Influence of the character of load distribution from the wheel on the structure of trailer ships according to the requirements of the Russian River Register

Abstract

The article analyzes the shape of the imprint and the nature of the pressure distribution over the contact patch from the wheels on rolling ships, required by the Rules of the Russian River Register (RRR). It has been found that the rectangular shape of the contact patch from the wheel prescribed by the RRR in most cases corresponds to real conditions. Distribution of uniform pressures along the length of the imprint of the wheel does not correspond to the actual picture, but in the direction of the width it is permissible. A formula is presented that describes a certain parabolic function and displays the form of non-uniform pressure along the contact patch. Using the specialized software complex FEMAP with NX NASTRAN, the finite element method was used to assess the stress-strain state of the floors of two trailer ships from the impact of the wheels of a truck and a car. The calculation was carried out taking into account two types of loads: with a uniform and parabolic nature of the pressure distribution along the contact patch. The peak value of the pressure with a parabolic shape turned out to be 1.5 times higher than with a uniform one. The difference in the results of the strength analysis for the maximum displacements and stresses in the beams was about 3%. At the same time, the highest stress values in the flooring, with different forms of pressure distribution over the wheel imprint, differ by 10–11%. The use of the proposed formula, which describes the parabolic nature of the load along the length of the contact patch, can be essential in determining the dimensions of the wheel imprint, the value of the maximum stress in the flooring, and the value of the admissible residual deflection of the flooring, in accordance with the requirements of the RRR Rules.