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Mass timber panel–concrete composite (MTPCC) floors combine timber and concrete through high-performance connections to create an efficient floor system with high stiffness, high strength, and low self-weight. Previous research on MTPCC floors focused on improving the composite efficiency of floors under static loadings by testing different types of shear connectors. The dynamic performances of MTPCC floors, which can govern the floor span and thickness, have not been well investigated. In this study, vibration tests were conducted on glued-laminated timber panels and notch-connected MTPCC floors with different spans, thicknesses, and connection layouts. The dynamic properties, including natural frequencies, damping ratios, and mode shapes, were obtained for floors under different supporting conditions. Test results showed that MTPCC floors with a 6-m span had fundamental natural frequencies generally higher than 8 Hz. The addition of the concrete layer to the bare timber panels improved the floor fundamental natural frequency and damping. Deflection tests and walking tests were performed on MTPCC floors to evaluate the floor vibration serviceability performance, and it was found that the existing design criteria predicted inconsistent results. The flexural stiffness of MTPCC floors determined from vibration and deflection tests was close to full composite, while only partial composite action in the composite floors was achieved under a higher load level in destructive bending tests. [ABSTRACT FROM AUTHOR]

• Examined added mass effects in concentric cylinders with a new set of narrow gaps. • Revisited theoretical added mass effects in concentric cylinders. • Accurately captured modal parameters with modal analysis and modal testing. • Confirmed added mass effects in narrow gap by tests on cylinders and reactor vessel. Nuclear reactor pressure vessels (RPVs) must be robust to external environmental excitations such as seismic loads. Precise numerical models that predict the dynamic responses to external loads are crucial for evaluating the safety of RPVs. Notably, in RPVs submerged in reactor coolant, it is necessary to examine the added mass effect of the fluid via fluid-structure interaction (FSI) analysis, employing either an analytical approach or a numerical analysis. The present study focuses on modeling and analyzing the added mass effect in the narrow gaps associated with the dense structural layout in the reactor. In this context, this paper validates analytical and numerical models that accurately describe the added mass effect for two cases: (i) simple concentric cylinders with a narrow gap filled with fluid and (ii) a complex small-scale RPV with narrow gaps also filled with fluid. Initially, the analytical model, employing Lagrange's equation of motion and velocity potential, and the numerical model, utilizing FE modeling in acoustic FSI through ANSYS, were validated through experimental modal testing for the added mass effect in the narrow gap between simple concentric cylinders. The analytical model for the concentric cylinders indicates that the added mass diverges to infinity as the gap approaches zero, which should be examined carefully. Through experiments for the concentric cylinders, the analytical and FEM-based added mass effects were validated with a natural frequency error of 3 %. Subsequently, based on the results for the concentric cylinders, a complex numerical model of the small-scale reactor with complex boundary conditions was developed and cross-validated through corresponding experimental modal testing of the small-scale RPV. The added mass model for the narrow gaps in the RPV was validated by substantial agreement of eight representative modes, as demonstrated by a 5 % natural frequency error. [ABSTRACT FROM AUTHOR]

Fibre reinforced polymer (FRP) panels are widely employed in ship and marine structures due to their better specific stiffness and strength when compared to metals. Therefore, an accurate estimation of the dynamic behaviour of such panels is necessary from its operational and serviceability point of view. In this study, the influence of exponential window functions and the associated decay rates on the damped dynamic responses of a Glass Fibre Reinforced Plastic (GFRP) plate has been investigated experimentally, using impact hammer testing. In a standard experimental modal testing of a structure, exponential window functions are commonly employed to prevent spectral leakage of the signal and achieve a good signal-to-noise ratio. However, this exercise modifies the Frequency Response Functions (FRFs) and introduces numerical damping into the measurements. A novel technique involving a Finite Element Model Updating using Inverse Eigen-Sensitivity algorithm is employed to estimate the unbiased FRFs and identify the induced numerical damping. The model updating is carried out in two stages: updating stiffness parameters first, followed by updating damping parameters in the second stage. The updating algorithm and the two-stage strategy adopted therein is found to be effective in identifying the induced numerical damping along with the unbiased FRF expressions. • Dynamic properties of a Glass Fibre Reinforced Plate were investigated experimentally. • Influence of exponential windows and related decay rates on damping estimates were observed. • Unbiased damped responses were extracted using finite element model updating. • Stiffness and damping parameters were updated using the Inverse Eigen-sensitivity method. [ABSTRACT FROM AUTHOR]

This article describes the simulation and experimental determination of the oscillation modes of a Coriolis Mass Flowmeter (CMF). The authors use the SolidWorks software to create a suitable model which is a double U-type of CMF. Based on SolidWorks software, the authors established the double-U tube model for CMF, adopted ANSYS-Workbench simulation software to make the modal analysis, and the exciting mode and Coriolis force mode of CMF are obtained by simulation. According to the results of modal analysis, the authors made the harmonic response analysis of the Flowmeter, got the displacement amplitude of the U-shaped tube excited by different frequency loads under the exciting force, and the maximum displacement amplitude at the resonant frequency was determined. Next, the authors use a laser vibrometer to perform an experimental modal test on the flowmeter. The result of the simulation of the finite element model was verified by modal test of the flowmeter. Provides an effective reference for CMF modelling and simulation in the future.

This article describes the simulation and experimental determination of the oscillation modes of a Coriolis Mass Flowmeter (CMF). The authors use the SolidWorks software to create a suitable model which is a double U-type of CMF. Based on SolidWorks software, the authors established the double-U tube model for CMF, adopted ANSYS-Workbench simulation software to make the modal analysis, and the exciting mode and Coriolis force mode of CMF are obtained by simulation. According to the results of modal analysis, the authors made the harmonic response analysis of the Flowmeter, got the displacement amplitude of the U-shaped tube excited by different frequency loads under the exciting force, and the maximum displacement amplitude at the resonant frequency was determined. Next, the authors use a laser vibrometer to perform an experimental modal test on the flowmeter. The result of the simulation of the finite element model was verified by modal test of the flowmeter. Provides an effective reference for CMF modelling and simulation in the future. [ABSTRACT FROM AUTHOR]

To verify the effectiveness and correctness of free modal analysis results from a Spiral bevel gear (SBG) wheel by using Finite element method (FEM), an experimental platform was constructed through the free-hanging support of the SBG wheel. The experiment used the hammer knock percussion for excitation and a three-directional acceleration sensor as signal acquisition equipment and utilized the LMS modal analysis module. The geometric model of the SBG wheel was constructed using an eight-node octagon instead of the SBG wheel outer contour. The experiment then extracted the modal parameters of the wheel using the PolyMAX method and obtained the first- and second-order natural frequencies, damping ratios, and mode shapes of the SBG wheel at 0-7 kHz during the experimental modal test. The results of the experimental test were compared with those of the FEM free modal analysis. The first- and second-order natural frequency error rates by FEM were 0.25 % and 0.45 %, respectively. The experimental modal test result verified the rationality of the model by FEM, thus showing that the result of modal analysis by FEM is reliable and providing a basis for the dynamic characteristic analysis of SBG. [ABSTRACT FROM AUTHOR]