“…The obtained outcomes are in good agreement with the results given by Howson and Zare. 3 The validation is further carried out by comparing the first three natural frequencies of the single-core sandwich beam under various end conditions with those reported by Subramani et al 23 The natural frequencies of the first three modes under different end conditions are determined and the percentage deviation is presented in Table 2. As can be seen from Table, the comparisons show an excellent agreement thus, the numerical model seems to be accurate.Figure 4.Finite element model for laminated composite multi-core sandwich beam.Figure 5.Layup sequence of the laminated composite multi-core sandwich beam.…”
This study investigates the free vibration responses of laminated composite sandwich beam with multi-cores using experimental and numerical methods. The laminated composite face sheets are made by using hand layup method. An experimental modal test has been carried for different configurations of multi-core sandwich beams under different end conditions. The single-core and multi-core sandwich beams has been modeled and the natural frequencies of sandwich beams are determined using ANSYS software. The numerical model is verified by comparing the obtained natural frequencies with experimental results. The numerical and experimental results indicate that the multi-core sandwich beam greatly influences the structural stiffness compared with single-core sandwich beam under different end conditions. Furthermore, the influence of several parameters such as the end conditions, thickness of the core layer, and stacking sequence on the natural frequencies of the various configurations of the multi-core sandwich beams are presented.
“…The obtained outcomes are in good agreement with the results given by Howson and Zare. 3 The validation is further carried out by comparing the first three natural frequencies of the single-core sandwich beam under various end conditions with those reported by Subramani et al 23 The natural frequencies of the first three modes under different end conditions are determined and the percentage deviation is presented in Table 2. As can be seen from Table, the comparisons show an excellent agreement thus, the numerical model seems to be accurate.Figure 4.Finite element model for laminated composite multi-core sandwich beam.Figure 5.Layup sequence of the laminated composite multi-core sandwich beam.…”
This study investigates the free vibration responses of laminated composite sandwich beam with multi-cores using experimental and numerical methods. The laminated composite face sheets are made by using hand layup method. An experimental modal test has been carried for different configurations of multi-core sandwich beams under different end conditions. The single-core and multi-core sandwich beams has been modeled and the natural frequencies of sandwich beams are determined using ANSYS software. The numerical model is verified by comparing the obtained natural frequencies with experimental results. The numerical and experimental results indicate that the multi-core sandwich beam greatly influences the structural stiffness compared with single-core sandwich beam under different end conditions. Furthermore, the influence of several parameters such as the end conditions, thickness of the core layer, and stacking sequence on the natural frequencies of the various configurations of the multi-core sandwich beams are presented.
“…Since the VEM core’s frequency-dependence is considered, the resulting eigenvalue problem is nonlinear, and solved through the iterative procedure 31 .…”
Section: Methodsmentioning
confidence: 99%
“…They found that higher modal damping coefficient makes smaller displacement amplitude and phase shifts in frequency response analysis. D’Ottavio et.al 31 studied the dynamic behavior of the multiple-core laminates based upon the sub-laminate LW approach within a variable kinematics framework. They demonstrated that the inclusion of transverse normal deformations in the analysis can improve structural damping, particularly for high-order modes.…”
The airborne sound insulation performance of finite sandwich panels is often significantly worsened by resonant transmission components in low and middle frequencies. In this paper, damping contribution of viscoelastic core on sound transmission loss (STL) of finite constrained layer damping (CLD) panels is studied in narrow frequency bands. A fully coupled layer-wise approach is used with a generalized high-order shear deformation hypothesis that accounts for all types of deformations in the core. The influence of several parameters is investigated extensively. Results show that the adverse impact of the first-three odd-odd order modes, namely (1,1), (3,1), and (1,3) modes, as well as some higher-order modes on STL cannot be disregarded. The constrained viscoelastic core plays a crucial role in enhancing, or even eliminating, dips of STL spectrum at resonant frequencies. Additionally, it can considerably counterbalance a relatively broadband reduction of STL caused by the inter-modal coupling in middle frequencies. The damping mechanism can be divided into two aspects: (i) the reduction of modal amplitude by vibration energy dissipation, and (ii) the change of bending modal shapes. CLD treatment is a concise and effective way to achieve stable sound insulation performance.
“…However, due to the complexity of the equation, it is currently mostly used in simple two-dimensional structural models and requires a large amount of calculation. The finite element method usually combines the finite element analysis and the modal strain energy method [9][10]. After modal analysis, we get the strain energy of each part of the structure, then the structural loss factor is obtained after considering the material loss.…”
Modal strain energy (MSE) method is a widely used approximation approach for parameter calculation of damped composite structures. In this paper, iterative MSE method is proposed to calculate the loss factor of composite damping structure by considering the frequency dependence of modulus and loss factor of viscoelastic damping materials. The proposed method is applied to free damping spline, free damping plate and constrain damping plate. The results show that: the proposed method obtains minimum relative errors of less than 5% and less than 20% for nature frequency and composite loss factor. The influence of different material parameters on the calculation results is also discussed. The error is smaller when using the storage modulus and loss factor measured by tensile mode as input parameter. The thickness of the sample to measure the dynamic material parameters has a great influence on accuracy. This work provides a way for the calculation of composite loss fator of damped composite structures with embedded viscoelastic layer.
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