Abstract
BACKGROUND: Vibrations occurring during operation of land transport-technological machines deteriorate the quality of control, reduce the productivity of the work performed, adversely affect the health of machine operators. In order to reduce the impact of vibrations on the operators, vibration protection systems of the cab and seat are used.
AIMS: For practical application of the developed design of the passive vibration protection system of the motor grader operators seat on the basis of a parallelogram mechanism, tensile spring, cable and rollers, it is necessary to develop an algorithm for optimizing the values of design parameters.
METHODS: The mean square value of seat acceleration in a stationary reference frame, determined as a result of simulation of the motor grader motion over a set of stochastic microprofiles of the support surface with various characteristics and velocities, was used as an optimization criterion. Comprehensive simulation mathematical model of a motor grader with cabin vibration protection supports and vibration protection system of a seat was used. All parameters of the optimization algorithm and model were divided into fixed, random and varying ones. The latter include a number of dimensions of the parallelogram mechanism of the seat vibration protection system, the coefficient of viscous friction of the mechanisms shock absorber, the height of the quasi-zero stiffness zone. The dependence of the criterion on the design parameters of the seat vibration protection mechanism, which has an implicit pattern and is determined by means of a simulation mathematical model, served as the target function. Boundary conditions were imposed on a number of parameters to ensure the operability of the mechanism, manufacturability of its parts as well as ergonomic considerations. Optimization of the values of the varying parameters was performed with the simplex method. At the same time, a part of the parameters unambiguously influencing the value of the target function was preliminarily maximized or minimized within the boundary ranges.
RESULTS: An algorithm for assignment and optimization of design parameters of the vibration protection system of a motor grader seat with quasi-zero stiffness is developed, one of the key features of which is the possibility to adjust the vibration protection system of the seat to the weight of the current operator. Examples of algorithm application are given.
CONCLUSIONS: The algorithm makes it possible to determine the optimal values of design parameters of the seat vibration protection system based on a parallelogram mechanism such as: the dimensions of the parallelogram mechanism, including the attachment points of rollers and cable, the coefficient of tensile spring stiffness, the coefficient of viscous friction of a shock absorber, the parameter of adjusting the mechanism to the weight of the current operator. The key feature of the developed vibration protection system and the optimization algorithm of its design parameters is the possibility of adjustment to the weight of the current operator.