Abstract
A theoretical method is proposed to predict the service life of metallurgical machinery parts according to the safety criterion of materials without the use of experimental data. It is based on the method of setting and solving the boundary value problems of the physical theory of mechanical systems element reliability rate. The main task of the research was to describe the process of formation of an element failure represented as a system of basic equations of the theory of parametric reliability of technical objects with the kinetic equation of its degradation (aging or defectiveness) in the process of future operation. The following equations are formed for the selected state parameter of the studied object as the basic equations of the theory of reliability: the equation of its evolution, the transition equation in limit state and the equation for calculation of design service life. The type of degradation equation is determined by the given conditions of loading of the product and the conjecturable criterion of its destruction. V.V. Fedorov’s fundamental equation of the thermodynamic theory of strength is used as degradation equation for the machinery parts in which static or cyclic loading conditions require their external probability of failure on the criteria of volume destruction. The universal dependence to calculate the average speed of damage to the structure of the most loaded volume of the test element in stationary loading conditions is proposed on its basis. The coeffi cient was calculated to take into account the resistance of the material structure according to Le Chatelier’s principle for the entire period of loading process until the destruction is detected. Energy-dependent basic mechanical concept of friction units is used as the degradation equation for details of machines operating under boundary friction. It is derived on the basis of the joint solution of the equations of energy and structural-molecular-mechanical theory of friction and allows us to evaluate the wear rate of frictional elements in steady-state conditions of friction engagement without experimental studies. The proposed method of analytical assessment of the predicted life (project life) of machinery parts is used in practice to increase the wearing quality of a number of metallurgical units as a method of formulating and solving boundary value problems of the physical theory of reliability on criteria for strength and total operation time of materials.
Highlights
A theoretical method is proposed to predict the service life of metallurgical machinery parts according to the safety criterion of materials without the use of experimental data
The main task of the research was to describe the process of formation of an element failure represented as a system of basic equations of the theory of parametric reliability of technical objects with the kinetic equation of its degradation in the process of future operation
The following equations are formed for the selected state parameter of the studied object as the basic equations of the theory of reliability: the equation of its evolution, the transition equation in limit state and the equation for calculation of design service life
Summary
Анцупов А.В. (мл.), к.т.н., доцент кафедры проектирования и эксплуатации металлургических машин и оборудования. Общая постановка задачи для описания процесса формирования отказа исследуемого элемента представляет систему базовых уравнений теории параметрической надежности технических объектов и кинетическое уравнение его деградации (старения, повреждаемости) в процессе будущей эксплуатации. Для выбранного параметра состояния исследуемого объекта в качестве базовых уравнений теории надежности формулируются: уравнение его эволюции, уравнение перехода в предельное состояние и уравнение для расчета проектного ресурса. Статические или циклические условия внешнего нагружения которых предполагают их вероятный отказ по критериям объемного разрушения, в качестве уравнения деградации использовано основополагающее уравнение термодинамической теории прочности В.В. Предложенный метод аналитической оценки проектного ресурса деталей машин, как метод постановки и решения краевых задач физической теории надежности по критериям прочности и износостойкости материалов, использован на практике для повышения долговечности ряда металлургических агрегатов. Уравнение (5) теряет смысл для диапазона напряжений σ, при котором аргумент гиперболического синуса меньше нуля, что противоречит практике и базовому положению кинетической теории
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