Residual service life of erbium-modified AM50 magnesium alloy under corrosion and stress environment

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 797-807
Author(s):  
Miao Yang ◽  
Liyun Xing ◽  
Xiaobo Liu ◽  
Yuqi Dong ◽  
Zhaoyu Chen ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Structural Material ◽  
Service Life ◽  
Residual Service Life ◽  
Distilled Water ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
Stress Environment ◽  
Surface Morphologies ◽  
Residual Service

Abstract Magnesium alloy will decrease strength with corrosion in use, thus affecting their service life. Service life as a structural material under stress and corrosion is one focus of the magnesium alloy used as structural material, and how to improve the residual service life of magnesium alloy is an important scientific issue. The X-ray diffraction, scanning electron microscopy, and slow strain rate tensile (SSRT) tests are used to study the residual service life of erbium (Er) effect in the AM50 magnesium alloy in air, distilled water, and NaCl solution. The results show that after rare earth Er addition to the AM50, the white granular Al3Er intermetallic compound was formed. With Er content increasing, the quantity of Al3Er phase was increased and the volume of β-Mg17Al12 phase was decreased. The SSRT results show that residual service life ratio increased with the Er addition compare with no Er alloy in distilled water. However, in 3.5% NaCl solution, 0.5% Er alloy shows the best service life. Moreover, Er addition does not change the alloy fracture mode, which remains quasi-cleavage. The main cause of the decline in service life in magnesium alloys is the change in surface morphology owing to the pitting corrosion nucleation and growth, which affects the stress distribution of the sample. The mechanism of film cracking plays a major role in the fracture process with the Er increased to change the surface morphologies.

Functional and operational risk as a criterion for assessing the durability of an autonomous energy system

2019 ◽  
Vol 12 (1) ◽  
pp. 56-62 ◽  
Author(s):  
A. O. Nedosekin ◽  
A. V. Smirnov ◽  
D. P. Makarenko ◽  
Z. I. Abdoulaeva
Keyword(s):  
Service Life ◽  
Structural Reliability ◽  
Residual Life ◽  
Fuzzy Random Variable ◽  
Operational Risk ◽  
Energy System ◽  
Technical System ◽  
Residual Service Life ◽  
Technological Parameters ◽  
Residual Service

The article presents new models and methods for estimating the residual service life of an autonomous energy system, using the functional operational risk criterion (FOR). The purpose of the article is to demonstrate a new method of durability evaluation using the fuzzy logic and soft computing framework. Durability in the article is understood as a complex property directly adjacent to the complex property of system resilience, as understood in the Western practice of assessing and ensuring the reliability of technical systems. Due to the lack of reliable homogeneous statistics on system equipment failures and recoveries, triangular fuzzy estimates of failure and recovery intensities are used as fuzzy functions of time based on incomplete data and expert estimates. The FOR in the model is the possibility for the system availability ratio to be below the standard level. An example of the evaluation of the FOR and the residual service life of a redundant cold supply system of a special facility is considered. The transition from the paradigm of structural reliability to the paradigm of functional reliability based on the continuous degradation of the technological parameters of an autonomous energy system is considered. In this case, the FOR can no longer be evaluated by the criterion of a sudden failure, nor is it possible to build a Markov’s chain on discrete states of the technical system. Assuming this, it is appropriate to predict the defi ning functional parameters of a technical system as fuzzy functions of a general form and to estimate the residual service life of the technical system as a fuzzy random variable. Then the FOR is estimated as the possibility for the residual life of the technical system to be below its warranty period, as determined by the supplier of the equipment.

Expected residual service life of reinforced concrete structures from current strength considerations

2019 ◽  
Vol 22 (7) ◽  
pp. 1631-1643
Author(s):  
Sushil Kumar Dhawan ◽  
Abhinav Bindal ◽  
Suresh Bhalla ◽  
Bishwajit Bhattacharjee
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Residual Life ◽  
Concrete Structures ◽  
Present Condition ◽  
Material Strength ◽  
Reinforced Concrete Structures ◽  
Residual Service Life ◽  
Remaining Service Life ◽  
Residual Service

Concrete is primarily used in the form of reinforced concrete for construction of buildings, bridges and other important structures. Due to normal usage and environmental effects, the structure would gradually deteriorate. The actual residual life needs to be worked at a given time vis-à-vis the design life of the structure, commensurate with the fulfilment of essential requirements of structural integrity and safety and from strength as well as serviceability considerations. Requirements for residual life assessment would depend upon the current parameters, such as the residual cross-sectional area of concrete as well as steel, Young’s modulus of elasticity and the in situ material strength of the constituent materials, namely, concrete and steel. This article aims to develop a rigorous methodology for expected remaining service life of a reinforced concrete structure from wind/seismic considerations, based on the present condition of the structure encompassing the residual material strength and the residual reinforcement/sectional areas. The methodology development section is followed by an illustrative example and a parametric study involving a 10-storeyed reinforced concrete building frame under wind and earthquake loads. Influences of various parameters such as concrete strength and residual rebar area on the expected remaining service life are studied in detail. The proposed methodology provides a simple but rational estimation of the residual service life for reinforced concrete structures.

Reliability and residual service life of the steampipe welded joints at the temperature of 540°C

1993 ◽  
Vol 12 (2) ◽  
pp. 99-104
Author(s):  
V. Pilous ◽  
K. Stránský ◽  
P. Drybčák ◽  
P. Šlechta
Keyword(s):  
Service Life ◽  
Welded Joints ◽  
Residual Service Life ◽  
Residual Service
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