Topic
Modal testing
About: Modal testing is a research topic. Over the lifetime, 4047 publications have been published within this topic receiving 64772 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: The modal strain energy (MSE) method has been proposed to estimate the modal loss factors or modal damping ratios of structures with viscoelastic dampers as mentioned in this paper.
Abstract: The modal strain energy (MSE) method has been proposed to estimate the modal loss factors or modal damping ratios of structures with viscoelastic dampers. There are certain assumptions made in deriving the MSE method, such as the computation of the modal loss factor directly from the ratios of the imaginary and real parts of the eigenvalues, and the neglect of the influence of the imaginary mode shapes, etc. These assumptions may result in overestimating the modal damping ratios of viscoelastically damped structures when the added damping is high. In this study, the effect of the assumptions made by the MSE method is investigated, and modified formulations of the MSE method are derived. The modified MSE method removes the assumptions made in the original MSE method. Furthermore, earthquake responses of a complex stiffness system and a linear viscous damping system, of which the modal damping ratios are estimated by the MSE method, are compared. Study results indicate that the difference arising f...
21 citations
TL;DR: In this paper, the effect of forcing and response amplitude on the variability of modal parameters of a bridge was examined experimentally, and a finite element model was used to assess the likely levels of structural damage that would have a similar effect on the natural frequencies as the amplitude dependence.
21 citations
TL;DR: In this article, a global/local method based on modal analysis was developed which facilitates the three-dimensional stress analysis of plain weave composite structures, and failure initiation prediction was found to match reasonably well with the conventional finite element prediction obtained using a detailed mesh for the entire plate.
21 citations
01 Jan 2011
TL;DR: Algorithms for modal and spectral interval computations on FE models with non-probabilistic computational approach for mechanical systems with structural uncertainties are proposed.
Abstract: Our paper deals with a non-probabilistic computational approach for mechanical systems with structural uncertainties. Uncertainties are considered as bounded possible values – intervals. The main goal is to propose algorithms for modal and spectral interval computations on FE models. An application of the chosen approaches is presented, i.e. the first one a simple combination of only inf-values or only sup-values; the second one presents full combination of all inf-sup values; the third one uses the optimization process as a tool for finding out a inf-sup solution and last one is Monte Carlo technique as a comparison tool.
21 citations
TL;DR: It is demonstrated that transient inputs for modal testing include much more than just hammer impacts, and many types of transient inputs can be applied, limited only by the application and the imagination of the engineer.
Abstract: This study demonstrated that transient inputs for modal testing include much more than just hammer impacts. All the techniques discussed are an important resource that should be maintained in an engineer’s “toolbox” for modal testing. These techniques are generally best suited for lightly damped, linear structures and are very versatile due to the variety of methods. Hammer impacts are fast, convenient, and very useful for quick diagnostics. Projectile impacts produce much higher frequency content, but generally the input cannot be measured unless the projectile can be instrumented. Explosive inputs contain incredible high-frequency content up to the MHz range. Again, no direct measurement of the explosive input is available, although the impulse can typically be calculated. Step relaxation is an underutilized yet highly capable technique, versatile for both small and very large structures, particularly for massive structures where very large forces are required for excitation. It can be used for operational structures in which it would be may be impossible to apply other kinds of excitation techniques. Electrodynamic shakers and drop tables can also be used for transient testing when base excitation is required by test specifications. In conclusion, many types of transient inputs can be applied, limited only by the application and the imagination of the engineer.
21 citations