PSI - Issue 59

M. Karuskevich et al. / Procedia Structural Integrity 59 (2024) 175–181 M. Karuskevich et al. / Structural Integrity Procedia 00 (2019) 000 – 000

179 5

The results presented on the diagrams below (Fig. 4) shows the possibility to avoid negative effect, probably by the change of the friction mode. From practical procedure point of view it means decrease of the CPC volume penetrating the gap of the riveted joints. Tests of specimens covered by the Reference Compound were not carried out because the fatigue life of this category with "Excessive" treatment has not demonstrated the lowest values, thus it could not be the reference point.

Fig. 4. Comparison of the average number of cycles to failure for groups of specimens: without CPC, and treated by the "Limited" procedure: by CPC1; by CPC2.

Numerical parameters that could be used for evaluation of CPC’s influence on riveted joints durability may be obtained from statistical processing of experimental data. In the test there were determined fatigue lives of specimens with no CPC in the joint, covered by Reference CPC, samples were treated by CPC1 and CPC2. On the basis of this data there were calculated average (expected) values of fatigue lives, variances, standard deviations, variation coefficients and made a try to describe the results by some known probability distributions (Table 5). Due to limited amount of specimens and experimental data the probability distribution approximation was possible only for no CPC case. The results show that the best correspondence can be seen in case of log-normal and Weibull distributions (Fig. 5 and 6).

Table 5. Parameters of probability distributions for specimens with different cover. Cover No CPC

Reference CPC

CPC1 Limited treatment

CPC1 Excessive treatment

CPC2 Limited treatment

CPC2 Excessive treatment

Parameter

Average number of cycles 162382

109950 16962 0.1542

208698 28096 0.1346

70277 31745 0.4517

169214 36605 0.2163

34071 10668 0.3131

Standard deviation

58233 0.3586

Coefficient of variation