scholarly journals CALCULATION OF PARAMETRICAL VIBRATIONS OF A SHIP SHAFT LINE SUBJECT TO RIGIDITY OF A STERN BEARING

2017 ◽  
pp. 108-114
Author(s):  
Alexander Alekseevich Migunov ◽  
Victor Andreevich Mamontov ◽  
Aleksey Aleksandrovich Khalyavkin
Keyword(s):  
Dynamic Stability ◽  
Cross Section ◽  
Design Model ◽  
External Loading ◽  
Propeller Shaft ◽  
Shaft Line ◽  
Mathieu’S Equation

The paper studies parametrical vibrations of the ship shaft line, which arise because of harmonical change in time of rigidity of a propeller shaft and a stern bearing. The design model of a propeller shaft shows a beam with a cross section constant along its length, which leans on hinged immovable and springy support simulating a stern bearing. At the end of a beam there is a disk simulating a propeller screw. Parametrical vibrations arise due to the external loading and as a result of amortization of the stern bearing. In the analysis of parametrical vibrations of the ship shaft line there are used Mathieu's equation and Strutt-Ince diagram. Dynamic stability of a ship shaft line is defined subject to a gap between a propeller shaft and a stern bearing.

Influence of Shape of Coarse Aggregate on Performance of Open Graded Friction Course

2011 ◽  
Vol 239-242 ◽  
pp. 3266-3274
Author(s):  
Jin Xi Zhang ◽  
Chao Wang
Keyword(s):  
Wear Resistance ◽  
Bulk Density ◽  
Dynamic Stability ◽  
Cross Section ◽  
Coarse Aggregate ◽  
Void Content ◽  
Horizontal Cross Section ◽  
Important Material ◽  
Large Bulk ◽  
Open Graded Friction Course

As a new kind of pavement material, the Open Graded Friction Course (called OGFC) has many advantages, and so is rapidly popularized in China recently. However, the performance of OGFC decreases with the utilization of road, such as the decrease in permeability, durability and so on. In the present study, the influence of the shape of coarse aggregate, which is the most important material in OGFC, on the performance of OGFC was investigated in laboratory. The shape of coarse aggregate is indicated by the bulk density and total 4 kinds of aggregates with different bulk density were produced artificially and tested in this study. When the shape of coarse aggregate changed, the wear resistance and dynamic stability of OGFC also changed lightly. The bulk density of aggregate has no serious influence on the void content, but has obvious influence on the permeability of OGFC. The shape of continuous void in horizontal cross-section becomes rounder when the aggregate with large bulk density is used. The rounder continuous void is benefit for the flowing of water, so the permeability of OGFC is improved.

Static and Dynamic Stability Analysis of a Rotating Taper Beam Having Elliptical Cross Section Subjected to Pulsating Axial Load With Thermal Gradient

2019 ◽  
Vol 24 (3) ◽  
pp. 440-450
Author(s):  
Madhusmita Pradhan ◽  
Mrunal Kanti Mishra ◽  
Pushparaj Dash
Keyword(s):  
Dynamic Stability ◽  
Cross Section ◽  
Thermal Gradient ◽  
Axial Load ◽  
Equations Of Motion ◽  
Elliptical Cross Section ◽  
Energy Principle ◽  
Elliptical Cross ◽  
Static And Dynamic Stability ◽  
Hill’S Equations

The static and dynamic stability of a rotating tapered beam having an elliptical cross-section subjected to a pulsating axial load with a thermal gradient is investigated under three different boundary conditions, such as clampedclamped (C-C), clamped-pinned (C-P), and pinned-pinned (P-P). The governing equations of motion have been derived by using Hamilton’s energy principle. A set of Hill’s equations have been obtained by the application of generalized Galerkin’s method. The effects of taper parameter, hub radius, rotational speed, thermal gradient, and geometric parameter on the static buckling loads and the regions of instability have been studied and the results are presented graphically

Reliability-Based Robust Design of Variable Cross-Section Wedge Beam

2012 ◽  
Vol 157-158 ◽  
pp. 74-77
Author(s):  
Tian Xiao Zhang ◽  
Xin Hui Liu ◽  
Qiao Ling Liu
Keyword(s):  
Normal Distribution ◽  
Reliability Analysis ◽  
Cross Section ◽  
Robust Design ◽  
Reliability Index ◽  
Variable Cross Section ◽  
Design Model ◽  
Engineering Practice ◽  
Variable Cross

Variable cross-section components are widely used in engineering practice. The paper discussed the reliability analysis, sensitivity numeration and robust design for variable cross-section components obeying normal distribution, built up the reliability-based robust design model, propose a method discussing reliability-based robust design of variable cross-section wedge beam. According to the numeration, obtain the graph of reliability index and reliability of variable cross-section components, obtain the method designing reliability-based robust of variable cross-section components with the certain reliability index.

On Choice of Finite Element Type for the Filled Bodies in Umbilicals for Deep Water Application

2010 ◽  
Author(s):  
Naiquan Ye ◽  
Janne K. O̸. Gjo̸steen ◽  
Svein Sævik
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Cross Section ◽  
Contact Area ◽  
Direct Contact ◽  
Friction Stress ◽  
Shell Element ◽  
Beam Element ◽  
External Loading ◽  
Element Type

Filled bodies are often built into umbilicals to support other key components such as tubes and electric elements. These bodies play an important role in transferring the contact load between bodies when the structure is loaded. The geometrical profile can be arbitrary to fill the voids within the umbilical cross section and this causes difficulties with respect to implementation into a general finite element model. Common practice is to omit the filled bodies in cross section modeling by enabling direct contact between components. However, it has been found that the friction stress will be over estimated by this method and cause over-conservative fatigue calculations. This may be critical specially for deep water dynamic umbilicals and more accurate estimation of the friction stress is therefore needed. UFLEX2D is a non-linear finite element computer program for stress analysis of complex umbilical cross sections, see [3] and [5]. The model can handle arbitrary geometries wound in an arbitrary order including filled bodies. Contact elements are used to handle the contact between bodies due to external loading. Thin-wall shell elements were used to model the steel tubes while beam elements were used for the filled bodies in the earlier version of UFLEX2D. A beam element is treated as a rigid body incapable of deforming under external loading. It has been found that the formulation of the beam element for the filled bodies yields relatively large contact pressure for the neighboring element due to its rigidity. As a consequence, friction stress owing to the contact pressure is overestimated by the choice of the beam element for the filled bodies, however, it will be smaller than the direct contact modeling technique mentioned above. A new element type, i.e. a beam-shell element, has been developed to represent the filled bodies so as to improve the contact formulation between the filled bodies and the other surrounding structural elements. Unlike the beam element, the beam-shell element is able to deform, therefore the contact area is varying while the external load updates. The friction stress will be accordingly affected by the redistribution of the contact pressure on an updated contact area. The paper outlines how different implementations of the filled bodies will affect the distribution of the contact pressure as well as the friction stress under cyclical loading. The effect of the original contact area, as well as the development of the contact area is also a part of the study fot the three alternative models investigated.

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