No abstract

Уменьшение износа зубьев является одной из основных задач при проектировании волновых зубчатых передач (ВЗП). Изложена методика оценки износостойкости боковых поверхностей зубьев в ВЗП с кулачковым генератором волн и гибким колесом, выполненным в виде стакана с гибким дном. Представлены результаты численного исследования влияния различных параметров на износ боковых поверхностей зубьев. Для теоретического определения износа зубьев предложено использовать новые показатели-коэффициент износа зубьев и осредненный коэффициент износа. Эти показатели учитывают влияние на износ контактных напряжений и пути трения. Найдены зависимости коэффициентов износа от радиальной деформации гибкого колеса, длины оболочки гибкого колеса, положения гибкого подшипника и момента сопротивления. Все расчеты выполнены с помощью математической модели ВЗП, учитывающей пространственный характер деформирования и взаимодействия элементов передачи. Разрешающая система уравнений получена методом Бубнова-Галеркина. Коэффициенты влияния определены методами теории упругости. Ключевые слова: волновая передача, гибкое колесо, жесткое колесо, генератор волн, износ рабочих поверхностей, интенсивность износа. Reduction of the tooth wear rate is one of the main problem to address when designing harmonic drives. The authors describe methods for evaluating wear resistance of the tooth side surfaces in a harmonic drive with a cam wave generator and a flex spline shaped as a cup with a flexible bottom. The results of numerical studies determining the influence of various parameters on the wear of the tooth side surfaces are presented. New criteriatooth wear coefficient and average wear coefficient-are proposed for theoretical determination of the tooth wear. These criteria take into account the influence of contact stresses and friction paths on the wear. Relations between the wear coefficients and radial deformation of the flex spline, length of the flex spline shell, position of the flexible bearing, and torque are determined. All the calculations are performed using a mathematical model allowing for spatial nature of the deformation and the interaction between the elements of the harmonic drive gears. The resolving system of equations is obtained using the Bubnov-Galerkin method. The coefficients are determined on the basis of the theory of elasticity.

No abstract

Разработана методика расчета тепловлагопереноса в специальной защитной обуви пожарного-спасателя, которая позволяет учесть терморегуляционные механизмы в стопе для оценки комфортности обуви, изготовленной из определенных пакетов материалов и эксплуатируемой в широком диапазоне внешних воздействий, как по тепловым и влажностным факторам, так и в зависимости от уровня активности (тяжести выполняемой работы) пожарного-спасателя. Для определения безопасной работы в специальной защитной обуви необходима оценка степени деструкции кожи (степень ожога). The article describes the solution of the problem of non-stationary heat transfer in the «foot – footwear – environment» system for multilayer flat, cylindrical or spherical materials and non-stationary heat transfer from the outer surface of the special protective footwear to firefighter's foot. The well-known biothermal equation and the generalized heat transfer equation are used as the basis for the model of heat and moisture transfer in boot materials, taking into account sweating on the human skin surface. It is possible to get data on the thermal state of the foot under various conditions by solving these equations with appropriate coefficients and boundary conditions: zero heat flow in the center of the foot and convective environmental conditions on the surface of the last layer of porous shoe material. Modeling for three cases of human activity: resting state, walking with a speed of 4.8 km/h, light work (in the office room) under the same environmental conditions was carried out. The obtained results showed that the model of heat and moisture transfer in protective boots, taking into account thermoregulatory processes in the foot, can be used to predict the functionality of the materials for the bottom and top of the boots in terms of the skin burns likelihood. The method for calculating heat and moisture transfer in special protective boots for a firefighter-rescuer has been developed, based on the simulation, which includes: - construction of a geometric image of a model of protective boots; - determination of the firefighter-rescuer operating mode; - selection of material packages for the details of the boot top and bottom. An indication of the thermophysical, structural, geometric characteristics of the materials allows, using the selected climatic conditions and the firefighter-rescuer operating mode, to establish the initial and boundary conditions for solving the basic system of heat and moisture transfer equations. The solution of the system of equations with the boundary and initial conditions makes it possible to assess the comfort of boots, as well as the rate of destruction of the skin under intense thermal effects (the probability of burns of varying degrees). Based on this analysis, further optimization of the boots design can be carried out by choosing different material packages or evaluating the thermal effect under various external influences.