Strength analysis of ship shafts made of polymer composite materials

В работе отмечена актуальность применения ПКМ для перспективных проектов судов при отсутствии инженерных методов расчета параметров НДС таких изделий. Сделана попытка исследования возможностей аналитического и численного подходов для анализа прочностных и жесткостных характеристик судовых валов из ПКМ. Разработана расчетная модель вала в виде цилиндрической оболочки, составленной из пакета нескольких монослоев, каждый из которых сформирован из армирующего волокна и связующей матрицы. Представлены аналитические зависимости для вычисления обобщенных характеристик жесткости оболочки вала и параметров НДС как оболочки в целом, так и ее монослоев. Эти зависимости использованы для расчетного исследования параметров прочности промежуточного вала из ПКМ для танкера химовоза. В процессе исследования варьировалась ориентация и количество монослоев в пакете. Верификация полученных результатов выполнена с помощью расчетных моделей МКЭ. В результате установлено, что аналитические зависимости позволяют получить достоверные результаты параметров НДС композитного тела вала, которые можно уверенно использовать в расчетном проектировании конструкций из ПКМ для анализа плоского напряженно-деформированного состояния оболочки вала. he relevance of the use of PCM for the first projects of ships in the absence of engineering methods for calculating the parameters of the strength of such products is noted. In structural mechanics, there are methods for calculating the strength of multicomponent anisotropic materials, but they are difficult to adapt to engineering methods of verification calculation and design. The article attempts to study the possibilities of analytical and FEM approaches for analyzing the strength and stiffness of ship shafts made of PCM. A model of the shaft consisting of a package of several monolayers. Analytical dependences are presented for calculating the characteristics of the stiffness of the shaft shell. These dependences are used for the computational study of the strength parameters of the intermediate shaft made of PCM for tanker. Verification of the obtained results was carried out using of the FEM. As a result, it is established that the analytical dependences allow us to obtain reliable results of the stress-strain parameters of the composite shaft housing, which can be used in the computational design of PCM structures to analyze the flat stress-strain state of the shaft shell.

DETERMINATION OF A TECHNICAL CONDITION OF THE EQUIPMENT OF THE LINE OF A DRIVE OF ROLLING ROLLS ON THE SPEED OF PROPAGATION OF THE SHOCK PULSE

One of the ways to determine the technical condition of the equipment of the line working rolls - spindles - gear cage - root coupling - reducer - intermediate shaft - engine is considered. In each connection there is wear of contact elements, for example, bronze inserts of spindles, teeth of gears. According to the known method, the amount of current wear of the elements and the gaps caused by them at the same time is determined by the time of delay of the reaction of sections of the line to the impact load during the capture of the strip by rolls. The greater the wear, the longer the delay time. The option of determining the state of the nodes of the line by determining the speed of propagation of the shock pulse from the rolling stand to the engine is considered. An example of measuring the reaction delay time of three sections of one of the stands with calculations of the pulse rate in these sections is given. It is shown that with increasing wear, the pulse velocity decreases significantly. Therefore, this speed characterizes the technical condition of the sites, ie has a diagnostic feature. Additionally, the influence of the presence of oil, scale, and contamination in the joints is considered. It is also recommended to use the ratio of the base speed of the shock pulse in the solid shaft to the actual speed in the nodes to determine their technical condition.

Innovative Multi Exercise Self Weight Machine Using Gear Changing Mechanism

Background: Background: The increase rate in global obesity is presenting a major public health spate to peoples of every age groups or region. Obesity increases health risks such as cardiovascular disease, cancer, diabetes, osteoarthritis, and chronic kidney diseases. Now a days, we have all seen the damage been done in humanity through the biggest world problem naming Covid,19. All past researches and traditional weight machines are found to be either plate loaded, or weight-stack loaded. The plate loaded machine requires location of various load plates and manual adjustment of load. Machines based on such techniques always have chances for user injury and to be a cumbersome task. Objective: The objective of developing new gym machine presents an innovation that provides a load lifting apparatus which does not require weight stacks or weight plates for the user to exercise, adapted to adjust user of various height and weight, requiring lower maintenance cost and more important is it’s safe and easy handling nature that offers cost effective alternative to existing devices. Methods: The present papers provide an innovation approach in developing multi exercise self-weight gym machine. Machine includes unique design with new features for holding handle during load lifting exercise, an input shaft having one or more first pulleys coupled to the handle for rotating the input shaft. An intermediate shaft having a first set of gears configured for selective engagement with the input shaft. Output shaft includes second set of gears which was configured for selective engagement with the intermediate shaft, and one or more second pulleys coupled for lifting one or more loads. A weight-based exercise machine depending on user weight will adds to its independency on adding or withdrawal of weight that leads to its low cost and weight. Addition of parallelogram linkages in its design benefitted in providing non-swing motion. The concept of maintaining proper resistance has also been an important factor during the design of machine. Patents: The paper present the idea of designing the multi self-weight exercise machines as an innovation of involving the gear change mechanism for user having different weights and height. Results: The results concerning the gear ratio for first and second lever are computed for respective machine. Effective gear ratio and standardized load values had been obtained towards weight lifted for 78 Kilogram to achieve load less or more than weight of the user. Conclusion: The machine designed has been proved to be efficient by involving innovative ideas and design consisting of as each engagement configuration of input shaft and intermediate shaft that further provide different gear ratio between the input, output & intermediate shaft. The concept of movable chairs in change of weight through gear mechanism and the use of machine in different exercises had proved it to be an effective and beneficial for users and manufacturer for its easy handling nature.

Frequency Based Damage Detection and Localization of Propeller Shaft of a Ship Using Experimental Modal Analysis

: The whole ship is dependent on the propeller shaft for its movement, the vibrations produced from the shaft destabilizes the whole ship and may lead to accidents. With this objective in mind, in this paper, we describe a methodology to detect and locate the crack present in the intermediate simply supported shaft using experimental modal analysis. In the present work, 304 stainless steel material shaft is taken as the specimen as it is one of the most versatile and widely used steels in the world for making different shafts used in any machinery equipment like ships propeller shaft, engine shafts, motor shafts. Initially, analytical analysis is done on the simply supported shaft then numerical modal analysis using ANSYS 2019 R3 software. Results obtained from the numerical modal analysis are compared with the experimental modal analysis which is done using FFT analyzer. Finally, the first three natural frequencies are used as a tool to detect damage detection and location in the propeller intermediate shaft

Self-Excited Torsional Vibration in the Flexible Coupling of a Marine Propulsion Shafting System Employing Cardan Shafts

The reliability of propulsion shafting systems is a major concern for ocean-going vessels because mid-ocean repairs can be time-consuming and spare parts must be available. To address this concern, vibration modeling and experimental measurements were conducted on a propulsion shafting system with a Z-drive propeller, with the objective of identifying the source of failure for the flexible rubber coupling connecting the diesel engine with the intermediate shaft. The torsional fluctuations in the flexible coupling dramatically increased and then abruptly ceased. The modeling results revealed that the frictional losses during power transmission through the universal joints could act as an excitation force for self-excited vibration. The coupling connected to the intermediate shaft did not have sufficient radial flexibility to dampen these vibrations. To avoid the effects of the self-excited torsional vibration, it is recommended that this coupling is replaced with one that is capable of absorbing the radial shaft displacement.

Vibration characteristics of filament wound composite tubes applied to the intermediate shaft in ship propulsion system

In this study, the CFRP shafts made up of T700-SC multilayered composites have been designed to replace the steel shaft of a ship. An important design variable to be considered when designing composite material intermediate shafts is the natural frequency for resonance avoidance at critical rotational speed and torsional strength for axial load. In order to satisfy these, strength and modal analysis were performed. In order to minimize the deformation of the shape due to the residual stress after mandrel removal, it was laminated by axial symmetry. The fibers orientation angle has a great influence on the natural frequency of the drive shaft. The carbon fiber should be closely oriented at [Formula: see text] to improve the modulus of elasticity in the direction of length of the intermediate shaft and to increase the natural frequency. Also, the optimum fiber orientation for maximum torsional strength should be close to [Formula: see text]. The stacking pattern and the stacking order were finally decided considering the results of the finite element analysis (FEA).

Optimization winding design of a composites intermediate shaft

The purpose of this study is to determine the correct estimation of the laminate patterns for composites intermediate shaft. The laminate patterns in the filament winding process are an important factor in determining the strength and life of the final structure. In this study, the structural safety was analyzed for the laminate patterns in four cases. In addition, this work evaluated the range of laminated angles for optimal thickness selection. The laminate patterns and the order of the layers were determined by considering the results of the finite element analysis. The shear stress equation of the hollow shaft for torsional loads showed that the thickness of the structure varied with the diameter ratio. At the maximum diameter ratio (the smallest shaft thickness), the required shear strength for the structure was 36.6 MPa. Also, the most stable stress distribution was selected at [Formula: see text] to [Formula: see text]. The shear modulus according to the laminated angle was considered to give the best strength value when stacked at [Formula: see text]. The research results in this study suggest that the design of an optimized intermediate shaft of composite materials can be supplemented.