Simulation of Secondary Contact to Generate Very High Accelerations

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Stuart T. Douglas ◽  
Moustafa Al-Bassyiouni ◽  
Abhijit Dasgupta ◽  
Kevin Gilman ◽  
Aaron Brown
Keyword(s):  
Finite Element ◽  
Contact Stiffness ◽  
Experimental Tests ◽  
Element Model ◽  
Parametric Modeling ◽  
Design Parameters ◽  
Secondary Contact ◽  
Element Analysis ◽  
Secondary Impact ◽  
Very High

This paper investigates the design of a typical commercially available drop system for generating very high shock and drop accelerations. Some commercially available drop towers produce accelerations greater than 5000 G by utilizing the dynamics of secondary impact, using an attachment termed a dual mass shock amplifier (DMSA). Depending on the design, some DMSAs are capable of repeatedly generating accelerations as high as 100,000 G. The results show that a finite element model (FEM) can capture the peak acceleration for the drop tower and the DMSA within 15%. In this paper, a detailed description of the test equipment and modeling techniques is provided. The effects of different design parameters, such as table mass, spring stiffness, and programmer material properties, on the drop profile, are investigated through parametric modeling. The effects of contact parameters on model accuracy are explored, including constraint enforcement algorithms, contact stiffness, and contact damping. Simple closed-form analytic models are developed, based on the basic principles of a single impact and the dynamics of secondary impact. Model predictions are compared with test results. Details of the test methodology and simulations guidelines are provided. Detailed finite element analysis (FEA) is conducted and validated against the experimental tests and compared to the simplified theoretical simulations. Benefits in exploring FEM to simulate contact between materials can be extrapolated to different architectures and materials such that with minimal experimental validation impact acceleration can be determined.

Parametric Modeling of Underground Powerhouse for Finite Element Analysis

2013 ◽  
Vol 405-408 ◽  
pp. 3222-3228
Author(s):  
Rong Gang Yin ◽  
Zhi Guo Li ◽  
Hong Xiang She ◽  
Jian Hai Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Model ◽  
Parametric Modeling ◽  
Element Analysis ◽  
Underground Powerhouse ◽  
Interactive Interface ◽  
Different Types ◽  
Basic Ideas ◽  
Display Window

In order to improve the modeling efficiency for finite element analysis pre-processing, a parametric modeling method of underground powerhouse for finite element analysis is proposed. By inputting the basic geometric parameters, different types of underground powerhouse models are built by using this method. The basic ideas, basic principle and the process of this parametric modeling are presented. And the parametric modeling procedure is coded by using VC++, interactive interface and display window are designed by using MFC and OpenGL. Finite element model of Houziyan underground powerhouse which is built by using the procedure proves that this method greatly improves the efficiency and precision of modeling.

scholarly journals Torsional Behaviour and Finite Element Analysis of the Hybrid Laminated Composite Shafts: Comparison of VARTM with Vacuum Bagging Manufacturing Method

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Mehmet Emin Taşdelen ◽  
Mehmet Halidun Keleştemur ◽  
Ercan Şevkat
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Glass Fibers ◽  
Laminated Composite ◽  
Experimental Tests ◽  
Element Model ◽  
Performance Criteria ◽  
Fiber Types ◽  
Element Analysis ◽  
Manufacturing Method

Braided sleeve composite shafts are produced and their torsional behavior is investigated. The braided sleeves are slid over an Al tube to create very strong and rigid tubular form shafts and they are in the form of 2/2 twill biaxial fiber fabric that has been woven into a continuous sleeve. Carbon and glass fibers braided sleeves are used for the fabrication of the composite shafts. VARTM (vacuum assisted resin transfer molding) and Vacuum Bagging are the two different types of manufacturing methods used in the study. Torsional behaviors of the shafts are investigated experimentally in terms of fabrication methods and various composite materials parameters such as fiber types, layer thickness, and ply angles. Comparing the two methods in terms of the torque forces and strain angles, the shafts producing entirely carbon fiber show the highest torque capacities; however, considering the cost and performance criteria, the hybrid shaft made up of carbon and glass fibers is the optimum solution for average demanded properties. Additionally, FE (finite element) model of the shafts was created and analyzed by using ANSYS workbench environment. Results of finite element analysis are compared with the values of twisting angle and torque obtained by experimental tests.

Development of a Belt Conveyor Cooling System for Concrete Aggregates

2011 ◽  
Author(s):  
Khaled I. E. Ahmed ◽  
A. M. S. Hamouda ◽  
M. S. Gadala
Keyword(s):  
Finite Element ◽  
Cooling System ◽  
Initial Conditions ◽  
Element Model ◽  
Design Parameters ◽  
Element Analysis ◽  
Conveyor System ◽  
Concrete Aggregates ◽  
Concrete Production ◽  
The Finite Element Analysis

Using hot aggregates, in concrete production, results in a drop in compressive strength of the produced concrete. Various methods have been proposed for cooling concrete aggregates. This paper proposes a new design for a conveyor system for cooling the aggregates during hot seasons. Simulation of the heat flow during the cooling process over the conveyor is analyzed with the objective of understanding the effect of the various design parameters and achieving minimum cooling time with the least possible power. A finite element model for the new design is proposed and discussed. Challenges facing numerical simulation are addressed in this paper. The results of the finite element analysis of the new design are presented for various initial conditions and cooling rates.

Combined Effects of Tube Projection, Initial Tube-Tubesheet Clearance, and Tube Material Strain Hardening on Rolled Joint Strength

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
N. Merah ◽  
A. Al-Aboodi ◽  
A. N. Shuaib ◽  
Y. Al-Nassar ◽  
S. S. Al-Anizi
Keyword(s):  
Finite Element ◽  
Strain Hardening ◽  
Contact Pressure ◽  
Joint Strength ◽  
Element Model ◽  
Design Parameters ◽  
Radial Clearance ◽  
Tube Material ◽  
Element Analysis ◽  
Interfacial Pressure

The tube-to-tubesheet joint strength is measured in terms of interfacial pressure between the tube’s outer surface and tubesheet bore. The strength of a rolled joint is influenced by several design parameters, including the type of tube and tubesheet materials, initial tube projection, and the initial radial clearance between the tube and tubesheet, among other factors. This paper uses finite element analysis (FEA) to evaluate the effect of several parameters on the strength of rolled joints having large overtolerances, a situation that applies to used equipment. An axisymmetric finite element model based on the sleeve diameter and rigid tube expanding roller concepts was used to analyze the effects of tube projection, initial tube-tubesheet clearance, and tube material strain-hardening property on the deformation behavior of the rolled tube and on the strength of the tube-tubesheet joint. The FEA results show that for zero tube projection (flush) the initial clearance effect is dependent on the strain-hardening capability of the tube material. For low strain-hardening tube material the interfacial pressure remains constant well above the Tubular Exchanger Manufacturer’s Association maximum overtolerance. A drastic reduction in joint strength is observed at high values of radial clearances. The cut-off clearance (clearance at which the interfacial pressure starts to drop) is found to vary linearly with the tube material hardening level, and the contact stress increases slightly for moderate strain-hardening tube materials but shows lower cut-off clearance levels. Furthermore, with flush tubes the maximum contact pressure occurs close to the secondary face (at the end of rolling) while for joints with initial tube projection the contact pressure shows two maxima occurring near the primary and the secondary faces. This is attributed to the presence of two elbows in tube deformation near the primary and secondary faces. The average interfacial pressure increased with increasing projection length for all clearances. Tube material strain hardening enhances the interfacial pressure in a similar fashion for all initial tube projection lengths considered in the analysis.

Nonlinear Finite Element Analysis of a Threaded Pipe Connection

2004 ◽  
Author(s):  
Farzad Tasbihgoo ◽  
John P. Caffrey ◽  
Sami F. Masri
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Tests ◽  
Element Model ◽  
Nonlinear Finite Element ◽  
Mitigation Measures ◽  
Element Analysis ◽  
Nonstructural Components ◽  
Small Water ◽  
Threaded Connections

For the past several years, USC has been involved in a major research project to study the seismic mitigation measures of nonstructural components in hospitals funded by the Federal Emergency Management Agency (FEMA). It was determined that piping was the one of the most critical components affecting the functionality of a hospital following an earthquake. Consequently, a substantial effort was spent on quantifying the behavior of typical piping components. During the loading of the threaded joint, it was common to hear a loud popping sound, followed by a small water leak. It was assumed that the sound and leakage were due to the sliding of the mating pipe threads. To confirm this theory, and to provide a tool to help understand the failure mode(s) for a wide class of threaded fittings, a detailed nonlinear finite element model was constructed using MSC/NASTRAN, and correlated to the measured failures. In this paper, a simplified model is presented first to demonstrate the modeling procedure and to help understand the sliding phenomenon. Next, a symmetric half 3D model was generated for modeling the physical experiments. It is shown that the finite element analysis (FEA) of the threaded connections captures the dominant mechanism that was observed in the experimental tests.

Numerical and Experimental Study of Elastic Interaction in Bolted Flange Joints

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Elastic Interaction ◽  
Element Model ◽  
Interaction Coefficient ◽  
Pressure Vessels ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Bolted Flange

Bolted flange joints are widely used to connect pressure vessels and piping equipment together and facilitate their disassembly. Initial tightening of their bolts is a delicate operation because it is extremely difficult to achieve the target load and uniformity due to elastic interaction. The risk of failure due to leakage and fatigue under service loading is consequently increased. This paper presents a study on the effect of elastic interaction that is present during the tightening of bolted flange joints using three-dimensional nonlinear finite-element modeling and experimentation. The nonlinear nonelastic behavior of the gasket is taken into account in the numerical simulation. The scatter in bolt preload produced during the tightening sequence is evaluated. Based on the elastic interaction coefficient method, the initial target tightening load in each bolt for every pass is determined by using the nonlinear finite-element model to obtain a uniform preload after the final tightening pass. The validity of the finite-element analysis (FEA) is supported by experimental tests conducted on a NPS 4 class 900 weld neck bolted flange joints using fiber and flexible graphite gaskets. This study provides guidance and enhances the safety and reliability of bolted flange joints by minimizing bolt load scatter due to elastic interaction.

A frequency response function-based updating technique for the finite element model of automotive structures

2008 ◽  
Vol 222 (10) ◽  
pp. 1781-1791 ◽  
Author(s):  
D-C Lee ◽  
C-S Han
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Design Parameters ◽  
External Loading ◽  
Element Analysis ◽  
Automotive Structures ◽  
Different Types ◽  
External Loads ◽  
The Finite Element Model ◽  
Huge Variety

Today's automotive industry uses finite element analysis (FEA) in a huge variety of applications in order to optimize structures and processes before hardware is produced. Efficiencies can be enhanced and margins are reduced because the external loads and structural properties are identified with higher confidence. The accuracy of FEA predictions has become increasingly important and directly influences the competitiveness of a product on the market. Because automotive structures are under dynamic environments, the correlation on the basis of static deformations independent of the mass and damping parameters do not provide a valuable reference from the view of the dynamic characteristics. In this paper, by systematically comparing the results from analytical and experimental analysis techniques, finite element (FE) models can be validated by the deterministic and robust design on the basis of each tolerance of design parameters, and improved so that they can be used with more confidence in further analysis. Making use of different types of test datum, a recommended procedure is to use a sequence of analysis in which mass, stiffness, damping, and external loading are validated and, if necessary, updated.

Frictional Analysis of MoS2 Coated Ball Bearings: A Three-Dimensional Finite Element Analysis

1997 ◽  
Vol 119 (4) ◽  
pp. 754-763 ◽  
Author(s):  
M. R. Lovell ◽  
M. M. Khonsari ◽  
R. D. Marangoni
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Element Model ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Hertzian Contact Theory

A brief review of finite element contact and friction theory is presented for low-speed bearing operations. A three-dimensional finite element model is developed to realistically characterize the friction experienced by a coated ball bearing element. The finite elements results, which are obtained for various normal loads and ball materials, are verified using Hertzian contact theory and previous experimental tests performed by the authors. From the results, general trends for the frictional behavior of coated bearing surfaces are established and implications to the field of controls, as applied to precision positioning and tracking instruments are discussed.

Characterization of Tissue Scaffolds Fabricated by Rapid Prototyping Techniques Aided by Finite Element Analysis

2006 ◽  
Author(s):  
Andrew R. Thoreson ◽  
James J. Stone ◽  
Kurtis L. Langner ◽  
Jay Norton ◽  
Bor Z. Jang
Keyword(s):  
Finite Element ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Cartilage Regeneration ◽  
Element Model ◽  
Tissue Scaffolds ◽  
Design Parameters ◽  
Element Analysis ◽  
Apparent Modulus ◽  
Wide Range

Numerous techniques for fabricating tissue engineering scaffolds have been proposed by researchers covering many disciplines. While literature regarding properties and efficacy of scaffolds having a single set of design parameters is abundant, characterization studies of scaffold structures encompassing a wide range of design parameters are limited. A Precision Extrusion Deposition (PED) system was developed for fabricating poly-ε-caprolactone (PCL) tissue scaffolds having interconnected pores suitable for cartilage regeneration. Scaffold structures fabricated with three-dimensional printing methods are periodic and are readily modeled using Computer Aided Design (CAD) software. Design parameters of periodic scaffold architectures were identified and incorporated into CAD models with design parameters over the practical processing range represented. Solid models were imported into a finite element model simulating compression loading. Model deformation results were used to identify apparent modulus of elasticity of the structure. PCL scaffold specimens with design parameters within the modeled range were fabricated and subjected to compression testing to physically characterize scaffold modulus. Results of physical testing and finite element models were compared to determine effectiveness of the method.

The Effects of Interbedded Friction on Load Capacity of Rhombic Wire Wound Vessel

2011 ◽  
Vol 221 ◽  
pp. 517-521
Author(s):  
Jun Fei Wu ◽  
Wei Gao ◽  
Xiao Chen Zhu
Keyword(s):  
Finite Element ◽  
Program Development ◽  
Load Capacity ◽  
Element Model ◽  
Parametric Modeling ◽  
Post Processing ◽  
Element Analysis ◽  
Whole Process ◽  
The Finite Element Analysis ◽  
The Finite Element Model

From the parametric modeling, the APDL tool can be used in ANSYS to build the finite element model of rhombic wire wound vessel. Only a small amount of parameters have to be input in order to accomplish the whole process of program development such as constructing model, meshing, creating contact pairs, bringing restrictions and loads to bear on vessels as well as solving and post-processing. It can be easy to use the developed batch program to achieve the finite element analysis of vessels and get the influence of interbedded friction on the load capacity of rhombic wire wound vessel under different working pressures.

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