File Name: theoretical and experimental modal analysis .zip
Modal analysis of the data obtained from structural testing, provides us with a definitive description of the response of a structure, which can be evaluated against design specifications. It also enables us to construct a powerful tool, the modal model, with which we can investigate the effects of structural modifications or predict how the structure will perform under changed operating conditions. A simplified definition of modal analysis can be made by comparing it to frequency analysis.
Key elastic properties of full-sized wood composite panels WCPs must be accurately determined not only for safety, but also serviceability demands. In this study, the modal parameters of full-sized WCPs supported on four nodes were analyzed for determining the modulus of elasticity E in both major and minor axes, as well as the in-plane shear modulus of panels by using a vibration testing method. The experimental modal analysis was conducted on three full-sized medium-density fiberboard MDF and three full-sized particleboard PB panels of three different thicknesses 12, 15, and 18 mm. The natural frequencies and mode shapes of the first nine modes of vibration were determined. Results from experimental modal testing were compared with the results of a theoretical modal analysis.
Model Order Reduction Techniques pp Cite as. As shown in the preceding chapter, the motion of a dynamic structure or system may be represented by a set of simultaneous differential equations using some discretization scheme, such as the finite element method, if necessary. The dynamic characteristics dynamic responses, strains, stresses, etc. Alternatively, these coupled equations of motion may be solved by transforming them into a set of independent uncoupled equations by means of a modal matrix. This procedure is the classic meaning of modal analysis.
Modal analysis is the study of the dynamic properties of systems in the frequency domain. Examples would include measuring the vibration of a car's body when it is attached to a shaker , or the noise pattern in a room when excited by a loudspeaker. Modern day experimental modal analysis systems are composed of 1 sensors such as transducers typically accelerometers , load cells , or non contact via a Laser vibrometer , or stereophotogrammetric cameras 2 data acquisition system and an analog-to-digital converter front end to digitize analog instrumentation signals and 3 host PC personal computer to view the data and analyze it. Classically this was done with a SIMO single-input, multiple-output approach, that is, one excitation point, and then the response is measured at many other points. In the past a hammer survey, using a fixed accelerometer and a roving hammer as excitation, gave a MISO multiple-input, single-output analysis, which is mathematically identical to SIMO, due to the principle of reciprocity.
Abstract Experimental modal analysis EMA is an accepted methodology for identifying modal parameters of complex system assemblies, but large channel counts and multiple references are usually required to perform a thorough modal survey of such structures. In these cases, modal testing can become very costly and time consuming. Moreover, success in accurately defining all the modes of interest from experimental data depends on a variety of factors, including how and where the excitation is applied, how and where measurement data is acquired, and how boundary conditions or other environmental conditions are simulated. This presentation suggest a methodology for virtual experimental modal analysis VEMA. Experimental modal analysis has grown steadily in popularity since the advent of the digital FFT spectrum analyser in the early s.
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