scholarly journals Validated Ultrasound Speckle Tracking Method for Measuring Strains of Knee Collateral Ligaments In-Situ during Varus/Valgus Loading

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1895
Author(s):  
Félix Dandois ◽  
Orçun Taylan ◽  
Johan Bellemans ◽  
Jan D’hooge ◽  
Hilde Vandenneucker ◽  
...  
Keyword(s):  
Knee Arthroplasty ◽  
Speckle Tracking ◽  
Absolute Error ◽  
Image Correlation ◽  
Correlation Technique ◽  
Collateral Ligaments ◽  
Tracking Method ◽  
Lateral Collateral Ligaments ◽  
Reference Strains

Current ultrasound techniques face several challenges to measure strains when translated from large tendon to in-situ knee collateral ligament applications, despite the potential to reduce knee arthroplasty failures attributed to ligament imbalance. Therefore, we developed, optimized and validated an ultrasound speckle tracking method to assess the in-situ strains of the medial and lateral collateral ligaments. Nine cadaveric legs with total knee implants were submitted to varus/valgus loading and divided into two groups: “optimization” and “validation”. Reference strains were measured using digital image correlation technique, while ultrasound data were processed with a custom-built speckle tracking approach. Using specimens from the “optimization” group, several tracking parameters were tuned towards an optimized tracking performance. The parameters were ranked according to three comparative measures between the ultrasound-based and reference strains: R2, mean absolute error and strains differences at 40 N. Specimens from the “validation” group, processed with the optimal parameters, showed good correlations, along with small mean absolute differences, with correlation values above 0.99 and 0.89 and differences below 0.57% and 0.27% for the lateral and medial collateral ligaments, respectively. This study showed that ultrasound speckle tracking could assess knee collateral ligaments strains in situ and has the potential to be translated to clinics for knee arthroplasty-related procedures.

scholarly journals Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

2021 ◽  
Vol 9 ◽  
Author(s):  
R. He ◽  
L. He ◽  
B. Guan ◽  
C. M. Yuan ◽  
J. Xie ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crack Front ◽  
Image Correlation ◽  
Correlation Technique ◽  
Direct Tension ◽  
Reservoir Stimulation ◽  
The Difference ◽  
Lower Temperature ◽  
Highly Strained

Insight into the difference between the mechanical properties of rocks at low and in situ deep reservoir temperatures is vital for achieving a better understanding of fracking technologies with supercritical CO2 and liquid nitrogen. To address this issue, the fracking-related mechanical properties of the Shaximiao Formation sandstone (SS) were investigated through direct tension, uniaxial compression, and three-point bending fracture tests at a typical low temperature (Tlow) of −10°C and a reservoir temperature (Tin situ) of 70°C. The results showed that the tensile strength σt, compressive strength σc, and fracture toughness KIC of the SS were all higher at Tlow than at Tin situ, although to different extents. The KIC of the SS increased slightly more than σt at the lower temperature, while both σt and KIC of the SS increased significantly more than σc at the lower temperature. In addition to the strength, the stiffness (particularly the tensile stiffness) and the brittleness indices of SS were similarly higher at Tlow than at Tin situ. In situ monitoring using the digital image correlation technique revealed that a highly strained band (HSB) always appeared at the crack front. However, because of the inhomogeneous microstructure of the SS, the HSB did not always develop along the line connecting the notch tip to the loading point. This was a possible cause of the highly dispersed KIC values of the SS. The HSB at the crack front was notably narrower at Tlow than at Tin situ, suggesting that low temperatures suppress the plastic deformation of rocks and are therefore beneficial to reservoir stimulation.

In-Situ Characterization of MWCNTs Reinforced Epoxy Nanocomposite Under Mechanical Load

2012 ◽  
Author(s):  
Xinnan Wang ◽  
Peng Cui ◽  
X. W. Tangpong
Keyword(s):  
Mechanical Load ◽  
Sample Surface ◽  
Image Correlation ◽  
Correlation Technique ◽  
In Situ Observation ◽  
Epoxy Nanocomposite ◽  
Multi Walled Carbon Nanotubes ◽  
Predicted Values ◽  
Walled Carbon Nanotubes

In this study, the mechanical properties of multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposite were measured with the custom-built micro/nano three point bending tester mounted on an atomic force microscope (AFM). With in-situ observation of the AFM, the movement of an individual MWCNT on the sample surface was traced, captured, and quantified using the image correlation technique. The Halpin-Tsai and Hui-shia models were applied and compared with the experimental data. Results showed that the elastic modulus from the experiment is much lower than the predicted values from the two models. Detailed mechanical deformation behavior and MWCNT reinforcement mechanism were discussed.

scholarly journals Stress characterization and temporal evolution of borehole failure at the Rittershoffen geothermal project

Solid Earth ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 1155-1180 ◽  
Author(s):  
Jérôme Azzola ◽  
Benoît Valley ◽  
Jean Schmittbuhl ◽  
Albert Genter
Keyword(s):  
Stress State ◽  
Time Lapse ◽  
In Situ Stress ◽  
Image Correlation ◽  
Geothermal System ◽  
Upper Rhine Graben ◽  
Correlation Technique ◽  
Stress Regime ◽  
Stress Rotation

Abstract. In the Upper Rhine Graben, several innovative projects based on enhanced geothermal system (EGS) technology exploit local deep-fractured geothermal reservoirs. The principle underlying this technology consists of increasing the hydraulic performances of the natural fractures using different stimulation methods in order to circulate the natural brine at commercial flow rates. For this purpose, knowledge of the in situ stress state is of central importance to predict the response of the rock mass to different stimulation programs. Here, we propose a characterization of the in situ stress state from the analysis of ultrasonic borehole imager (UBI) data acquired at different key moments of the reservoir development using a specific image correlation technique. This unique dataset has been obtained from the open-hole sections of the two deep wells (GRT-1 and GRT-2, ∼2500 m) at the geothermal site of Rittershoffen, France. We based our analysis on the geometry of breakouts and drilling-induced tension fractures (DITFs). A transitional stress regime between strike-slip and normal faulting consistent with the neighboring site of Soultz-sous-Forêts is evident. The time-lapse dataset enables us to analyze both in time and space the evolution of the structures over 2 years after drilling. The image correlation approach developed for time-lapse UBI images shows that breakouts extend along the borehole with time and widen (i.e., angular opening between the edges of the breakouts) but do not deepen (i.e., increase in the maximal radius of the breakouts). The breakout widening is explained by wellbore thermal equilibration. A significant stress rotation at depth is evident. It is shown to be controlled by a major fault zone and not by the sediment–basement interface. Our analysis does not reveal any significant change in the stress magnitude in the reservoir.

scholarly journals Stress Characterization and Temporal Evolution of Borehole Failure at the Rittershoffen Geothermal Project

2019 ◽  
Author(s):  
Jérôme Azzola ◽  
Benoît Valley ◽  
Jean Schmittbuhl ◽  
Albert Genter
Keyword(s):  
Stress State ◽  
Time Lapse ◽  
In Situ Stress ◽  
Image Correlation ◽  
Geothermal System ◽  
Upper Rhine Graben ◽  
Correlation Technique ◽  
Stress Regime ◽  
Stress Rotation

Abstract. In the Upper Rhine Graben, several innovative projects based on the Enhanced Geothermal System (EGS) technology exploit local deep fractured geothermal reservoirs. The principle underlying this technology consists of increasing the hydraulic performances of the natural fractures using different stimulation methods in order to circulate the natural brine with commercially flow rates. For this purpose, the knowledge of the in-situ stress state is of central importance to predict the response of the rock mass to the different stimulation programs. Here, we propose a characterization of the in-situ stress state from the analysis of Ultrasonic Borehole Imager (UBI) data acquired at different key moments of the reservoir development using a specific image correlation technique. This unique dataset has been obtained from the open hole sections of the two deep wells (GRT-1 and GRT2, ~ 2500 m) at the geothermal site of Rittershoffen, France. We based our analysis on the geometry of breakouts and of drilling induced tension fractures (DITF). A transitional stress regime between strike-slip and normal faulting consistently with the neighbour site of Soultz-sous-Forêts is evidenced. The time lapse dataset enables to analyse both in time and space the evolution of the structures over two years after drilling. The image correlation approach developed for time lapse UBI images shows that breakouts extend along the borehole with time, widen (i.e. angular opening between the edges of the breakouts) but do not deepen (i.e. increase of the maximal radius of the breakouts). The breakout widening is explained by wellbore thermal equilibration. A significant stress rotation at depth is evidenced. It is shown to be controlled by a major fault zone and not by the sediment-basement interface. Our analysis does not reveal any significant change in the stress magnitude in the reservoir.

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