Weibull probability distribution for reactor steel 20MnMoNi55 cleavage fracture in transition temperature

This paper presents the results and methods used for determining of fracture toughness of reactor steel, denoted as 20MnMoNi55, typically used for structures working at low temperatures, in transition temperature area. In addition, the effect of test specimen geometry and temperature on fracture toughness was investigated in order to predict the fracture behavior and probability of failure. Failure probabilities (i.e. cleavage fracture) in the function of J(c) for large test specimens, CT100 and CT200 were determined based on the results obtained by testing of small CT50 specimens, for the purpose of direct savings and decreased costs of specimen testing. Failure probability, represented using Weibull distribution of experimental data, will provide a clear insight into material behavior at different temperatures. Other factors affecting the obtained test results will also be discussed

Weibull probability distribution for reactor steel 20MnMoNi55 cleavage fracture in transition temperature

This paper presents the results and methods used for determining of fracture toughness of reactor steel, denoted as 20MnMoNi55, typically used for structures working at low temperatures, in transition temperature area. In addition, the effect of test specimen geometry and temperature on fracture toughness was investigated in order to predict the fracture behavior and probability of failure. Failure probabilities (i.e. cleavage fracture) in the function of J(c) for large test specimens, CT100 and CT200 were determined based on the results obtained by testing of small CT50 specimens, for the purpose of direct savings and decreased costs of specimen testing. Failure probability, represented using Weibull distribution of experimental data, will provide a clear insight into material behavior at different temperatures. Other factors affecting the obtained test results will also be discussed

Supplementary data for article: Relić, D.; Đorđević, D. S.; Popović, A. R. Assessment of the Pseudo Total Metal Content in Alluvial Sediments from Danube River, Serbia. Environmental Earth Sciences 2011, 63 (6), 1303–1317. https://doi.org/10.1007/s12665-010-0802-1

Supplementary material for: [https://doi.org/10.1007/s12665-010-0802-1]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1170

Finite element modeling of hip implant static loading

In this paper a numerical investigation of replacement implant for partial hip arthroplasty is presented. The long-term stability of hip implants depends, among other things, on the loads acting across the joint. Forces occurring in vivo can be much greater than the recommended test values, because a typical gait cycle generates forces up to 6-7 times the body weight in the hip joint. A finite element analysis (FEA) was performed using 3-dimensional models to examine the mechanical behaviour of the femoral component at forces ranging from 2.5 to 6.3 kN. This implant design was chosen for numerical analysis because stress concentration in femoral component lead to implant fracture. Results show that the force magnitudes acting on the implant are of interest, and that they can cause implant stress field changes and implant stability problems, which can lead to implant failure

Finite element modeling of hip implant static loading

In this paper a numerical investigation of replacement implant for partial hip arthroplasty is presented. The long-term stability of hip implants depends, among other things, on the loads acting across the joint. Forces occurring in vivo can be much greater than the recommended test values, because a typical gait cycle generates forces up to 6-7 times the body weight in the hip joint. A finite element analysis (FEA) was performed using 3-dimensional models to examine the mechanical behaviour of the femoral component at forces ranging from 2.5 to 6.3 kN. This implant design was chosen for numerical analysis because stress concentration in femoral component lead to implant fracture. Results show that the force magnitudes acting on the implant are of interest, and that they can cause implant stress field changes and implant stability problems, which can lead to implant failure

Finite element modeling of hip implant static loading

In this paper a numerical investigation of replacement implant for partial hip arthroplasty is presented. The long-term stability of hip implants depends, among other things, on the loads acting across the joint. Forces occurring in vivo can be much greater than the recommended test values, because a typical gait cycle generates forces up to 6-7 times the body weight in the hip joint. A finite element analysis (FEA) was performed using 3-dimensional models to examine the mechanical behaviour of the femoral component at forces ranging from 2.5 to 6.3 kN. This implant design was chosen for numerical analysis because stress concentration in femoral component lead to implant fracture. Results show that the force magnitudes acting on the implant are of interest, and that they can cause implant stress field changes and implant stability problems, which can lead to implant failure

Specijacija odabranih mikro- i makroelemenata u uzorcima lignita termoelektrane 'Nikola Tesla A' (Obrenovac, Srbija)

Four samples of milled lignite used in the "Nikola Tesla A" power plant located in Obrenovac near Belgrade, were subjected to a five-step sequential extraction, comprising of the following phases: distilled water, 1M ammonium acetate, 0.2M ammonium oxalate/0.2M oxalic acid, acidic solution of H2O2and a 6M solution of HCl. The concentrations of the different elements obtained in the extractions were statistically analyzed. The majority of the examined elements were found to be most probably associated with inorganic fractions of lignite, only aluminum, silicon, chromium and arsenic have a larger extractable organic/sulfide fraction than an extractable inorganic fraction. Alumosilicates of magnesium (carriers of arsenic, zinc, lead, copper and chromium), silicates of potassium (scavengers of lead and nickel), mixed aluminates of iron and magnesium (carriers of arsenic, zinc, copper and chromium) and compounds of iron that do not contain aluminum and magnesium (scavengers of manganese) were dissolved in the fifth phase of the sequential extraction. Copper is a substrate of alumosilicates of potassium and magnesium, while zinc and chromium are substrates of compounds of iron leached in the third phase of the sequential extraction. Interphase correlation revealed that the adsorbed and ion-exchangeable fractions of most of the examined elements do not exhibit preferential binding to the components of the inorganic matrix of lignite ash.Četiri uzorka mlevenog lignita korišćenog u Termoelektrani "Nikola Tesla A" u Obrenovcu u Beograda su podvrgnuta sekvencijalnoj ekstrakcija koja se sastojala od pet faza: u prvoj je korišćena destilovana voda, u drugoj 1M amonijum-acetat, u trećoj 0,2M amonijum-oksalat i 0,2M oksalna kiselina, u četvrtoj kiseo rastvor H2O2 i u petoj 6M rastvor HCl. Dobijene koncentracije izabranih elemenata su statistički analizirane, kako bi se utvrdile veze između različitih elemenata. Najveći deo ispitivanih elemenata je uglavnom asociran sa ekstrahovanom neorganskom fazom uglja, samo aluminijum silicijum, hrom i arsen imaju unutar ekstraktibilnog dela elemenata veću organsku/sulfidnu frakciju od neorganske. Od jedinjenja rastvornih u petoj fazi ekstrakcije uglja, alumosilikati magnezijuma su nosilac arsena, cinka olova, bakra i hroma, silikati kalijuma nosilac olova i nikla, mešoviti aluminati gvožđa i magnezijuma nosilac arsena, cinka, bakra i hroma, a jedinjenja gvožđa koja nisu povezana sa aluminatima ni magnezijumom nosilac mangana. U trećoj fazi ekstrakcije uglja se rastvaraju alumosilikati kalijuma i magnezijuma asocirani sa bakrom, dok su jedinjenja gvožđa rastvorna u trećoj fazi ekstrakcije asocirana sa cinkom i hromom. Interfazna korelaciona analiza je pokazala da se adsorbovana i jonoizmenjiva frakcija većine ispitivanih elemenata ne vezuje preferencijalno za delove neorganske matrice čestica pepela

Influence of multiple defects in welded joints subjected to fatigue loading according to sist en iso 5817: 2014

Structural integrity of pressure vessels is of great importance in ensuring their safe exploitation. Due to this, a number of standards are developed in order to define the criteria according to which materials, technologies and test methods are selected for pressure vessels, particularly when it comes to welded joints. Because of the nature of the welding process, welded joints will typically contain different types of defects, some of which could greatly endanger their integrity. Cracks in particular are the cause of pressure vessel failure. The goal of this paper is to present the standard SIST EN ISO 5817: 2014 and emphasize the changes and additions that are made, compared to the previous version, SIST EN 5817: 2007. The standard includes recommendations and requirements related to the presence of multiple types of defects in welded joints subjected to fatigue loading. Since fatigue crack growth greatly contributes to failure of pressure vessels, for the first time this standard covers a very important topic. Some of the earlier work related to multiple defects in welded joint is also shown in the paper, and used as examples

Numerical analysis of different weld geometries of lap welded joint in ammonia transport tanks

Presented is a comparison of stress and strain distribution in lap welded joints of different geometries, which are part of a pressure vessel used as an ammonia transport tank. For this purpose, two numerical models are developed using finite element method (FEM). The models are subjected to tensile load and the obtained stress and strain results are compared in order to determine how the difference in welded joint dimensions affects the behaviour of the weld as a whole. It is concluded that in this case, the differences in distribution and stress/strain values are negligible, as expected due to very similar mechanical properties of the materials used

Structural Integrity Assessment of Welded Pipeline Designed with Reduced Safety

The main goal of this paper was to assess the integrity of welded joints in the main pipeline of the reversible hydropower plant "Bajina Bata". Japanese steel Sumiten 80P (SM 80P) was used as the parent material. European recommendation for pipeline safety factor is equal to 1.7 and this value was used for calculations of the RHPP "Bajina Bata", whereas the value recommended by Japanese standards is 2.1. A relatively small safety factor, which is different from the Japanese recommendation (since the material itself is Japanese), represented one of the main reasons for a detailed investigation of the pipeline structural integrity and safety, using the prototype. In the case of pressure vessels, the welded joint is a location of stress concentration, which can act in the same way as residual stresses. Assessment of prototype test results is possible to perform based on stress and strain calculations of vessels with ideal geometry. For this reason, the solution for thin-walled vessels is given, both in elastic and elastic-plastic areas. Numerous tests were performed in order to obtain a reliability assessment necessary for the construction of the pipeline, since the consequences of potential failure would be disastrous in this case. A numerical simulation, based on the experimentally determined mechanical properties of the material used, was also performed in order to obtain the stress/strain distribution. These results were then compared to the experimentally obtained ones, and it was concluded that there is a good level of compliance between numerical and experimental results