Evaluation of Residual Stresses in Butt-Welded Joints by Residual Magnetic Field Measurements

2012 ◽  
Vol 217-219 ◽  
pp. 2427-2434 ◽  
Author(s):  
Bin Liang ◽  
Jian Ming Gong ◽  
Hai Tao Wang ◽  
Cheng Ye
Keyword(s):  
Residual Stress ◽  
Quantitative Method ◽  
Normal Component ◽  
Field Measurements ◽  
Stray Field ◽  
The Finite Element Method ◽  
Promising Tool ◽  
Magnetic Field Measurements ◽  
Ferromagnetic Steels ◽  
Welded Seam

Measuring residual stray field (RMF) signals provides a promising tool to analyze the stress in ferromagnetic welded materials. In this paper, the variations of the normal component of the RMF, Hp(y), perpendicular to welded seam are measured. The finite element method is used to model residual stress in the specimen. The influence of residual stress on the Hp(y) component is shown. It is found that the distributions of the Hp(y) component are described by a Boltzmann fitting curve, show a good qualitative correlation with residual stress. A quantitative method for the evaluation of residual stress in ferromagnetic steels based on the gradient of the Hp(y) component and equivalent (vonMises) stress is presented.

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.

Evaluation of the residual stress in stainless steel 304L hydraulically expanded joints

2020 ◽  
pp. 095440892096401
Author(s):  
Ying Hong ◽  
Xuesheng Wang ◽  
Yan Wang ◽  
Zhao Zhang ◽  
Yong Han
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Yield Strength ◽  
Residual Stresses ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
The Finite Element Method ◽  
Power Stations ◽  
Stainless Steel 304 ◽  
Initial Clearance

Stainless steel 304 L tubes are commonly used in the fabrication of heat exchangers for nuclear power stations. The stress corrosion cracking (SCC) of 304 L tubes in hydraulically expanded tube-to-tubesheet joints is the main reason for the failure of heat exchangers. In this study, 304 L hydraulically expanded joint specimens were prepared and the residual stresses of a tube were evaluated with both an experimental method and the finite element method (FEM). The residual stresses in the outer and inner surfaces of the tube were measured by strain gauges. The expanding and unloading processes of the tube-to-tubesheet joints were simulated by the FEM. Furthermore, an SCC test was carried out to verify the results of the experimental measurement and the FEM. There was good agreement between the FEM and the experimental results. The distribution of the residual stress of the tube in the expanded joint was revealed by the FEM. The effects of the expansion pressure, initial tube-to-hole clearance, and yield strength of the tube on the residual stress in the transition zone that lay between the expanded and unexpanded region of the tube were investigated. The results showed that the residual stress of the expanded joint reached the maximum value when the initial clearance was eliminated. The residual stress level decreased with the decrease of the initial tube-to-hole clearance and yield strength. Finally, an effective method that would reduce the residual stress without losing tightness was proposed.

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