Quantitative Comparison Between Precision Closed-Die Forging-Force Data and Computer Simulations

1992 ◽  
Vol 114 (4) ◽  
pp. 465-471 ◽  
Author(s):  
J. N. Majerus ◽  
K. P. Jen ◽  
H. Gong
Keyword(s):  
Cross Section ◽  
Quantitative Comparison ◽  
Elastic Behavior ◽  
Material Parameters ◽  
Closed Die Forging ◽  
Billet Material ◽  
Forging Force ◽  
Force Data ◽  
Significant Data ◽  
Good Agreement

This paper presents a study of precision closed-die, isothermal, forgings via both experiments and computer simulation. The closed-die cross-section was an “H” shape and Tin/Lead eutectic solder was used for the billet material. Extensive statistical analysis of the axial force versus displacement history was conducted using replicated forging experiments. The purpose of the experiment was to obtain statistically significant data so that accuracy tests could be conducted on different FEM computer models, e.g., ALPID, EPIC2D, NIKE2D, and DYNA2D. Overall, the forging history exhibited complex behavior consisting of five distinct regions. The experimental results yield a 5.2 percent COV in the required forging force for a specific top-die displacement. A 6.5 percent COV in the “stiffness” of the first region (elastic behavior) of the forging history was also obtained. One set of simulations with one FEM computer model, ALPID Version 2.1 for rigid-thermoviscoplastic behavior, was conducted. The occurrence of all four viscoplasticflow regions was qualitatively predicted by the simulations. Quantitatively, the simulations are within the experimental bounds for the early viscoplastic regions, but out of bounds for the later regions. It appears that, for the eutectic tin/lead billet material, there is no combination of “power-law” material parameters that yield good agreement with the later stages of the forging force history.

Creep Ovalization and Buckling of a Linear Viscoelastic Externally Pressurized Pipe

2004 ◽  
Vol 126 (2) ◽  
pp. 208-215 ◽  
Author(s):  
Carl H. Popelar ◽  
Donald Evans
Keyword(s):  
Cross Section ◽  
Viscoelastic Material ◽  
Inversion Method ◽  
Analysis Model ◽  
Initial Shape ◽  
Simple Estimate ◽  
Material Parameters ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
Good Agreement

An analysis model is developed for the creep ovalization and buckling of an imperfect plastic pipe subjected to a uniform external pressure. The pipe’s cross section is assumed to have a known initial out of roundness or ovality and to be composed of a linear viscoelastic material. The governing equations are transformed using Laplace and Carson transforms. The transformed deviation of the cross section from its initial shape is inverted exactly by evaluating the Bromwich integral and approximately by the simpler direct inversion method. The two inversion methods, which yield nearly identical results, are compared with the quasi-elastic method wherein the elastic modulus in the solution to the equivalent elastic problem is replaced by the relaxation modulus. The model predictions are quite sensitive to the viscoelastic material parameters for small values of the relaxation exponent and this sensitivity has direct implications with respect to the reliability of the predicted life expectancy for the pipe. Predictions and measurements made in creep ovalization tests of a high density polyethylene (HDPE) pipe at 50°C and different pressures are compared. Very good agreement is obtained between predicted and measured response in short-term tests and in an extended test. Bi-directional shifting is used to translate inferred material parameters at 50°C to 35°C for making comparisons of predictions with measurements at the latter temperature. While the predicted ovalization overestimates the measurement, very good agreement is obtained when one material parameter is decreased by 10% and the other is increased by 7%; thereby demonstrating the sensitivity of the predictions to small changes in the material parameters for small values of the relaxation exponent. The efficacy of a simple estimate for the limiting creep buckling or collapse pressure as a function of the design life is presented and compared with measurements.

Prediction of Cutting Forces in Milling Stainless Steels using Chamfered Main Cutting Edge Tool

2005 ◽  
Vol 21 (3) ◽  
pp. 145-155 ◽  
Author(s):  
C.-S. Chang
Keyword(s):  
Stainless Steel ◽  
Cutting Forces ◽  
Steel Plate ◽  
Cutting Edge ◽  
304 Stainless Steel ◽  
Workpiece Material ◽  
Material Force ◽  
Force Data ◽  
Edge Tool ◽  
Good Agreement

AbstractTo study the cutting forces, the carbide tip's surface temperature, and the mechanism of secondary chip and main chip formation of face milling stainless steel with a chamfered main cutting edge has been investigated. Theoretical values of cutting forces were calculated and compared to the experimental results with SUS 304 stainless steel plate as a workpiece material. Force data from these tests were used to estimate the empirical constants of the mechanical model and to verify its prediction capabilities. A comparison of the predicted and measured forces shows good agreement. A preliminary discussion is also made for the design of special tool holders and their geometrical configurations. Next, the tips mounted in the tool holders are ground to a chamfered width and the tool dimensions are measured by using a toolmaker microscope.

Uncertainty Quantification in Predicting Behaviour of Rubber-Like Materials in Uni-Axial Loading

2020 ◽  
Author(s):  
Aref Ghaderi ◽  
Vahid Morovati ◽  
Pouyan Nasiri ◽  
Roozbeh Dargazany
Keyword(s):  
Uncertainty Quantification ◽  
Mechanical Response ◽  
Pure Shear ◽  
Constitutive Models ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Deterministic Models ◽  
Data Set ◽  
Material Parameters ◽  
Axial Extension

Abstract Material parameters related to deterministic models can have different values due to variation of experiments outcome. From a mathematical point of view, probabilistic modeling can improve this problem. It means that material parameters of constitutive models can be characterized as random variables with a probability distribution. To this end, we propose a constitutive models of rubber-like materials based on uncertainty quantification (UQ) approach. UQ reduces uncertainties in both computational and real-world applications. Constitutive models in elastomers play a crucial role in both science and industry due to their unique hyper-elastic behavior under different loading conditions (uni-axial extension, biaxial, or pure shear). Here our goal is to model the uncertainty in constitutive models of elastomers, and accordingly, identify sensitive parameters that we highly contribute to model uncertainty and error. Modern UQ models can be implemented to use the physics of the problem compared to black-box machine learning approaches that uses data only. In this research, we propagate uncertainty through the model, characterize sensitivity of material behavior to show the importance of each parameter for uncertainty reduction. To this end, we utilized Bayesian rules to develop a model considering uncertainty in the mechanical response of elastomers. As an important assumption, we believe that our measurements are around the model prediction, but it is contaminated by Gaussian noise. We can make the noise by maximizing the posterior. The uni-axial extension experimental data set is used to calibrate the model and propagate uncertainty in this research.

The continuous absorption of light in alkali-metal vapours

1953 ◽  
Vol 219 (1136) ◽  
pp. 89-101 ◽  
Keyword(s):  
Cross Section ◽  
Alkali Metals ◽  
Theoretical Calculations ◽  
Wave Length ◽  
Energy Difference ◽  
Continuous Absorption ◽  
Absorption Of Light ◽  
Sodium Vapour ◽  
Good Agreement ◽  
Dipole Length

The first section of this paper is an account of some experiments on the absorption of light in sodium vapour from the series limit at 2412 Å to about 1600 Å (an energy difference of 2·6 eV). The absorption cross-section at the limit is 11·6 ± 1·2 x 10 -20 cm 2 . The cross-section decreases giving a minimum of 1·3 ± 0·6 x 10 -20 cm 2 at 1900 Å and then increases to 1600 Å. A theoretical calculation by Seaton based on the dipole-length formula gives good agreement with the experiments at the series limit and also correctly predicts the wave-length for the minimum, but it predicts a significantly lower absorption at the minimum. The experiments described in the first section of the paper conclude a series on the absorption of light in the alkali metals. The second section consists of a general discussion of the results of these experiments and of their relation to theoretical calculations. There is good agreement between theory and experiment except in regard to the magnitude of the absorption at the minimum.

scholarly journals The Numerical Techniques for Thermal Distribution Analysis in Optical Waveguides

2008 ◽  
Vol 4 (2) ◽  
Author(s):  
Maslina Yaacob ◽  
Mohd Haniff Ibrahim ◽  
Norazan Mohd Kassim ◽  
Abu Bakar Mohammad
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Optical Waveguides ◽  
Distribution Analysis ◽  
Heat Transfer Mechanism ◽  
Numerical Techniques ◽  
Planar Optical Waveguide ◽  
Thermal Distribution ◽  
Single Heater ◽  
Good Agreement

In this paper, the analysis of thermal distribution in planar optical waveguide cross-section when a single heater electrode applied is presented. Starting from the heat equation, the thermal analysis has been done using two proposed numerical methods which are include finite difference method (FDM) and finite element method (FEM). By considering conduction as the only heat transfer mechanism, the obtained results from the mentioned methods are shown to have a good agreement.

scholarly journals Studies of Deuteron–Proton Collisions at 100 MeV

2021 ◽  
Vol 62 (4) ◽  
Author(s):  
I. Skwira-Chalot ◽  
N. Kalantar-Nayestanaki ◽  
St. Kistryn ◽  
A. Kozela ◽  
E. Stephan
Keyword(s):  
Cross Section ◽  
Effective Field Theory ◽  
Beam Energy ◽  
Effective Field ◽  
Breakup Reaction ◽  
Low Energy ◽  
Chiral Effective Field Theory ◽  
Proton Collisions ◽  
Realistic Potentials ◽  
Good Agreement

AbstractDifferential cross section for the $$^1H(d,pp)n$$ 1 H ( d , p p ) n reaction is sensitive to various dynamical ingredients and allows for thorough tests of theoretical potentials describing the interaction in the three nucleon systems. The analysis of the experimental data collected for the breakup reaction at the beam energy of 100 MeV has been performed and the first cross section results for selected configurations are presented in this paper. They are in good agreement with calculations based on the realistic potentials. Studies at this relatively low energy will also be important for examining awaited calculations within the Chiral Effective Field Theory.

scholarly journals Design analysis of four-wave-mixing in SiN nanowires integrated with graphene oxide films

2020 ◽  
Author(s):  
David Moss
Keyword(s):  
Graphene Oxide ◽  
Kerr Nonlinearity ◽  
Four Wave Mixing ◽  
Wave Mixing ◽  
Trade Off ◽  
Material Parameters ◽  
Highly Nonlinear ◽  
Thermal Changes ◽  
Strong Mode ◽  
Good Agreement

<p>We theoretically investigate and optimize four-wave mixing (FWM) in silicon nitride (SiN) waveguides integrated with two-dimensional (2D) layered graphene oxide (GO) films. Based on extensive previous measurements of the material parameters of the GO films, we perform detailed analysis for the influence of device parameters including waveguide geometry, GO film thickness, length, and coating position on the FWM conversion efficiency (CE) and conversion bandwidth (CB). The influence of dispersion and photo-thermal changes in the GO films is also discussed. Owing to the strong mode overlap between the SiN waveguides and the highly nonlinear GO films, FWM in the hybrid waveguides can be significantly enhanced. We obtain good agreement with previous experimental results and show that by optimizing the device parameters to balance the trade-off between Kerr nonlinearity and loss, the FWM CE can be improved by as much as ~20.7 dB and the FWM CB can be increased by ~4.4 folds, relative to the uncoated waveguides. These results highlight the significantly enhanced FWM performance that can be achieved in SiN waveguides by integrating 2D layered GO films.<i></i></p>

Numerical and Experimental Evaluation of Turbulent Flow in Volute

2003 ◽  
Author(s):  
Akitomo Igarashi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto ◽  
Toshimichi Sakai
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Result ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Flow Angle ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Good Agreement

The performance of centrifugal fans is considerably influenced by the design of tongue at the re-circulation port. The flow in the volute of a centrifugal fan was studied both experimentally and numerically. In this experiment, flow angle, pressure and velocity profiles were measured at a large number of locations in the volute. The flow field in the volute passage was analyzed using Computational Fluid Dynamics. The flow was assumed to be three dimensional, turbulent and steady. The numerical simulation produced qualitatively good agreement with the experimental result. The results from experiment and numerical simulation indicated that the adoption of a re-circulating flow port improved fan performance for all flow conditions. In addition, the existence of strong secondary flow was apparent at the cross-section of the volute passage.

scholarly journals Radar Cross-Section Formulation of a Shell-Shaped Projectile Using Modified PO Analysis

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Mohammad Asif Zaman ◽  
Md. Abdul Matin
Keyword(s):  
Differential Geometry ◽  
Cross Section ◽  
Current Density ◽  
Surface Current ◽  
Radar Cross Section ◽  
Analysis Procedure ◽  
Physical Optics ◽  
Surface Current Density ◽  
Filtering Method ◽  
Good Agreement

A physical optics based method is presented for calculation of monostatic Radar Cross-Section (RCS) of a shell-shaped projectile. The projectile is modeled using differential geometry. The paper presents a detailed analysis procedure for RCS formulation using physical optics (PO) method. The shortcomings of the PO method in predicting accurate surface current density near the shadow boundaries are highlighted. A Fourier transform-based filtering method is proposed to remove the discontinuities in the approximated surface current density. The modified current density is used to formulate the scattered field and RCS. Numerical results are presented comparing the proposed method with conventional PO method. The results are also compared with published results of similar objects and found to be in good agreement.

Analysis of Uniform Deep Oval Reinforcing Rings

1964 ◽  
Vol 8 (02) ◽  
pp. 21-28 ◽  
Author(s):  
William P. Vafakos
Keyword(s):  
Hydrostatic Pressure ◽  
Cross Section ◽  
Composite Structure ◽  
Reference Line ◽  
Taylor Model ◽  
Test Results ◽  
Local Curvature ◽  
Oval Cross Section ◽  
Ring Shell ◽  
Good Agreement

Equations which are applicable to uniform deep oval rings in which the local curvature of an arbitrary reference line is prescribed are derived and simplified for application to oval ring-shell combinations. Theoretical estimates of the stresses and displacements are obtained for a typical reinforcing ring of a ring-stiffened oval cylinder recently tested under hydrostatic pressure by the David Taylor Model Basin. These results are obtained by appropriately approximating the oval cross section and by assuming that the composite structure responds as an oval ring. The theoretical flange stresses are shown to be in good agreement with available test results.

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