Finite Element Analysis of the Unsteady Thrust Characteristics of Pulse Detonation Engines

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Dibesh D. Joshi ◽  
Frank K. Lu
Keyword(s):  
Finite Element ◽  
Specific Impulse ◽  
A Priori ◽  
Structural Response ◽  
Element Model ◽  
Detonation Pressure ◽  
Element Analysis ◽  
Pulse Detonation ◽  
Pressure Pulses ◽  
Detonation Engine

A general, dynamical approach developed a high-fidelity, finite element model of a pulse detonation engine (PDE). The approach deconvolved the structural response due to cyclic acceleration that would be measured by a load cell, thereby obtaining the actual thrust that is produced. The model was excited with pressure pulses that simulated actual detonation pressure characteristics at different frequencies. A two-step process was developed. In the first step, the system dynamics was established and validated by deconvolving from a known input in the form of pressure pulses from which the reconstructed thrust output was obtained. The second step required that the deconvolved thrust be compensated for system acceleration. This step required the effective mass and induced acceleration to be determined which then yielded an inertial load that has to be removed from the reconstructed thrust to obtain the actual thrust. The compensated thrust values were expressed in the form of specific impulse for the PDE which compared well with a priori pulsed thrust loading.

Numerical investigation on behaviour and design of cold-formed steel built-up column composed of lipped sigma channels

2019 ◽  
Vol 22 (8) ◽  
pp. 1817-1829 ◽  
Author(s):  
M Anbarasu
Keyword(s):  
Finite Element ◽  
Structural Response ◽  
Element Model ◽  
Width Ratio ◽  
Element Analysis ◽  
Design Strength ◽  
Steel Columns ◽  
The North ◽  
Cold Formed Steel ◽  
Ultimate Resistance

This article aims at investigating the structural response and predicting the ultimate resistance of cold-formed steel built-up columns composed of lipped sigma sections with pinned ends. For this purpose, a numerical model is established by using the finite element code ABAQUS. The finite element models include geometric, material nonlinearity. The effects of initial local and overall geometric imperfections have been taken into consideration in the finite element modelling. The results of the nonlinear finite element analysis were validated with the available experimental results present in the literature. A parametric study was carried out using the developed finite element model to study the effect of member slenderness, height-to-width ratio and depth of trapezoidal stiffener on the ultimate resistance of cold-formed steel closed built-up columns. On the basis of the parametric results, presented herein, appropriateness of the current direct strength method in the North American Specification for cold-formed steel columns is assessed. Based on such comparison, design expression is proposed to provide reliable design strength prediction of cold-formed steel built-up column composed of lipped sigma sections and verified through reliability analysis.

scholarly journals Parametric study on structural behavior of a two-span continuous bridge deck and a curved span deck

2021 ◽  
Vol 2 (3) ◽  
pp. 1-7
Author(s):  
Tirimisiyu Abiodun Buari
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bridge Deck ◽  
Structural Response ◽  
Element Model ◽  
Element Analysis ◽  
Finite Element Analysis Result ◽  
The Finite Element Analysis ◽  
Grillage Analysis ◽  
Combined Impact

This research investigated the comparative structural response of a straight and curved continuous bridge deck subjected to realistic working loads. The study involved examining the variance in analysis results obtained while utilizing the grillage and finite element methods for an idealized bridge deck. The combined impact of continuity at the intermediate support and the curvature on the overall structure was examined. The idealized case study is a 45m two-span continuous bridge deck with a 22.5m straight span and an equivalent 22.5m curved span with a centerline radius of approximately 14.32m. The bridge deck was designed for design dead load and 45 units of HB load, these loads were computed based on recommendations given in BS 5400-2:2006 and BD 37/01-1:2001[1,2]. For the Grillage Analysis Sap2000 version 22 software was utilized while CSI Bridge version 21 was used to simulate the Finite Element model. The findings from the study revealed that the results obtained from the grillage analysis method were more conservative with respect to midspan sagging moments and support shear force. However, the finite element analysis result was more conservative for support hogging moments, deflection and torsional moments. It was concluded that finite element analysis result values differed from the grillage analysis, but the values were close enough with the disparity not calling for serious concerns.

Intelligent Automatic Mesh Generation for Multichip Modules

1993 ◽  
Author(s):  
Anagha G. Jog ◽  
Ian R. Grosse ◽  
Daniel D. Corkill
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Mesh Generation ◽  
A Priori ◽  
Three Dimensional ◽  
Element Model ◽  
Design Tool ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Element Modeling

Abstract Currently, the pre-processing stage of finite element analysis is a major stumbling block towards automation of the entire finite element modeling and analysis (FEMA) process. The lack of complete automation of FEMA greatly limits its impact as a design tool. This paper presents a blackboard-based, object-oriented modeling system for intelligent a-priori automatic three dimensional mesh generation. The modeling system enables the user to define the physical system at a natural domain-specific high level of abstraction and automatically derives lower-level finite element model representations. Knowledge sources interact with the blackboard to make modeling idealizations and select optimal meshing strategies. An example application in the domain of finite element modeling of multi-chip module microelectronic devices is presented.

Agricultural aircraft wing slat tolerance for bird strike

2017 ◽  
Vol 89 (4) ◽  
pp. 590-598 ◽  
Author(s):  
Adam Deskiewicz ◽  
Rafał Perz
Keyword(s):  
Finite Element ◽  
Impact Velocity ◽  
Structural Response ◽  
Element Model ◽  
Bird Strike ◽  
Element Analysis ◽  
Content Type ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
The Impact

Purpose The aim of this study is to assess and describe possible consequences of a bird strike on a Polish-designed PZL-106 Kruk agricultural aircraft. Due to its susceptibility to such events, a wing slat has been chosen for analysis. Design/methodology/approach Smooth particle hydrodynamics (SPH) formulation has been used for generation of the bird finite element model. The simulations were performed by the LS-Dyna explicit finite element analysis software. Several test cases have been analysed with differing parameters such as impact velocity, initial velocity vector direction, place of impact and bird mass. Findings Results of this study reveal that the structure remains safe after an impact at the velocity of 25 m/s. The influence of bird mass on slat damage is clearly observable when the impact velocity rises to 60 m/s. Another important finding was that in each case where the part did not withstand the applied load, it was the lug where first failure occurred. Some of the analysed cases indicated the possibility a consequent wing box damage. Practical implications This finding provides the manufacturer an important insight into the behaviour of the slat and suggests that more detailed analysis of the current lug design might improve the safety of the structure. Originality/value Even though similar analyses have been performed, they tended to focus on large transport aircraft components. This investigation will enhance our understanding of structural response of small, low-speed aircraft to a bird impact, which is a realistic scenario for the chosen case of an agricultural plane.

Finite Element Analysis of a Pressure Vessel Subjected to an Internal Blast Load

2018 ◽  
Author(s):  
I. Barsoum ◽  
L. Sadiq
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stainless Steel ◽  
Pressure Vessel ◽  
Structural Response ◽  
Element Model ◽  
Decomposition Temperature ◽  
Blast Load ◽  
Element Analysis ◽  
Cause Of Failure

The objective of the current work is to model a stainless steel SA 316L autoclave explosion and rupture that occurred during a research laboratory experiment designed to study the thermal decomposition of ammonium tetrathiomolybdate in the presence of dimethyl sulfoxide (DSMO) in an autoclave. The explosion was believed to have occurred because DMSO was used in excess in the experiment and heated beyond its decomposition temperature. The aim of the current study is to investigate the effect of internal blast load on a pressure vessel made of stainless steel AISI 316L through finite element analysis. Numerical simulation using FEA is performed to better understand the cause of failure of the pressure vessel. The finite element model predicts very well the structural response and subsequent failure of the actual incident and the results reveal that the root cause to failure was an internal blast load, which arose from the decomposition of DMSO at high temperature.

Finite element analysis of the constrained Dirichlet boundary control problem governed by the diffusion problem

2020 ◽  
Vol 26 ◽  
pp. 78
Author(s):  
Thirupathi Gudi ◽  
Ramesh Ch. Sau
Keyword(s):  
Finite Element ◽  
Control Problem ◽  
Dirichlet Boundary ◽  
A Priori ◽  
Diffusion Problem ◽  
Discrete Control ◽  
Optimal Order ◽  
Control Constraints ◽  
Element Analysis ◽  
Dirichlet Boundary Control

We study an energy space-based approach for the Dirichlet boundary optimal control problem governed by the Laplace equation with control constraints. The optimality system results in a simplified Signorini type problem for control which is coupled with boundary value problems for state and costate variables. We propose a finite element based numerical method using the linear Lagrange finite element spaces with discrete control constraints at the Lagrange nodes. The analysis is presented in a combination for both the gradient and the L2 cost functional. A priori error estimates of optimal order in the energy norm is derived up to the regularity of the solution for both the cases. Theoretical results are illustrated by some numerical experiments.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

Torsional Analysis of a Steel Cord-Rubber Tire Belt Structure

1996 ◽  
Vol 24 (4) ◽  
pp. 339-348 ◽  
Author(s):  
R. M. V. Pidaparti
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structures ◽  
Three Dimensional ◽  
Element Model ◽  
Torsional Stiffness ◽  
Element Analysis ◽  
Rubber Belt ◽  
Steel Cord ◽  
Torsional Analysis

Abstract A three-dimensional (3D) beam finite element model was developed to investigate the torsional stiffness of a twisted steel-reinforced cord-rubber belt structure. The present 3D beam element takes into account the coupled extension, bending, and twisting deformations characteristic of the complex behavior of cord-rubber composite structures. The extension-twisting coupling due to the twisted nature of the cords was also considered in the finite element model. The results of torsional stiffness obtained from the finite element analysis for twisted cords and the two-ply steel cord-rubber belt structure are compared to the experimental data and other alternate solutions available in the literature. The effects of cord orientation, anisotropy, and rubber core surrounding the twisted cords on the torsional stiffness properties are presented and discussed.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

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