A Numerical Approach for the Prediction and Reduction of Structure-Borne Noise During the Design Stage of Ground Vehicles

1993 ◽  
Author(s):  
Nickolas Viahopoulos ◽  
Edward V. Shalis ◽  
Michael A. Latcha
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Numerical Approach ◽  
Design Stage ◽  
Structural Components ◽  
Ground Vehicles ◽  
Radiated Noise ◽  
Forcing Function ◽  
Military Applications ◽  
Commercial Applications

Abstract During the design stage of ground vehicles it is important to reduce the noise emitted from structural components. In commercial applications the reduction of the interior noise for passenger comfort is a concern with increased significance. In military applications noise radiated from the exterior of the vehicle is of primary importance for the survivability of the vehicle. Numerical acoustic prediction software can be used during the design stage to predict and reduce the radiated noise. Two formulations, the Rayleigh integral equation1 and the direct boundary element method2,3 were implemented into software for acoustic prediction. The developed code can accept information from a finite element model with a known input forcing function. Specifically, the predicted velocities on the structural surfaces can be used as input to the acoustic code for predicting the noise emitted from a vibrating structure. Computation of acoustic sensitivities4 was also implemented in the code. This information can identify the portions of the boundary that effect the radiated noise most, and it can be used in an optimization process to reduce the noise radiated from a vibrating structure.

Optimization Design of Pressure Shell in Underwater Vehicle Based on Response Surface Model

2009 ◽  
Vol 419-420 ◽  
pp. 89-92
Author(s):  
Zhuo Yi Yang ◽  
Yong Jie Pang ◽  
Zai Bai Qin
Keyword(s):  
Finite Element ◽  
Response Surface ◽  
Optimization Design ◽  
Engineering Application ◽  
Element Model ◽  
Response Surface Model ◽  
Design Stage ◽  
Surface Model ◽  
Design Variables ◽  
Structure Strength

Cylinder shell stiffened by rings is used commonly in submersibles, and structure strength should be verified in the initial design stage considering the thickness of the shell, the number of rings, the shape of ring section and so on. Based on the statistical techniques, a strategy for optimization design of pressure hull is proposed in this paper. Its central idea is that: firstly the design variables are chosen by referring criterion for structure strength, then the samples for analysis are created in the design space; secondly finite element models corresponding to the samples are built and analyzed; thirdly the approximations of these analysis are constructed using these samples and responses obtained by finite element model; finally optimization design result is obtained using response surface model. The result shows that this method that can improve the efficiency and achieve optimal intention has valuable reference information for engineering application.

scholarly journals Effect of spatial distribution of fibers on elastic properties of unidirectional carbon/carbon composites

2021 ◽  
Vol 309 ◽  
pp. 01214
Author(s):  
M.V.N Mohan ◽  
Ramesh Bhagat Atul ◽  
Vijay Kumar Dwivedi
Keyword(s):  
Finite Element ◽  
Spatial Distribution ◽  
Elastic Properties ◽  
Element Model ◽  
Experimental Methods ◽  
Design Stage ◽  
Carbon Composites ◽  
Numerical Predictions ◽  
Numerical Finite Element ◽  
Very High

Carbon/Carbon composites finds its applications in several high temperature applications in the field of Space, Aviation etc. Designing of components or sub systems with carbon/carbon composites is a challenging task. It requires prediction of elastic properties with a very high accuracy. The prediction can be normally done by analytical, numerical or experimental methods. At the design stage the designers resort to numerical predictions as the experimental methods are not feasible during design stage. Analytical methods are complex and difficult to implement. The designers use numerical methods for prediction of elastic properties using Finite Element Modeling (FEM). The spatial distribution of fibers in matrix has an effect on results of prediction of elastic constants. The generation of random spatial distribution of fibers in representative volume element (RVE) challenging. The present work is aimed at study of effect of spatial distribution of fiber in numerical prediction of elastic properties of unidirectional carbon/carbon composites. MATLAB algorithm is used to generate the spatial distribution of fibers in unidirectional carbon/carbon composites. The RVE elements with various random fiber distributions are modeled using numerical Finite element Model using ABAQUS with EasyPBC plugin. The predicted elastic properties have shown significant variation to uniformly distributed fibers.

Dynamic Behavior of String Subjected to Travelling Mass

2019 ◽  
Author(s):  
Shakti P. Jena ◽  
S. Naresh Kumar ◽  
Hemanth Cheedella
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Green’S Function ◽  
Dynamic Behavior ◽  
Green's Function ◽  
Transverse Vibration ◽  
Element Model ◽  
Numerical Approach ◽  
Complete Analysis ◽  
Numerical Example

Abstract The present study is based on the transverse vibration analogy of a string subjected to a travelling mass. The string is considered to be fixed at their both ends. The responses of the string due to the dynamic behavior of the travelling mass are determined using a numerical approach i.e. Green’s function. A Finite Element Model (FEM) has been developed to authenticate the numerical approach. For the responses analysis of the string, numerical example has been illustrated to study the behavior of the string due to the travelling mass and to check the convergence of the two proposed analogies (Green’s function and FEM). The complete analysis has been performed at constant travelling speed and different masses. The two approaches converge well and the Green’s function methodology found to be suitable one.

A Review of In-Place Design Approaches for Spar Hulls

2005 ◽  
Author(s):  
Cheng-Yo Chen ◽  
Trevor Mills
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Current Practice ◽  
State Of The Art ◽  
Element Model ◽  
Maximum Strength ◽  
Design Approach ◽  
Structural Components ◽  
Advantages And Disadvantages ◽  
Design Loads

This paper reviews the current practice for the in-place design of Spar hulls. Both the commonly-used approach and the state-of-the-art procedure for the maximum strength and fatigue conditions will be presented. Key assumptions for various design approaches will be discussed along with advantages and disadvantages of each approach. The review will focus on how each approach generates hydrodynamic loadings, performs global motions analysis, and maps design loads from motion analyses to structural finite-element model. Important aspects relating to Spar design will be addressed. In particular, effect of vortex induced hull motions (VIM) will be discussed, and an approach for including the VIM effect in the design of moorings and risers will also be described. Impact on the maximum strength and fatigue capacity of critical structural components due to the assumptions employed in the commonly-used design approach will be evaluated and quantified as compared to the results from the more rigorous state-of-the-art approach.

scholarly journals A Study on Fluid Self-Excited Flutter and Forced Response of Turbomachinery Rotor Blade

2014 ◽  
Vol 2014 ◽  
pp. 1-20 ◽  
Author(s):  
Chih-Neng Hsu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Power Plants ◽  
Single Mode ◽  
Element Model ◽  
Forced Response ◽  
Structural Dynamic ◽  
Turbine Engine ◽  
Forcing Function ◽  
Structural Dynamic Characteristics

Complex mode and single mode approach analyses are individually developed to predict blade flutter and forced response. These analyses provide a system approach for predicting potential aeroelastic problems of blades. The flow field properties of a blade are analyzed as aero input and combined with a finite element model to calculate the unsteady aero damping of the blade surface. Forcing function generators, including inlet and distortions, are provided to calculate the forced response of turbomachinery blading. The structural dynamic characteristics are obtained based on the blade mode shape obtained by using the finite element model. These approaches can provide turbine engine manufacturers, cogenerators, gas turbine generators, microturbine generators, and engine manufacturers with an analysis system to remedy existing flutter and forced response methods. The findings of this study can be widely applied to fans, compressors, energy turbine power plants, electricity, and cost saving analyses.

An Elastic/Viscoplastic Finite Element Model for Predicting Polymerization Stresses in Light-Activated Dental Composites

2003 ◽  
Author(s):  
Gayle A. Laughlin ◽  
John L. Williams ◽  
J. David Eick
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Numerical Approach ◽  
Mechanical Analysis ◽  
Dental Composite ◽  
Time Dependent ◽  
Dental Composites ◽  
Cavity Preparation ◽  
Constitutive Parameters ◽  
Perzyna's Theory

The purpose of this paper is to apply a finite deformation, elastic/viscoplastic approach to predict curing stresses in three light-cured dental composites, using Perzyna’s theory. Time-dependent constitutive parameters were obtained from mercury dilatometry, dynamic mechanical analysis and constrained shrinkage strerss testing. The numerical approach was verified by using the results of an experiment on a simple aluminum tooth model of a cavity preparation that was bulk-filled with light-cured dental composite restorative materials. The numerically predicted strain patterns were similar to those seen experimentally for the three different dental composites.

Assessment of Corner Failure Depths in the Deep Drawing of 3D Panels Using Simplified 2D Numerical and Analytical Models

2000 ◽  
Vol 123 (2) ◽  
pp. 248-257 ◽  
Author(s):  
Hong Yao ◽  
Jian Cao
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Analytical Models ◽  
Design Stage ◽  
Beam Model ◽  
Preliminary Design ◽  
Powerful Means ◽  
Preliminary Design Stage ◽  
Blank Size

Methodologies of rapidly assessing maximum possible forming heights are needed for three-dimensional 3D sheet metal forming processes at the preliminary design stage. In our previous work, we proposed to use an axisymmetric finite element model with an enlarged tooling and blank size to calculate the corner failure height in a 3D part forming. The amount of enlargement is called center offset, which provides a powerful means using 2D models for the prediction of 3D forming behaviors. In this work, an analytical beam model to calculate the center offset is developed. Starting from the study of a square cup forming, a simple analytical model is proposed and later generalized to problems with corners of an arbitrary geometry. The 2D axisymmetric models incorporated with calculated center offsets were compared to 3D finite element simulations for various cases. Good assessments of failure height were obtained.

A Combined Analytical and Numerical Approach to Analyze Mud Motor Excited Vibrations in Drilling Systems

2015 ◽  
Author(s):  
Andreas Hohl ◽  
Carsten Hohl ◽  
Christian Herbig
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Field Measurements ◽  
Element Model ◽  
Numerical Approach ◽  
Analytical Models ◽  
Finite Element Models ◽  
Beam Model ◽  
Direct Influence ◽  
Practical Applications

Severe vibrations in drillstrings and bottomhole assemblies can be caused by cutting forces at the bit or mass imbalances in downhole tools. One of the largest imbalances is related to the working principle of the so-called mud motor, which is an assembly of a rotor that is maintained by the stator. One of the design-related problems is how to minimize vibrations excited by the mud motor. Simulation tools using specialized finite element methods (FEM) are established to model the mechanical behavior of the structure. Although finite element models are useful for estimating rotor dynamic behavior and dynamic stresses of entire drilling systems they do not give direct insight how parameters affect amplitudes and stresses. Analytical models show the direct influence of parameters and give qualitative solutions of design related decisions. However these models do not provide quantitative numbers for complicated geometries. An analytical beam model of the mud motor is derived to calculate the vibrational amplitudes and capture basic dynamic effects. The model shows the direct influence of parameters of the mud motor related to the geometry, material properties and fluid properties. The analytical model is compared to the corresponding finite element model. Vibrational amplitudes are discussed for different modes and parameter changes. Finite element models of the entire drilling system are used to verify the findings from the analytical model using practical applications. The results are compared to time domain and statistical data from laboratory and field measurements.

scholarly journals Behaviour of Cold Formed Light Gauge Steel Angle Columns Subjected To Eccentric Loading

2019 ◽  
Vol 8 (6) ◽  
pp. 384-396
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Eccentric Load ◽  
Steel Columns ◽  
Cold Bending ◽  
Steel Angle ◽  
Wide Range ◽  
Angle Section ◽  
Commercial Applications ◽  
Hot Rolled

Coldformed steel is an exceptional engineering material for residential and commercial applications because of its inherent structural efficiency obtained by hot and cold bending and its wide range of prefabricated geometries.A lot of research has been done to study the structuralbehaviour of light gauge axially loaded steel angle columns. The study of cold formed light gauge steel angle columns subjected to eccentric load is to be required to know its performance in the place of hot rolled steel columns. The load is varying from shear centre to centre of gravity of angle section. The study of such columns can be done experimentally with varying thickness and b/t ratios by taking fixed-hinged end condition and the same can be validated in the finite element model by using ABAQUS / CAE 6.14 finite element softwareto find the buckling behaviour of different columns

scholarly journals A new circular spinneret system for electrospinning numerical approach and electric field optimization

2019 ◽  
Vol 23 (4) ◽  
pp. 2229-2235 ◽  
Author(s):  
Ziming Zhu ◽  
Han Wang ◽  
Guojie Xu ◽  
Rouxi Chen ◽  
Lixiong Huang ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Finite Element ◽  
Electric Field ◽  
Large Scale ◽  
Energy Harvester ◽  
Wearable Sensors ◽  
Element Model ◽  
Numerical Approach ◽  
Electrospinning Process ◽  
Effective Technique

Electrospinning is believed to be the most effective technique to produce microfibers or nanofibers at large scale, which can be applied in various hightech areas, including energy harvester, tissue engineering, and wearable sensors. To enhance nanofiber throughput during a multi-needle electrospinning process, it is an effective way to keep the electric field uniform by optimizing electrospinning spinnerets. For this purpose, a novel circular spinneret system is designed and optimized numerically by a 3-D finite element model, the optimal collector shape is also obtained.

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