Design and FEM analysis of hatch ramps for sea freight transport

Abstract

The capping ramp is a movable bridge between the ferry and the port during the disembarkation of land, sea and rail vehicles over the ferry to unload their cargo. It is a bridge that can be raised and lowered by means of hydraulic cylinders and placed on the ship to reduce the static and dynamic level differences that may occur in this way in unit distance and to minimize the ramp climbing angle of these level differences, especially in railway vehicles. Ferries are equipped with rail channels and rails to carry railroad vehicles. In this study, the static analysis of the hatch ramp is carried out by finite element method. In the study, the ramp, which consists of four slices, is designed so that a row of wagons can pass over each slice and one loaded truck can pass over each slice. The total wheel mass of each wagon is 100000 kg, and the total wheel mass of the truck is 33500 kg. Since the ramp slices were designed to be equivalent, the rails on the ramp had to coincide with those on the ship, which caused small differences between them. Since this does not affect the results of the finite element analysis, there is no need to calculate each slice separately. The model was built to cover two slices and half of the fixed part. A half model was prepared according to the symmetrical axis parallel to the YZ plane and finite element analysis was performed. The entire ramp beam was modeled, and the semi-model was not used because it is simpler in structure than the ramp. Since it carries only the weight of the ramp, it was modeled and calculated separately. The deflection caused by the wagon is 29 mm and the deflection ratio is 1/700. According to the yield strength, the safety coefficient is 1.87. The weight of the beam itself and the weight of the ramps cause a deflection of 41.5 mm at the midpoint and the deflection value according to the beam length is 1/500. The safety coefficient of the beam is 1.64. It is seen that the stress and deflection values of the beam meet the expectations. As a result, it was found that the compound stress values were satisfactory, and the stress and deflection values met the expectations.