scholarly journals Effects of Tension–Compression Asymmetry on Bending of Steels

2020 ◽  
Vol 10 (9) ◽  
pp. 3339 ◽  
Author(s):  
Hamed Mehrabi ◽  
Richard (Chunhui) Yang ◽  
Baolin Wang
Keyword(s):  
Analytical Method ◽  
Metal Forming ◽  
Yield Function ◽  
Asymmetry Coefficient ◽  
Pure Bending ◽  
Material Parameters ◽  
Mechanical Responses ◽  
Tension Compression Asymmetry ◽  
Full Loading ◽  
Good Agreement

Stainless steels (SUS) and dual-phase (DP) steels have tension-compression asymmetry (TCA) in mechanical responses to full loading cycles. This phenomenon can significantly influence sheet metal forming of such metals, however, it is difficult to describe this behaviour analytically. In this research, a novel analytical method for asymmetric elastic-plastic pure bending using the Cazacu–Barlat 2004 asymmetric yield function is proposed. It only uses material parameters in tension along with an asymmetry coefficient related to the yield function. Bending operations of SUS304 and DP980 are investigated as two case studies. In the pure bending for both SUS304 and DP980, moment–curvature diagrams are analytically obtained. Furthermore, linear and nonlinear springback behaviours of SUS304 are analytically investigated. Moreover, using the analytical model as a user-defined material, a numerical model is developed for both steels under pure bending. In the V-bending case of SUS304 with and without TCA effects, the springback behaviours of the material are investigated numerically. In addition, considering friction effects, the analytical method is further modified for predicting springback behaviours in the V-bending of 16 types of SUS304 with various strengths are determined. All the analytical and numerical results have good agreement with those experimental results from literature for validation.

Inspection and Model Experiment of a Damaged Arch Bridge

2007 ◽  
Vol 340-341 ◽  
pp. 223-228
Author(s):  
Ying Fang Fan ◽  
Zhi Qiang Hu ◽  
Jing Zhou
Keyword(s):  
Model Experiment ◽  
Dynamic Test ◽  
Dynamic Responses ◽  
Dynamic Tests ◽  
Arch Bridge ◽  
Mechanical Responses ◽  
Organic Glasses ◽  
Bridge Model ◽  
Static And Dynamic Tests ◽  
Good Agreement

The structural behavior of an old six-span reinforced concrete arch bridge, which has been in service for about 40 years, is investigated. Field monitoring (inclusive of test of material property, static and dynamic test of the bridge) was conducted, static and dynamic responses of the bridge are obtained. Based on the primitive bridge, a scaled one-span bridge model was fabricated by organic-glasses. Both the static and dynamic tests were executed on the bridge model in the laboratory. Since the arch rib is the crucial member for the arch bridge, 7 notches were cut on both arch ribs of the bridge model to simulate different damages of the arch rib. Mechanical responses of the bridge with different damages on the arch ribs were achieved. FEM analyses were preformed on the bridge as well. Numerical results show good agreement with the experimental results.

Study on Metal Forming by Macro-Micro Combine Numerical Analysis

2007 ◽  
Vol 340-341 ◽  
pp. 671-676
Author(s):  
Shao Rui Zhang ◽  
Da Yong Li ◽  
Zhong Wei Yin ◽  
Ying Hong Peng ◽  
Fei Zhou
Keyword(s):  
Metal Forming ◽  
Deformation Process ◽  
Metal Flow ◽  
Yield Function ◽  
Slip Systems ◽  
Crystallographic Slip ◽  
Deformation Properties ◽  
Simulation Results ◽  
True Relation ◽  
Anisotropy Coefficients

It has long been found that the crystal orientations would induce macroscopic anisotropy during deformation process, and then affect the deformation properties of sheet metal. So it is very important to find the true relation between texture distribution and macroscopic anisotropy. In this paper, the anisotropy coefficients of the yield function are fitted by Taylor factor and crystal plastic model. Metal flow is assumed to occur by crystallographic slip on given slip systems within each crystal. Then this simulation results are compared with those of microscopic crystal plastic method.

Influence of Anisotropic Yield Functions on Parameters of Yoshida-Uemori Model

2013 ◽  
Vol 554-557 ◽  
pp. 2440-2452 ◽  
Author(s):  
Hirotaka Kano ◽  
Jiro Hiramoto ◽  
Toru Inazumi ◽  
Takeshi Uemori ◽  
Fusahito Yoshida
Keyword(s):  
Effective Strain ◽  
Yield Function ◽  
Strain Response ◽  
Material Parameters ◽  
International Conference ◽  
Polynomial Type ◽  
Calculated Stress ◽  
Yield Functions ◽  
Order Polynomial ◽  
Von Mises

Yoshida-Uemori model (Y-U model) can be used with any types of yield functions. The calculated stress strain response will be, however, different depending on the chosen yield function if the yield function and the effective strain definition are inappropriate. Thus several modifications to Y-U model were proposed in the 10th International Conference on Technology of Plasticity. It was ascertained that in the modified Y-U model, the same set of material parameters can be used with von Mises, Hill’s 1948, and Hill’s 1990 yield function. In this study, Yld2000-2d and Yoshida’s 6th-order polynomial type 3D yield function were examined and it was clarified that the same set of Y-U parameters can be used with these yield functions.

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>

FEM-Simulation of the electrode temperature distribution and crater formation. Part I: Breakdown of an electrical discharge

2004 ◽  
Vol 120 ◽  
pp. 429-437
Author(s):  
F. Soldera ◽  
A. Lasagni ◽  
F. Mücklich
Keyword(s):  
Metal Forming ◽  
Electrical Discharge ◽  
Cathode Surface ◽  
Fem Simulation ◽  
Crater Formation ◽  
Impact Zone ◽  
Electrode Temperature ◽  
Material Loss ◽  
Cylindrical Samples ◽  
Good Agreement

An electrical discharge causes an energy input into the electrode, which melts and evaporates the metal forming a crater on the cathode surface. The larger part of material loss is produced by the ejection of molten particles from the molten pool. From calorimetric results, the amount of energy delivered to the cathode was estimated. Based on FEM, a model was developed to simulate the local temperature increase in the vicinity of the plasma impact zone. Considering phase transitions, it was possible to define a molten and an evaporated region, whose dimensions were compared with the dimensions of experimental craters. Single sparks were produced on cylindrical samples (Pt, Ir, Ru, Al, Au, Ag, Cu, W, Ni, Sn and Pb) in air and nitrogen with pressures ranging from 1 to 9 bar and electrode gaps of 1 and 2 mm. The volumes of experimental craters lay between the volumes of the simulated regions for 5 and 7 bar. For 1 and 3 bar, the volumes of the evaporated regions were overestimated. The shape of the simulated regions showed a very good agreement with the real craters. The relative volumes of the molten regions showed a very good agreement with the relative volumes of eroded material in the different metals.

Calculation of stress-concentration factors for grooved shafts in bending using the point-matching technique

1973 ◽  
Vol 8 (2) ◽  
pp. 113-118 ◽  
Author(s):  
G J Matthews ◽  
C J Hooke
Keyword(s):  
Stress Concentration ◽  
Numerical Technique ◽  
Pure Bending ◽  
Point Matching ◽  
Matching Technique ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
Stress Concentration Effect ◽  
Axisymmetric Bodies ◽  
Good Agreement

A general numerical technique is presented for the solution of the problem of elastic bending of axisymmetric bodies. Results obtained by this method are compared with existing results for grooved and shouldered shafts in pure bending and good agreement is obtained in each case. Additional results are presented for the stress-concentration effect of flat-bottomed circumferential grooves in cylindrical shafts for which no experimental or analytical results are available.

Effects of Local Metal Loss on Deformability of Line Pipes Subjected to Compressive Load

2005 ◽  
Author(s):  
Yoshikazu Hashimoto ◽  
Hiroshi Yatabe ◽  
Naoto Hagiwara ◽  
Noritake Oguchi
Keyword(s):  
Analytical Method ◽  
Compressive Load ◽  
Fe Analysis ◽  
Ground Movement ◽  
Metal Loss ◽  
Line Pipe ◽  
Parametric Studies ◽  
Scale Experiment ◽  
The Relationship ◽  
Good Agreement

In this paper, the deformability of line pipe with local metal loss was examined. A full-scale experiment and a finite element (FE) analysis were carried out for line pipe with local metal loss subjected to an axial compressive load. As a result, a good agreement was obtained between the analytical and experimental results. This indicated that the present analytical method was applicable to evaluate the deformability of line pipes with local metal loss subjected to a large ground movement. Parametric studies were then conducted to clarify the relationship between the geometry of the local metal loss and the deformability using the FE analytical method.

Modeling dielectric permittivity of polymer composites filled with transition metal dichalcogenide nanoparticles

2020 ◽  
Vol 54 (25) ◽  
pp. 3841-3855
Author(s):  
AD Drozdov ◽  
J deClaville Christiansen
Keyword(s):  
Dielectric Permittivity ◽  
Transition Metal ◽  
Electromagnetic Spectrum ◽  
Transition Metal Dichalcogenide ◽  
Governing Equations ◽  
Microwave Frequencies ◽  
Material Parameters ◽  
Reduced Graphene ◽  
Matrix Components ◽  
Good Agreement

A model is developed for the dielectric permittivity of polymer nanocomposites reinforced with transition metal dichalcogenide fillers at microwave frequencies. The model takes into account aggregation of nanoparticles into clusters (that involve both filler and matrix components) and the aspect ratio of aggregates. The governing equations involve four material parameters that are found by matching observations on the real and imaginary parts of the dielectric permittivity of polymers reinforced with MoS2 and WS2 micro- and nanospheres, MoS2 nanosheets and nanoflowers, and composite heterostructures formed by MoS2 and MoS2-CoS2 nanoparticles with graphene and reduced graphene oxide. Good agreement is demonstrated between results of simulation and the experimental data at frequencies in the S, X, and Ku bands of the electromagnetic spectrum. It is shown that composite heterostructures have superior dielectric properties compared with those of neat transition metal dichalcogenide nanoparticles.

Determination of Bitterness of Olives

1967 ◽  
Vol 50 (5) ◽  
pp. 1194-1195
Author(s):  
S Cohen ◽  
A Lifshitz ◽  
Z Samish
Keyword(s):  
Spectrophotometric Determination ◽  
Analytical Method ◽  
Good Agreement

Abstract An objective analytical method for the estimation of bitterness of fresh and fermented olives has been developed. Results of the bitterness estimation by the proposed method were in good agreement with organoleptic tests performed concomitantly. The method is based on the extraction with acetone of a bitter constituent from the olive, adsorption of possible interfering materials on gelatin and alumina, and spectrophotometric determination of the resulting bitter solution.

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