An Infrared Interferometer for Elastoplastic Crack-Tip Field Investigation of Homogeneous and Bimaterial Beams: A Study of Three-Dimensional Effects and J-Dominance

1998 ◽  
Vol 65 (4) ◽  
pp. 1032-1041
Author(s):  
J. K. Sinha ◽  
H. V. Tippur
Keyword(s):  
Plane Deformation ◽  
Three Dimensional ◽  
Surface Preparation ◽  
Field Measurements ◽  
Sample Surface ◽  
Field Investigation ◽  
Crack Tip Field ◽  
Full Field ◽  
Infrared Wavelength ◽  
Dimensional Effects

An infrared interferometer capable of performing real-time full-field noncontacting deformation field measurements on optically rough surfaces is proposed as a tool for elastoplastic fracture mechanics investigations. The choice of the infrared wavelength allows interferometric measurements on fracture samples with little or no surface preparation and is more tolerant of the damage accumulation near the crack. The interferometer also bridges a sensitivity gap among existing techniques for out-of-plane deformation measurement. First, a rigorous Fourier optics analysis is provided for the interferometer and the range of surface roughness that can be studied using this interferometer is examined. The interferometer is then used for mapping deformations near elastoplastically deformed cracks in aluminum beams and solder-copper bimaterials. The regions of dominant three-dimensional effects and J-dominance are examined on the sample surface by evaluating measurements along with companion finite element analyses and the HRR fields.

scholarly journals An open-source tool for the validation of finite element models using three-dimensional full-field measurements

2020 ◽  
Vol 77 ◽  
pp. 125-129
Author(s):  
Alexander Abel ◽  
Stephanie L. Kahmann ◽  
Stephen Mellon ◽  
Manfred Staat ◽  
Alexander Jung
Keyword(s):  
Finite Element ◽  
Open Source ◽  
Three Dimensional ◽  
Field Measurements ◽  
Finite Element Models ◽  
Full Field ◽  
Open Source Tool

Three-Dimensional Concentration and Velocity Measurements of a Pulsatile Contaminant Release in a Model of Oklahoma City

2020 ◽  
Author(s):  
Michael Benson ◽  
Daniel Chung ◽  
Gabriel Fuhrman ◽  
David Helmer ◽  
Ty Homan ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Fluid Velocity ◽  
Water Channel ◽  
Three Dimensional ◽  
Central Business District ◽  
Field Measurements ◽  
Oklahoma City ◽  
Scaled Model ◽  
Full Field ◽  
City Model

Abstract Motivated by the Joint Urban 2003 field project and subsequent studies, magnetic resonance imaging (MRI) techniques were used to collect full-field measurements of three-dimensional fluid velocity and concentration across a scaled model of 2003 Oklahoma City. The study was intended to develop, test, and demonstrate a repeatable puff release with MRI compatible equipment. In order to accomplish this, a contaminant was injected through the floor of a city model in discrete puffs using a solenoid valve. Sealed to fit inside a water channel, the 1:2,206 scale city model covered the central business district of the city as it was in 2003. The main flow was fully turbulent with a Reynolds number of 36,000, while vertical puff injection occurred at a Reynolds number of 2,642. Using MRV and MRC methods, the three components of velocity and concentration were measured at more than 2 million locations for each of the 12 phases of the injection period. MRV measurements examined the fluid flow with respect to building geometry. Collected at heights corresponding to this MRV data, MRC measurements enabled the analysis of the vertical and lateral dispersion of the contaminant. Ultimately, the study demonstrated a novel MRI technique through contaminant puff release and can be used for the validation of urban contaminant dispersion models.

scholarly journals Blowing and drifting snow in Alpine terrain: numerical simulation and related field measurements

1998 ◽  
Vol 26 ◽  
pp. 174-178 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Field Measurements ◽  
Blowing Snow ◽  
Related Field ◽  
Drifting Snow ◽  
Physically Based ◽  
Snow Transport

A physically based numerical model of drifting and blowing snow in three-dimensional terrain is developed. The model includes snow transport by saltation and suspension. As an example, a numerical simulation for an Alpine ridge is presented and compared with field measurements.

scholarly journals Sediment Transport and Water Flow Resistance in Alluvial River Channels: Modified Model of Transport of Non-Uniform Grain-Size Sediments

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2038
Author(s):  
Gennady Gladkov ◽  
Michał Habel ◽  
Zygmunt Babiński ◽  
Pakhom Belyakov
Keyword(s):  
Sediment Transport ◽  
Water Flow ◽  
Transport Model ◽  
Flow Characteristics ◽  
Field Measurements ◽  
Field Investigation ◽  
Empirical Modeling ◽  
River Channels ◽  
Channel Deformations ◽  
East European

The paper presents recommendations for using the results obtained in sediment transport simulation and modeling of channel deformations in rivers. This work relates to the issues of empirical modeling of the water flow characteristics in natural riverbeds with a movable bottom (alluvial channels) which are extremely complex. The study shows that in the simulation of sediment transport and calculation of channel deformations in the rivers, it is expedient to use the calculation dependences of Chézy’s coefficient for assessing the roughness of the bottom sediment mixture, or the dependences of the form based on the field investigation data. Three models are most commonly used and based on the original formulas of Meyer-Peter and Müller (1948), Einstein (1950) and van Rijn (1984). This work deals with assessing the hydraulic resistance of the channel and improving the river sediment transport model in a simulation of riverbed transformation on the basis of previous research to verify it based on 296 field measurements on the Central-East European lowland rivers. The performed test calculations show that the modified van Rijn formula gives the best results from all the considered variants.

scholarly journals In-Process Measurement of Three-Dimensional Deformations Based on Speckle Photography

2021 ◽  
Vol 11 (11) ◽  
pp. 4981
Author(s):  
Andreas Tausendfreund ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Evaluation Method ◽  
Process Analysis ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Machining Process ◽  
Image Correlation ◽  
Speckle Photography ◽  
Process Measurement ◽  
Out Of Plane ◽  
Plane Deformations

In the concept of the process signature, the relationship between a material load and the modification remaining in the workpiece is used to better understand and optimize manufacturing processes. The basic prerequisite for this is to be able to measure the loads occurring during the machining process in the form of mechanical deformations. Speckle photography is suitable for this in-process measurement task and is already used in a variety of ways for in-plane deformation measurements. The shortcoming of this fast and robust measurement technique based on image correlation techniques is that out-of-plane deformations in the direction of the measurement system cannot be detected and increases the measurement error of in-plane deformations. In this paper, we investigate a method that infers local out-of-plane motions of the workpiece surface from the decorrelation of speckle patterns and is thus able to reconstruct three-dimensional deformation fields. The implementation of the evaluation method enables a fast reconstruction of 3D deformation fields, so that the in-process capability remains given. First measurements in a deep rolling process show that dynamic deformations underneath the die can be captured and demonstrate the suitability of the speckle method for manufacturing process analysis.

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