Central Bursting and Optimal Die Profile for Axisymmetric Extrusion

1996 ◽  
Vol 118 (4) ◽  
pp. 579-584 ◽  
Author(s):  
N. Venkata Reddy ◽  
P. M. Dixit ◽  
G. K. Lal
Keyword(s):  
Material Properties ◽  
Process Conditions ◽  
Simple Criterion ◽  
Geometric Conditions ◽  
Die Profile ◽  
Good Agreement

A simple criterion for predicting the initiation of central burst in extrusion is proposed. The geometric conditions to avoid central bursting are predicted by using the proposed criterion under various process conditions and material properties. The optimal die profiles which minimize the extrusion power are also obtained for various process conditions. The mixed (pressure-velocity) formulation is used along with the Householder method to solve the resulting equations. It is shown that the optimal die profiles satisfy the conditions for prevention of central burst. The predictions based on the proposed criterion are in good agreement with the experimental observations and are in conformity with the results published earlier.

Device Modeling of a-Si:H Alloy Solar Cells: Calibration Procedure for Determination of Model Input Parameters

1998 ◽  
Vol 507 ◽  
Author(s):  
M. Zeman ◽  
R.A.C.M.M. Van Swaaij ◽  
E. Schroten ◽  
L.L.A. Vosteen ◽  
J.W. Metselaar
Keyword(s):  
Solar Cell ◽  
Material Properties ◽  
Calibration Procedure ◽  
Model Parameters ◽  
Model Input ◽  
A Value ◽  
Input Parameters ◽  
Simulated Material ◽  
Good Agreement

ABSTRACTA calibration procedure for determining the model input parameters of standard a-Si:H layers, which comprise a single junction a-Si:H solar cell, is presented. The calibration procedure consists of: i) deposition of the separate layers, ii) measurement of the material properties, iii) fitting the model parameters to match the measured properties, iv) simulation of test devices and comparison with experimental results. The inverse modeling procedure was used to extract values of the most influential model parameters by fitting the simulated material properties to the measured ones. In case of doped layers the extracted values of the characteristic energies of exponentially decaying tail states are much higher than the values reported in literature. Using the extracted values of model parameters a good agreement between the measured and calculated characteristics of a reference solar cell was reached. The presented procedure could not solve directly an important issue concerning a value of the mobility gap in a-Si:H alloys.

An enhanced composting process with bioaugmentation: Mathematical modelling and process optimization

2021 ◽  
pp. 0734242X2110337
Author(s):  
Tea Sokač ◽  
Anita Šalić ◽  
Dajana Kučić Grgić ◽  
Monika Šabić Runjavec ◽  
Marijana Vidaković ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Model Simulation ◽  
Process Conditions ◽  
Air Flow Rate ◽  
Optimal Process ◽  
Composting Process ◽  
Different Types ◽  
Adiabatic Reactor ◽  
The Mathematical Model ◽  
Good Agreement

In this paper, two different types of biowaste composting processes were carried out – composting without and with bioaugmentation. All experiments were performed in an adiabatic reactor for 14 days. Composting enhanced with bioaugmentation was the better choice because the thermophilic phase was achieved earlier, making the composting time shorter. Additionally, a higher conversion of substrate (amount of substrate consumed) was also noticed in the process enhanced by bioaugmentation. A mathematical model was developed and process parameters were estimated in order to optimize the composting process. Based on good agreement between experimental data and the mathematical model simulation results, a three-level-four-factor Box-Behnken experimental design was employed to define the optimal process conditions for further studies. It was found that the air flow rate and the mass fraction of the substrate have the most significant effect on the composting process. An improvement of the composting process was achieved after altering the mentioned variables, resulting in shorter composting time and higher conversion of the substrate.

A New Method to Assess Ductility of CFT Box Columns with Binding Bars under Axial Compression

2012 ◽  
Vol 446-449 ◽  
pp. 78-81 ◽  
Author(s):  
Yue Ling Long ◽  
Jian Cai
Keyword(s):  
Experimental Data ◽  
Axial Compression ◽  
Material Properties ◽  
New Method ◽  
Box Columns ◽  
Good Agreement

A new method based on material properties instead of experimental data was proposed to assess the ductility of concrete-filled steel box columns with binding bars and those without binding bars. Comparison between ductility coefficients based on experimental data and the calculated values by the proposed method shows good agreement.

Prediction of Residual Stresses in Welded T- and I-Joints Using Inherent Strains

1996 ◽  
Vol 118 (2) ◽  
pp. 229-234 ◽  
Author(s):  
M. G. Yuan ◽  
Y. Ueda
Keyword(s):  
Residual Stresses ◽  
Material Properties ◽  
Strain Distribution ◽  
Elastic Analysis ◽  
Fillet Weld ◽  
Average Temperature ◽  
Input Material ◽  
Geometric Ratio ◽  
Inherent Strain ◽  
Good Agreement

In order to develop a predicting method of residual stresses in fillet welded T- and I-joints, a concept of inherent strain, being regarded as a source of the residual stresses, was introduced. With the proposed method, the residual stress of an interested weldment may be predicted by performing an elastic analysis, in which the inherent strain is replaced to equivalent distributed loads. The inherent strain distributions in various welded T- and I-joints were investigated by numerical simulations. The results showed that the inherent strains distributing in flange side and in web side of the several joints are almost the same. The inherent strains vary not only with the average temperature rise due to welding, but with the geometric ratio of the joints. Being simplified by a trapezoid curve, the inherent strain distribution in a fillet weld was expressed by formulas, in which heat input, material properties, and geometric dimensions were taken into account. Welding residual stresses in T- and I-joints, predicted by the proposed method employing the derived formulas, were compared with those obtained by thermal elasto-plastic analysis, and good agreement was recognized. The validity of the proposed method was also confirmed by experiments.

scholarly journals Prospects for defect engineering in Cu2ZnSnS4 solar absorber films

2020 ◽  
Vol 8 (31) ◽  
pp. 15864-15874
Author(s):  
Katharina Rudisch ◽  
Alexandra Davydova ◽  
Lars Riekehr ◽  
Joakim Adolfsson ◽  
Luciano Quaglia Casal ◽  
...  
Keyword(s):  
Thin Films ◽  
Material Properties ◽  
Process Conditions ◽  
Defect Engineering ◽  
Solar Absorber ◽  
New Approaches

Composition spread Cu2ZnSnS4 thin films unveil the complicated interplay between process conditions and material properties, pointing to new approaches towards defect engineering.

Rate-Dependent Material Properties of Adhesively Bonded Joints - Must Have or Nice to Have?

2020 ◽  
Vol 858 ◽  
pp. 14-19
Author(s):  
Michael May
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Material Properties ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Crash Simulation ◽  
Adhesively Bonded Joints ◽  
Rate Dependent ◽  
Element Simulation ◽  
Good Agreement

In the context of automotive crash simulation, rate-dependent properties are sought for all materials undergoing deformation. Measuring rate-dependent properties of adhesively bonded joints is a challenging and associated with additional cost. This article assesses the need for having rate-dependent properties of adhesively bonded joints for the example of a typical automotive structure, an adhesively bonded metallic T-joint. Using Finite Element simulation it could be shown that good agreement between experiment and simulation was only achieved if rate-dependent properties were considered for the adhesive.

Mechanical Bending Simulation of Thin Stainless Steel by Using Isotropic and Orthotropic Properties

2011 ◽  
Vol 421 ◽  
pp. 312-315
Author(s):  
Somsak Siwadamrongpong ◽  
Usanee Kitkamthorn ◽  
Chaiyapak Sajjawattana
Keyword(s):  
Stainless Steel ◽  
Material Properties ◽  
Mechanical Response ◽  
Thin Sheet ◽  
Disk Drive ◽  
Simple Calculation ◽  
Orthotropic Materials ◽  
Mechanical Bending ◽  
Orthotropic Properties ◽  
Good Agreement

The most important factors in hard disk drive suspension manufacturing is the suspension preload, so call “gram load”. The suspensions were generally made from cold rolled stainless steel (SUS304). The suspensions were formed by mechanical forming and gram load was adjusted by mechanical bending until reached a specification. The material properties in mechanical bending simulation of thin stainless steel were usually as isotropic for simple calculation. But the properties of thin stainless steel should be defined as orthotropic materials. Therefore, this work aimed to study gram load results of using isotropic and orthotropic properties. The thin stainless sheet was cut and test for mechanical properties in rolling and transverse directions. The properties of the thin sheet were applied to simulation model. It was found that orthotropic material properties shows a good agreement with the experimental results more than using isotropic material properties. Therefore, the results of this work could be used to explain and predict the mechanical response on the suspension manufacturing.

Reversible Stepwise Motion by a Novel Symmetric Scratch Drive Actuator

2002 ◽  
Author(s):  
Shawn Chen ◽  
Wensyang Hsu
Keyword(s):  
Experimental Data ◽  
Material Properties ◽  
Previous Literature ◽  
Geometrical Parameters ◽  
Driving Voltage ◽  
Analysis Scheme ◽  
Simulation Results ◽  
Good Agreement

A novel symmetric scratch drive actuator (SSDA) capable of two-way motion is proposed here. An analysis scheme is presented, and also can be applied to the conventional scratch drive actuator (SDA). The analysis derived here is the first to be able to relate the step increment and driving voltage with given geometrical parameters and material properties for SSDA or SDA. In order to verify the analysis, the simulation results are compared to experimental data of SDA in previous literature [1], and it shows good agreement. In the analysis of SSDA, it is found that SSDA can provide the same order of step increment with the same driving voltage, and it may move in two directions by one device.

An alternative method for a reliable estimation of seismicity with an application in Greece and the surrounding area

1999 ◽  
Vol 89 (1) ◽  
pp. 111-119
Author(s):  
C. Papazachos
Keyword(s):  
Material Properties ◽  
B Value ◽  
Linear Constraints ◽  
Return Periods ◽  
Surrounding Area ◽  
Main Hypothesis ◽  
B Values ◽  
Alternative Method ◽  
Occam’S Inversion ◽  
Good Agreement

Abstract An alternative method is proposed for the robust estimation of a and b values of the Gutenberg-Richter relation. The main hypothesis is that b values depend on material properties and the seismotectonic setting and therefore should vary relatively smoothly in space. As far as the a values are concerned, more sharp variations are allowed because these values determine the seismicity level, once the b value is fixed. The study area is organized into a grid, and the a and b values are simultaneously determined for the whole grid by solving an appropriate linear system. Smooth b variations are imposed by introducing additional linear constraints, similar to the Occam's inversion used in tomography studies. The method is applied to Greece and the surrounding area, which is a high seismicity area. The results are in very good agreement with previous studies and further enhance our knowledge for the study area. Moreover, additional seismicity measures (return periods, probabilities, etc.) are estimated robustly because they depend on the a and b values obtained for this area.

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