scholarly journals Numerical modeling of contact problems with the finite element method utilizing a B-Spline surface for contact surface smoothing

Author(s):  
Daniel Barbedo Vasconcelos Santos ◽  
Alex Alves Bandeira
Author(s):  
Joanna M. Brown ◽  
Malcolm I. G. Bloor ◽  
M. Susan Bloor ◽  
Michael J. Wilson

Abstract A PDE surface is generated by solving partial differential equations subject to boundary conditions. To obtain an approximation of the PDE surface in the form of a B-spline surface the finite element method, with the basis formed from B-spline basis functions, can be used to solve the equations. The procedure is simplest when uniform B-splines are used, but it is also feasible, and in some cases desirable, to use non-uniform B-splines. It will also be shown that it is possible, if required, to modify the non-uniform B-spline approximation in a variety of ways, using the properties of B-spline surfaces.


Author(s):  
Я.Б. Немировский ◽  
И.В. Шепеленко ◽  
С.Е. Шейкин ◽  
Ю.А. Цеханов ◽  
Ф.Й. Златопольский ◽  
...  

Разработан алгоритм и проведена оценка прочности сборных твердосплавных элементов со сплошной и дискретной рабочими поверхностями. Получены зависимости, позволяющие установить связь между конструктивными параметрами сборных деформирующих инструментов и их прочностью. Выполнены прочностные расчеты деформирующего инструмента для обработки отверстий значительного диаметра со сплошной и дискретной рабочими поверхностями. Численным моделированием, методом конечных элементов получены распределения эквивалентных напряжений в элементах инструмента и контактных напряжений по поверхности контакта твердосплавная вставка-корпус, что позволило проанализировать прочность инструмента под нагрузкой. Определены конструктивные параметры инструмента и приведены алгоритмы последовательности расчета сборных деформирующих элементов (ДЭ). Разработан алгоритм последовательности расчета сборного ДЭ для дискретного протягивания. Предложенная конструкция сборного рабочего элемента позволяет не только улучшить обрабатываемость изделия резания, но и уменьшить расход остродефицитного твердого сплава по сравнению с твердосплавным ДЭ аналогичных размеров на 6 кг. Полученные результаты можно использовать в инженерных расчетах при проектировании сборного инструмента для дискретного деформирования, а также для оценки прочности сборных инструментов, например, фрез, зенкеров, разверток при уточнении внешних нагрузок We developed an algorithm and assessed the strength of prefabricated carbide elements with solid and discrete working surfaces. We obtained dependencies that make it possible to establish a relationship between the design parameters of prefabricated deforming tools and their strength. We performed strength calculations of the deforming tool for machining holes of significant diameter with solid and discrete working surfaces. We obtained the distributions of equivalent stresses in the elements of the tool and contact stresses over the contact surface of the hard-alloy insert - body by numerical modeling, by the finite element method, which made it possible to analyze the strength of the tool under load. We determined the design parameters of the tool and here we give algorithms for the sequence of calculation of prefabricated deforming elements (DE). We developed an algorithm for the sequence of calculating the prefabricated DE for discrete broaching. The proposed design of the prefabricated working element allows not only to improve the machinability of the cutting product but also to reduce the consumption of an acutely deficient hard alloy in comparison with a hard alloy DE of similar dimensions by 6 kg. The results obtained can be used in engineering calculations when designing a prefabricated tool for discrete deformation, as well as for assessing the strength of prefabricated tools, for example, cutters, countersinks, reamers when specifying external loads


Author(s):  
Jingmang Xu ◽  
Ping Wang ◽  
Xiaochuan Ma ◽  
Jieling Xiao ◽  
Rong Chen

Wheel–rail contact is more complex in railway a turnout than in ordinary track and, thus, necessitates an advanced model to simulate dynamic interaction and predict rail wear. The main aim of the present work is to assess the application of several wheel–rail rolling contact models in railway turnout. For normal contact problems, wheel–rail contact models based on four different methods are compared: Hertz theory, the semi-Hertzian method, CONTACT, and the finite element method. The assessment is based on the results of contact patch shape and size and contact pressure for several wheelset lateral displacements. The load is set to a constant and equal to static wheel load. Calculations are performed at the section of switch rail head with width 35 mm in CN60-1100-1:18 turnout; both standard and worn rail profiles are accounted for. For tangential contact problems, four corresponding methods are assessed, based on the calculation of creep forces, distribution of the stick/slide region and computational efficiency: Shen–Hedrick–Elkins theory, FASTSIM, improved FASTSIM based on semi-Hertzian method, and CONTACT. It is found that the normal contact problems solved by the semi-Hertzian method and CONTACT correlate well with the finite element method, and the tangential contact problems solved by improved FASTSIM and CONTACT are quite favorable. The conclusions of this work can provide some guidance for contact model selection in the dynamic simulation and wear prediction of railway turnout.


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