Detection and prediction of creep‐damage of copper using nonlinear acoustic techniques
05 Mar 2010-Vol. 1211, Iss: 1, pp 1410-1417
TL;DR: In this article, the authors used nonlinear acoustic techniques for the characterization of material damage gradient in 99.98% pure copper due to high temperature creep, and showed that the third harmonic was more sensitive to creep damage compared to second and static component nonlinearity.
Abstract: This paper describes the use of nonlinear acoustic techniques for the characterization of material damage gradient in 99.98% pure copper due to high temperature creep. Creep damage progression was monitored by conducting continuous and interrupted modes of creep tests. In case of continuous loading, nonlinear ultrasonic (NLU) measurements were conducted, after fracture at different locations along the gage length of the sample. For interrupted tests, the NLU measurements were conducted at different creep life fractions, through periodic interruption of creep test. The third harmonic was more sensitive to creep damage compared to second and static component nonlinearity. All samples show one peak in the nonlinear response at 25–45% of creep life. Finally, we presented the results of nonlinear response working at low power levels, since the interesting effect of accumulated dislocations. Using that effect we applied to creep damage detection. In this the NLU amplitude vs. input amplitude was observed to correlate well with the micro‐void concentrations caused by creep conditions.
Citations
More filters
TL;DR: In this article, the authors present a comprehensive review of the current state of knowledge of second harmonic generation (SHG) measurements, a subset of nonlinear ultrasonic non-destructive evaluation techniques.
Abstract: This paper presents a comprehensive review of the current state of knowledge of second harmonic generation (SHG) measurements, a subset of nonlinear ultrasonic nondestructive evaluation techniques. These SHG techniques exploit the material nonlinearity of metals in order to measure the acoustic nonlinearity parameter, $$\beta $$
. In these measurements, a second harmonic wave is generated from a propagating monochromatic elastic wave, due to the anharmonicity of the crystal lattice, as well as the presence of microstructural features such as dislocations and precipitates. This article provides a summary of models that relate the different microstructural contributions to $$\beta $$
, and provides details of the different SHG measurement and analysis techniques available, focusing on longitudinal and Rayleigh wave methods. The main focus of this paper is a critical review of the literature that utilizes these SHG methods for the nondestructive evaluation of plasticity, fatigue, thermal aging, creep, and radiation damage in metals.
271 citations
Cites background from "Detection and prediction of creep‐d..."
...[152] reported measurements of the static component and second...
[...]
Abstract: Wood and composites cantilever beam structure has gained attention among researchers in the current years due to its universal structural applications, such as bridges, aeroplane wings, buildings, and transmission towers. However, when the structure is exposed to a constant loading for a very long time, it induces a structural collapse due to creep deformation. Therefore, it is essential to understand and identify the initial creep that can lead to structural collapse. In this study, wood and composite materials exhibit the same structural material morphology which performs as anisotropic material as it majorly contributes to failure. In this study, a state-of-the-art review of creep analysis and engineering design is carried out, with particular emphasis on the creep methodology of a cantilever beam. The existing theories and creep design approaches are grouped into two analysis methods, namely experimental and numerical approaches. To be more specific, the experimental works involved two main methods, namely load-based (conventional) and temperature-based (accelerated) techniques. Selected creep test on cantilever beam structure and coupon scale of wood and composite were highlighted and proposed as the building blocks for a prospective structural creep methodology. These aids build confidence in the underlying methods while guiding future work and areas, especially for long-term service of full-scale structure. At the end, the challenges of creep behaviour description accuracy and improvement on the strength criteria in engineering design were presented.
100 citations
TL;DR: In this article, the hybridization of conceptual design methods is presented in the development of multi-operations creep flexural test rig, and the integration of theory of inventive problem solving (TRIZ), Morphological chart, and Analytic Network Process (ANP) method to ensure the quality function is fulfilled with the essential requirements.
Abstract: The hybridisation of conceptual design methods is presented in the development of multi-operations creep flexural test rig. The paper explains the integration of theory of inventive problem solving (TRIZ), Morphological chart, and Analytic Network Process (ANP) method to ensure the quality function is fulfilled with the essential requirements. The objective of this project is to produce and choose the best design concept for the product development depending on the product design specifications (PDS). In the early stage of product development, the TRIZ contradiction principles and 40 TRIZ inventive solutions were applied as the guidance tools. To refine the specification of the product design, the principle solution parameters were detailed systematically with the aid of morphological chart. In this article, four innovative conceptual designs of the multi-operations creep flexural test rig were produced and the selection process was conducted using ANP method to perform the multi-criteria decision making process in selecting the best concept design.
42 citations
25 Jun 2019
TL;DR: In this paper, the authors provide an overview of the creep theory and the existing creep testing methodology for the full-scale crossarm of transmission line (TL) towers and present a new test rig has to be developed to cater the testing operation using the uniaxial tension creep test.
Abstract: Most of transmission line (TL) towers are designed and fabricated in the form of lattice using galvanized steel. The crossarm of the TL is made of Neobalanocarpus or Chengal wood. Recently, it has been reported by an electrical corporation situated in Malaysia that mechanical performance of the wooden crossarm declined below their service life of 40 years due to the extreme tropical weather in Malaysia. At present, composite crossarm made of glass fibre reinforced polymer composite were introduced as substitute in the 132 kV TL tower. However, the research findings lack of information on creep life estimation for the full-scale crossarm. Hence, a new test rig has to be developed to cater the testing operation using the uniaxial tension creep test. The primary objective of this review is to provide an overview of the creep theory and the existing creep testing methodology.
26 citations
Cites background from "Detection and prediction of creep‐d..."
...A shift parameter (at) is defined to address the creep behaviour at a referred temperature [33, 49, 54]....
[...]
...This would also mean that the material would not have distinct stages, which would make the breaking point of a material less predictable [19, 49]....
[...]
TL;DR: In this article, a locally made creep testing machine was used to measure the deformation of aluminum alloy at high temperature and applied at a different stress level and temperature, the data are plotted in a simple manner, but analysis easily shows the effect of increased stress due the reduction in specimen cross-section as strain increases.
Abstract: Mechanical systems and components like steam generators or boilers, nuclear reactors, turbine rotors are operated at very high temperature under significant stress. For this reason, the components and structures need to be designed so that excessive creep distortion must not occur within the expected operating life of the system. Creep is defined as a time-dependent deformation that happens when metals are subjected to constant load at high temperature over a period of time. Knowledge of the creep behavior of metals is therefore important and for this reason Creep testing machines are predominantly used to measure how a given material will perform under constant load, at elevated temperature. This paper aims to study creep properties of various materials being used in high temperature applications through locally made creep testing machine. The basic design of a creep testing machine is the support structure, the loading device, the fixture device (grips and pull rods), and the furnace. The specimen being tested is held in place by the grips and a furnace surrounds the test section and maintains a constant temperature. Maximum applied load on the specimen can be 15 kg and tests could be carried out at maximum temperature of 500°C. Creep curves of strain versus time of aluminum alloy were plotted at a different stress level and temperature. The data are plotted in a simple manner, but analysis easily shows the effect of increased stress due the reduction in specimen cross-section as strain increases. The creep testing machine developed in this work has proven to be satisfactory, cost effective and good alternative to imported creep testing machine.
1 citations
Cites background from "Detection and prediction of creep‐d..."
...This is important to note because going straight to the tertiary state causes the material to break faster from its form [6]....
[...]
...This is a disadvantage to scientists and engineers when trying to determine the level of creep the object can handle [6]....
[...]
References
More filters
Book•
31 Mar 1994
TL;DR: In this article, the authors present a model for creep crack initiation and growth at high temperatures. But they do not consider the effects of high temperature on the growth of the crack.
Abstract: Introduction. Processes of deformation and fracture at high temperatures. Stress analysis of uncracked bodies. Stress analysis of cracked bodies. Models for creep crack initiation and growth. Creep-fatigue crack growth. Experimental determinations of high temperature crack growth. Practical applications. Index.
360 citations