Cable Modal Parameter Identification. II: Modal Tests |
| |
Authors: | Wei-Xin Ren Wei-Hua Hu |
| |
Affiliation: | 1Distinguished Professor, Dept. of Civil Engineering, Central South Univ., Changsha, Hunan Province, 410075, People’s Republic of China (corresponding author). E-mail: renwx@mail.csu.edu.cn 2Ph.D. Student, Dept. of Civil Engineering, Faculty of Engineering, Univ. of Porto, Rua Dr. Roberto Frias, s/n 4200-465, Porto, Portugal. E-mail: hu.weihua@fe.up.pt
|
| |
Abstract: | The cable dynamic stiffness describes the load–deformation behavior that reflects the cable intrinsic dynamic characteristics. It is defined as a ratio of response to excitation and represents a very similar frequency response property to the frequency response function (FRF). Therefore, by fitting both analytical cable dynamic stiffness and measured frequency response function, the modal parameters of cables can be identified. Based on the simplified cable dynamic stiffness proposed in the first part of the two-part paper, this paper presents a cable dynamic stiffness based procedure to identify the cable modal parameters (natural frequencies and damping ratios) by modal tests. To carry out the curve fitting, a nonlinear least-squares approach is used. A numerical simulation example is first introduced to illustrate the feasibility of the proposed method. Further, a series of cable modal tests are conducted in the laboratory with different cable tensions and the frequency response functions are measured accordingly. A number of issues related to the cable modal tests have been discussed, such as accelerometer arrangement and excitation placement, frequency resolution, windowing, and averaging. It is demonstrated that the cable modal parameters can be effectively identified by using the proposed method through the cable modal tests. |
| |
Keywords: | Cables Stiffness Vibration Parameters Least squares method |
|
|