JUSTIFICATION OF TECHNIQUE FOR COMFORT AND SAFETY ANALYSIS AT PASSENGER TRANSPORTATION ON VIBRATION LOAD DECREASE OF PASSENGER CAR BODY

Abstract

The purpose of the work is to increase comfort and safety of railway passenger transportation, at the expense of passenger car body vibration load decrease. The analysis of the investigations carried out and dedicated to the definition of rigidity property impact upon the level of passenger comfort and traffic safety has shown that the first mode of vertical bending impacts considerably upon car body dynamic behavior. The analysis of vibration load impact upon passenger car body was carried out in accordance with Dumitriu’s technique. As apposed to the investigations carried out earlier in the paper the data on car metal structure acceleration are obtained through the methods of mathematical modeling based on solid and finite element models. On the basis of the data obtained and natural running tests there was created and verified a particularized lamellar finite-element model of a car body with the aid of which there were obtained values of vertical and horizontal accelerations of a car body metal structure. The analysis of the results obtained has shown that within the frequency range of 8.9. – 20 Hz there are observed acceleration surges which are among the most sensitive ones in terms of the impact upon man and transport comfort support. At the frequencies obtained there was carried out a passenger comfort investigation with the aid of which it was defined that at the frequency of car body own bending oscillations of 8.9 Hz – a comfort index is above 4 units that shows a low comfort level. A frequency of 8.9 Hz corresponds to a vertical bending mode which is the most significant mode of car body deformation in terms of passenger comfort support. With regard to this in the works there was offered a number of efficient measures for strengthening car body structure bearing capacity with the goal of its bending rigidity increase which provides an installation of a supplementary bearing partition in the mid-section of a car body, and also the introduction of auxiliary longitudinal elements in a frame supporting design. For the effectiveness assessment of measures offered there was carried out re-investigation according to the technique described. As a result of the computation it was defined that the design measures offered allowed increasing a frequency value of own bending vibration of car body metal structure up to 11.7 Hz. The analysis of the results obtained allowed drawing a conclusion of the effectiveness of design solutions offered on car body vibration load decrease.