The Effect of Graded Strength on Damage Propagation in Continuously Nonhomogeneous Materials

2003 ◽  
Vol 125 (4) ◽  
pp. 412-417 ◽  
Author(s):  
Priya Thamburaj ◽  
Michael H. Santare ◽  
George A. Gazonas
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Damage Model ◽  
Numerical Results ◽  
Finite Element Code ◽  
Different Boundary Conditions ◽  
One Dimensional ◽  
Damage Propagation ◽  
Dynamic Finite Element ◽  
Nonhomogeneous Materials

A damage model developed by Johnson and Holmquist is implemented into a dynamic finite element code. This is then used to study the effect of grading of the phenomenological damage parameters on the propagation of damage through the material. The numerical results for two one-dimensional example problems with different boundary conditions are presented, wherein the effect of a gradient in the intact strength of the material on damage propagation is studied. The results show that introducing different strength gradients can alter the location of the site of maximum damage. This may have important implications in the design of impact resistant materials and structures.

Exact Elasticity Solutions for Stresses and Deflections in Curved Beams and Rings of Exponential and T-Sections

1991 ◽  
Author(s):  
Cemil Bagci
Keyword(s):  
Differential Equations ◽  
Boundary Conditions ◽  
Plane Stress ◽  
Numerical Results ◽  
Neutral Axis ◽  
Curved Beams ◽  
Equilibrium Stress ◽  
Different Boundary Conditions ◽  
Stress Functions ◽  
Elasticity Solutions

Abstract Exact elasticity solutions for stresses and deflections (displacements) in curved beams and rings of varying thicknesses are developed using polar elasticity and state of plane stress. Basic forms of differential equations of equilibrium, stress functions, and differential equations of compatibility are given. They are solved to develop expressions for radial, tangential, and shearing stresses for moment, force, and combined loadings. Neutral axis location for each type of loading is determined. Expressions for displacements are developed utilizing strain-displacement relationships of polar elasticity satisfying boundary conditions on displacements. In case of full rings stresses are as in curved beams with properly defined moment loading, but displacements differ satisfying different boundary conditions. The developments for constant thicknesses are used to develop solutions for curved beams and rings with T-sections. Comparative numerical results are given.

Effective Shear Area in One Dimensional Ship Hull Finite Element Models to Predict Natural Frequencies of Vibration

2013 ◽  
Author(s):  
Osvaldo Pinheiro de Souza e Silva ◽  
Severino Fonseca da Silva Neto ◽  
Ilson Paranhos Pasqualino ◽  
Antonio Carlos Ramos Troyman
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Numerical Results ◽  
Computational Method ◽  
Scale Model ◽  
Dimensional Model ◽  
One Dimensional ◽  
Shear Area

This work discusses procedures used to determine effective shear area of ship sections. Five types of ships have been studied. Initially, the vertical natural frequencies of an acrylic scale model 3m in length in a laboratory at university are obtained from experimental tests and from a three dimensional numerical model, and are compared to those calculated from a one dimensional model which the effective shear area was calculated by a practical computational method based on thin-walled section Shear Flow Theory. The second studied ship was a ship employed in midshipmen training. Two models were made to complement some studies and vibration measurements made for those ships in the end of 1980 decade when some vibration problems in them were solved as a result of that effort. Comparisons were made between natural frequencies obtained experimentally, numerically from a three dimensional finite element model and from a one dimensional model in which effective shear area is considered. The third and fourth were, respectively, a tanker ship and an AHTS (Anchor Handling Tug Supply) boat, both with comparison between three and one dimensional models results out of water. Experimental tests had been performed in these two ships and their results were used in other comparison made after the inclusion of another important effect that acts simultaneously: the added mass. Finally, natural frequencies experimental and numerical results of a barge are presented. The natural frequencies numerical results of vertical hull vibration obtained from these approximations of effective shear areas for the five ships are finally discussed.

ON THE PROTECTION CAPABILITY OF THE FLYING PLATE AGAINST TO LONG-ROD PENETRATORS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1285-1290
Author(s):  
STANISLAV ROLC ◽  
JAROSLAV BUCHAR ◽  
ZBYNEK AKSTEIN
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Numerical Results ◽  
Finite Element Code ◽  
Plate Material ◽  
3D Finite Element ◽  
Plate Velocity ◽  
Long Rod ◽  
Protection Capability

The interaction of the flying plate with the Long-rod penetrator has been studied both experimentally and numerically using the LS DYNA 3D finite element code. The influence of the plate velocity and plate material on this interaction has been investigated in details. Numerical results show that there was a relatively large damage of the projectiles. The extent of this damage well agree with our experimental foundings. The numerical simulation of the damaged projectiles with some targets has been also performed

Study on Mechanical Properties of the Corrugated Waist Rail with the Dynamic Finite Element Method

2014 ◽  
Vol 898 ◽  
pp. 209-212
Author(s):  
Jin Hong Ma ◽  
Shen Bai Zheng ◽  
Bin Tao
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Comparative Study ◽  
Special Kind ◽  
Lateral Load ◽  
Finite Element Code ◽  
Contact Behavior ◽  
Dynamic Finite Element ◽  
Element Method

The corrugated waist rail has been successfully rolled in the Mill Research Institute of Yanshan University. It is necessary to conduct a comparative study on the mechanical properties of this special kind of rail with that of the ordinary rail. ANSYS/LS-DYNA, the finite element code, is used to simulate the contact behavior of wheel and rail. The study aims to investigate the influences of axle and lateral load on the stresses and displacement of the rail. It draws a conclusion that the mechanical properties of the corrugated waist rail is superior to that of the ordinary rail. It also provides a method and useful data for the further research on fatigue and wear of corrugated waist rail.

Forced Motions of Composite Conoidal Shell Roofs with Complicated Boundary Conditions

2010 ◽  
Vol 123-125 ◽  
pp. 89-92
Author(s):  
Kaustav Bakshi ◽  
Hari Sadhan Das ◽  
Dipankar Chakravorty
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Forced Vibration ◽  
Vibration Characteristics ◽  
Finite Element Code ◽  
Isoparametric Finite Element

An eight noded isoparametric finite element code is applied to study static bending, free and forced vibration characteristics of composite conoidal shell roofs with complicated boundary conditions which are often encountered in the industry.

scholarly journals Simulation of Aircraft Landing Gears with a Nonlinear Dynamic Finite Element Code

2002 ◽  
Vol 39 (1) ◽  
pp. 142-147 ◽  
Author(s):  
Karen H. Lyle ◽  
Karen E. Jackson ◽  
Edwin L. Fasanella
Keyword(s):  
Finite Element ◽  
Nonlinear Dynamic ◽  
Finite Element Code ◽  
Dynamic Finite Element ◽  
Aircraft Landing ◽  
Landing Gears

Finite Element Analysis of Polyurethane Based Composite Shafts Under Different Boundary Conditions

2014 ◽  
Author(s):  
Mosfequr Rahman ◽  
F. N. U. Aktaruzzaman ◽  
Saheem Absar ◽  
Aniruddha Mitra ◽  
Awlad Hossain
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Polymer Matrix ◽  
Three Dimensional ◽  
Woven Fabric ◽  
Bending Test ◽  
Matrix Composites ◽  
Fiber Glass ◽  
Different Boundary Conditions ◽  
Simply Supported

Depending on the type of matrix materials, composites can be broadly divided into three different major classifications: Organic-matrix composites (OMC), metal-matrix composites (MMC), and ceramic-matrix composites (CMC). OMC can be further sub-classified into polymer-matrix composites (PMC) and carbon-matrix composites or carbon-carbon composites. In this paper the main objective is to focus on polyurethane based PMC composites. Polyurethane is one of the widely used polymer matrix materials. It has diversified applications, easily available and cheap. In this computational study a composite shaft with a core made of matrix material completely wrapped around by a woven fiber cloth with a very strong bonding between core and fibers is considered. Three different types of woven fibers: fiber glass, Kevlar 49, and carbon fibers, are considered. A woven fabric is the interlocking or weaving of two unidirectional fibers. This configuration is often used to produce curve surfaces because of the ease with which it could be placed on and conform to curved surfaces. Authors had fabricated these three composites in their in-house laboratory. They had also experimentally measured the mechanical properties of these composites using 3-point bending test which already been published. In this current study finite element analyses has been performed for the modeling of the static response of these three different polyurethane based composite shafts as fiber glass reinforced polyurethane epoxy, carbon fiber reinforced polyurethane epoxy, and Kevlar fibers reinforced polyurethane epoxy for three different boundary conditions. These three boundary conditions are simply supported, cantilever, both end fixed types with bending loads applied at the middle for simply supported case and distributed load along the length of the shaft for the last two types of boundary conditions. A three dimensional model of the composite beam has been implemented in this study using SolidWorks. A finite element commercial software ANSYS is used to investigate the stress response and deformation behavior of the model geometry for these three polyurethane based composite shafts for these three boundary conditions. A twenty node three dimensional element has been implemented for the finite element formulation of the modeled geometry such that it is applicable for the analysis of a layered composite structure, while providing support for linear, large rotation, and large strain nonlinear loading conditions. Convergence has also been ensured for various mash configurations in this work.

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