Development of a Novel Test Procedure to Investigate the Impact of Strain Gradients on the Fatigue Endurance of Stainless Steel

2017 ◽  
Author(s):  
Mohammed-Rafi Riley ◽  
Catrin M. Davies ◽  
Stephen Garwood
Keyword(s):  
Stainless Steel ◽  
Stress Field ◽  
Low Cycle Fatigue ◽  
Test Procedure ◽  
Stress Gradient ◽  
Small Scale ◽  
Design Criteria ◽  
Thermal Transients ◽  
The Impact ◽  
Fatigue Endurance

In recent years, there has been an increasing need for component specific testing in nuclear power plant (NPP) materials. This has arisen from changes in fatigue design criteria outlined within the ASME Boiler Pressure and Vessel and Pipe Code (BPVC). These are primarily derived from low-cycle fatigue (LCF) testing on idealized small-scale specimens. For the case of stainless steel (SS), testing is performed under membrane loading on traditional uniaxial round-bar specimens according to standards such as ASTM E606. Here, failure is defined as a 25% drop in load, that typically corresponds to a 3 mm deep crack. Real NPP components however, rarely experience such membrane loading due to their complex geometry and in-service loading (combined primary and secondary stresses). For the case of an internally-pressurized pipe subjected to thermal transients, due to temperature fluctuations in the coolant, an additional through-wall stress field gradient is present. This results in fatigue crack initiation and propagation occurring into a decreasing stress field, which may be expected to result in longer fatigue lives than within small specimen testing and, hence, a large degree of inherent over-conservatism may exist in the ASME design data. This paper describes the development of a novel test procedure able to incorporate the effect of a stress gradient within fatigue endurance testing. A bespoke eight-point bend (8PB) setup has been developed that is capable of performing load-, displacement- and strain-controlled LCF tests. A series of trials have been conducted in all three control modes with the material response validated against finite element analysis (FEA). It is anticipated that this testing procedure can provide a better representation of NPP components under fatigue loading conditions, providing results that would be used to remove over-conservatism within the current design criteria.

scholarly journals Stability design criteria for closely spaced built-up stainless steel columns

2021 ◽  
Vol 64 (4) ◽  
pp. 235-250
Author(s):  
Jelena Dobrić ◽  
Nina Gluhović ◽  
Zlatko Marković ◽  
Dragan Buđevac
Keyword(s):  
Stainless Steel ◽  
Shear Stiffness ◽  
Minor Axis ◽  
Structural Performance ◽  
Design Criteria ◽  
Geometric Imperfections ◽  
Steel Columns ◽  
Flexural Buckling ◽  
The University ◽  
The Impact

This paper aims to develop design recommendations for closely spaced built-up stainless steel columns, based on findings gained in performed research at the University of Belgrade. The research focuses on pin-ended built-up columns formed from two press-braked channel chords oriented back-to-back and addresses their flexural buckling capacity about the minor axis. The impact of overall and local chord slenderness, interconnection stiffness, geometric imperfections and material nonlinearity is evaluated. In order to fully exploit their structural performance, two separate approaches for the design of built-up columns with welded or bolted interconnections are defined that include different formulas for shear stiffness.

Comparison of Component Fatigue Test Data With Proposed EAF Methodologies for Austenitic Stainless Steel

2009 ◽  
Author(s):  
Rim Nayal ◽  
Hasan Charkas
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Low Cycle Fatigue ◽  
Nuclear Regulatory Commission ◽  
Fatigue Curve ◽  
Asme Code ◽  
Regulatory Commission ◽  
License Renewal ◽  
The Impact

The U.S. Nuclear Regulatory Commission (NRC) currently requires evaluation of the effect of environmental fatigue for both license renewal and new plants. NRC required the use of methodology in EPRI MRP-47, Rev. 1 addressing NUREG/CR-5704, be used for license renewal of stainless steel (SS) components, and NUREG/CR-6909 for use in new plants. These two methodologies are based on applying an environmental correction factor (Fen) on the number of in-air design cycles. These factors are applied to the fatigue usage from each individual range of stress (or range of strain). The focus of this paper is to compare the two aforementioned methodologies; this includes comparison of the fatigue curve as well as the comparison of the environmental correction factors (Fen). Fatigue test results data reported by others are also compared with these two methodologies. It is important to evaluate the impact of using any of those methodologies on the design fatigue life of the components. It is concluded that NUREG/CR-5704 is more severe than NUREG/CR-6909 in the LCF (low-cycle fatigue) regime, while NUREG/CR-6909 is more severe elsewhere, and both NUREG’s extremely underestimate fatigue life in PWR environment. It is also concluded that the current ASME-code fatigue curve for stainless steel reasonably estimates fatigue life in an LWR environment with reasonable margins.

A Study of the Low Cycle Fatigue Characteristics of Annealed AISI 347 Stainless Steel And Overaged 6951-T6 Aluminum Push-Pull Specimens

1977 ◽  
Vol 99 (3) ◽  
pp. 391-398
Author(s):  
J. A. Friedericy ◽  
R. F. Graves
Keyword(s):  
Stainless Steel ◽  
Stress Field ◽  
Room Temperature ◽  
Elastic Limit ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Test Machine ◽  
Cycle Fatigue ◽  
Temperature Levels

In a cyclic application the Neuber theory becomes the Wetzel-Morrow approach. The Neuber theory for stresses and strains in a notch is extended to apply to specimens for which the nominal stresses and strains in the material in the field adjacent to the notch may exceed the elastic limit. Also, when the cyclic nominal stresses and strains exceed the elastic or proportional limit of the materials, this extension can be applied if a mechanism external to the nominal stress field is applied to cause the stress field to change in a predetermined manner for each successive cycle. In the case of a notched push-pull specimen, the external mechanism would be a tensile test machine and the field adjacent to the notch would be that of the nominally induced stresses and strains by means of the machine. The state of stress and strain in the notch is the result of the shape and size of the notch as well as the nominal stresses and strains adjacent to the notch. A supporting test program is discussed which dealt with the low cycle fatigue testing of two metals, AISI 347 stainless steel and 6951-T6 aluminum. A push-pull specimen was used which was designed to handle fully reversed cyclic loads from 100 cycles on up. Both fatigue and cyclic stress-strain tests were performed. The strain ranges predicted by the extended theory were inserted in the Universal Slopes equation and the cyclic lives of the specimens at various applied stress levels were determined, including those exceeding the elastic limit of the material. Good correlation was obtained between theory and experiment at the temperature levels tested. The steel specimens were tested at room temperature and 1000°F (537°C) and the aluminum specimens at room temperature and 300°F (149°C).

scholarly journals Techno-Economic Assessment in a Fluidized Bed Membrane Reactor for Small-Scale H2 Production: Effect of Membrane Support Thickness

Membranes ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 116 ◽  
Author(s):  
Di Marcoberardino ◽  
Knijff ◽  
Binotti ◽  
Gallucci ◽  
Manzolini
Keyword(s):  
Stainless Steel ◽  
Fluidized Bed ◽  
Membrane Reactor ◽  
Hydrogen Permeation ◽  
Membrane Surface ◽  
Small Scale ◽  
Relevant Parameter ◽  
Economic Point ◽  
Ceramic Support ◽  
The Impact

This paper investigates the influence of the support material and its thickness on the hydrogen flux in Palladium membranes in the presence of sweep gas in fluidized bed membrane reactors. The analysis is performed considering both ceramic and metallic supports with different properties. In general, ceramic supports are cheaper but suffer sealing problems, while metallic ones are more expensive but with much less sealing problems. Firstly, a preliminary analysis is performed to assess the impact of the support in the permeation flux, which shows that the membrane permeance can be halved when the H2 diffusion through the support is considered. The most relevant parameter which affects the permeation is the porosity over tortuosity ratio of the porous support. Afterward, the different supports are compared from an economic point of view when applied to a membrane reactor designed for 100 kg/day of hydrogen, using biogas as feedstock. The stainless steel supports have lower impact on the hydrogen permeation so the required membrane surface area is 2.6 m2 compared to 3.6 m2 of the best ceramic support. This ends up as 5.6 €/kg H2@20bar and 6.6 €/kg H2@700bar for the best stainless steel support, which is 3% lower than the price calculated for the best ceramic support.

Investigation on Compressive Strength after Impact Damage of Carbon/Epoxy Laminate

2014 ◽  
Vol 627 ◽  
pp. 397-400
Author(s):  
Hyun Bum Park
Keyword(s):  
Compressive Strength ◽  
Composite Structure ◽  
Impact Damage ◽  
Damage Zone ◽  
Test Procedure ◽  
Standard Test ◽  
Small Scale ◽  
Foreign Object Damage ◽  
Residual Compressive Strength ◽  
The Impact

Development of the Korean small scale aircraft (KC-100) has been carried out by KAI (Korea Aerospace Industry Ltd.) for the BASA(Bilateral Aviation Safety Agreement) program with FAA. The KC-100 aircraft adopted the environmental friendly whole composite structure concept due to low fuel consumption owing to its light weight. However the composite structure has a disadvantage. They are very weak against impact damage due to FOD (Foreign Object Damage). This study is to investigate the residual compressive strength of the carbon/epoxy fabric and UD (Unidirectional prepreg tape) laminate due to impact damages. This residual compressive strength test follows fully the ASTM standard test procedure. Experimental investigation results reveal the residual strengths and the damage mode and size of impact damage specimens. Through these tests, it is found that the residual strength of the impact damage specimens is greatly reduced in comparison to the undamaged specimens depending on increase of both the indentation depth and the impact energy. The size and shape of damage zone greatly affects the reduction of the compressive strength.

Can Values of Honesty, Hard Work, Loyalty and Discipline Predict Entrepreneurial Orientation of Muslim Owner Managers?

2015 ◽  
Vol 3 (1) ◽  
pp. 31 ◽  
Author(s):  
Rohani Mohd ◽  
Badrul Hisham Kamaruddin ◽  
Khulida Kirana Yahya ◽  
Elias Sanidas
Keyword(s):  
Entrepreneurial Orientation ◽  
Two Dimensions ◽  
Hard Work ◽  
Small Scale ◽  
Sampling Frame ◽  
Policy Makers ◽  
Learning Institutions ◽  
Innovative Orientation ◽  
The Impact ◽  
True Values

The purpose of the present study is twofold: first, to investigate the true values of Muslim owner managers; second, to examine the impact of these values on entrepreneurial orientations of Muslim small-scale entrepreneurs. 850 Muslim owner managers were selected randomly using the sampling frame provided by MajlisAmanah Rakyat Malaysia (MARA). 162 completed questionnaires were collected and analyzed. For this paper only two dimensions of entrepreneurial orientations were analyzed: proactive orientation and innovative orientation. Interestingly, the findings revealed that Muslim businessmen/women are honest, loyal, disciplined and hard working. Loyalty and honesty are positively related to proactive orientation, while discipline and hard-work are positively related to innovative orientation. The findings provide implications for existing relevant theories, policy makers, practitioners and learning institutions. 

Comparative analytical study of Ashuddha Karaveera and Shuddha Karaveera

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Apeksha D. Patil ◽  
Dhiraj B. Patil
Keyword(s):  
Stainless Steel ◽  
Analytical Study ◽  
Warm Water ◽  
Foreign Matter ◽  
Steel Vessel ◽  
Mild Heat ◽  
Stainless Steel Vessel ◽  
The Impact

Karaveera (Cerebra thevetia Linn.) is reported under Upavisha Dravya in classical ayurvedic pharmacopeias. It is observed that Shodhana (purification procedures) of the mool should be carried out before its internal administration. There are different Shodhana methods mentioned in Ayurveda. In this study Godugdha was used as media. The impact of Shodhana was evaluated by physico analytical study. It clearly proves physico analytical changes during Shodhana. Ashuddha Karaveera was taken on white clean cloth and they dumped in Pottali with Godugdha. Pottali was tied to middle of wooden rod dipped in Godugdha in stainless steel vessel and mild heat given to pottali in Dolayantra. Shuddha Karaveera was obtained and then washed with leuk warm water and dried. Ashuddha Karaveera contains toxin in it which was removed after Shodhana process. So that foreign matter, loss on drying was less in Shuddha Karaveera and due to Shodhan process with Godugdha total ash, acid insoluble ash was more than that of Ashuddha Karaveera.

scholarly journals Land Subsidence Estimation for Aquifer Drainage Induced by Underground Mining

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4658
Author(s):  
Artur Guzy ◽  
Wojciech T. Witkowski
Keyword(s):  
Environmental Impact ◽  
Land Subsidence ◽  
Field Data ◽  
Underground Mining ◽  
Small Scale ◽  
Aquifer System ◽  
Maximum Value ◽  
The Impact ◽  
Method Model ◽  
Impact Of Mining

Land subsidence caused by groundwater withdrawal induced by mining is a relatively unknown phenomenon. This is primarily due to the small scale of such movements compared to the land subsidence caused by deposit extraction. Nonetheless, the environmental impact of drainage-related land subsidence remains underestimated. The research was carried out in the “Bogdanka” coal mine in Poland. First, the historical impact of mining on land subsidence and groundwater head changes was investigated. The outcomes of these studies were used to construct the influence method model. With field data, our model was successfully calibrated and validated. Finally, it was used for land subsidence estimation for 2030. As per the findings, the field of mining exploitation has the greatest land subsidence. In 2014, the maximum value of the phenomenon was 0.313 cm. However, this value will reach 0.364 m by 2030. The spatial extent of land subsidence caused by mining-induced drainage extends up to 20 km beyond the mining area’s boundaries. The presented model provided land subsidence patterns without the need for a complex numerical subsidence model. As a result, the method presented can be effectively used for land subsidence regulation plans considering the impact of mining on the aquifer system.

scholarly journals Foreign investment in emerging legal medicinal cannabis markets: the Jamaica case study

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Marta Rychert ◽  
Machel Anthony Emanuel ◽  
Chris Wilkins
Keyword(s):  
Civil Society ◽  
Foreign Investment ◽  
Production Efficiency ◽  
Production Quality ◽  
Small Scale ◽  
Organic Cultivation ◽  
Enhanced Production ◽  
Political Interference ◽  
Medicinal Cannabis ◽  
The Impact

Abstract Introduction The establishment of a legal market for medicinal cannabis under the Dangerous Drugs Amendment Act 2015 has positioned Jamaica at the forefront of cannabis law reform in the developing world. Many local cannabis businesses have attracted investment from overseas, including from Canada, US and Europe. Aim To explore the opportunities and risks of foreign investment in an emerging domestic legal cannabis market in a developing country. Methods Thematic analysis of semi-structured face-to-face interviews with 22 key informants (KIs) from the Jamaican government, local cannabis industry, academia and civil society, and field observations of legal and illegal cannabis cultivators. Results KIs from the Jamaican public agencies and domestic cannabis entrepreneurs saw foreign investment as an essential source of capital to finance the start-up costs of legal cannabis businesses. Local cannabis entrepreneurs prioritised investors with the greatest financial resources, brand reputation and export networks. They also considered how allied an investor was with their business vision (e.g., organic cultivation, medical vs. recreational). The key benefits of partnering with a foreign investor included transfer of technical knowledge and financial capital, which enhanced production, quality assurance and seed-to-sale tracking. Some KIs expressed concern over investors’ focus on increasing production efficiency and scale at the expense of funding research and development (R&D) and clinical trials. KIs from the local industry, government agencies and civil society highlighted the risks of ‘predatory’ shareholder agreements and domestic political interference. Concerns were raised about the impact of foreign investment on the diversity of the domestic cannabis sector in Jamaica, including the commitment to transition traditional illegal small-scale cannabis cultivators to the legal sector. Conclusion While foreign investment has facilitated the commercialisation of the cannabis sector in Jamaica, regulatory measures are also needed to protect the domestic industry and support the transition of small-scale illegal cultivators to the legal regime. Foreign investments may alter the economic, social and political determinants of health in transitioning from illegal to legal cannabis market economy.

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