Repository of the Institute for Material Testing (RIMS)
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Application of Paris' Law Under Variable Loading
No full textThe most important characteristics for service safety of welded joints are those describing crack initiation and growth caused by variable loading. Crack initiation and growth caused by variable loading is the subject of numerous investigations. This paper shows the determination of parameters of the fatigue crack for constituents of welded joints produced of high strength low alloyed steel. The crack growth law of Paris establishes the relation between the applied variable load quantity or the corresponding stress intensity factor range and crack growth per cycle. Results have shown that the position of the notch and crack initiation affect the values of the stress intensity range of fatigue threshold Delta Kth and parameters in the Paris' equation
Determination of LCF Plastic and Elastic Strain Components of Steel
No full textThe behavior of steel in low-cycle fatigue (LCF) is tested experimentally, in accordance with ISO 12106:2017 (E) and/or ASTM E 606-04. For this purpose, smooth specimens which are exposed to low-cycle fatigue at several levels of regulated strains and/or loads at room, elevated or reduced temperatures are used. Stress–strain response at LCF has the shape of an ideal hysteresis loop. The strain range Δε corresponds to overall loop width, while the stress range Δσ corresponds to its overall height. The paper presents a method for determining the intersection of the idealized hysteresis loop and the positive part of the strain axis in order to determine the values of elastic, Δεe/2, and plastic, Δεp/2, components of the strain amplitude to characterize the behavior of steel under low cyclic fatigue. The values of elastic and plastic components of the strain amplitude are needed to determine the characteristic curves of low-cycle fatigue, which describe the behavior of steel under the loading of low-cycle fatigue
Experimental analysis of fire resistance of clay hollow-brick masonry non-load bearing wall
Get PDFTesting the clay hollow-brick masonry non-load-bearing wall helps us to understand the behaviour of this type of wall during a fire. It is important to know the fire resistance of hollow brick walls so that we can prevent the fire from spreading to other rooms. In this paper, the experimental analysis of fire resistance of non-load-bearing wall with dimensions 3000 mm x 3000 mm thickness 200 mm were presented. The wall was made from clay hollow-brick masonry blocks with dimensions 500 mm x 200 mm x 249 mm (L x D x H) with mortar on both side of wall of thickness 15 mm. The wall was exposed to a standard fire test according to SRPS EN 1363-1:2014. The temperatures on the unexposed side of the wall were measured in thirteen positions with thermocouples (K – type) according to the national standard SRPS EN 1364-1: 2014, and at the junction between mortar and clay hollow-brick. Deflection of the wall in five places was measured also. Obtained results depending on the time of reaching the critical temperature during the fire test were presented
Compatible Mortars for the Architectural Conservation of the Danube Limes in Serbia – Importance of the Raw Component Characterisation
No full textRecipes for compatible mortars for conservation must be based on raw materials whose presence was determined during the characterisation of historical mortars used on buildings on which we perform renewal or repairs. Additional materials are often used that improve the resistance of conservation mortars to various influences, while all the time ensuring that they do not have any negative effects on any part of the structure
What is the most relevant method for water absorption determination in ceramic tiles produced by illitic-kaolinitic clays? The mystery behind the gresification diagram
Get PDFThis study presents the 51 mixtures of ceramic clays characterized by using XRF, XRD, granulometry, and dilatometry analyses. After firing in a 1000-1250 °C range, water absorption (WA) according to EN standards by boiling in water, under vacuum, and by 24 h soaking is determined. The results indicated that there was a high and statistically significant correlation between the standard methods, but the testing under vacuum gave the highest saturation of the samples fired at 1200 °C and 1250 °C. It is determined that these illitic-kaolinitic clays can be used to produce floor ceramic tiles belonging to the BIIa group (water absorption between 3% and 6%). The study also aimed to reveal which method of WA determination is suitable to read the sintering interval from the gresification diagrams, which is compared to the beginning of sintering as read from dilatometry curves
Kvalitet tucanika za zastor železničkih pruga, uporedna analiza koeficijenta Los Anđeles i koeficijenta mikro-Deval
No full textKvalitet kamenog agregata koji se koristi za izradu zastora železničkih pruga u direktnoj je vezi sa životnim vekom ovih saobraćajnica. Odabir kvalitetnog kamenog agregata obezbedjuje stabilan oslonac železničkim kompozicijama, umanjuje pritisak na podlogu, omogućava drenažu konstrukcije i dr. Definisanje kvaliteta ovog agregata vrši se putem ispitivanja granulometrijskog sastava, fizičkih i mehaničkih svojstava i postojanosti na vremenske uslove. Mehanička svojstva obuhvataju otpornost prema drobljenju metodom Los Anđeles i otpornost prema habanju mikro-Deval, metodom još uvek relativno manje poznatom na našim prostorima. U radu je dat uporedni pregled rezultata ispitivanja tucanika silikatnog sastava sa prostora Srbije ovim dvema metodama, sa ciljem sagledavanja njihove korelacije i formiranja kriterijuma za rezultate ispitivanja metodom mikro-Deval
The effects of alloying elements on mechanical properties of NIOMOL 490K steel
Get PDFThis paper is to study the effect of alloying elements on mechanical properties of highstrength
low-alloy steel, NIOMOL 490K. This steel grade belongs to the class of
molybdenum microalloyed steels, in which microalloying with molybdenum serves to
increases the heat resistance of steel along with the effect of increasing the influences of
other alloying elements. This steel grade is designed for welded pressure vessels fabrication
and is primarily applied for dynamic loading conditions at low operating temperatures. Highstrength
low-alloy steels used nowadays are usually obtained by means of suitable chemical
composition and thermo-mechanical treatment. In present paper, the tensile and hardness
tests were used to determine the effect of mechanical properties of NIOMOL 490K steel
Damage occurrence in welded structures of the bucket-wheel boom
Get PDFCauses of damage occurrence in vital components of welded structures of the bucket-wheel
excavator boom (DU1) at the coal landfill of the thermal power plant 'Nikola Tesla A' in Obrenovac
(Serbia) are investigated. Bucket-wheel excavator was produced by French company 'Ameco' and it
moves along the circular track. Taking into account lack of technical documentation, all tests and
were carried out under the assumption that welded structures were made of structural steels S355 and
S235. Investigation of causes of damage occurrence are based on results of non-destructive tests
(NDT) and tensometric measurements