The stress measurement system for the JUNO Central Detector acrylic panels

2021 ◽  
Vol 16 (12) ◽  
pp. P12040
Author(s):  
X. Yang ◽  
Y. Heng ◽  
Z. Li ◽  
X. Ma ◽  
X. Qian ◽  
...  
Keyword(s):  
Measurement System ◽  
Stress Measurement ◽  
Liquid Scintillator ◽  
Life Time ◽  
Structural Safety ◽  
Spherical Vessel ◽  
Optical Coefficient ◽  
Central Detector ◽  
Measurement Principle ◽  
Tooling Design

Abstract The Jiangmen Underground Neutrino Observatory (JUNO) Central Detector (CD) is a huge acrylic spherical vessel containing 20,000 tons of liquid scintillator; the sphere is composed of 263 pieces of acrylic spherical panels bonded by the mass polymerization. The operation life time of the JUNO CD is 20 years. To ensure the structural safety during the JUNO CD life time, the acrylic stress of CD is required not to be greater than 3.5 MPa. The stresses of acrylic spherical panels are required to be measured during the installation on-site; unfortunately there is no suitable commercial measurement equipment that can meet JUNO's requirements. Therefore, a measurement setup based on photo-elastic principle and spectrometric methods was designed, developed and tested for on-site measurements. The measurement system performs accurate calibration of stress-optical coefficient of acrylic in JUNO, and gives reliable results of acrylic stresses. The measurement system has been tested in the Taixing Donchamp Acrylic Ltd mechanical workshop, and the achieved results meet the JUNO's requirements. The measurement principle, the system components, and the tooling design are introduced in the paper. Moreover, the calibration of stress-optical coefficient of the acrylic and measurements results on JUNO acrylic spherical panels are discussed in the following.

Analysis of Eddy-Current Measurement System for Residual Stress Assessment in Stainless Steel Grade 304

2015 ◽  
Vol 659 ◽  
pp. 623-627 ◽  
Author(s):  
Cherdpong Jomdecha ◽  
Isaratat Phung-On
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Eddy Current ◽  
Measurement System ◽  
System Analysis ◽  
Stress Measurement ◽  
Steel Grade ◽  
Current Measurement ◽  
Residual Stress Measurement ◽  
Stress Assessment

The objective of this paper is an analysis of statistical discreteness and measurement capability of an eddy-current measurement system for residual stress assessment in stainless steel Grade 304 (SS304). Cylindrical specimens with 50 mm in diameter and 12 mm thickness were prepared to generate residual stress by Resistance Spot Welding at which the welding currents were set at 12, 14, and 16 kA. The eddy-current measurement system was including a probe with frequency range of 0.1 to 3 MHz and an eddy current flaw detector. They were performed by contacting the probe on the specimen. The measurements were performed particularly in the vicinity of heat affected zone (HAZ). In order to determine the results of the residual stress measurement, the calibration curves between static tensile stress and eddy current impedance at various frequencies were accomplished. The Measurement System Analysis (MSA) was utilized to evaluate the changed eddy-current probe impedance from residual stress. The results showed that using eddy current technique at 1 MHz for residual stress measurement was the most efficient. It can be achieved the Gauge Repeatability & Reproducibility %GR&R at 16.61479 and Number of Distinct Categories (NDC) at 8. As applied on actual butt welded joint, it could yield the uncertainty of ± 58 MPa at 95 % (UISO).

The SCATMES Device for Measurement of Concentrated Solar Radiation

1999 ◽  
Vol 121 (2) ◽  
pp. 116-120 ◽  
Author(s):  
A. Neumann ◽  
A. Schmitz
Keyword(s):  
Solar Radiation ◽  
Measurement System ◽  
Flux Distribution ◽  
Optical Design ◽  
Video Camera ◽  
Solar Furnace ◽  
Camera Systems ◽  
Measurement Principle ◽  
Concentrated Solar Radiation ◽  
Compact Geometry

Video camera systems monitoring a diffuse reflecting target for measuring the flux distribution of concentrated solar radiation are quite common. This technique cannot be used if parts of the experimental setup screen the surface of the target. The development of a new measurement system with a compact geometry and a new optical design is described. With this system it is possible to measure the flux distribution behind parts of an experiment and at any position of the plane of measurement, without any alteration of the setup. The sources of error, especially those of the target and the camera, are described and discussed, and finally a comparison to the existing FATMES-System, which has been performed at the solar furnace of the DLR in Cologne, is presented. Due to its measurement principle the new system is called ’Scanning Camera and Target Measurement System‘ (acronym: SCATMES).

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