Papers by Keyword: Scanning Laser Vibrometer

Abstract: In this paper the results of modal analysis of a four storey building are presented. To excite the investigated structure, impact excitation was applied in two different points located on pillars supporting the building. In order to extract dynamic parameters of the structure, experimental modal analysis was applied. The parameters of vibration resulting from this excitation were measured by a scanning laser vibrometer; additionally piezoelectric accelerometers were utilized. To compare the results and monitor the state of the building a finite element model (FE) was built. It seems that a reliable identification of the state of building structures using a laser scanning vibrometer is feasible and relevant from a practical point of view. To monitor local changes additional piezoelectric accelerometers should be used. Moreover, it is applicable for damage detection to refine theoretical and experimental modal models for each natural frequency and to calculate the stress distribution for each refined model. Consequently, the sum of these particular stresses conveys information for building engineers and enables comparison with their in situ observations. The analysed building is situated on the terrain of underground coal mine exploitation so the aim of the research is not only to observe the state of the building but also to analyse possible changes during the process of excavation and after it was completed.

Abstract: This paper presents an experimental investigation of a new method for damage detection based on the most fundamental concept in continuum mechanics: strain compatibility. Compliance with this principle implies a deformed material is free from discontinuities, which are indicative of many types of structural damage. Therefore the principle of strain compatibility, in its ability to identify discontinuities, is very promising as a new foundation for future research into non-destructive evaluation and structural health monitoring technologies. The proposed method has many advantages compared to existing damage detection techniques, such as its invariance to material properties, type and intensity of loading, and the geometry of the structure. In this paper, a proposed formulation of the strain compatibility equation for beam structures, which is invariant to loading intensity, is presented. An experimental investigation of the proposed algorithm was conducted on a delaminated cantilever beam, utilising a PSV-3D scanning laser vibrometer. The experiment demonstrated that the strain compatibility technique can accurately locate delamination damage in composite beam structures.