SAILING YACHT MAST STRESS ANALYSIS IN THE GOOSENECK AREA
The article is devoted to the design of masts of sailing ships and yachts, in particular, to the study of the local stress-strain state (SSS) of the mast in the area of the boom gooseneck - one of the most loaded mast areas. The article provides a description and capabilities of the original technique for designing masts, developed at St. Petersburg State Marine Technical University and consisting of the MAST program module for determining wind loads on the spars and rigging and the FESTA program module for modeling and calculating the SSS and stability of the spatial cable-rod system consisting of mast an standing rigging with a gradual increase in wind loads up to the loss of the system’s overall stability. It is noted that in recent years the capabilities of these modules have been expanded and their interface has been improved. The article also shows how it is possible to evaluate the local strength and stability of the most loaded mast areas, such as the boom gooseneck attachment area. To do this, it is proposed to create a detailed spatial finite element model of the investigated area, on the boundaries of which it is necessary to set the displacements calculated in the FESTA module at the corresponding nodes using the «hard area» procedure. Examples of the calculation for a specific mast with circular tube cross section made of a polymer-composite material (PCM) with carbon-fiber reinforcement and an aluminum alloy are given. It turns out that the most stressed area of a PCM mast is the area directly under the booms gooseneck and for the same aluminum alloy mast, it is above the gooseneck. The failures of carbon-fiber masts known to the authors confirm the results of the calculations. Based on the results obtained, a conclusion is made about the effectiveness of using an external or internal thickening of the mast wall for a PCM mast by 50%, which makes it possible to reduce the largest local stresses by 25% and 20%, respectively. It is also concluded that a similar thickening for an aluminum mast is ineffective.