International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In this paper is presented the optimal design of quarter car vehicle suspensions. During the optimisation the three design criteria which have been used are; vertical vehicle body acceleration, dynamic tire load and suspension working space. For implementing a optimization a comparison of two optimisation algorithms: Sequential Quadratic Program (SQP) and Genetic Algorithms (GAs). will be chosen five design parameters: sprung and un-sprung mass, spring stiffness, damping coefficient and tire stiffness. Through the simulation in Matlab it will be shown that GA is more powerful tool to find the global optimal point, without any restrictive requirements on the gradient and Hessian Matrix, while SQP has local convergence properties. The main focus of this research will be on minimising the vertical vehicle body acceleration subjected to a suspension working space and the dynamic tire load. At the end of this paper, it will be shown the comparison between the simulation carried out with nominal and optimal values of design parameters.

This paper deals with dynamic analysis of bridge crane with single girder in order to determine material deformations in their main parts – cables and girder’s, while moving and carrying load. It is known that these are mostly loaded parts in crane, while they accept forces, moments and oscillations from lifting mechanism and load. Analysis will be accomplished using computer modeling and simulations. Work process of crane in the study is forward travel motion. It is assumed that this motion process makes major impact in the deformations of lifting cables and girders due to stress, oscillations, and negative effect of load swinging. The analysis will be concentrated in finding the nature of oscillations that acts on crane and finding the extent and form of materials stress and deformations that can cause fatigue, failures and accidents. Question is whether acting loads exceed elasticity limits, or there are plasticity deformations which lead to permanent damages. Results will be shown in the form of diagrams, contour stress and strain in cables and girders. They will be compared with experimental measurements. Conclusions of these analyses can be useful for design considerations and safety.

This paper deals with the simulation of vertical displacement vehicle car body with one and two DOFs by using and comparing results of two softwares Working Model and MatLab. The aim of this paper was to show that is very easy is to solve the differential equations that describe both models of vehicle system with one and two DOFs. The results simulations performed with both software’s are almost the same for calculating displacement and velocity of sprung and unsprung mass and for different road excitations. The results of simulations have been analysed in terms of stability and road holding since sprung mass or vehicle body oscillations have direct impact on the passenger comfort.