Prediction of individual deformation characteristics of structural elements by a ``leader'' product

V. P. Radchenko ; E. A. Afanaseva

Journal of Samara State Technical University, Ser. Physical and Mathematical Sciences, Tome 26 (2022) no. 3, pp. 500-519

Résumé

We propose a numerical method for predicting the individual deformation characteristics of structural elements by a “leader” product. The basis of this method is generalized one-parameter models. These models relate the integral characteristics of the stress state to the integral characteristics of the deformation state in the “generalized load – generalized displacement” coordinates. The scope of the method is structural elements of the same type, which are under identical conditions of external loading and are characterized by a large spread of deformation characteristics (generalized displacement). It is assumed that the operation of one structural element (prototype) begins some time earlier than the others. A hypothesis on the similarity of all realizations reduced to a single origin by a time shift in the “generalized displacement – time” coordinates is introduced. Using statistical information on the initial sections of “lagging” structural elements and the sample prototype, the statistical characteristics of the similarity parameter of the operated structural element are determined in relation to the “leader” product, and then its deformation characteristics are predicted. In the paper, we investigate friction units and structural elements (rods, threaded connections) under creep conditions. Based on statistical correlation analysis of the experimental information, a verification of the similarity hypothesis usabilty for all implementations of the structural elements studied is carried out. The method was illustrated by an example of predicting the wear of the friction units of the front landing gear of the aircraft depending on the number of take-off and landing cycles. The method was also illustrated with an example of how to calculate the elongation of rods made of a polyvinylchloride compound under uniaxial loading and axial displacement of the screwing area of a threaded joint under creep conditions. The experimental data for the generalized displacement of specific implementations are shown to not exceed the calculated limits of the confidence interval for mathematical expectation for all structural elements considered in prediction time intervals of one to four “basic” intervals, within which estimates of random parameters for specific structural elements were determined.

Détail

Keywords: prediction, generalized displacement, individual deformation characteristics, friction unit, creep, rod, threaded connection.