Наука и техника (May 2015)
ON ASSESSMNENT OF PHYSICAL WEAR IN ELEMENTS OF TECHNICAL DEVICES
Abstract
Real assessment of wear in technical devices, construction structures, minings, their elements and connections is of great importance for provision of operational security and efficiency. Natural properties of the overwhelming majority of materials follow to probabilistic (stochastic) laws due to various reasons (external influence, processing technologies and others). An assessment of physical wear rate of buildings and structures and their elements is carried out in the former republics of the USSR mainly in accordance with external physical signs (deflections, cracks, layer separations, etc.) but wear percentage is often calculated on the basis of replacement cost in comparison with the initial one even without taking into account inflation which did not officially exist in the USSR. In this case destruction or failure of structure or their elements are considered as 100 % wear.The paper proposes a new methodology for assessment of physical wear rate in accordance with probability ratio of nofailure operation (reliability), minimum ratio is assigned to admissible limit value in conformity with technical requirements for the technical devices, construction structures, minings in question, their elements and connections. In this context minimum permissible wear probability (reliability) is taken as 100 % wear rate and its initial index is considered as 0 % wear rate. That is why wear intensity in time depends on type of value probability distribution while determining the rate of physical property. The proposed methodology is intended for probabilistic wear assessment in case of relatively simple changes in strength properties of materials (for example, within the elastic limit).
