Estimation of Product Response: The Empirical Similitude Method and Technique of Conformal Mapping

2004 ◽  
Author(s):  
Srikanth Tadepalli ◽  
Kristin L. Wood ◽  
Richard H. Crawford ◽  
Brian L. Doud
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Conformal Mapping ◽  
Dimensional Analysis ◽  
Selective Laser Sintering ◽  
Functional Testing ◽  
Non Linear ◽  
Scaling Process ◽  
Linear Material ◽  
Product Response

Functional testing of representative prototypes is an important phase in the evolution of most products. Layer Fabrication methods, importantly the Selective Laser Sintering (SLS) process allow for quick fabrication of test prototypes such that the experimental data derived from them can be used to predict the response of a hypothetical product for a desired variable of interest. Traditional Similitude Method (TSM) or Buckingham π theorem has been used conventionally for dimensional analysis to correlate the similarity between different structures. Some of its inherent limitations have prompted researchers to include the effects of non-linear material variations and geometric distortions during the scaling process. Thus, the development of the Empirical Similitude Method (ESM) is largely based on the hypothesis that these non-linear variations and distortions can be captured mathematically by using intermediate test specimens. In an effort to improve ESM, conformal mapping has been hypothesized to be an important technique for scaling and analysis. This paper explores the technique of Conformal Mapping as a potential equivalence procedure based on the principle of ESM. The methodology is elucidated along with a heat transfer example.

scholarly journals EFFECTS OF DAMAGE FIELD ON THE CRACK-TIP STRESS FIELD IN NON-LINEAR MATERIAL

2017 ◽  
Vol 19 (9.2) ◽  
pp. 31-36
Author(s):  
M.E. Fedina
Keyword(s):  
Experimental Data ◽  
Stress Field ◽  
Crack Tip ◽  
Non Linear ◽  
Damage Field ◽  
Linear Material ◽  
Crack Tip Stress

Based on experimental data it is supposed that the boundary of the area in which the process of accumulation of damages takes place, is semiellipse and beams that are parallel to the edges of the crack. Setting by this hypothesis the form of area of the process, asymptotic decompositions of component of tensor of strain and damage are defined.

Experimental investigations on nucleate pool boiling over micro-finned cylindrical surfaces

2022 ◽  
pp. 095440622110627
Author(s):  
Balkrushna Shah ◽  
Kathit Shah ◽  
Parth Patel ◽  
Vikas J Lakhera
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Dimensional Analysis ◽  
Heat Exchangers ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Experimental Investigations ◽  
Boiling Heat Transfer Coefficient

The nucleate pool boiling heat transfer over micro-finned cylindrical surfaces has application in the heat exchangers used in thermal power plants and chemical industries. The estimation of boiling heat transfer coefficient is an important parameter in the design of two-phase heat exchangers using micro-finned cylindrical surfaces. In the present work, related experimental investigations on four micro-finned cylindrical surfaces with different surface geometry using refrigerant R-141b at atmospheric pressure are conducted to determine the boiling heat transfer coefficient over micro-finned cylindrical surfaces. A correlation is developed by dimensional analysis wherein the effects of geometrical parameters, operating pressure and thermo-physical properties of fluids are taken into consideration and dimensional analysis conducted using Buckingham π-theorem. The correlation developed utilizes experimental data obtained over the present study as well as from previous studies by various researchers including experimental data for water over different micro-finned cylindrical surfaces at 1 bar by Mehta and Kandlikar, experimental data for R123 at 0.97 bar by Saidi et al. and experimental data for R134a over micro-finned cylindrical surface at 6.1 bar, 8.1 bar, 10.1 bar and 12.2 bar by Rocha et al. The heat flux ranging from 5 to 1100 kW/m2 are considered for the analysis. The data points have been compared with the proposed correlation and the absolute average deviation of the whole data set was obtained as 13.43% with root mean square deviation of 0.0273. All the predicted values were within ±15% of the experimental values of the boiling heat transfer coefficient.

A Heat Transfer and Solidification Model of Continuous Cast

2010 ◽  
Vol 154-155 ◽  
pp. 1431-1434
Author(s):  
Qi Zhang ◽  
La Dao Yang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Material Properties ◽  
Shell Thickness ◽  
Phase Changes ◽  
Continuous Cast ◽  
Solidification Model ◽  
Temperature Distributions ◽  
Linear Material ◽  
Heat Transfer And Solidification

A model of heat transfer and solidification of continuous cast has been established, including boundary conditions in the mold and spray zones. A finite difference method was used for the numerical simulation. The model calculates the shell thickness and temperature distributions of the slab real time. The importance effect of non-linear material properties of specific heat and thermal conductivity as well as phase changes during solidification is treated. The adequacy of model has been proved by industrial and experimental data. The model can be applied to solve some practical problems in continuous cast.

An Observation on the use of Dimensional Analysis and Similarity Relations in Non-Uniform Heat Transfer

1961 ◽  
Vol 65 (607) ◽  
pp. 505-507 ◽  
Author(s):  
Henry Barrow
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Dimensional Analysis ◽  
Theoretical Study ◽  
Turbulent Convection ◽  
Circular Section ◽  
Circular Duct ◽  
Similarity Relations ◽  
Classical Work

The theoretical study of heat transfer in ducts and passages which are not circular is difficult. In addition to geometrical and hydrodynamic problems, thermal aspects such as non-uniformity of heat transfer at the section boundary, increase the number of variables to be taken into account. The popular and perhaps simplest technique for the prediction of heat transfer in forced turbulent convection in non-circular ducts, is to use the more easily determined equation for an equivalent circular section. The form of the equation, which is used to correlate experimental data for the simpler case of heat transfer in the circular section, may be derived from considerations of similarity or alternatively by dimensional analysis. (Reference may be made to the classical work of W. Nusselt at the early part of the present century for the derivation of such an equation.) The equivalent circular pipe is equivalent in two respects. It is a pipe which has the same pressure drop and same heat transfer as the non-circular duct under consideration for the same conditions. The diameter of the equivalent pipe which replaces the non-circular section will be discussed later.

scholarly journals PERHITUNGAN BEBAN KRITIS STRUKTUR PLASTIS DENGAN MENGGUNAKAN METODE SOUTHWELL

2010 ◽  
Vol 1 (2) ◽  
Author(s):  
Darwin Sebayang
Keyword(s):  
Experimental Data ◽  
Critical Load ◽  
Modulus Of Elasticity ◽  
Plastic Region ◽  
Strain Diagram ◽  
Plastic Buckling ◽  
Stress Strain ◽  
Non Linear ◽  
Linear Material ◽  
The Stability

The structure of the cylinder can be found in the structure of a rocket, an aircraft of chimney. The stability of the cylinder is very important to know the capability cylinder to support the load. It is required to give a load up to plastic region in order to optimize the load capability of the material. Therefore it is required to obtain the procedure to calculate the plastic buckling. Herewith it is shown the Southwell's Method to calculate the plastic buckling of the cylinder made of the non linear material. The approximation based on the Ramberg-Osgood is used to illustrate the stress-strain diagram. The diagram of Karman is used to obtain the Modulus of elasticity which is valid for the plastic region. The result based on this method are campared to the experimental data. The results are satisfactory. This method can be used to calculate the critical load of the LAPAN's rocket by considering the plasticity of the material and structure can be lighter.

scholarly journals Influence of the Porosity of Polymer Foams on the Performances of Capacitive Flexible Pressure Sensors

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 1968 ◽  
Author(s):  
Sylvie Bilent ◽  
Thi Hong Nhung Dinh ◽  
Emile Martincic ◽  
Pierre-Yves Joubert
Keyword(s):  
Experimental Data ◽  
Linear Model ◽  
Dielectric Material ◽  
Pressure Sensors ◽  
Volume Ratio ◽  
Measurement Range ◽  
Polymer Foams ◽  
First Order ◽  
Non Linear ◽  
Flexible Pressure Sensors

This paper reports on the study of microporous polydimethylsiloxane (PDMS) foams as a highly deformable dielectric material used in the composition of flexible capacitive pressure sensors dedicated to wearable use. A fabrication process allowing the porosity of the foams to be adjusted was proposed and the fabricated foams were characterized. Then, elementary capacitive pressure sensors (15 × 15 mm2 square shaped electrodes) were elaborated with fabricated foams (5 mm or 10 mm thick) and were electromechanically characterized. Since the sensor responses under load are strongly non-linear, a behavioral non-linear model (first order exponential) was proposed, adjusted to the experimental data, and used to objectively estimate the sensor performances in terms of sensitivity and measurement range. The main conclusions of this study are that the porosity of the PDMS foams can be adjusted through the sugar:PDMS volume ratio and the size of sugar crystals used to fabricate the foams. Additionally, the porosity of the foams significantly modified the sensor performances. Indeed, compared to bulk PDMS sensors of the same size, the sensitivity of porous PDMS sensors could be multiplied by a factor up to 100 (the sensitivity is 0.14 %.kPa−1 for a bulk PDMS sensor and up to 13.7 %.kPa−1 for a porous PDMS sensor of the same dimensions), while the measurement range was reduced from a factor of 2 to 3 (from 594 kPa for a bulk PDMS sensor down to between 255 and 177 kPa for a PDMS foam sensor of the same dimensions, according to the porosity). This study opens the way to the design and fabrication of wearable flexible pressure sensors with adjustable performances through the control of the porosity of the fabricated PDMS foams.

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