scholarly journals Nondestructive Testing of Ceramic Hip Joint Implants with Laser Spot Thermography

2017 ◽  
Vol 62 (4) ◽  
pp. 2133-2139
Author(s):  
J. Roemer ◽  
L. Pieczonka ◽  
M. Juszczyk ◽  
T. Uhl
Keyword(s):  
Damage Detection ◽  
Measurement Techniques ◽  
Infrared Camera ◽  
Field Measurements ◽  
Ceramic Materials ◽  
Test Sample ◽  
Theoretical Background ◽  
Laser Spot ◽  
Signal Acquisition ◽  
Full Field

AbstractThe paper presents an application of laser spot thermography for damage detection in ceramic samples with surface breaking cracks. The measurement technique is an active thermographic approach based on an external heat delivery to a test sample, by means of a laser pulse, and signal acquisition by an infrared camera. Damage detection is based on the analysis of surface temperature distribution near the exciting laser spot. The technique is nondestructive, non-contact and allows for full-field measurements. Surface breaking cracks are a very common type of damage in ceramic materials that are introduced in the manufacturing process or during the service period. This paper briefly discusses theoretical background of laser spot thermography, describes the experimental test rig and signal processing methods involved. Damage detection results obtained with laser spot thermography are compared with reference measurements obtained with vibrothermography. This is a different modality of active thermography, that has been previously proven effective for this type of damage. We demonstrate that both measurement techniques can be effectively used for damage detection and quality control applications of ceramic materials.

Stress Analysis and Identification with Full-Field Measurements

2006 ◽  
Vol 3-4 ◽  
pp. 9-16 ◽  
Author(s):  
M. Grédiac
Keyword(s):  
Model Updating ◽  
Measurement Techniques ◽  
Field Measurements ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Strain Fields ◽  
Full Field ◽  
Full Field Measurement ◽  
Constitutive Parameters ◽  
The Finite Element Model

The wealth of information provided by full-field measurement techniques is very useful in experimental mechanics. Among different possible applications, full-field measurements can be used to identify parameters governing constitutive equations from heterogeneous strain fields. This keynote lecture first describes the different possible uses of such measurements. It then focuses on the virtual fields method which has been proposed to extract constitutive parameters from full-field measurements. Finally, the method is compared with the finite element model updating technique which is usually used for solving such a problem.

scholarly journals Validation of a multi-scale Ti-6Al-4V drilling model by means of thermomechanical field measurements

2021 ◽  
Author(s):  
Camille Bonnet ◽  
Thomas Pottier ◽  
Yann Landon ◽  
Abdallah Bouzid
Keyword(s):  
High Speed ◽  
Infrared Camera ◽  
Field Measurements ◽  
Image Correlation ◽  
3D Fem ◽  
Full Field ◽  
Multi Scale ◽  
Thermal Fields ◽  
Significant Magnitude ◽  
Drilling Operations

Drilling operations lead to temperatures and forces that may locally reach significant magnitude and thus impair the surface and material integrity. Optimizing the cutting conditions could limit these degradations, which are more significant in the case of low thermal conductivity materials such as titanium alloys. Robust numerical modelling is a relevant alternative to such issues but must rely on strong in-process experimental measurements. Unfortunately, the confined nature of the cutting area during drilling prevent from any straight forward field-measurement. The proposed multi-scale strategy consists in validating the developed 3D FEM models both at micrometric and millimetric scales, using coupled full-field measurements. The limited access to the cutting area is overcome by means i) of oblique cutting tests at microscale and ii) tube drilling tests. Thermal fields are evaluated using an infrared camera while kinematic fields are determined by image correlation (DIC) using a high-speed camera. The experimental and numerical fields are then compared, and numerical results are extended over several revolutions by means of purely thermal 2D analytical model.

Direct Strain Imaging for Full Field Measurements

2012 ◽  
Author(s):  
Athanasios Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Digital Imaging ◽  
Continuum Hypothesis ◽  
Measurement Techniques ◽  
Synthetic Data ◽  
Grid Method ◽  
Field Measurements ◽  
Absolute Error ◽  
Imaging Data ◽  
Displacement Fields ◽  
Full Field

Full field strain measurement techniques are based on computing the spatial derivatives of the approximation or interpolation of the underlying displacement fields extracted from digital imaging methods. These methods implicitly assume that the medium satisfies the compatibility conditions, which for any practical reason is only true in the case of a continuum body that remains continuum throughout the history of its mechanical loading. In the present work we introduce a method that can be used to calculate the strain components directly from typical digital imaging data, without the need of the continuum hypothesis and the need for displacement field differentiation. Thus it allows the imaging and measurement of strain fields from surfaces with discontinuities (i.e. small cracks). Numerical comparisons are performed based on synthetic data produced from an analytical solution for an open hole domain in tension. Mean absolute error distributions are calculated for the cases of both the traditional mesh free random grid method and the direct strain method introduced in the paper are given. It is established that the more refined representation of strain provided by this approach is more accurate everywhere in the domain, but most importantly, near the boundaries of the representation domain, where the error is higher for traditional methods.

Development of an Electronic Speckle Pattern Interferometer for Measurement of Concentration Gradients in a Binary Mixture

Volume 1 ◽  
2004 ◽  
Author(s):  
David McGuire ◽  
Julie Garvey ◽  
Tara M. Dalton ◽  
Mark R. Davies
Keyword(s):  
Binary Mixture ◽  
Speckle Pattern ◽  
Ccd Camera ◽  
Field Measurements ◽  
Theoretical Background ◽  
Phase Shifting ◽  
Concentration Gradients ◽  
Full Field ◽  
Optical Process ◽  
And Performance

This paper describes the construction and performance of an Electronic Speckle Pattern Interferometer (ESPI) developed for measurements of concentration gradients in a binary mixture. The system uses a Mach-Zehnder interferometer with a commercially available CCD camera for image acquisition. A phase-shifting algorithm is employed to give full field measurements. The theoretical background to the optical process involved in these methods is also presented, with emphasis on using the system for analysing concentration gradients. Problems pertaining to the unknown Gladstone-Dale constants of a binary mixture are also discussed.

Accuracy of Wearable Sensor Technology in Hand Goniometry: A Systematic Review

Hand ◽  
2021 ◽  
pp. 155894472110146
Author(s):  
Francisco R. Avila ◽  
Rickey E. Carter ◽  
Christopher J. McLeod ◽  
Charles J. Bruce ◽  
Davide Giardi ◽  
...  
Keyword(s):  
Systematic Review ◽  
Range Of Motion ◽  
Health Care Professionals ◽  
Inertial Sensors ◽  
Measurement Techniques ◽  
Infrared Camera ◽  
Wearable Devices ◽  
Sensor Technology ◽  
Accuracy Evaluation ◽  
Wearable Sensor

Background Wearable devices and sensor technology provide objective, unbiased range of motion measurements that help health care professionals overcome the hindrances of protractor-based goniometry. This review aims to analyze the accuracy of existing wearable sensor technologies for hand range of motion measurement and identify the most accurate one. Methods We performed a systematic review by searching PubMed, CINAHL, and Embase for studies evaluating wearable sensor technology in hand range of motion assessment. Keywords used for the inquiry were related to wearable devices and hand goniometry. Results Of the 71 studies, 11 met the inclusion criteria. Ten studies evaluated gloves and 1 evaluated a wristband. The most common types of sensors used were bend sensors, followed by inertial sensors, Hall effect sensors, and magnetometers. Most studies compared wearable devices with manual goniometry, achieving optimal accuracy. Although most of the devices reached adequate levels of measurement error, accuracy evaluation in the reviewed studies might be subject to bias owing to the use of poorly reliable measurement techniques for comparison of the devices. Conclusion Gloves using inertial sensors were the most accurate. Future studies should use different comparison techniques, such as infrared camera–based goniometry or virtual motion tracking, to evaluate the performance of wearable devices.

scholarly journals Experimental and Computational Approach to Fatigue Behavior of Polycrystalline Tantalum

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 416 ◽  
Author(s):  
Damien Colas ◽  
Eric Finot ◽  
Sylvain Flouriot ◽  
Samuel Forest ◽  
Matthieu Mazière ◽  
...  
Keyword(s):  
Free Surface ◽  
Low Cycle Fatigue ◽  
Large Strain ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Field Measurements ◽  
Test Sample ◽  
Lattice Rotation ◽  
Element Simulation ◽  
Crack Initiation Criterion

This work provides an experimental and computational analysis of low cycle fatigue of a tantalum polycrystalline aggregate. The experimental results include strain field and lattice rotation field measurements at the free surface of a tension–compression test sample after 100, 1000, 2000, and 3000 cycles at ±0.2% overall strain. They reveal the development of strong heterogeneites of strain, plastic slip activity, and surface roughness during cycling. Intergranular and transgranular cracks are observed after 5000 cycles. The Crystal Plasticity Finite Element simulation recording more than 1000 cycles confirms the large strain dispersion at the free surface and shows evidence of strong local ratcheting phenomena occurring in particular at some grain boundaries. The amount of ratcheting plastic strain at each cycle is used as the main ingredient of a new local fatigue crack initiation criterion.

Improved infrared temperature mapping of elastohydrodynamic contacts

2009 ◽  
Vol 223 (8) ◽  
pp. 1165-1177 ◽  
Author(s):  
T Reddyhoff ◽  
H A Spikes ◽  
A V Olver
Keyword(s):  
Effective Means ◽  
Field Measurements ◽  
Operating Conditions ◽  
Mapping Technique ◽  
Shear Stresses ◽  
Measured Temperature ◽  
Ir Camera ◽  
Full Field ◽  
Group I ◽  
Increased Sensitivity

An effective means of studying lubricant rheology within elastohydrodynamic contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. In the current work, the experimental approach initially developed by Sanborn and Winer and then by Spikes et al., has been advanced to include a high specification infrared (IR) camera and microscope. Besides the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions: namely lower loads, speeds, and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. These new possibilities have been used to investigate and compare the rheological properties of a range of lubricants: namely a group I and group II mineral oil, a polyalphaolephin (group IV), the traction fluid Santotrac 50, and 5P4E, a five-ring polyphenyl-ether. As expected, contact temperatures increased with lubricant refinement, for the mineral base oils tested. Using moving heat source theory, the measured temperature distributions were converted into maps showing rate of heat input into each surface, from which shear stresses were calculated. The technique could therefore be validated by integrating these shear stress maps, and comparing them with traction values obtained by direct measurement. Generally there was good agreement between the two approaches, with the only significant differences occurring for 5P4E, where the traction that was deduced from the temperature over-predicted the traction by roughly 15 per cent. Of the lubricants tested, Santotrac 50 showed the highest average traction over the contact; however, 5P4E showed the highest maximum traction. This observation is only possible using the IR mapping technique, and is obscured when measuring the traction directly. Both techniques showed the effect of shear heating causing a reduction in traction.

In-situ Full Field Measurements During Inter-Facial Debonding in Single Fiber Composite Under Transverse Load

2018 ◽  
Vol 58 (9) ◽  
pp. 1451-1467 ◽  
Author(s):  
I. Tabiai ◽  
R. Delorme ◽  
D. Therriault ◽  
M. Levesque
Keyword(s):  
Fiber Composite ◽  
Field Measurements ◽  
Single Fiber ◽  
Transverse Load ◽  
Full Field
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