Experimental and Numerical Analysis of the Effect of Segmentation on Modal Loss Factor of Constrained Layer Damped Beam

2014 ◽  
Author(s):  
Pravin P. Hujare ◽  
Anil D. Sahasrabudhe ◽  
Sanket D. Chinchawade
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Shear Deformation ◽  
Loss Factor ◽  
Three Dimensional ◽  
Bending Moment ◽  
Constrained Layer Damping ◽  
Three Dimensional Model ◽  
Modal Strain Energy ◽  
Damping Material

This paper presents experimental investigation on the damping effects of constrained layer treatment by cutting the constraining layer and constrained layer of viscoelastic material (VEM). The constraining layer causes shear in the damping material as the structure deforms. The shear deformation occurring in the viscoelastic core is mainly responsible for the dissipation of energy. The shear deformation in the VEM is not significant in regions where the bending moment is maximal. Mostly only extensional deformation occurs in the damping layer. The local high-shear deformation in the damping material is produced by placing a cut at the region of highest curvature. Cutting both the constraining and the constrained layer, which leads to segmentation, increases the shear deformation at that position. This appropriate position of high bending moment for segmentation is obtained by MATLAB program. The modal loss factor of constrained layer damped (CLD) beam is obtained by half-power bandwidth method using FFT analyzer. The CLD beams are prepared as per ASTM Standard E 756-05. Extensive experiments are conducted by making number of separate segmented CLD beams of different viscoelastic damping materials. A three dimensional model of cantilever CLD beam has been used for numerical analysis. In this work, finite element commercial software MSC/NASTRAN is used to simulate the dynamic response of a CLD beam. The modal loss factor of constrained layer damped (CLD) beam is measured by Modal Strain Energy (MSE) Method. This is a new method for enhancement of damping capabilities of constrained layer damping. It is found that the performance of segmented CLD beam using passive treatment shows significant improvement in modal loss factor which leads to vibration attenuation of beam. The numerical results are corroborated with experimental data obtained for segmented CLD beam. The analyzed finite element models are found to provide reliable results and compared very well with experimentally acquired data.

scholarly journals Dynamic Optimization of Constrained Layer Damping Structure for the Headstock of Machine Tools with Modal Strain Energy Method

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Yakai Xu ◽  
Weiguo Gao ◽  
Yuhan Yu ◽  
Dawei Zhang ◽  
Xiangsong Zhao ◽  
...  
Keyword(s):  
Loss Factor ◽  
Strain Energy ◽  
Dynamic Stiffness ◽  
Optimization Method ◽  
Original Structure ◽  
Damping Capacity ◽  
Machining Accuracy ◽  
Constrained Layer Damping ◽  
Modal Strain Energy ◽  
Damping Material

Dynamic stiffness and damping of the headstock, which is a critical component of precision horizontal machining center, are two main factors that influence machining accuracy and surface finish quality. Constrained Layer Damping (CLD) structure is proved to be effective in raising damping capacity for the thin plate and shell structures. In this paper, one kind of high damping material is utilized on the headstock to improve damping capacity. The dynamic characteristic of the hybrid headstock is investigated analytically and experimentally. The results demonstrate that the resonant response amplitudes of the headstock with damping material can decrease significantly compared to original cast structure. To obtain the optimal configuration of damping material, a topology optimization method based on the Evolutionary Structural Optimization (ESO) is implemented. Modal Strain Energy (MSE) method is employed to analyze the damping and to derive the sensitivity of the modal loss factor. The optimization results indicate that the added weight of damping material decreases by 50%; meanwhile the first two orders of modal loss factor decrease by less than 23.5% compared to the original structure.

A Fluid-Structure Coupled Computational Framework for Fluid-Induced Failure and Fracture

2015 ◽  
Author(s):  
Patrick D. Lea ◽  
Charbel Farhat ◽  
Kevin G. Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Extended Finite Element ◽  
Computational Framework ◽  
Fluid Structure ◽  
Fracture Models

This work extends and generalizes a recently developed fluid-structure coupled computational framework to model and simulate fluid-induced failure and fracture. In particular, a novel surface representation approach is proposed to represent a fractured fluid-structure interface in the context of embedded boundary method. This approach is generic in the sense that it is applicable to many different computational fracture models and methods, including the element deletion (ED) technique and the extended finite element method (XFEM). Two three-dimensional model problems are presented to demonstrate the salient features of the computational framework, and to compare the performance of ED and XFEM in the context of fluid-induced failure and fracture.

A Fast Three-Dimensional Model for Strip Rolling

2016 ◽  
Vol 716 ◽  
pp. 566-578 ◽  
Author(s):  
Christian Overhagen ◽  
Paul Josef Mauk
Keyword(s):  
Finite Element ◽  
Stress Gradient ◽  
Three Dimensional ◽  
Significant Loss ◽  
Three Dimensions ◽  
Beam Model ◽  
Stress Distributions ◽  
Three Dimensional Model ◽  
Strip Rolling ◽  
Lateral Direction

Rolling Models have come a long way from the first empirical relations about forward slip and bite conditions to their current state, which allows local quantities to be calculated in two and three dimensions. In this paper, state-of-the-art of analytical modelling of the rolling process is shown with a fully three-dimensional rolling model for hot and cold strip rolling with stress distributions in the longitudinal, vertical and lateral directions. For this purpose, von Karman’s strip approach is extended to account for the stress gradient in lateral direction, as was already shown in different papers. The stress gradient in the vertical (through-thickness) direction is introduced by a modern implementation of Orowan’s inhomogeneous deformation theory. The local stress distributions are compared to results from Finite-Element Calculations obtained with modern FEM codes. It will be shown, under which circumstances expensive FEM calculations can be replaced by simpler models like the one proposed here, which are more time and cost-effective without a significant loss in result precision. The rolling model is extended with a Finite Element Beam Model for work and backup roll deformation, as well as local work roll flattening and thermal crown for hot rolling. The Effects of those features on stress distribution and exit strip profile are shown for hot and cold rolling.

scholarly journals A Review on Numerical Analysis of RC Flat Slabs Exposed to Fire

2020 ◽  
Vol 27 (1) ◽  
pp. 1-5
Author(s):  
Hanadi Naji ◽  
Nibras Khalid ◽  
Mutaz Medhlom
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Analysis ◽  
Bending Moment ◽  
Mechanical And Thermal Properties ◽  
Vertical Deflection ◽  
Element Analysis ◽  
Flat Slabs ◽  
Numerical Studies ◽  
The Finite Element Analysis

This paper aims at presenting and discussing the numerical studies performed to estimate the mechanical and thermal behavior of RC flat slabs at elevated temperature and fire. The numerical analysis is carried out using finite element programs by developing models to simulate the performance of the buildings subjected to fire. The mechanical and thermal properties of the materials obtained from the experimental work are involved in the modeling that the outcomes will be more realistic. Many parameters related to fire resistance of the flat slabs have been studied and the finite element analysis results reveal that the width and thickness of the slab, the temperature gradient, the fire direction, the exposure duration and the thermal restraint are important factors that influence the vertical deflection, bending moment and force membrane of the flat slabs exposed to fire. However, the validation of the models is verified by comparing their results to the available experimental date. The finite element modeling contributes in saving cost and time consumed by experiments.

scholarly journals Microstructural Topology Optimization of Constrained Layer Damping on Plates for Maximum Modal Loss Factor of Macrostructures

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhanpeng Fang ◽  
Lei Yao ◽  
Shuxia Tian ◽  
Junjian Hou
Keyword(s):  
Topology Optimization ◽  
Loss Factor ◽  
Strain Energy ◽  
Design Method ◽  
Optimization Method ◽  
Constrained Layer Damping ◽  
Viscoelastic Materials ◽  
Modal Strain Energy ◽  
Design Variables ◽  
Microstructural Topology Optimization

This paper presents microstructural topology optimization of viscoelastic materials for the plates with constrained layer damping (CLD) treatments. The design objective is to maximize modal loss factor of macrostructures, which is obtained by using the Modal Strain Energy (MSE) method. The microstructure of the viscoelastic damping layer is composed of 3D periodic unit cells. The effective elastic properties of the unit cell are obtained through the strain energy-based method. The density-based topology optimization is adopted to find optimal microstructures of viscoelastic materials. The design sensitivities of modal loss factor with respect to the design variables are analyzed and the design variables are updated by Method of Moving Asymptotes (MMA). Numerical examples are given to demonstrate the validity of the proposed optimization method. The effectiveness of the optimal design method is illustrated by comparing a solid and an optimized cellular viscoelastic material as applied to the plates with CLD treatments.

scholarly journals FEM analysis of a new miniplate: stress distribution on the plate, screws and the bone

2012 ◽  
Vol 06 (01) ◽  
pp. 009-015 ◽  
Author(s):  
Didem Nalbantgil ◽  
Murat Tozlu ◽  
Fulya Ozdemir ◽  
Mehmet Oguz Oztoprak ◽  
Tulin Arun
Keyword(s):  
Finite Element ◽  
Cortical Bone ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Force Distribution ◽  
Bone Surface ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

ABSTRACTObjectives: Non-homogeneous force distribution along the miniplates and the screws is an unsolved question for skeletal anchorage in orthodontics. To overcome this issue, a miniplate structure was designed featuring spikes placed on the surface facing the cortical bone. The aim of this study was to examine and compare the force distribution of the newly designed plate-screw systems with the conventional one.Methods: A model of bone surface with 1.5 mm cortical thickness, along with the two newly designed miniplates and a standard miniplate-screw were simulated on the three-dimensional model. 200 g experimental force was applied to the tip of the miniplates and the consequential effects on the screws and cortical bone was evaluated using three-dimensional finite element method.Results: As a result of this finite element study, remarkably lower stresses were observed on the screws and the cortical bone around the screws with the newly designed miniplate when compared with the conventional one.Conclusion: The newly designed miniplate that has spikes was found effective in reducing the stress on and around the screws and the force was distributed more equivalently. (Eur J Dent 2012;6:9-15)

Finite-element analysis of multi-body contacts for pile driving using a hydraulic pile hammer

2011 ◽  
Vol 225 (5) ◽  
pp. 1153-1161 ◽  
Author(s):  
Y Guo ◽  
J P Hu ◽  
L Y Zhang
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Test Point ◽  
Pile Driving ◽  
Penalty Function Method ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
Material Choice ◽  
Multi Body ◽  
The Impact

This article treats the pile driving as multi-body dynamic contacts. By using the penalty function method and three-dimensional model of finite-element method, the dynamic process of pile driving is acquired and a method for choosing the cushion material of the hydraulic pile hammer to improve driving efficiency is proposed. The process of pile driving in the real situation of an industrial experiment is simulated. The results of stress on test point are consistent with the test point. By analysing the stress distributed along the direction of pile radius and pile axis, the rule of the stress distribution on the pile is concluded. The rule for cushion material choice is obtained by comparing the influence for the impact stress with different elastic modulus ratio of the hammer cushion to the pile and the pile cushion to the pile.

Sign in / Sign up

Export Citation Format

Share Document