This study presents a significant advancement in the analysis of threaded connections by introducing a finite element model based on the Iwan model, which effectively captures nonlinear contact behaviors during the tightening process. Threaded connections are integral to the safety and reliability of mechanical structures, yet traditional methods of controlling preload force through tightening torque often overlook the complex geometry and behaviors inherent to these connections.
The research, conducted by authors Sun L., Li L., and Gao X., leverages the power of finite element analysis (FEA) to model and simulate the impact of various factors on the performance of threaded bolts. One of the major challenges in analyzing these connections is the nonlinear relationship between applied torque and the resulting preload force. This nonlinear behavior can lead to phenomena such as normal preload oscillations, interface separation, and friction-induced energy dissipation, which critically affect the dynamics and stability of structures.
Utilizing the ABAQUS software, the authors developed a specialized subroutine for the Iwan model. This approach improves upon traditional linear models by allowing for more accurate simulations of the complex contact behavior occurring at the interfaces of bolted connections. By constructing this model, the study aimed to clarify the relationship between tightening torque and preload force of the threads, which is not just academic; it's instrumental for ensuring structural integrity across numerous applications.
One significant finding highlighted within the study is the effect of the coefficient of friction on the mechanical response of the threaded connection. "The finite element model based on the Iwan model is able to accurately capture the nonlinear contact behavior in threaded joints,” the authors note. This enhanced model suggests not only stronger preload forces with increased friction, but also signals heightened risks of stress concentration and deformation under certain conditions.
Further analysis within the study addressed the impact of rotational amplitude during tightening. It was observed: "Higher rotation amplitude increases the preload, but at the same time, it may cause stress concentration on the thread contact surface and increase the risk of plastic deformation of the structure.” These findings underline the delicate balance engineers must maintain when designing bolted joints; too much torque can lead to failure, even as too little can compromise stability.
With traditional studies often focusing on isolated factors, this study broadens the scope by examining the combined effects of friction and rotational amplitude. The results hold importance not only for mechanical designers but also for industries reliant on precision fastening applications.
Overall, the research emphasizes the need for more sophisticated modeling techniques to understand the behavior of threaded connections accurately. It sheds light on how optimizing these parameters can significantly improve the performance and stability of mechanical assemblies. The authors imply future research may yield even more refined models to predict long-term behavior and performance under varying loading conditions, ensuring increased reliability and safety standards in engineering practices.