scholarly journals Investigation of Nailed Timber Connections Using the Laser Interferometry Method

2018 ◽  
Vol 26 (4) ◽  
pp. 32-38
Author(s):  
Mykola Savytskyi ◽  
Svitlana Shekhorkina ◽  
Alexander Kesariiskyi ◽  
Valeriy Kondrashchenko ◽  
Stanislav Dukát
Keyword(s):  
Holographic Interferometry ◽  
Laser Interferometry ◽  
Element Model ◽  
Optimum Conditions ◽  
Stress Strain ◽  
Strain Behavior ◽  
Interferometry Method ◽  
Timber Connections ◽  
Holographic Interferometry Method ◽  
Laser Holographic Interferometry

Abstract The paper presents an adapted methodology of laser holographic interferometry for an investigation of the stress-strain state of nailed timber connections. During the study the possibility of detecting local deformations in the connection were verified. The optimum conditions for fixing the samples and the loading ranges to ensure an optimal interference pattern were determined. An investigation of the peculiarities of the interaction between the elements and the stress-strain behavior of nailed timber connections was performed. The experimental data obtained on the stress-strain behavior of a nailed timber connection using the laser holographic interferometry method have sufficient repeatability between different series and can also be used as a criterion verification for a finite-element model.

scholarly journals Intensification of heat transfer between heat exchange surfaces at low RE values

2015 ◽  
Vol 36 (3) ◽  
pp. 331-344
Author(s):  
Jozef Cernecky ◽  
Zuzana Brodnianska ◽  
Jan Koniar
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Friction Coefficient ◽  
Holographic Interferometry ◽  
Temperature Fields ◽  
Pressure Losses ◽  
Interferometry Method ◽  
Transfer Parameters ◽  
Holographic Interferometry Method ◽  
Quantitative Evaluations

Abstract This contribution deals with the heat transfer parameters and pressure losses in heat exchange sets with six geometrical arrangements at low Re values (Re from 476 to 2926). Geometrical arrangements were characterised by the h/H ratio ranging from 0.2 to 1.0. The experiments used the holographic interferometry method in real time. This method enables visible and quantitative evaluations of images of temperature fields in the examined heat exchange. These images are used to determine the local and mean heat transfer parameters. The obtained data were used to determine the Colburn j-factor and the friction coefficient f. The measured values show that by using the profiled heat exchange surfaces and inserting regulating tubes, an intensification of heat transfer (increase of Num, and/or j) was achieved. However, pressure losses recorded a significant increase (increase of f).

A Comparative Multifield FEA and Experimental Study on the Enhanced Manufacturability of 6061-T6511 Aluminum Using dc Current

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Amir Khalilollahi ◽  
David H. Johnson ◽  
John T. Roth
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Tensile Specimen ◽  
Transient Temperature ◽  
Stress Strain ◽  
Strain Behavior ◽  
Deformation Force ◽  
Property Changes ◽  
Dc Current

An electric current, applied during deformation, has been shown to reduce the deformation force/energy, while also increasing the maximum achievable strain and decreasing springback. Considering this, the present work initiates the development of a finite element model to investigate electricity’s thermal/structural effects on a tensile specimen. The model allows the effect of joule-heating to be separated from other nonthermal property changes caused by the electricity. Comparison with experimental tensile testing with respect to the predicted stress-strain behavior and transient temperature profiles demonstrates the model predicts these behaviors adequately. A multifield large deformation finite element model is then developed. The model evaluates the stress-strain characteristics of the material while the specimen is carrying a large dc current and is being deformed, incorporating the effect of thermal softening. The simulation results are compared with surface infrared temperature measurements in order to verify the finite element model and then to actual deformation results in order to attain more qualitative and quantitative insight into the effects of the electric field.

scholarly journals Holographic interferometry method for assessment of static load stress distribution in dog mandible

2006 ◽  
Vol 17 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Tomie N. Campos ◽  
Lena K. Adachi ◽  
Jose E. Chorres ◽  
Antonio C. Campos ◽  
Mikiya Muramatsu ◽  
...  
Keyword(s):  
Holographic Interferometry ◽  
Static Load ◽  
Control Group ◽  
Double Exposure ◽  
Experimental Conditions ◽  
Interferometry Method ◽  
Initial Force ◽  
Double Exposure Holographic Interferometry ◽  
Tension Direction ◽  
Holographic Interferometry Method

This study compared the transmission of tensions in fresh, fixed and macerated dog mandibles in order to clarify the diversity of behavior of bone tissues under dry and moist conditions. Double-exposure holographic interferometry was applied and holograms were obtained from 12 fresh hemi-mandibles under static load (control group), which were randomly assigned to 2 groups: 6 were fixed in 10% formalin and 6 were macerated. The specimens were submitted to the same initial force and their respective holograms were obtained. Analysis of the holograms showed that the fresh specimens transmitted significantly less tension than the fixed and macerated ones (p<0.05), and the tension direction was different. An average two-fold tension increment was observed in the experimental conditions. The holographic interferometry method was efficient in quantifying and qualifying tension transmission. However, depending on the type of analysis, the anatomical specimens must be fresh because macerated specimens will produce different results.

scholarly journals Study Numerical Simulation of Stress-Strain Behavior of Reinforced Concrete Bar in Soil using Theoretical Models

2019 ◽  
Vol 5 (11) ◽  
pp. 2349-2358
Author(s):  
Ali Sabah Al Amli ◽  
Nadhir Al-Ansari ◽  
Jan Laue
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Element Model ◽  
Stress Strain ◽  
Strain Behavior ◽  
Concrete Members ◽  
Steel Bar ◽  
Three Dimensional Finite Element

Nonlinear analysis for reinforced concrete members (R.C.) with two types of bars also with unsaturated and saturated soils was used to represent the models. To control the corrosion in the steel bar that used in R.C. member and decrease the cost, the geogrid with steel bar reinforcement are taken in this study to determine the effect of load-deflection and stress-strain relationships. The finite element method is used to model the R.C. member, bars and soil. A three-dimensional finite element model by ABAQUS version 6.9 software program is used to predict the load versus deflection and stress versus strain response with soil. The results for the model in this study are compared with the experimental results from other research, and the results are very good. Therefore, it was concluded that the models developed in this study can accurately capture the behavior and predict the load-carrying capacity of such R.C. members with soil and the maximum stresses with strains. The results show plastic strain values in the R.C. member with saturated soil are larger than their values in unsaturated soil about (54%, 58%, and 55% and 52%) when the geogrid ratios are (without geogrid, 60%, 40% and 20%) respectively, with the same values of stresses.

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