การหาค่าคงที่ของสปริงแบบคิวบิกของระบบระดับความเสรีขั้นเดียวไม่เชิงเส้น

Abstract

This research introduces a method for determining the parameter of cubic nonlinear springs by least square regression method. Calculations are conducted in both the time-domain and the frequency-domain. It was observed that both approaches yielded equally accurate results, regardless of whether the system exhibited over-damping or under-damping characteristics. In terms of computational time, the time-domain calculation proved to be approximately 10% faster than the frequency-domain calculation, with a theoretical calculation error of less than 10^-10%. Furthermore, it was discovered that the error was directly associated with the type of variables used.  When employing double variables, the error remained within the range of 10^-10%, while using long double variables ensured that the error did not exceed 10^-12%.