scholarly journals Design Optimization of HANARO Irradiation Capsule for Long-Term Irradiation Testing

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Kee Nam Choo ◽  
Man Soon Cho ◽  
Seong Woo Yang ◽  
Byung Hyuk Jun ◽  
Myong Seop Kim
Keyword(s):  
Neutron Fluence ◽  
Fatigue Property ◽  
Inert Gas ◽  
Fatigue Properties ◽  
Optimized Design ◽  
Eb Welding ◽  
Nuclear Systems ◽  
Pile Testing ◽  
Applied Stresses

As HANARO has been recently required to support new R&D relevant to future nuclear systems requiring much higher neutron fluence, two types of bottom rod tip of the capsule were preliminarily prepared. The first one is a conventional design made of STS304 and welded using a tungsten inert gas (TIG) welding method. The other is a new design made of STS316L and welded using electron beam (EB) welding to strengthen the fatigue property of the rod tip. During the out-pile testing, they failed after 40 and 203 days, respectively. The fracture surfaces were examined using microscopes and the maximal applied stresses were estimated. The combination of these stresses was proved to be sufficient to cause a fatigue failure of the rod tip of the capsule. Based on the failure analysis, an optimized design of the rod tip of the capsule was made for long-term irradiation testing. It was designed to improve the welding and fatigue properties, to decrease the applied stress on the rod tip, and to fundamentally eliminate the effect of residual stress due to welding. The newly designed capsule was safely out-pile-tested up to 450 days and will be utilized for HANARO irradiation testing.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

scholarly journals A Comprehensive Evaluation of Rejuvenator on Mechanical Properties, Durability, and Dynamic Characteristics of Artificially Aged Asphalt Mixture

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1554 ◽  
Author(s):  
Pan Pan ◽  
Yi Kuang ◽  
Xiaodi Hu ◽  
Xiao Zhang
Keyword(s):  
Mechanical Properties ◽  
Dynamic Characteristics ◽  
Comprehensive Evaluation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Physical Property ◽  
Fatigue Property ◽  
Physical Test ◽  
Aged Asphalt

In this study, the aged asphalt binder and mixture were laboratory prepared through short-term ageing testing and long-term ageing testing. Firstly, the effect of rejuvenator on physical properties of aged asphalt binders was investigated. In addition, a series of laboratory tests were performed to evaluate the influence of ageing and rejuvenator content on the mechanical properties, durability and dynamic characteristics of asphalt mixtures. Physical test results of asphalt binder testified that rejuvenator used can efficiently recover the aged asphalt binder. However, the effect of ageing and rejuvenator content exhibits different trends depending on the physical property tests conducted. Moreover, artificially aged asphalt mixture with rejuvenator has better ability to resist moisture damage and ravelling. In addition, the ITSR value is more suitable to evaluate the moisture susceptibility for asphalt recycling. Although rejuvenator improves the thermal cracking resistance and fatigue property of aged asphalt mixture, rejuvenated mixture shows greater modulus and inferior ability to resist reflective cracking than the unaged mixture. Moreover, rejuvenated mixture shows less dependence on frequency at high temperature regions and stronger dependence at low temperature regions compared to unaged and long-term aged mixtures.

Thermal Fatigue Characteristics of Heat-Resisting Stainless Steel for Automotive Exhaust

2007 ◽  
Vol 539-543 ◽  
pp. 4944-4949 ◽  
Author(s):  
Tae Kwon Ha ◽  
Hwan Jin Sung
Keyword(s):  
Thermal Fatigue ◽  
Stainless Steels ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Automotive Exhaust ◽  
Load Relaxation ◽  
Temperature Ranges ◽  
Fatigue Characteristics ◽  
Efficiency And Reliability

Thermal fatigue is a complex phenomenon encountered in materials exposed to cyclically varying temperatures in the presence or absence of external load. Continually increasing working temperature and growing need for greater efficiency and reliability of automotive exhaust require immediate investigation into the thermal fatigue properties especially of high temperature stainless steels. In this study, thermal fatigue properties of 304 and 429EM stainless steels have been evaluated in the temperature ranges of 200-800oC and 200-900oC. Systematic methods for control of temperatures within the predetermined range and measurement of load applied to specimens as a function of temperature during thermal cycles have been established. Thermal fatigue tests were conducted under fully constrained condition, where both ends of specimens were completely fixed. Thermal fatigue property of STS 304 was superior to that of STS 429EM. Load relaxation behavior at the temperatures of thermal cycle was closely related with the thermal fatigue property.

scholarly journals Optimized Design of Modular Multilevel DC De-Icer for High Voltage Transmission Lines

Electronics ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 204 ◽  
Author(s):  
Jiazheng Lu ◽  
Qingjun Huang ◽  
Xinguo Mao ◽  
Yanjun Tan ◽  
Siguo Zhu ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Engineering Application ◽  
Optimized Design ◽  
Multilevel Converter ◽  
Power Outage ◽  
Total Cost ◽  
Technical Performance ◽  
Promising Solution

Ice covering on overhead transmission lines would cause damage to transmission system and long-term power outage. Among various de-icing devices, a modular multilevel converter based direct-current (DC)de-icer (MMC-DDI) is recognized as a promising solution due to its excellent technical performance. Its principle feasibility has been well studied, but only a small amount of literature discusses its economy or hardware optimization. To fill this gap, this paper presents a quantitative analysis and calculation on the converter characteristics of MMC-DDI. It reveals that, for a given DC de-icing requirement, the converter rating varies greatly with its alternating-current (AC) -side voltage, and it sometimes far exceeds the melting power. To reduce converter rating and improve its economy, an optimized configuration is proposed in which a proper transformer should be configured on the input AC-side of converter under certain conditions. This configuration is verified in an MMC-DDI for a 500 kV transmission line as a case study. The result shows, in the case of outputting the same de-icing characteristics, the optimized converter is reduced from 151 MVA to 68 MVA, and the total cost of the MMC-DDI system is reduced by 48%. This conclusion is conducive to the design optimization of multilevel DC de-icer and then to its engineering application.

The Fatigue Property Research of Steel Q345 Butt Welded Joint

2014 ◽  
Vol 692 ◽  
pp. 424-427
Author(s):  
Wei Ping Ouyang ◽  
Liang Sheng Chen ◽  
Xiu Dong Xu
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Modeling ◽  
Significant Influence ◽  
Welded Joints ◽  
Welded Joint ◽  
Fatigue Property ◽  
Fracture Analysis ◽  
Fatigue Tests ◽  
Fatigue Properties

The fatigue property of the butt welded joint has significant influence to hoisting equipment’s design, manufacture and using safety for its extensive application. This paper conducted a study on the fatigue properties of a series of the most commonly used thickness steel Q345 butt welded joints. Through fatigue tests and fracture analysis, the fatigue pattern and fracture law of the joints were revealed. Combining with the finite element modeling, the all field stress distribution situation was obtained. This has profound reference significance to hoisting machinery research.

scholarly journals Using ‘subcement’ to simulate the long-term fatigue response of cemented femoral stems in a cadaver model: Could a novel preclinical screening test have caught the Exeter matt problem?

2009 ◽  
Vol 224 (4) ◽  
pp. 585-597 ◽  
Author(s):  
A Race ◽  
M A Miller ◽  
K A Mann
Keyword(s):  
Substantial Effect ◽  
Stair Climbing ◽  
Fatigue Properties ◽  
Short Term ◽  
Femoral Stems ◽  
Post Test ◽  
Implant Size ◽  
Clinical Consequences ◽  
Combining Information

Previously, cement was formulated with degraded fatigue properties (subcement) to simulate long-term fatigue in short-term cadaver tests. The present study determined the efficacy of subcement in a ‘preclinical’ test of a design change with known clinical consequences: the ‘polished’-to-‘matt’ transition of the Exeter stem (revision rates for polished stems were twice those for matt stems). Contemporary stems were bead blasted to give Ra = 1 μm (matt finish). Matt and polished stems were compared in cadaver pairs under stair-climbing loads (three pairs of size 1; three pairs of size 3). Stem micromotion was monitored during loading. Post-test transverse sections were examined for cement damage. Cyclic retroversion decreased for polished stems but increased for matt stems ( p<0.0001). The implant size had a substantial effect; retroversion of (larger) size-3 stems was half that of size-1 stems, and polished size-3 stems subsided 2.5 times more than the others. Cement damage measures were similar and open through-cracks occurred around both stems of two pairs. Stem retroversion within the mantle resulted in stem—cement gaps of 50—150 μm. Combining information on cyclic motion, cracks, and gaps, it was concluded that this test ‘predicted’ higher revision rates for matt stems (it also implied that polished size-3 stems might be superior to size-1 stems).

Study on the Fatigue Property for Aged Asphalt Mixtures by Using Four Point Bending Tests

2009 ◽  
Vol 614 ◽  
pp. 289-294 ◽  
Author(s):  
Guo Jun Zhu ◽  
Shao Peng Wu ◽  
Ran Liu ◽  
Lei Zhou
Keyword(s):  
Natural Aging ◽  
Fatigue Property ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Fatigue Properties ◽  
Modified Asphalt ◽  
Four Point Bending ◽  
Aged Asphalt ◽  
Polymer Modified Asphalt ◽  
Effects Of Aging

The effects of aging on the fatigue property of polymer modified asphalt mixtures are investigated in this paper. Two kinds of aging procedures are adopted for the aging of specimens prepared with polymer modified asphalt mixtures. One is the short-time aging which means that the hot asphalt mixtures was heated in the oven for 4 hours at 135°C before compacted; The other called natural aging, with the original specimen exposed in the sunlight and subjected to the rain and temperature change for 3, 6 and 9 months. Four-Point Bending Test was conducted to evaluate fatigue properties of aged asphalt mixtures at 15°C compared with the original specimens. Test results indicate that the fatigue line of aged specimens have the same tendency as the original asphalt mixtures. However, the life of aged specimen is decreased significantly when compared with the original ones, especially of the natural aged specimens.

Serviceability Characterization of Composite Storage Tanks

2007 ◽  
Author(s):  
Vladimir M. Shkolnikov
Keyword(s):  
Structural Design ◽  
Design Procedure ◽  
Fatigue Properties ◽  
Storage Tanks ◽  
Safety Factors ◽  
Analytical Technique ◽  
Term Operation ◽  
Temperature Exposure

This paper outlines an analytical technique enabling serviceability characterization of a storage tank made of a Polymer Matrix Composite (PMC) with regards to a specified profile of long-term operation of the tank. The technique combines force-temperature exposure (conceivably changing over a tank’s service life) and fatigue properties of a composite utilized within the tank structure. Along with a serviceability assessment, the technique is capable of providing a well-grounded specification of design knock-downs and safety factors relevant to the conventional structural design procedure.

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