Dynamic Visualization of Crack Tip Stress Field and Propagation Using the Mechano-Luminescence in SrAl2O4: (Eu,Dy,Nd)

2005 ◽  
Vol 475-479 ◽  
pp. 1121-1124 ◽  
Author(s):  
Ji Sik Kim ◽  
Yong Nam Kwon ◽  
Kee Sun Sohn
Keyword(s):  
Applied Load ◽  
Loading Rate ◽  
Light Emission ◽  
Propagation Speed ◽  
Compact Tension ◽  
Dynamic Visualization ◽  
Sharp Notch ◽  
Propagating Crack ◽  
Crack Propagation Speed

The present investigation aimed at visualizing the propagating crack in a mechano-luminescence (ML) material, which enabled us to measure instantaneous R-curves and observe directly the bridging (shielding) stress in the fast-propagating crack system. The well-known ML compound, SrAl2O4:Eu,Dy,Nd, was adopted as a testing material. The crack initiation and growth from the mechanically machined sharp notch tip in the disc shaped compact tension (CT) specimen at a relatively fast loading rate were found to be associated with the extent of light emission around the crack. The in-situ measurement of crack length and applied load for 0.3 sec yielded an instantaneous R-curve at the conventional crack propagation speed.

scholarly journals Development of friction-induced triboluminescent sensor for load monitoring

2017 ◽  
Vol 29 (5) ◽  
pp. 883-895 ◽  
Author(s):  
Md Abu S Shohag ◽  
Zhengqian Jiang ◽  
Emily C Hammel ◽  
Lucas Braga Carani ◽  
David O Olawale ◽  
...  
Keyword(s):  
Applied Load ◽  
Loading Rate ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Loading Rates ◽  
Load Monitoring ◽  
The Coefficient Of Friction ◽  
Dynamic Structures ◽  
Sample Configuration

Real-time load monitoring of critical civil and mechanical structures especially dynamic structures such as wind turbine blades is imperative for longer service life. This article proposed a novel sensor system based on the proprietary in situ triboluminescent optical fiber (ITOF) sensor for dynamic load monitoring. The new ITOF sensor patch consists of an ITOF sensor network with micro-exciters integrated within a polymer matrix. The sensor patch was subjected to repeated flexural loading and produced triboluminescent emissions due to the friction between micro-exciters and ITOF sensors corresponding to each loading cycle. The friction-induced triboluminescent intensity directly depends on the loading rate, the coefficient of friction, and the applied load on patch. In general, the triboluminescent intensity increases exponentially with an increase in load. Additionally, the sensor patches comprising the coarser micro-exciters exhibited better results. Similarly, better results were achieved at higher loading rates although a threshold loading rate is required to excite the triboluminescent crystals for this sample configuration. The proposed new sensor has the ability to monitor dynamic continuous applied loads.

Sensitivity of Modeling Parameters in Proximal Femur Analyses

2000 ◽  
Author(s):  
Eric L. Wang ◽  
Yanyao Jiang ◽  
Lixia Fan ◽  
Brian Greer
Keyword(s):  
Hip Fracture ◽  
Proximal Femur ◽  
Material Properties ◽  
Applied Load ◽  
Loading Rate ◽  
Frictional Resistance ◽  
Fracture Load ◽  
Loading Direction ◽  
Structural Capacity ◽  
Femoral Geometry

Abstract Hip fracture risk can be quantified using a factor of risk (Hayes et al., 1996): (1) Φ = Applied load / Fracture load The structural capacity, the denominator, can be affected by many parameters including femoral geometry, material properties, load locations, loading direction, loading rate, and frictional resistance.

Deriving CME volume and density from remote sensing data

2021 ◽  
Author(s):  
Manuela Temmer ◽  
Lukas Holzknecht ◽  
Mateja Dumbovic ◽  
Bojan Vrsnak ◽  
Nishtha Sachdeva ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Remote Sensing Data ◽  
Propagation Speed ◽  
Solar Wind Density ◽  
Sheath Region ◽  
Pile Up ◽  
Mass Ejection ◽  
Interplanetary Propagation

<p>Using combined STEREO-SOHO white-light data, we present a method to determine the volume and density of a coronal mass ejection (CME) by applying the graduated cylindrical shell model (GCS) and deprojected mass derivation. Under the assumption that the CME  mass is roughly equally distributed within a specific volume, we expand the CME self-similarly and calculate the CME density for distances close to the Sun (15–30 Rs) and at 1 AU. The procedure is applied on a sample of 29 well-observed CMEs and compared to their interplanetary counterparts (ICMEs). Specific trends are derived comparing calculated and in-situ measured proton densities at 1 AU, though large uncertainties are revealed due to the unknown mass and geometry evolution: i) a moderate correlation for the magnetic structure having a mass that stays rather constant and ii) a weak correlation for the sheath density by assuming the sheath region is an extra mass - as expected for a mass pile-up process - that is in its amount comparable to the initial CME deprojected mass. High correlations are derived between in-situ measured sheath density and the solar wind density and solar wind speed as measured 24 hours ahead of the arrival of the disturbance. This gives additional confirmation that the sheath-plasma indeed stems from piled-up solar wind material. While the CME interplanetary propagation speed is not related to the sheath density, the size of the CME may play some role in how much material is piled up.</p>

scholarly journals Dynamically tuned non-classical light emission from atomic defects in hexagonal boron nitride

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Snežana Lazić ◽  
André Espinha ◽  
Sergio Pinilla Yanguas ◽  
Carlos Gibaja ◽  
Félix Zamora ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Information Technologies ◽  
Light Emission ◽  
Hexagonal Boron Nitride ◽  
Theoretical Calculations ◽  
Optical Emission ◽  
Spectral Tuning ◽  
Spectral Detection ◽  
On Chip

Abstract Luminescent defects in hexagonal boron nitride (h-BN) have recently emerged as a promising platform for non-classical light emission. On-chip solutions, however, require techniques for controllable in-situ manipulation of quantum light. Here, we demonstrate the dynamic spectral and temporal tuning of the optical emission from h-BN via moving acousto-mechanical modulation induced by stimulated phonons. When perturbed by the propagating acoustic phonon, the optically probed radiative h-BN defects are periodically strained and their sharp emission lines are modulated by the deformation potential coupling. This results in an acoustically driven spectral tuning within a 2.5-meV bandwidth. Our findings, supported by first-principles theoretical calculations, reveal exceptionally high elasto-optic coupling in h-BN of ~50 meV/%. Temporal control of the emitted photons is achieved by combining the acoustically mediated fine-spectral tuning with spectral detection filtering. This study opens the door to the use of sound for scalable integration of h-BN emitters in nanophotonic and quantum information technologies.

scholarly journals Crack propagation speed in ceramic during quenching

2018 ◽  
Vol 38 (7) ◽  
pp. 2879-2885 ◽  
Author(s):  
Yingfeng Shao ◽  
Boyang Liu ◽  
Xiaohuan Wang ◽  
Long Li ◽  
Jiachen Wei ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Propagation Speed ◽  
Crack Propagation Speed

Finite element simulation of fracture toughness testing of 20MnMoNi55 steel and the effect of loading rate on reference temperature

2020 ◽  
pp. 146442072095667
Author(s):  
Swagatam Paul ◽  
Snehasish Bhattacharjee ◽  
Sanjib Kumar Acharyya ◽  
Prasanta Sahoo
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Finite Element Simulation ◽  
Loading Rate ◽  
Flow Characteristics ◽  
Material Model ◽  
Compact Tension ◽  
Reference Temperature ◽  
Viscoplastic Material ◽  
Element Simulation

Fracture toughness of ferritic steel in the ductile-to-brittle transition zone is scattered and probabilistic owing to embrittlement. Use of master curve along with the reference temperature ( T0) adopted in ASTM E-1921 is widely accepted for characterization of this embrittlement. Reference temperature is a measure of embrittlement in the temperature scale. Factors affecting fracture toughness like geometry and loading rate are expected to influence the reference temperature. In the present study, the role of the loading rate on the reference temperature for 20MnMoNi55 steel is assessed experimentally using compact tension C(T) and three-point bend (TPB) specimens. Finite element simulation of tests at different loading rates and cryogenic temperature are carried out using a suitable viscoplastic material model that incorporates flow characteristics of the material for varying displacement rates and cryogenic temperatures. Results from simulation studies are compared with experimental ones.

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