# Analysis of Interference-Fit Joints
## 4 Conclusions  
Numerical simulations and experimental tests lead to the following conclusions:  
1. A large convergence of breaking force value obtained from the numerical simulation with the mean value of this force obtained from experimental tests confirmed the correctness of the numerical model.
2. Even though in J1 and J2 joint the pressures in the contact zone are in the elastic range (no plastic strain), the difference between the value of the force breaking the joint calculated from formulas (2 and 4) and the value of the force obtained from numerical simulations is 1707 N (for J2 3137\(-\)1430 = 1707 N), which gives a relative percentage error of 54%.
3. As shown by numerical simulations in J3-J15 joints, surface pressures exceeding the value of the yield point appear in contact zones. This is accompanied by the formation of plastic strains, which leads to the conclusion that the load capacity of the joint  
Figure 14: Force-displacement graph for J5 joint obtained during the test.  
Figure 13: Measuring stand.  
cannot be determined from Formula (2) based on the solution of the linear-elastic Lame's problem.
4. As results from numerical simulations for J3-J15 joints, increasing interference increases the value of the assembly force of the joint, but does not significantly increase the value of the joint breaking force. The observation is in line with those in the paper [10]. This is due to the plasticization of the entire contact surface occurring along the entire length of the joint and continuing deeper into the joined elements.  
Calculations conducted on the experimentally verified numerical model prove that even in the case of an elastic joint, the result of numerical analysis differs from the result based on the circular-symmetric task of the linear theory of elasticity. When selecting a specific type of fit, it is not possible to assess a priori whether the pressure level in the joint will be elastic or elastic-plastic. Therefore, the problem of determining the load capacity of press-fit joints generally remains an issue that requires further research and analysis.  
The authors' further works aim to build a mathematical model and an expert system that allows one to determine the load-bearing capacity of interference joints for different joint lengths and different diameters of joined elements. This system can be built based on numerical simulations based on artificial intelligence tools.  
Conceptualization, J.M.; Formal analysis, J.M. and M.S.; Investigation, J.M. and M.S.; Methodology, M.S.; Project administration, J.M.; Resources, M.S.; Software, M.S.; Supervision, J.M.; Validation, J.M. and M.S.; Visualization, J.M.; Writing--original draft, J.M.; Writing--review & editing, J.M. and M.S. All authors have read and agreed to the published version of the manuscript. This research received no external funding.  
Not applicable.  
Data Availability Statement: Data is contained within the article.  
The authors would like to thank the Department of Mechanical Engineering Fundamentals of the University of Bielsko-Biala, Bielsko-Biala, Poland, for the laboratory infrastructure and technical support.  
The authors declare no conflict of interest.