scholarly journals Magnetic stray field measurements to identify and localise impact-induced plastic deformation in a steel structure

2021 ◽  
pp. 106990
Author(s):  
P.C. Meijers ◽  
C.T. Jolink ◽  
A. Tsouvalas ◽  
A.V. Metrikine
Keyword(s):  
Plastic Deformation ◽  
Steel Structure ◽  
Field Measurements ◽  
Stray Field

scholarly journals The fluxgate magnetometer of the Low Orbit Pearl Satellites (LOPS): overview of in-flight performance and initial results

2021 ◽  
Vol 10 (2) ◽  
pp. 227-243
Author(s):  
Ye Zhu ◽  
Aimin Du ◽  
Hao Luo ◽  
Donghai Qiao ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current System ◽  
Field Measurements ◽  
Stray Field ◽  
Fluxgate Magnetometer ◽  
General Description ◽  
Flight Performance ◽  
Spatial Coverage ◽  
Magnetic Field Measurements ◽  
Initial Results

Abstract. The Low Orbit Pearl Satellite series consists of six constellations, with each constellation consisting of three identical microsatellites that line up just like a string of pearls. The first constellation of three satellites were launched on 29 September 2017, with an inclination of ∼ 35.5∘ and ∼ 600 km altitude. Each satellite is equipped with three identical fluxgate magnetometers that measure the in situ magnetic field and its low-frequency fluctuations in the Earth's low-altitude orbit. The triple sensor configuration enables separation of stray field effects generated by the spacecraft from the ambient magnetic field (e.g., Zhang et al., 2006). This paper gives a general description of the magnetometer including the instrument design, calibration before launch, in-flight calibration, in-flight performance, and initial results. Unprecedented spatial coverage resolution of the magnetic field measurements allow for the investigation of the dynamic processes and electric currents of the ionosphere and magnetosphere, especially for the ring current and equatorial electrojet during both quiet geomagnetic conditions and storms. Magnetic field measurements from LOPS could be important for studying the method to separate their contributions of the Magnetosphere-Ionosphere (M-I) current system.

Empirical Analysis of the Effects of Parasitic Magnetic Stray Field on Force Output of Electromagnetic Actuators

2016 ◽  
Vol 1140 ◽  
pp. 384-391 ◽  
Author(s):  
Andreas Heyder ◽  
Stefan Steinbeck ◽  
Matthaeus Brela ◽  
Alexander Meyer ◽  
Sandra Abersfelder ◽  
...  
Keyword(s):  
Statistical Methods ◽  
Model Building ◽  
Field Measurements ◽  
Relevant Information ◽  
Field Analysis ◽  
Stray Field ◽  
Force Output ◽  
Electromagnetic Actuators ◽  
Magnetic Actuators ◽  
Six Sigma Methodology

Electromagnetic actuators are used in a variety of technical applications especially in the automotive industry. In-line process control methods are an essential component of the Lean and Six Sigma methodology to ensure process quality. However, the current state of the art in process and quality control is largely limited to end-of-line measurements of the force output. Analysing the magnetic stray field is a promising method that can be used to draw conclusions on the properties and defects of the flux-conducting magnetic materials. This phenomenon can potentially be used to identify defects in magnetic actuators thus allowing inline quality-monitoring. In order to realize this feature, patterns in the magnetic stray field of an actuator have to be identified and linked to a specific defect. The resulting challenge is the analysis of large datasets in order to characterize the stray field anomalies. This paper summarizes the results of a study on linear magnetic actuators trying to prove a relationship between parasitic magnetic stray field and the overall force output of an actuator by analysing the data with statistical methods. The findings of this study suggest that certain statistical methods, like regression, are not well suited to build a prediction model for defects in actuators using a similar approach of measuring stray field outside the actuator. This is mainly due to the fact that prerequisites for model building are difficult to full fill within the context of stray field analysis. Nevertheless, the findings also suggest that methods of exploratory data analysis can be used to derive quality relevant information from data of stray field measurements. The paper elaborates on the problem of defining a population, choosing variables for model building, as well as model error.

Prototype Support Structure for Seabed Mounted Tidal Current Turbines

2005 ◽  
Vol 219 (4) ◽  
pp. 173-183 ◽  
Author(s):  
A Owen ◽  
I G Bryden
Keyword(s):  
Steel Structure ◽  
Field Measurements ◽  
Model Fit ◽  
Scale Model ◽  
Conceptual Basis ◽  
Simple Mathematical Model ◽  
Low Aspect Ratio ◽  
Induced Drag ◽  
Tidal Turbine ◽  
Drag And Lift

This paper introduces the patented concept of the Sea Snail, a pin-jointed tubular steel structure carrying an array of symmetrical section hydrofoils, which is used as a means of fixing a tidal turbine, or other devices, to the seabed. The concept is evaluated as a simple mathematical model, tested as a one-eighth-scale model and subsequently developed into a 21 t model fit for sea trials. Pressure differences created by the flow over the upper and lower surfaces of the hydrofoils generate negative lift, or downforce, which is communicated to the supporting structure. The effects of induced drag on low-aspect-ratio hydrofoils are discussed. This paper gives an overview of the evaluative techniques employed in the Sea Snail's concept and design. The need for the device is outlined and its conceptual basis discussed. In particular, the response of a hydrofoil to increasing angles of attack within a steady flow is examined. Field measurements of the drag and lift forces applied to an NACA0013 section hydrofoil is presented in the context of the Sea Snail. The fundamental design criteria are discussed and the Sea Snail's ability to match these criteria is demonstrated.

scholarly journals The Role of Surface Topography on Deformation-Induced Magnetization under Inhomogeneous Elastic-Plastic Deformation

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1518 ◽  
Author(s):  
Nadja Sonntag ◽  
Birgit Skrotzki ◽  
Robert Stegemann ◽  
Peter Löwe ◽  
Marc Kreutzbruck
Keyword(s):  
Plastic Deformation ◽  
Ferromagnetic Material ◽  
Image Correlation ◽  
Stray Field ◽  
Inhomogeneous Deformation ◽  
Elastic Plastic ◽  
Lift Off ◽  
Gmr Sensor ◽  
Magnetic States ◽  
Field Formation

It is widely accepted that the magnetic state of a ferromagnetic material may be irreversibly altered by mechanical loading due to magnetoelastic effects. A novel standardized nondestructive testing (NDT) technique uses weak magnetic stray fields, which are assumed to arise from inhomogeneous deformation, for structural health monitoring (i.e., for detection and assessment of damage). However, the mechanical and microstructural complexity of damage has hitherto only been insufficiently considered. The aim of this study is to discuss the phenomenon of inhomogeneous “self-magnetization” of a polycrystalline ferromagnetic material under inhomogeneous deformation experimentally and with stronger material-mechanical focus. To this end, notched specimens were elastically and plastically deformed. Surface magnetic states were measured by a three-axis giant magnetoresistant (GMR) sensor and were compared with strain field (digital image correlation) and optical topography measurements. It is demonstrated that the stray fields do not solely form due to magnetoelastic effects. Instead, inhomogeneous plastic deformation causes topography, which is one of the main origins for the magnetic stray field formation. Additionally, if not considered, topography may falsify the magnetic signals due to variable lift-off values. The correlation of magnetic vector components with mechanical tensors, particularly for multiaxial stress/strain states and inhomogeneous elastic-plastic deformations remains an issue.

The Effect of Ball Bearing Steel Structure on Rolling Friction and Contact Plastic Deformation

1960 ◽  
Vol 82 (2) ◽  
pp. 302-306 ◽  
Author(s):  
Richard C. Drutowski ◽  
Ernie B. Mikus
Keyword(s):  
Plastic Deformation ◽  
Retained Austenite ◽  
Elastic Limit ◽  
Ball Bearing ◽  
Steel Structure ◽  
Steel Structures ◽  
Rolling Friction ◽  
Bearing Steel ◽  
Very High ◽  
Ball Bearing Steel

The rolling friction, contact plastic deformation, and elastic limit were determined for SAE 52100 steel structures with retained austenite contents from zero to 18.4 per cent. The force necessary to roll a ball on a plate decreased as the retained austenite was decreased. The contact stress necessary for the initiation of plastic deformation and the elastic limit of the material increased as the retained austenite content decreased from 18.4 to 3.9 per cent. No further change occurred when the retained austenite was reduced to zero. The extent of plastic deformation at very high contact stresses was reduced by the presence of retained austenite contents up to at least 7.4 per cent. These observations were applied to the problem of selecting the best steel structure for an instrument ball bearing.

scholarly journals The Fluxgate Magnetometer of the Low Orbit Pearl Satellites  (LOPS): overview of in-flight performance and initial results 

2021 ◽  
Author(s):  
Ye Zhu ◽  
Aimin Du ◽  
Hao Luo ◽  
Donghai Qiao ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current System ◽  
Equatorial Electrojet ◽  
Field Measurements ◽  
Stray Field ◽  
Fluxgate Magnetometer ◽  
General Description ◽  
Flight Performance ◽  
Spatial Coverage ◽  
Initial Results

Abstract. The Low Orbit Pearl Satellite series consists of six constellations, with each constellation consisting of three identical micro-satellites which line up just like a string of pearls. The first constellation of three satellites were launched on September 29, 2017, with an inclination of ~ 35.5° and ~ 600 km altitude. Each satellite is equipped with three identical Fluxgate Magnetometers (FGM), which measure the in-situ magnetic field and its low frequency fluctuations in the Earth’s low altitude orbit. The triple sensor configuration enables separation of stray field effects generated by the spacecraft from the ambient magnetic field [e.g. Zhang et al., 2006]. This paper gives a general description of the magnetometer about the instrument design, calibration before launch, in flight calibration, as well as the in-flight performance and initial results. Unprecedented spatial coverage resolution of the magnetic field measurements allow for investigating the dynamic processes and electric currents of ionosphere and magnetosphere, especially for the ring current and equatorial electrojet (EEJ) during both geomagnetic quiet conditions and storms. It could be important for studying the method to separate their contributions of the M-I current system.

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