This paper presents the main physical parameters, dependencies, calculation methods in the physical structural-energy theory of the strength of a deformed solid. The initial physical and mechanical parameters of the strength of steel 45 were determined analytically. The physical methods were used to calculate the durability, fatigue, and steel damage for non-stationary mechanical and thermal loads. The relationship between physical and mechanical strength parameters is analytically determined. The results of calculations of the modified characteristics of the strength of the damaged material are presented, plastic deformations, cyclic stresses of arbitrary shape, and temperature conditions are taken into account. The originality of the study consists in that we used our own program for calculating the new characteristics of the damaged material for different stress functions. The application value of the research is that the physical method allows to analyze the data of load sensors, indentation according to ISO 14577 in the elements of machines. The physical parameters of the material and the new theoretical calculation methods can be used to control the state of the strength of the machinery mechanisms during operation.