 263.8908 mm/s. The synchronous belt based engine timing transmission is more stable and the dynamic performance is better. It laid a solid foundation for the optimization of the tooth profile and load conditions of the engine timing system.

The contemporary deployment of unmanned aerial vehicles (UAVs) for commercial purposes and electromagnetic pulse (EMP) threat to mechatronic devices necessitates the study of EMP on surveillance UAVs. This research paper describes the effect of EMP interference on the structure, communication and cabling circuit of the UAV. This was achieved using the CST microwave studio with an induced plane wave referring to MIL-STD464 and applying the transmission line matric solver method. The cable field coupling for bi-directional, uni-directional radiation and uni-directional irradiation were carried out with a constant resistive load of 50 Ω and the induced coupling currents and voltages, current in space domain, TLM mesh is obtained indicating the susceptibility of the UAV under different conditions of EMP interference and the electromagnetic distribution in the UAV circuit layout. Experimentally, the UAV is setup with an EMP generator and its response was observed at 12 m, 10 m and 8 m from the radiation source with the corresponding field strengths.

Property of flow field over a dynamic body has extensively been considered as a topic of interest in recent past as an aerodynamic and futuristic solution. However, a stiff object of common shape is fixed inside a wind tunnel. The drag force asserted on it by the wind is ascertained by a new method based on plain fundamental Physics ideas, provided one has a solver, any solver, for the resembling dynamic Navier-Stokes equation which determines the wind velocity field around the object. The method is completely usual, but here we apply it to the conventional problem of a long cylinder vertical to the wind. For different Reynolds number the comparative analysis between the flow characteristics of non-rotating and rotating cylinder has been done here. And for the rotating cylinder two rotational speeds have been provided to analyze and compare the effects. Main focus of this study is to determine the characteristics of flow field created over a rotating cylinder and non-rotating cylinder and also find out the variation of this effect over different flow velocities and rotational speeds. This study differentiates among the performances and sets up characteristics graphs which helps to find out more scopes about flow field. The main inspiration behind this study is to find out the Magnus effect asserted on an object in motion. The slightest variation of flow field leads to a certain amount of impact which can be a futuristic solution for energy problems. So, an attempt has been made to find out this variation using closed loop wind tunnel and a bluff body, in this case a cylinder. Flow over the cylinder when it has a certain rpm significantly changes than that of when it is not rotating and for different rotational speeds change is even more noticeable. It is suggested to use a subtle Pitot-Static Tube for measuring the velocity.

In order to evaluate the influence of the dynamics parameters of the electric vehicles on the ride comfort, an electric vehicle dynamic model is established to simulate under various operation conditions of the electric vehicles. The electric vehicle dynamic equations and parameters are then solved based on the Simulink model built on Matlab software. The acceleration responses at centre of gravity of the vertical and pitching electric vehicle vibrations are two objective functions. The research results show that the ride comfort of electric vehicles is greatly influenced by their dynamics parameters and strongly reduced in comparison with the traditional vehicles. Therefore, the electric vehicles equipped with in-wheel motors should be optimized or controlled to improve the ride comfort.

In order to study the influence of heavy truck dynamic parameters on the vehicle’s ride comfort under the random road excitation, the weighted RMS (root-mean-square) acceleration responses of the vertical driver’s seat and cab pitch angle are chosen as objective function, a dynamic model of the vehicle with 10 degrees of freedom is established to simulate and analyze the results. The influence of different parameters of all the suspension systems of the vehicle, such as the stiffness and damping of the suspensions of the seat, cab, vehicle, and wheel, on the vertical driver’s seat and cab pitch angle are respectively analyzed. The study results show that the influence of the stiffness and damping parameters in the suspension systems on the vehicle ride comfort is very obvious. The vehicle’s ride comfort changes worse with the increase of the suspension stiffness and the reduction of the suspension damping, and vice versa. The study proposes an optimal range of the stiffness and damping parameters for the optimal design and control of the vehicle suspension systems, concurrently, the study can also provide a theoretical basis for the suspension system designed for heavy trucks.