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.

scholarly journals Effective Elastic Properties of 3D Carbon-Carbon Composites at High Temperature

1996 ◽  
Vol 5 (2) ◽  
pp. 096369359600500
Author(s):  
X.D. He ◽  
J.C. Han ◽  
S.Y. Du
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Elastic Modulus ◽  
High Temperature ◽  
Finite Element Model ◽  
Tensile Properties ◽  
Elastic Properties ◽  
Element Model ◽  
Carbon Composites ◽  
Fiber Spacing

This paper describes a mini-finite element model for evaluation of high temperature elastic modulus of 3D C/C composite and the variation of tensile properties with substrate parameters such as xy-woven layers, fiber boundles and fiber spacing was analyzed. The results predicted suit the experimental data well.

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.

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.

The sagittal curvature of the spine can be a leading cause of scoliosis in pediatric spine

2021 ◽  
Author(s):  
S Pasha
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Early Stage ◽  
Element Model ◽  
Sagittal Profile ◽  
Deformation Pattern ◽  
Element Simulation ◽  
Curve Deformation ◽  
Numerical Finite Element ◽  
Deformation Patterns

The etiology of the adolescent idiopathic scoliosis (AIS) remains unknown. Variations in the sagittal profile of the spine between the early stage scoliotic and non-scoliotic pediatric patients have been shown. However, no quantitative study has shown the link between the sagittal profile and 3D deformity of the spine. 126 right thoracic scoliosis with spinal and 3D reconstructions were included. A 2D finite element model was developed for each of the sagittal curve types without any deformity in the frontal or axial planes. Physiological loadings were determined from the literature and were applied in the finite element model. The 3D deformation patterns of the models were compared to the 3D spinal patterns of the AIS with the same sagittal type. A significant correlation was found between the 3D deformity of the scoliotic curves and the numerical finite element simulation of the corresponding sagittal profile as determined by pattern correlation, p<0.001. The sagittal curve deformation patterns corresponded to the spinal deformities in the patients with the same sagittal curvature. Finite element models of the spines, representing different sagittal types in 126 AIS patients showed that deformation pattern of the sagittal types changes as a function of the spine curvature and associates with the patterns of 3D spinal deformity in AIS patients with the same sagittal curves. This finding provided evidence that the sagittal curve of the spine can determine the deformity patterns in AIS.

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.

Equivalent core concept for large-scale structural-level applications

2017 ◽  
Vol 21 (4) ◽  
pp. 1595-1616
Author(s):  
Woo Geun Lee ◽  
Jung Seok Kim ◽  
Jae-Yong Lim
Keyword(s):  
Finite Element ◽  
Elastic Properties ◽  
Large Scale ◽  
Sandwich Beam ◽  
Discrete Models ◽  
Equivalent Model ◽  
Design Stage ◽  
Solid Core ◽  
Structural Level ◽  
Core Concept

This study examined the applicability of the equivalent core concept, which replaces a discrete core with a homogenized solid core representing its elastic properties, on a large-scale structure. To this end, numerical verifications were performed for corrugated core structures at two levels, the specimen level and structural level. Before the verifications, analytical equations were gathered from previous reports to obtain the homogenized elastic properties of corrugated cores. At the specimen-level verifications, the maximum deflections of the corrugated core panel specimens subject to three-point bending were calculated with sandwich beam theory, finite element models with discretely modeled cores and equivalent cores. For the structural-level verifications, the maximum deflection and natural frequency were computed from a discrete finite element model and an equivalent model of a railway car body structure. The results revealed that the equivalent models gave excellent agreement with the theoretical values if the same underlying boundary conditions were used; however, greater discrepancies were observed with the discrete models. In addition, for the structural-level verifications the equivalent core model reasonably approximated the discrete model with marginal accuracy. Therefore, employing the equivalent core concept can be expected to save computational costs in the initial design stage of large-scale structures.

Effects of radial aerodynamic forces on rotor-bearing dynamics of high-speed turbochargers

2014 ◽  
Vol 228 (14) ◽  
pp. 2503-2519 ◽  
Author(s):  
A Alsaeed ◽  
G Kirk ◽  
S Bashmal
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Pressure Variation ◽  
Experimental Results ◽  
Aerodynamic Forces ◽  
Aerodynamic Loads ◽  
Numerical Predictions ◽  
Reaction Forces ◽  
Bearing Dynamics

This study investigates the radial aerodynamic forces that may develop inside the centrifugal compressor and the turbine volutes due to pressure variation of the circulating gas. The forces are numerically predicted for magnitudes, directions, and locations. The radial aerodynamic forces are numerically simulated as static forces in the turbocharger finite element model with floating ring bearings and solved for nonlinear time-transient response. The numerical predictions of the radial aerodynamic forces are computed with correlation to earlier experimental results of the same turbocharger. The outcomes of the investigation demonstrate a significant influence of the radial aerodynamic loads on the turbocharger dynamic stability and the bearing reaction forces. The numerical predictions are also compared with experimental results for validation.

Finite-Element Modelling of Ballistic Impact of Plain-Woven Aramid Fabric

2014 ◽  
Vol 553 ◽  
pp. 769-773 ◽  
Author(s):  
E.A. Flores-Johnson ◽  
J.G. Carrillo ◽  
R.A. Gamboa ◽  
Lu Ming Shen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Modelling ◽  
Permanent Deformation ◽  
Element Model ◽  
Ballistic Impact ◽  
Elastic Model ◽  
Numerical Predictions ◽  
Aramid Fabric ◽  
The Finite Element Model

In this work, a 3D finite-element model of the ballistic impact of a multi-layered plain-woven aramid fabric style 720 (Kevlar®129 fibre, 1420 denier, 20×20 yarns per inch) impacted by a 6.7-mm spherical projectile was built at the mesoscale in Abaqus/Explicit by modelling individual crimped yarns. Material properties and yarn geometry for the model were obtained from reported experimental observations. An orthotropic elastic model with a failure criterion based on the tensile strength of the yarns was used. Numerical predictions were compared with available experimental data. It was found that the finite-element model can reproduce the physical experimental observations, such as the straining of primary yarns and pyramidal-shaped deformation after perforation. The permanent deformation of fabric targets predicted by the numerical simulations was compared with available experimental results. It was found that the model fairly predicted the permanent deformation with a difference of about 21% when compared with experiments.

scholarly journals Effect of a rigid toroidal inhomogeneity on the elastic properties of a composite

2018 ◽  
Vol 24 (4) ◽  
pp. 1129-1146 ◽  
Author(s):  
Stanislav Krasnitskii ◽  
Anton Trofimov ◽  
Enrico Radi ◽  
Igor Sevestianov
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Finite Element Model ◽  
Elastic Medium ◽  
Elastic Properties ◽  
Element Model ◽  
Uniform Strain ◽  
Model Calculations ◽  
Torus Surface ◽  
Strain Components

An analytical solution is obtained for the problem of an infinite elastic medium containing a rigid toroidal inhomogeneity under remotely applied uniform strain. The traction on the torus surface is determined as a function of torus parameters and strain components applied at infinity. The results are utilized to calculate components of the stiffness contribution tensor of the rigid toroidal inhomogeneity that is required for calculation of the overall elastic properties of a material containing multiple toroidal inhomogeneities. The analytical results are verified by comparison with finite element model calculations.

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