scholarly journals Numerical Simulation on Stress Measurement with Eddy Current Thermography

2020 ◽  
Author(s):  
Shuwen Deng ◽  
Suixian Yang ◽  
Yong Yao
Keyword(s):  
Stress State ◽  
Temperature Distribution ◽  
Eddy Current ◽  
Material Properties ◽  
Stress Measurement ◽  
Heating Process ◽  
Parameter Distribution ◽  
Induction Current ◽  
Electromagnetic Characteristics ◽  
Nondestructive Testing Method

Stress in components will lead to the change of material properties and even failure. Therefore, the assessment for the stress state of components is play an important role in testing industry. As a non-contact and multi-physical field nondestructive testing method, eddy current thermography (ECT) can be applied to detect non-homogeneous electromagnetic characteristics parameter distribution in conductive materials. Internal stress and its distribution in a material will affect the value of electromagnetic characteristic parameters. If induction current applied on conductive material, the Joule’s heat, which generate in the sample will lead to the temperature rise on the surface of the specimen by induction heating process. The temperature distribution on the specimen surface can be recorded by infra camera and stored as IR images or videos. The feature of the temperature distribution and its variation can be used to express the stress state in the specimen. It is concluded that there is an approximate linear relationship between the surface temperature appreciation and the loading force when the excitation source condition remains unchanged.

scholarly journals Evaluation of Eddy Current Response Due to the Applied Stress on a Steel Plate Using Phase Diagram

2020 ◽  
Author(s):  
Sanjeema Bajracharya ◽  
Eiichi Sasaki
Keyword(s):  
Phase Diagram ◽  
Stress State ◽  
Relative Permeability ◽  
Eddy Current ◽  
Steel Plate ◽  
Stress Measurement ◽  
Excitation Frequency ◽  
Steel Structures ◽  
Probe Size ◽  
Lift Off

Structural health monitoring of steel structures is crucial for inspection of corrosion and cracking in structural members, compromising their safety and serviceability. In the present study, the prospective of evaluation of change in stress state of structural member due to corrosion and cracking through eddy current based stress measurement is investigated. For this, three-dimensional numerical simulations are carried out in the FE software COMSOL Multiphysics 5.2a for a steel plate subjected to change in relative permeability, representative of change in stress state, whereby the eddy current indices are characterized, including the effects of additional influential parameters namely, lift-off, excitation frequency, and probe size. Phase Diagram is then proposed as a concise method to evaluate the variation of relative permeability and lift-off concurrently in a single graph for an excitation frequency and probe size. It further facilitates the selection of suitable excitation frequency and probe size to conduct the eddy current based stress measurement.

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).

scholarly journals Shape Effect on the Temperature Field during Microwave Heating Process

2018 ◽  
Vol 2018 ◽  
pp. 1-24 ◽  
Author(s):  
Zhijun Zhang ◽  
Tianyi Su ◽  
Shiwei Zhang
Keyword(s):  
Electromagnetic Field ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Microwave Cavity ◽  
Heating Process ◽  
Shape Effect ◽  
Power Absorption ◽  
Sample Shape ◽  
Distribution Uniformity ◽  
Microwave Process

Aiming at improving the food quality during microwave process, this article mainly focused on the numerical simulation of shape effect, which was evaluated by microwave power absorption capability and temperature distribution uniformity in a single sample heated in a domestic microwave oven. This article only took the electromagnetic field and heat conduction in solid into consideration. The Maxwell equations were used to calculate the distribution of microwave electromagnetic field distribution in the microwave cavity and samples; then the electromagnetic energy was coupled as the heat source in the heat conduction process in samples. Quantitatively, the power absorption capability and temperature distribution uniformity were, respectively, described by power absorption efficiency (PAE) and the statistical variation of coefficient (COV). In addition, we defined the comprehensive evaluation coefficient (CEC) to describe the usability of a specific sample. In accordance with volume or the wave numbers and penetration numbers in the radial and axial directions of samples, they can be classified into different groups. And according to the PAE, COV, and CEC value and the specific need of microwave process, an optimal sample shape and orientation could be decided.

scholarly journals Detection of Fatigue Microcrack Using Eddy Current Pulsed Thermography

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xiang Zhang ◽  
Jianping Peng ◽  
Luquan Du ◽  
Jie Bai ◽  
Lingfan Feng ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Signal Processing ◽  
Eddy Current ◽  
Material Properties ◽  
Principal Component ◽  
Tucker Decomposition ◽  
Pulsed Thermography ◽  
Signal Processing Algorithms ◽  
Microcrack Detection ◽  
Processing Algorithms

Microcracks are a common metallic defect, resulting in degradation of material properties. In this paper, specimens with different fatigue microcracks were detected by eddy current pulsed thermography (ECPT). Signal processing algorithms were investigated to improve the detectability and sensitivity; principal component analysis (PCA) and Tucker decomposition were used to compare the performance of microcrack detection. It was found that both algorithms were highly adaptable. A thermal quotient was used to assess the temperature variation trend. Furthermore, the potential correspondence between crack closure and temperature change was investigated.

scholarly journals Longitudinal Residual Stress Analysis in AA2024-T3 Friction Stir Welding

2013 ◽  
Vol 7 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Pierpaolo Carlone ◽  
Gaetano S. Palazzo
Keyword(s):  
Friction Stir Welding ◽  
Residual Stresses ◽  
Process Parameters ◽  
Material Properties ◽  
Stress Measurement ◽  
Dynamic Performance ◽  
Contour Method ◽  
Influence Of Process Parameters ◽  
Friction Stir ◽  
Longitudinal Residual Stress

Friction Stir Welding (FSW) is an innovative solid-state joining process, which is gaining a great deal of attention in several applicative sectors. The opportune definition of process parameters, i.e. minimizing residual stresses, is crucial to improve joint reliability in terms of static and dynamic performance. Longitudinal residual stresses, induced by FSW in AA2024-T3 butt joints, have been inferred by means of a recently developed technique, namely the contour method. Two approaches to stress measurement have been adopted; the former is based on the assumption of uniform material properties, the latter takes into account microstructural effects and material properties variations in the welding zones. The influence of process parameters, namely rotating and welding speeds, on stress distribution is also discussed.

Evaluation by FEM of the Influence of the Preheating and Post-Heating Treatments on Residual Stresses in Welding

2014 ◽  
Vol 627 ◽  
pp. 93-96 ◽  
Author(s):  
Raffaele Sepe ◽  
Enrico Armentani ◽  
Giuseppe Lamanna ◽  
Francesco Caputo
Keyword(s):  
Temperature Distribution ◽  
Residual Stresses ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Element Model ◽  
Butt Joint ◽  
Temperature Fields ◽  
Heating Process ◽  
Butt Weld ◽  
Metal Arc Welding

During the last few years various experimental destructive and non-destructive methods were developed to evaluate residual stresses. However it is impossible to obtain a full residual stress distribution in welded structures by means of experimental methods. This disadvantage can be solved by means of computational analysis which allows to determine the whole stress and strain fields in complex structures. In this paper the temperature distribution and residual stresses were determined in a single-pass butt joint welded by GMAW (Gas Metal Arc Welding) process by finite element model (FEM). A 3D finite parametric element model has been carried out to analyze temperature distribution in butt weld joints and thermo-mechanical analyses were performed to evaluate resulting residual stresses. Temperature fields have been investigated by varying an initial preheating treatment. Moreover the technique of “element birth and death” was adopted to simulate the process of filler metal addition The high stresses were evaluated, with particular regard to fusion zone and heat affected zone. The influence of preheating and post-heating treatment on residual stresses was investigated. The residual stresses decrease when preheating temperature increases. The maximum value of longitudinal residual stresses without pre-heating can be reduced about 12% and 38% by using the preheating and post-heating process respectively.

Using Indentation Test to Evaluate the Properties of Metallic Material with Strain Aging

2015 ◽  
Vol 751 ◽  
pp. 131-136
Author(s):  
Jie Tang ◽  
Mao Cheng ◽  
Guo Gen Huang ◽  
Hong Shu ◽  
Hui Ting Xu
Keyword(s):  
Nondestructive Testing ◽  
Experimental Verification ◽  
Material Properties ◽  
Strain Aging ◽  
Experimental Testing ◽  
Indentation Test ◽  
Metallic Materials ◽  
Metallic Material ◽  
Testing Method ◽  
Nondestructive Testing Method

In this paper, research on a testing method of indentation test proposed by F M Haggag is discussed first, and the experimental testing research on metallic material properties with strain aging is carried out and discussed using indentation test. The authors proposed to use indentation test to measure the properties of metallic materials with strain aging embrittlement based on experimental verification. And it provides a possibility to measure the properties of metallic materials with strain aging using nondestructive testing method.

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