Nonlinear structures exhibit multiple responses under steady-state excitation,making it challenging to directly obtain their dynamic characteristics using traditional vibration test methods. To address this issue,a constant-force dynamic characteristics testing method based on acceleration-response-controlled step-sine frequency sweep test technology is proposed. First,the acceleration response at the excitation point is selected as the control signal,and a step-sine frequency sweep experiment is performed by maintaining a constant response amplitude. Secondly,the resulting simple harmonic excitation spectrum and acceleration response spectrum are obtained through experiments under various acceleration amplitude conditions,and a smooth simple harmonic force surface is constructed using linear interpolation. Then,by extracting the contour lines corresponding to constant force amplitude from this surface,the frequency response curve of the nonlinear structure under constant-force conditions is derived. Finally,the dynamic characteristics of a typical bolted nonlinear structure are investigated. The results show that the proposed approach can accurately capture the frequency response characteristics of bolted nonlinear structures,revealing the pronounced nonlinear dependence on force amplitude. Furthermore,bolt preload and structural reassembly are found to significantly influence the dynamic characteristics of the connection structure.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |