scholarly journals Coupled Multi-Disciplinary Simulation of Composite Engine Structures in Propulsion Environment

1992 ◽  
Author(s):  
Christos C. Chamis ◽  
Surendra N. Singhal
Keyword(s):  
Acoustic Analysis ◽  
Acoustic Noise ◽  
Computational Simulation ◽  
Aircraft Engine ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Element Analysis ◽  
Composite Mechanics

A computational simulation procedure is described for the coupled response of multi-layered multi-material composite engine structural components which are subjected to simultaneous multi-disciplinary thermal, structural, vibration, and acoustic loadings including the effect of hostile environments. The simulation is based on a 3D finite element analysis technique in conjunction with structural mechanics codes and with the acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i.e., the laminate/ply/fiber and matrix constituents, via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometrical, material, loading, and environmental behavior of aircraft engine fan blades, are presented. Results for deformed shape, vibration frequencies, mode shapes, and acoustic noise emitted from the fan blade, are discussed for their coupled effect in hot and humid environment. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multi-disciplinary computational simulation and the various advantages of composite materials compared to metals.

scholarly journals Coupled Multidisciplinary Simulation of Composite Engine Structures in Propulsion Environment

1993 ◽  
Vol 115 (2) ◽  
pp. 300-306
Author(s):  
C. C. Chamis ◽  
S. N. Singhal
Keyword(s):  
Acoustic Analysis ◽  
Acoustic Noise ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Element Analysis

A computational simulation procedure is described for the coupled response of multilayered multimaterial composite engine structural components that are subjected to simultaneous multidisciplinary thermal, structural, vibration, and acoustic loading including the effect of hostile environments. The simulation is based on a three-dimensional finite element analysis technique in conjunction with structural mechanics codes and with the acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i.e., the laminate/ply/fiber and matrix constituents, via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometric, material, loading, and environmental behavior of aircraft engine fan blades are presented. Results for deformed shape, vibration frequencies, mode shapes, and acoustic noise emitted from the fan blade are discussed for their coupled effect in hot and humid environments. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multidisciplinary computational simulation and the various advantages of composite materials compared to metals.

Finite Element Analysis on Nitinol Medical Applications

2002 ◽  
Author(s):  
Xiao-Yan Gong ◽  
Alan R. Pelton
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Element Analysis ◽  
Highly Nonlinear ◽  
Device Applications ◽  
Specific Material

Nitinol, an alloy of about 50% Ni and 50% Ti, is a very unique material. At constant temperature above its Austenite finish (Af) temperature, under uniaxial tensile test, the material is highly nonlinear and capable of large deformation to the ultimate strain on the order of 15%. This material behavior, known as superelasticity, along with its excellent biocompatibility and corrosion resistance, makes Nitinol a perfect material candidate for many medical device applications. However, the nonlinear material response also requires a specific material description to perform the stress analysis. The user developed material subroutine from HKS/West makes the simulation of the Nitinol devices possible. This article presents two case studies of the nonlinear finite element analysis using ABAQUS/Standard and the Nitinol UMAT.

Structural vibration design of a pod structure including an optical system of a fighter aircraft

2021 ◽  
Vol 263 (1) ◽  
pp. 5555-5561
Author(s):  
Taeyoung Yoon ◽  
Jaemyung Cho ◽  
Sungsoo Na ◽  
Seongho Yoon
Keyword(s):  
Structural Dynamics ◽  
Optical System ◽  
Natural Frequencies ◽  
Free Vibration Analysis ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Element Analysis ◽  
Fighter Aircraft ◽  
Frequency Responses ◽  
Improving Accuracy

Structural vibration design of a pod structure including an optical system installed on a fighter aircraft is very significant in improving accuracy of targeting system to the target objects. To reduce and isolate the vibration generated during the flight, it is crucial to properly design the rubber mount between the pod and the aircraft. In this study, free vibration analysis of the pod is conducted through finite element analysis (FEA) and experiments. Correlations are performed with reasonably acceptable accuracy about the natural frequencies, mode shapes, and frequency response functions obtained by FEA and experiment. Then to optimize the structural dynamics of the pod, three variables are considered, which are mass of the dummies, the numbers of and positions of rubber mounts, and hyperelastic property of rubber mounts. In addition, the position of the pod on the fighter is analysed by FEM to estimate the possibility of further enhancement of its structural dynamics. Finally, forced vibration was undertaken using random signals of a shaker with 1Grms, 2Grms and 2.65Grms considering the test standard. It is found out that frequency responses of the pod are sensitive below 100 Hz to the values of the excitation signals. It is thus indeed to design appropriately the rubber mounts to improve structural dynamics of the pod, which results in the accuracy of targeting system.

Vibro-Acoustic Analysis of a Simple Gear Box

2013 ◽  
Author(s):  
Chan Il Park ◽  
Linguo Rong
Keyword(s):  
Acoustic Analysis ◽  
Complex Geometry ◽  
Helical Gear ◽  
Mode Shapes ◽  
Commercial Software ◽  
Element Analysis ◽  
Helical Gears ◽  
Harmonic Response ◽  
Gear Box ◽  
The Impact

Mesh forces of helical gears produce forces and moments in bearings, which generate the housing vibration, and noise radiates. It is difficult to know the noise contribution of a gear box, because the gear box usually has very complex geometry. This work used a cylindrical shell-type gear box with end circular plates to understand the noise and vibration characteristics of a simple gear box and investigated the noise and the vibration of the helical gear box due to the force excitation. The helical gear box of this study consisted of a pairs of helical gears, shafts, bearings, and a gear box. Finite element analysis for the helical gear box calculated mode shapes and natural frequencies and the forced harmonic response by the commercial software. The models were validated by the impact test. Using the forced harmonic response, acoustic analysis was conducted by the commercial software and relations on vibration and noise were discussed.

Theoretical Research on Two Improved Optimal Sensor Placement Methods

2013 ◽  
Vol 351-352 ◽  
pp. 1122-1129 ◽  
Author(s):  
Wei Liu ◽  
Wei Cheng Gao ◽  
Hui Li
Keyword(s):  
Kinetic Energy ◽  
Computational Simulation ◽  
Multiple Input Multiple Output ◽  
Sensor Placement ◽  
Theoretical Research ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Optimal Sensor Placement ◽  
Advantages And Disadvantages ◽  
Improved Methods

Optimal sensor placement technique plays a key role in structural health monitoring and structural vibration control. Based on the advantages and disadvantages of effective independence (EI) and modal kinetic energy (MKE) methods, two improved optimal sensor placement methods which are Effective Independence - Average Acceleration Amplitude (EI-AAA) method and Effective Independence - Modal Kinetic Energy (EI-MKE) method are proposed in this paper. Firstly the formulas are deduced from modal expansion of multiple-input-multiple-output (MIMO) displacement frequency response function matrix. Then a computational simulation of steel cross beam structure has been implemented to demonstrate the feasibility of the two improved methods above. The obtained optimal sensor locations using the two improved methods are compared with those gained by EI method and MKE method. Finally six classical comparison criteria are employed to demonstrate the advantage and disadvantage of these four methods. The results showed that some innovations proposed in this paper are effective and reliable. The two improved optimal sensor placement methods (EI-AAA method and EI-MKE method) can not only make the truncated mode shapes as linearly independent as possible but also enable the measured modal kinetic energy to maintain the maximum value.

Finite Element Analysis of Composite Piezoelectric Actuators Incorporating Nonlinear Material Behavior

2010 ◽  
Author(s):  
M. A. Siddiq Qidwai ◽  
Virginia G. DeGiorgi
Keyword(s):  
Electric Field ◽  
Predictive Modeling ◽  
Nonlinear Modeling ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Linear Material ◽  
Bimorph Actuators ◽  
Computational Resources ◽  
The Impact

There is always the question of choosing the appropriate constitutive model when simulating and analyzing piezoelectric material performance. Linear material modeling typically requires less computational resources; however this approach may not accurately capture the performance. In this paper, the scope of linear predictive modeling was analyzed by comparison with nonlinear modeling. Monomorph and bimorph actuators were modeled with each approach, and their respective performances were compared. It was found that even under small magnitudes of electric field, differences arise between the two approaches. The magnitude of the deviations depended upon actuator composition, applied electric field and boundary conditions. The impact of these differences can be considerable, such as for precision-based applications and cyclic applications where initial design errors could compound.

Combining Energy Boundary Element and Energy Finite Element Simulations for Airborne Noise Analysis

2006 ◽  
Author(s):  
Nickolas Vlahopoulos ◽  
Sheng Li ◽  
Jiulong Sun
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Acoustic Field ◽  
Acoustic Noise ◽  
Noise Analysis ◽  
Structural Vibration ◽  
Noise Sources ◽  
Element Analysis ◽  
High Frequencies ◽  
Airborne Noise

The Energy Boundary Element Analysis (EBEA) has been utilized in the past for computing the exterior acoustic field at high frequencies (above ~400Hz) around vehicle structures and numerical results have been compared successfully to test data. The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration of complex structures at high frequencies and validations have been presented in previous publications. The frequency range of applicability of the EFEA depends on the dynamic characteristics of the structure. In this paper the EBEA is utilized for computing the acoustic field around a vehicle structure due to external acoustic noise sources. The computed exterior acoustic field comprises the excitation for the EFEA analysis. Appropriate loading functions have been developed for representing the exterior acoustic loading in the EFEA simulations, and a formulation has been developed for considering the acoustic treatment applied on the interior side of structural panels. In order to demonstrate how the new developments can be combined in airborne noise applications, a case study is presented.

Strength Assessment of a Pressurized Thick-Walled Cylinder Using Structural-Thermal Coupled Finite Element Analysis

2007 ◽  
Author(s):  
John Feldhacker ◽  
Zhong Hu ◽  
Fereidoon Delfanian
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Damage ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Thick Wall ◽  
Firing Process ◽  
Surface Erosion ◽  
Element Analysis ◽  
Strength Assessment

Upon analysis, thick wall cylinders designed for use in cannon barrel applications experience thermal and mechanical loading very near their fatigue limit. Chief factors in determining the lifetime of a cannon barrel involve internal thermal and mechanical damage caused by projectile firing. The most significant damage experienced in the cannon barrel is surface crack propagation which aids in surface erosion and fatigue failure. Adequate knowledge of these failure phenomena and the ability to predict the lifetime of gun barrels will greatly increase the successful application of their designs. This study will investigate three-dimensional stress of a pressurized thick cylinder using computer simulation based on structural-thermal coupled finite element analysis. The effects of high temperature and high pressure, as well as nonlinear material behavior, on stress-strain distribution during the firing process will be evaluated. This computer-based stress analysis will prove to be a valuable tool for assessing strength and forecasting the lifetime of cannon barrels.

Modal Analysis of a Container Filled with Water

2014 ◽  
Vol 592-594 ◽  
pp. 2122-2126
Author(s):  
M.L. Chandravanshi ◽  
Alok Kumar Mukhopadhyay
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Fem Analysis ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Design Stage ◽  
Modal Parameters ◽  
Element Analysis ◽  
Empty Container ◽  
Ansys Workbench

Modal analysis plays an important role at design stage which helps in diagnosing problems related to structural vibration. This paper delineates about the experimental work to investigate the modal parameters, such as mode shapes and natural frequencies of a metallic container. The modal parameters have been experimentally determined for the empty container, the container filled with one liter of water and the container filled with two liters of water. Theoretical analysis is also carried out through finite element analysis using ANSYS workbench 14 for finding out modal parameters of the empty container only. The boundary conditions of the container in the experimental and FEM analysis have been kept same. The values of modal parameters obtained by the two methods then compared for their proximity

Study of Passive Vibration Absorbers Attached on Beam Structure

2014 ◽  
Vol 660 ◽  
pp. 511-515 ◽  
Author(s):  
Izzuddin Zaman ◽  
Muhammad Mohamed Salleh ◽  
Maznan Ismon ◽  
Bukhari Manshoor ◽  
Amir Khalid ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Structural Vibration ◽  
Mode Shapes ◽  
Small Scale ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Structural Dynamic

Structural vibration is undesirable, wasting energy and possibly leading to excessive deflections and structure and machine’s failure. In order to reduce structural vibration, one of the common way is considering vibration absorber system attach to the structure. In this study, a vibration absorber is developed in a small scale size. The host structure selected for the study is a fixed-fixed ends beam. The effectiveness of vibration absorbers attached to a beam is investigated through experimental study. In prior to experiment, a finite element analysis of Solidworks® and analytical equations of Matlab® are produced in order to determine the structural dynamic response of the beam, such as the natural frequency and mode shapes. The preliminary results of finite element analysis demonstrate that the first five natural frequency of fixed-fixed end beam are 17Hz, 46Hz, 90Hz, 149Hz and 224Hz, and these results are in agreement with the beam’s analytical equations. However, there are slight discrepancies in experiment result due to noise and error occurred during the setup. In the later stage, the experimental works of beam are performed with attached vibration absorber. Result shows that the attachment of vibration absorber produces better outcome, which is about 45% vibration reduction. It is expected that by adding more vibration absorber to the structure, the vibration attenuation can significant.

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