Papers by Keyword: Modal Experiment

Abstract: Aiming at the defects of classical modal parameter estimation approach, the impulse hammer modal test during body-in-white (BIW) stage was done through polyMAX method method. Based on modal analysis theory, an experimental model of BIW was established. The compositions of the experimental modal testing system, the design of testing scheme as well as its validation were described in detail in this paper. The collected data were identified via the polyMAX modal analysis method. The dynamic characteristics of BIW were confirmed by Modal Assurance Criterion. Influence of low frequency distribution characteristics on complete vehicle NVH was also analyzed. On the basis of above investigation, sensitivity analysis of the structure of BIW was conducted and sensitive structural parameters were determined. The test results show that the modal testing system can meet the requirement of precision with reliable results of parameter identification and sensitivity analysis, which can serve as a basis for the improvement of BIW structural design.

Abstract: Modal experiment and 3D finite element analysis are performed on a newly-built self-anchored suspension bridge. The structural modal parameters are identified under ambient vibration excitation. Before that, a 3D finite element model of the bridge is generated using a commercially available finite element package. The measured data as well as the calculated are compared carefully. It illustrates that both of them are in reasonable concordance. The natural frequency of the actual structure is relatively higher than that of finite element model which means the actual bridge is much stiffer than its original design model.

Abstract: The U-shaped pipe located in the compressor piping system of the lyophilizer is studied in this paper. Its finite element modal analysis is carried out through the software ABAQUS, and at the same time, the experimental modal analysis is conducted by the software LMS Test.lab and its corollary equipment. Through the comparison between the finite element modal analysis results and the experimental modal results, it can be seen that the two results have good consistence, which verifies that the finite element model is reasonable. This paper provides reference for the further studies of the curving pipe vibration.

Abstract: As a major force-bearing structure of Active Phased Array Radar, the Active Fixing-boards vibration characteristics should be investigated in the engineering design stage and the prototype stage. In this paper, Finite Element Method (FEM) is used for modal simulation and the detailed modal experiment is used to analyze the modal parameters of the first 6 modes. The results show that the modal parameters calculated by FEM agree well with those by modal experiment.

Abstract: In order to analysis modal characteristic of bearing with pre-tightening force on main spindle of numerical control lathe, this paper proposes a model of spindle modality analysis. This model is used to simulate the preloaded bearing shaft system modal, and the simulation results are verified by modal experiment. This paper takes 7005c as the research object to establish the equivalent-spring model based on the Hertz theory considering the pre-tightening force, whose focus is dealing with the contact between bearings rolling element and raceway. Then the model will be used to get the bearing stiffness for finite element simulation analysis. The shafting modal with preloaded bearing test platform is structured to get the shaft system modal parameters, which is compared with and verified the simulation analysis.

Abstract: Modal analysis is a main method of researching the dynamic performance of the system structure. The deformation of Needle-punching machine frames in the work will affect the whole machine performance, which would seriously influence acupuncture frequency, reduce production efficiency. At the meantime, machine life will be shortened. Here, Needle-punching machine modal experiment has been done, the static natural frequencies and modal deformation animation of frame also has been calculated, that provides a reliable guide and basis for the actual work of deformation for needle-punching machine.

Abstract: The finite element model of the liner rolling guide of the CNC machine tool is established. Then the natural frequencies and the corresponding vibration modes of the liner rolling guide (LRG) are obtained by analyzing the finite element model (FEM) of the linear rolling guide in two different boundary conditions. By comparing the modal characters of the two states it is proved that the movable joint and bolted interfaces of the rail have certain effects on the dynamic performance of linear rolling guide. Besides, the liner rolling guide also have been tested dynamically, obtaining the modal parameters of the rail guide; finally, the validity of finite element model and the effect of boundary conditions on the interface of the linear rolling guide are verified by comparing the finite element analysis of frequency and experimental analysis of frequency

Abstract: To study the dynamic properties and seismic responses of masonry structure strengthened with Basalt Fiber Reinforced Plastic (BFRP) laminates, modal experiment and shaking table test were performed on a two-storey and two-bay masonry structure model involving constructional columns. Through the test, the dynamic properties of reinforced masonry structure were obtained, the development of cracks and degradation of stiffness of the reinforced masonry structure under earthquake were studied and the variations of displacement, acceleration, stress of this structure were analyzed. Based on the modal experiment using the impact hammer test method, a simplified numerical analysis model of the test model was proposed for modal analysis. From the shaking table test, it is concluded that BFRP laminates can slow down the degradation of structural stiffness and the development of cracks effectively, and the masonry structure reinforced with BFRP laminates has excellent seismic performance.

Abstract: The hydraulic long-straight pipeline system of the shield machine is to be studied in this paper. Modal parameters of the hydraulic long-straight pipeline whose length is 8m under three kinds of spans (single span, double spans and four spans) were measured and analyzed. Considering the inherent vibration characteristics of the shield machine, we limited the natural frequency of the multi-span long straight pipeline studied within the range of 0~ 200Hz.What the experiment shows is as follows: Firstly, the natural frequency of the hydraulic long-straight pipeline is densely distributed mainly in the low frequency; Secondly, the natural frequencies of vibration in the horizontal plane are slightly higher than those of corresponding orders in the vertical plane, although the difference is little; In addition, by increasing the number of supports, pipeline span can be reduced and the natural frequencies of pipeline can be significantly increased, but this will make the vibration mode change irregularly.

Abstract: Aiming at solving issues of load bearing deformation compensation and sympathetic vibration, this paper takes a large span and heavy load crossbeam of a domestic heavy-type numerical control milling planer for research object, the final purpose is to improve machining precision and stability of the heavy machine tool product. The load curve considering the influence of columns deformation, natural frequency and vibration model are obtained, respectively by the dynamic and static simulation analysis of the crossbeam with the finite element analysis method. Then, the modal analysis results are verified through the model experiment. Lastly, this paper presents an approach by estimating the load curve to improve machining precision, points out the weak links, and provides guidance for crossbeam structure design, optimization and reverse manufacture.