NUMERICAL PARAMETRIC STUDIES FOR THERMOGRAPHIC INSPECTION IN CONCRETE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Rilya Rumbayan ◽  
Glenn Washer
Keyword(s):  
Finite Element Method ◽  
Environmental Conditions ◽  
Imaging Technique ◽  
Direct Access ◽  
The Finite Element Method ◽  
Constant Multiple ◽  
Thermal Contrast ◽  
Thermographic Imaging ◽  
Parametric Studies ◽  
Practical Tool

Thermographic imaging technique provides a practical tool for the detection of subsurface delaminations in concrete from a distance without direct access to the surface. In the previous study, a numerical model to predict the thermal contrasts resulting from subsurface voids (i.e., delaminations) in concrete under a given set of environmental conditions was developed using the finite element method. The model was verified using the experimental test data, and the results indicated that the model could be an effective tool to support the thermography inspection of the concrete. In this present study, the use of the verified model to evaluate the effects of other key parameters expected to influence the detectability of the subsurface voids, such as the depth and thickness of a subsurface delamination. The effect of these parameters on the thermal contrast developed on the surface above a subsurface delamination was assessed under a specific set of environmental conditions. The results shown that the maximum thermal contrast decreased exponential by a constant multiple of 0.98 as the void depth increased and the maximum thermal contrast increased nonlinearly with increasing thickness of the void.

Parametric Studies of Guyed Tower Platforms

1991 ◽  
Vol 113 (3) ◽  
pp. 228-234 ◽  
Author(s):  
D. G. Owen ◽  
Y. J. Shi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Environmental Conditions ◽  
Parametric Study ◽  
Structural Parameters ◽  
The Finite Element Method ◽  
Motion Response ◽  
Theoretical Predictions ◽  
Parametric Studies

A parametric study presented in this paper has investigated the interactions between structural properties and dynamic response for a guyed tower platform. The finite element method is introduced to simulate the guyed tower motion response under various environmental conditions. The structural parameters which could significantly influence the motion response are the objectives to be investigated. The topside weight, guyline restraints and P-Δ or B-Δ effects are the vital aspects. A number of model tests were conducted to support and verify the theoretical predictions. The analysis concluded that the guyline stiffness is the most important characteristic which determines the guyed tower motion response.

scholarly journals The Effect of Material Present in the Void for Thermography Inspection in Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 6427-6430
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Model ◽  
Test Data ◽  
Experimental Test ◽  
Environmental Conditions ◽  
Epoxy Adhesive ◽  
The Finite Element Method ◽  
Thermal Contrast ◽  
Element Method

In the previous study by the author, a numerical model to predict the thermal contrasts resulting from subsurface voids (i.e. delaminations) in concrete under a given set of environmental conditions was developed using the finite element method. The model was verified using the experimental test data, and the results indicated that the model could be an effective tool to support the thermography inspection of the concrete. In this present study, the use of the verified model to evaluate the effects of materials present in the void created by the delamination expected to influence the detectability of the subsurface voids. The effect of this parameter on the thermal contrast developed on the surface above a subsurface delamination was assessed under a specific set of environmental conditions. The results indicated that air-filled void produced a significant thermal contrast compared to water-filled void, ice-filled void, and epoxy adhesive-filled void.

scholarly journals The influence of the layered character of snow cover on the triggering of slab avalanches

1993 ◽  
Vol 18 ◽  
pp. 193-198 ◽  
Author(s):  
Jürg Schweizer
Keyword(s):  
Finite Element Method ◽  
Snow Cover ◽  
Shear Failure ◽  
Stability Evaluation ◽  
The Finite Element Method ◽  
Soft Layer ◽  
Weak Layer ◽  
Order Of Magnitude ◽  
Practical Tool ◽  
Avalanche Warning

One of the principal aims of avalanche warning is to prevent slab avalanches triggered by skiers. Other than explosives, the best practical tool for stability evaluation is the Rutschblock test. Whether the slab may be triggered by a skier depends on various slab characteristics. Important factors seem to be depth of the weak layer, slab hardness and sublayering of the slab. The stress distribution induced by a skier is calculated by the finite element method for typical snow-cover configurations. The additional shear stress is of the same order of magnitude as the shear strength of weak layers. Besides the critical weak layer — prerequisite for a slab avalanche — hard layers seem to be important. The analysis suggests that a shear failure is most probable at the transition from a hard to a soft layer. This corresponds well to observations of slab-avalanche profiles. The results may help to improve and quantify the analysis of snow profiles.

scholarly journals Modeling of Harmonic Wave Propagation Through a Metasurface with Helmholtz Resonator Shaped Cells

2021 ◽  
Vol 2117 (1) ◽  
pp. 012002
Author(s):  
A Y Ismail ◽  
B Y Koo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Harmonic Wave ◽  
Helmholtz Resonator ◽  
Numerical Results ◽  
Shape Design ◽  
The Finite Element Method ◽  
Parametric Studies ◽  
Engineering Practices

Abstract Harmonic wave propagation through a novel metasurface design is presented in this paper. The metasurface is formed by using the Helmholtz resonator as the cells shape design since such resonator has uniqueness and advantageous performances. The study is conducted both numerically using the finite element method and experimentally using specific measurements to validate the numerical results. Parametric studies of the selected variables are also conducted to obtain broader information on the performance. From the result, it is found that the new proposed metasurface design has the potential to be implemented in future engineering practices.

Numerical Analysis of Cold Tube Drawing Operation using Finite Element Method

2011 ◽  
Vol 5 ◽  
pp. 44-52 ◽  
Author(s):  
M.H. Oladeinde ◽  
John A. Akpobi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
The Finite Element Method ◽  
Galerkin Finite Element ◽  
Tube Drawing ◽  
Present Solution ◽  
Numerical Experimentation ◽  
Parametric Studies ◽  
Finite Difference Solution ◽  
Element Method

In this paper the effect of semi die angle on drawing load in cold tube drawing has been investigated numerically using the finite element method. The equation governing the stress distribution was derived and solved using Galerkin finite element method. An isoparametric formulation for the governing equation was utilized along with C0 cubic isoparametric element. Numerical experimentation showed that the results obtained using the present method is very close to the analytical solution and more accurate than finite difference solution. Having established the accuracy of the present solution method, parametric studies were carried out to show the effect of semi die angle on the drawing load for different tube drawing processes. The analysis was carried out using a Visual Basic.Net program developed by the authors. The results are presented in both graphical and tabular forms.

Fast Computation of Microscale Temperature Distribution in LSI Chips

2003 ◽  
Author(s):  
Shigeki Hirasawa ◽  
Satoru Isomura
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Temperature Distribution ◽  
Silicon On Insulator ◽  
Fast Computation ◽  
The Finite Element Method ◽  
Fast Calculation ◽  
Temperature Distributions ◽  
Network Method ◽  
Practical Tool

A network method for quickly calculating the temperature distributions in an LSI chip with silicon-on-insulator (SOI) transistors and multi-layered lines has been developed. Its calculation time is less than 1/1000 of that of the finite element method, and its error is within 15%. The developed fast calculation method can be used in the case of more than 300 heating devices and more than 1000 lines in an LSI chip. It is thus a practical tool for designing the optimum layout of devices to prevent local temperature increases in an LSI chip.

scholarly journals The influence of the layered character of snow cover on the triggering of slab avalanches

1993 ◽  
Vol 18 ◽  
pp. 193-198 ◽  
Author(s):  
Jürg Schweizer
Keyword(s):  
Finite Element Method ◽  
Snow Cover ◽  
Shear Failure ◽  
Stability Evaluation ◽  
The Finite Element Method ◽  
Soft Layer ◽  
Weak Layer ◽  
Order Of Magnitude ◽  
Practical Tool ◽  
Avalanche Warning

One of the principal aims of avalanche warning is to prevent slab avalanches triggered by skiers. Other than explosives, the best practical tool for stability evaluation is the Rutschblock test. Whether the slab may be triggered by a skier depends on various slab characteristics. Important factors seem to be depth of the weak layer, slab hardness and sublayering of the slab. The stress distribution induced by a skier is calculated by the finite element method for typical snow-cover configurations. The additional shear stress is of the same order of magnitude as the shear strength of weak layers. Besides the critical weak layer — prerequisite for a slab avalanche — hard layers seem to be important. The analysis suggests that a shear failure is most probable at the transition from a hard to a soft layer. This corresponds well to observations of slab-avalanche profiles. The results may help to improve and quantify the analysis of snow profiles.

The Analytical and Experimental Analyses of a Skeletal Antenna Cluster System for Space Applications

1989 ◽  
Vol 4 (4) ◽  
pp. 218-227 ◽  
Author(s):  
M. O'Neill ◽  
L. Hollaway
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Large Scale ◽  
The Finite Element Method ◽  
Large Space ◽  
Space Applications ◽  
Communications Networks ◽  
Skeletal Structures ◽  
Parametric Studies ◽  
Element Method

A new generation of large space structures (LSS), remotely deployed and stationed at geosynchronous equatorial orbit, is currently being considered for use in terrestial communications networks. These skeletal structures, which would be manufactured from high technology thermoplastics composite materials, would include multi-functional large scale platforms on which a variety of reflector assemblies would be attached. A scaled perspex model of a proposed LSS has been constructed and an experimental examination of its modal behaviour in simulated unrestrained conditions has been undertaken. These results have been used to establish the level of agreement it is possible to obtain from natural frequency extractions of the structure modelled using the finite element method. Both impact and sine dwell testing techniques have been applied in determining the modal responses of the model and it has been found that selection of the most appropriate method should be made in consideration of its anticipated modal behaviour. Very good agreement has been found between the frequency characteristics obtained experimentally analytical and frequency extractions for this model, although both methods have been hampered by the presence of the flexible arrays which have been modally active in the frequency ranges of interest. The results of this study have demonstrated that a measure of confidence can be placed on similar parametric studies on large scale unrestrained skeletal structures using the finite element method.

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