Instrumented Indentation Technique to Measure Flow Properties: A Novel Way to Enhance the Accuracy of Integrity Assessment

2003 ◽  
Author(s):  
Jae-Il Jang ◽  
Yeol Choi ◽  
Yun-Hee Lee ◽  
Jung-Suk Lee ◽  
Dongil Kwon ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crack Detection ◽  
Structural Integrity ◽  
Instrumented Indentation ◽  
Flow Properties ◽  
Integrity Assessment ◽  
Indentation Technique ◽  
Failure Assessment ◽  
Similar Vein ◽  
Non Destructive

While most in-field technologies for structural integrity diagnosis focus on precise crack detection, the instrumented indentation technique has emerged as one of the most practically useful technologies for non-destructive and quantitative in-field measurement of mechanical properties. In a similar vein, here an advanced indentation technique for determining tensile properties and its application to structural integrity assessment are introduced and discussed. This novel indentation technique can enhance the accuracy of fitness-for-service (FFS) assessment by application to failure assessment diagram (FAD) construction.

Application of a portable indentation rig with Rockwell indenter to determine mechanical properties and residual stresses on an aluminum plate

2020 ◽  
Vol 55 (7-8) ◽  
pp. 246-257
Author(s):  
Saba Salmani Ghanbari ◽  
Amir-Hossein Mahmoudi
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Indentation Load ◽  
Instrumented Indentation ◽  
Unknown Parameters ◽  
Plastic Properties ◽  
Wide Range ◽  
Portable Apparatus ◽  
Non Destructive

Measuring residual stresses is still a dilemma in many engineering applications. It is even more crucial when the industrial requirements demand for a non-destructive technique in order to avoid compromising the structural integrity of the engineering components. Furthermore, estimating the mechanical properties of the materials, especially when the components are aged, is of importance. Instrumented indentation has gained much interest in recent years. There are many studies in the literature which are focused on measuring residual stresses or mechanical properties using instrumented indentation. Since in many cases there is no possibility of transferring large samples or those under service, for possible measurements, having a portable rig can be very useful. Furthermore, indentation procedure is a low-cost non-destructive method with high accuracy which is able to measure the plastic properties of material as well as its residual stresses on which the designing and construction of the portable apparatus were based. The instrumented indentation testing details were followed according to the ASTM E2546-15 standard practice. In this research, a wide range of simulations were performed on a group of aluminum alloys in order to estimate the equi-biaxial residual stresses by analyzing the indentation load–displacement curves which were obtained from the experimental outcomes. Then neural networks were employed to estimate the unknown parameters. The performance accuracy of the designed portable apparatus and the acceptable precision of the introduced method were then verified with experimental tests performed on Al 2024-T351.

Advanced Indentation Techniques: NDE for Flow Properties and Residual Stresses of Pipelines

2002 ◽  
Author(s):  
Yeol Choi ◽  
Dongil Son ◽  
Jae-Il Jang ◽  
Joon Park ◽  
Woo-Sik Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Potential Method ◽  
Indentation Load ◽  
Welding Residual Stress ◽  
Destructive Testing ◽  
Integrity Assessment ◽  
Indentation Technique

Structural integrity assessment is indispensable for preventing catastrophic failure of industrial structures/components/facilities that are faced with time-dependent and environmentally-accelerated degradation. This diagnosis of operating components should be done periodically for safe maintenance and economical repair. However, conventional standard methods for mechanical properties have the problems of bulky specimen, destructive and complex procedure of specimen sampling. So, an advanced indentation technique has been developed as a potential method for non-destructive testing of in-field structures. This technique measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation such as yield strength, tensile strength and work-hardening index. Also the advanced indentation technique can evaluate residual stresses based on the concept that indentation load-depth curves were shifted with the direction and the magnitude of residual stress applied to materials. In this study, we characterized the tensile properties and welding residual stress of various Industrial pipeline steels through the new techniques, and the results are introduced and discussed.

Measurement of Weld Mechanical Properties Using an Instrumented Indentation Technique

2017 ◽  
Vol 754 ◽  
pp. 383-386
Author(s):  
Kee Nam Song
Keyword(s):  
Mechanical Properties ◽  
Heat Affected Zone ◽  
Weld Zone ◽  
Base Material ◽  
Metal Structure ◽  
Instrumented Indentation ◽  
Welded Structures ◽  
Indentation Technique ◽  
Lower Confidence ◽  
Welded Structure

Different microstructures in the weld zone of a metal structure including a fusion zone and a heat affected zone, are formed as compared to the base material. Consequently, the mechanical properties in the weld zone are different from those in the base material to a certain degree owing to different microstructures and residual welding stresses. When a welded structure is loaded, the mechanical behavior of the welded structure might be different from the case of a structure with homogeneous mechanical properties. It is known that obtaining the mechanical properties in the weld is generally difficult owing to the narrow regions of the weld and interfaces. As an alternative way to obtain the weld mechanical properties, the weld mechanical properties of Alloy800HT, SUS316L, and Alloy617, were recently measured using an instrumented indentation technique, and the representative weld mechanical properties of these materials were estimated with a 95% lower confidence level for later structural analyses of the welded structures.

scholarly journals Development of a Structural Integrity Non-destructive Inspection System for Bridges Made of Weathering Steel

2019 ◽  
Vol 278 ◽  
pp. 03006
Author(s):  
Björn Torsten Salmen ◽  
Marina Knyazeva ◽  
Frank Walther
Keyword(s):  
Structural Steel ◽  
Crack Detection ◽  
Structural Integrity ◽  
Test Methods ◽  
Point Of View ◽  
Inspection System ◽  
Weathering Steel ◽  
Steel Bridge ◽  
Electro Magnetic ◽  
Non Destructive

Due to the increasing volume of traffic, bridges are exposed to higher loads as it was considered during the planning phase. Therefore, a regular inspection is necessary in order to detect cracks at very early stages. The use of weathering structural steel in bridges, as well as in composite bridge constructions is an alternative to conventional bridges, not only from an economic but also from an ecological point of view, since it is not necessary to apply a corrosion protection layer and renew it during the lifetime of the bridge. Unfortunately, conventional visual inspection or magnetic particle inspection on the weathering steel bridge are hindered by the protective patina and requires development of new test methods. Within the framework of this project, a combined crack detection technique using non-destructive inspection by means of Active Thermography and by Electro-Magnetic Acoustic Transducer (EMAT) were evaluated in laboratory environments and in real conditions on bridge structures made of weathering structural steel.

Structural Integrity Assessment of Notched Components

2011 ◽  
Author(s):  
Sergio Cicero ◽  
Virginia Madrazo ◽  
Isidro Carrascal ◽  
Miguel Laporta
Keyword(s):  
Structural Integrity ◽  
Notch Effect ◽  
Single Edge ◽  
Integrity Assessment ◽  
Failure Assessment ◽  
Notched Components ◽  
Notch Analysis

This paper analyzes the notch effect and presents a methodology, based on failure assessment diagrams and the notch analysis approaches based on the theory of critical distances, for the structural integrity assessment of notched components, which allows more accurate structural analyses to be made. The methodology is applied to a set of tests performed on PMMA single edge notched bending (senb) specimens, providing better results than those obtained when the analysis is performed considering that notches behave as cracks.

scholarly journals Effect of Weld Properties on the Crush Strength of the PWR Spacer Grid

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Kee-nam Song ◽  
Sang-hoon Lee
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Structural Component ◽  
Weld Zone ◽  
Base Material ◽  
Instrumented Indentation ◽  
Spacer Grid ◽  
Indentation Technique ◽  
Weld Properties ◽  
Crush Strength

Mechanical properties in a weld zone are different from those in the base material because of different microstructures. A spacer grid in PWR fuel is a structural component with an interconnected and welded array of slotted grid straps. Previous research on the strength analyses of the spacer grid was performed using base material properties owing to a lack of mechanical properties in the weld zone. In this study, based on the mechanical properties in the weld zone of the spacer grid recently obtained by an instrumented indentation technique, the strength analyses considering the mechanical properties in the weld zone were performed, and the analysis results were compared with the previous research.

On the Constraint-Based Failure Assessment of Surface Cracks in T-Plate Welded Joints

2003 ◽  
Author(s):  
X. Wang ◽  
R. Bell ◽  
S. B. Lambert
Keyword(s):  
Lower Bound ◽  
Welded Joints ◽  
Structural Integrity ◽  
Constraint Effect ◽  
Engineering Structures ◽  
Integrity Assessment ◽  
Failure Assessment ◽  
Recent Developments ◽  
Failure Predictions ◽  
Crack Tip Constraint

The loss of crack tip constraint leads to enhanced resistance to both cleavage and ductile tearing. However, conventional failure assessment schemes (CEGB-R6, BS-7910) use lower bound toughness obtained from highly constrained test specimens. Cracks in many real engineering structures are not highly constrained, which makes failure predictions using conventional failure assessment schemes based on lower bound fracture toughness values overly pessimistic. Excessive pessimism in the structural assessment can lead to unwarranted repair or decommissioning of structures, and thus cause unneeded cost and inconvenience. Recent developments on constraint-based fracture mechanics have enabled the practical assessment of defective components including the constraint effect. For example, the recent revision of R6 and the newly developed structural integrity assessment procedures for European industry (SINTAP) have suggested a framework for failure assessments including the constraint effect. In this paper, the constraint-based failure assessment of surface cracked T-plate welded joints under tension load is presented. Different issues including the constraint-based failure assessment diagrams, the treatment of combining primary and the secondary loads, and the calculation of stress intensity factors, limit loads and constraint parameters for surface cracked T-plate joints are discussed. It is demonstrated that when the lower constraint effect is properly accounted for, the maximum allowable tensile stress level increases substantially.

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