Repository of the Institute for Material Testing (RIMS)
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Rection to fire - SBI test
Get PDFThe fire reaction represents the behavior of materials during a fire event, i.e., how much the material contributes to the fire development. The importance of determining the fire reaction class stems from the need to provide sufficient time for the individuals inside a building to evacuate safely in the event of a fire. The fire reaction class is determined through a series of tests, depending on the material, with the most significant test in this group being the SBI (Single Burning Item) test. The paper describes the preparation method of test samples, the testing procedure itself, as well as the output data used for determination of the fire resistance class for tested material. According to the SRPS EN 13823 standard, a sample of a multilayered facade system with mineral wool was tested. The testing process itself, as well as the processed results, are stated in the conclusionof the study
Procedures for preventing corrosion of welded joints
Get PDFThis paper describes the procedures for preventing corrosion of welded joints. Also, a theoretical
overview of the forms of corrosion that are most prevalent in welded joints is presented.
The concept of corrosion in welded joints is very pronounced in real conditions. Welded joints are
inseparable joints that form an integral part of steel welded constructions. The internal energy
increases during the fusion welding especially in the heat affected places around the welded joint,
which become initiating spot of corrosion degradation. That is why it is of vital importance to focus
on ways to increase the resistance of welded structures to the impact of corrosion
Optimal numerical model of a non-stationary heat transfer through a wall
Get PDFThe problems of steady-state and transient heat conduction for a given geometry can be
solved analytically and numerically. While the use of analytical solutions is limited,
numerical methods can be used to solve heat transfer problems in complex geometries
with more intricate boundary conditions, using computer simulations. Complex
geometries are discretized to form an efficient numerical mesh for solving the given
problem. This paper focuses on the calculation of one-dimensional, transient heat
transfer for a wall with a thickness of 4 cm. The wall temperatures are calculated for
each mesh node at a given moment in time. Two types of analyses were performed,
using FSM analysis (Finite Strip Method) and FEM analysis (Finite Element Method).
The former was conducted using Microsoft Excel, while the latter was calculatedusing
ANSYS software. A parametric study was performed in order to analyse the influence
of spatial and temporal step size on the accuracy of the solution. Finally, the optimal
solution was determined to obtain temperature results with the lowest relative error
within the wall nodes, while maintaining the efficiency of the computational model
Influence of Barite Sand on The Strength on Self-Compacting Concrete with Fly Ash
No full textThis study compared the performance of self-compacting concrete (SCC) based on fly ash addition and limestone filler. A SCC prepared with Portland cement, river sand, and limestone filler was used as a reference sample. Additional experimental self-compacting concretes with different types of fine aggregates, fillers, and special additives for increasing freeze-thaw resistance were prepared and optimized. The correlation between mix design, i.e., percentage of barite sand and additives, on properties of hardened SCC (compressive and flexural strengths), were investigated and discussed
Merni mehatronički sistem za nadzor ugiba grednih struktura praćenjem dilatacija u osnovnom materijalu
Get PDFPonašanje struktura pod delovanjem različitih vrsta opterećenja
određene su njenim deformacionim karakteristikama, globalnim
deformacionim karakteristikama - pomeranjima i rotacijama i lokalnim
deformacionim karakteristikama - dilatacijama u osnovnom materijalu
strukture. Poznavanjem globalnih i lokalnih deformacionih karakteristika
strukture u toku njene eksploatacije ostvarujemo mogućnost da pratimo
ponašanje strukture u celini ili nekog njenog segmenta, kao i da u slučaju pojave
oštećenja, koja mogu nastati na osnovu različitih uzroka, pravovremeno
delujemo i sprečimo nastajanje havarijskih događaja koji kao posledicu mogu
imati kako ekonomske, tako i posledice sa ljudskim žrtvama.
Istraživanje u okviru ove disertacije obuhvata razvoj mernog
mehatroničkog sistema za nadzor ugiba grednih struktura praćenjem dilatacija u
osnovnom materijalu. Za utvrđivanje globalne deformacijske veličine
vertikalnog pomeranja - ugiba, na osnovu izmerenih lokalnih deformacionih
veličina, tj. posredno utvrđivanje ugiba strukture na njenoj ukupnoj dužini, na
osnovu poznatih vrednosti dilatacija u osnovnom materijalu strukture, usled
delujućeg opterećenja, razvijen je numerički postupak proračuna koji na osnovu
izmerenih vrednosti dilatacija u specifičnim tačkama na strukturi izračunava
vrednosti ugiba strukture, na celokupnom rasponu. Vrednosti dobijenih ugiba
primenom ovog postupka upoređene su sa vrednostima dobijenih putem direktnog
merenja ugiba na eksperimentalnim modelima i na realnoj strukturi.
Istraživanje je obuhvatalo tri faze:
1. Eksperimentalno ispitivanje na modelu čeličnog I nosača statičkog sistema
proste grede, direktno merenje ugiba usled nekoliko nivoa delujućeg opterećenja,
posredno izračunavanje ugiba primenom razvijenog numeričkog postupka
proračuna na osnovu izmerenih vrednosti dilatacija u osnovnom materijalu i
upoređenje vrednosti dobijenih na osnovu navedena dva postupka.
2. Eksperimentalno ispitivanje na strukturi nosača kranske staze pod delujućim
opterećenjem (realna struktura u eksploataciji), direktno merenje ugiba usled
delujućeg opterećenja, posredno izračunavanje ugiba primenom razvijenog
numeričkog postupka proračuna na osnovu izmerenih vrednosti dilatacija u
osnovnom materijalu i upoređenje vrednosti dobijenih na osnovu navedena dva
postupka.
3. Razvoj i provera rada mernog mehatroničkog sistema za nadzor ugiba grednih
struktura praćenjem dilatacija u osnovnom materijalu, u koji je implementiran
razvijeni numerički postupak proračuna, na eksperimentalnom modelu
statičkog sistema proste grede, direktno merenje pomeranja usled nekoliko
nivoa delujućeg opterećenja i upoređenje vrednosti dobijenih na osnovu navedena
dva postupka.
Kod prve dve faze istraživanja, kao i kod razvijenog mehatroničkog
sistema u koji je implementiran predloženi numerički postupak proračuna,
nisu zabeležene relativne razlike veće od 6 %, između direktno merenih i
posredno određenih vrednosti ugiba
Ispitivanja zavarenih spojeva niskolegiranog čelika povišene čvrstoće klase 700 mpa
Get PDFZahtevi ekonomične potrošnje energije i sirovina
upućuju proizvođače čelika na proizvodnju
zavarljivih čelika povišene čvrstoće, a projektante i
konstruktore na njihovu primenu u zavarenim
konstrukcijama. Primena niskolegiranih čelika
povišene čvrstoće (HSLA) u metalnim
konstrukcijama je sve zastupljenija pre svega zbog
njihovog svojstva oblikovanja gde zavarljivost ima
poseban značaj. Stoga se vremenom razvio čitav
niz postupaka ispitivanja kojima je cilj da se
svojstva zavarenog spoja pomenutih materijala što
bolje upoznaju i tako što racionalnije iskoriste.
Analizirana svojstva kao što su ispitivanje
zatezanjem, udarna žilavost i tvrdoća, daju širu
sliku o samim zavarenim spojevima niskolegiranih
čelika i njihovim osobinama i upoređuju se sa
zahtevima međunarodnih standarda iz oblasti
elektrolučnog zavarivanja.The requirements of economical consumption of
energy and raw materials direct steel producers to
the production of weldable steels of high strength,
and designers and constructors to their application
in welded constructions. The use of high strength
low alloy steel (HSLA) in metal constructions is
increasingly prevalent, primarily due to their forming
properties, where weldability is of particular
importance. Therefore, over time, a whole series of
test procedures has been developed, the aim of
which is to better understand the properties of the
welded joint of the mentioned materials and to use
them more rationally. The analyzed properties,
such as tensile testing, impact toughness and
hardness, give a broader picture of the welded
joints of high strength low alloy steel and their
properties and compared with the requirements of
international standards in the field of arc welding
Efficient and Thermally Stable Wide Bandgap Perovskite Solar Cells by Dual-Source Vacuum Deposition
No full textWide bandgap perovskites are being widely studied in view of their potential
applications in tandem devices and other semitransparent photovoltaics.
Vacuum deposition of perovskite thin films is advantageous as it allows the
fabrication of multilayer devices, fine control over thickness and purity, and it
can be upscaled to meet production needs. However, the vacuum processing
of multicomponent perovskites (typically used to achieve wide bandgaps)
is not straightforward, because one needs to simultaneously control several
thermal sources during the deposition. Here a simplified dual-source vacuum
deposition method to obtain wide bandgap perovskite films is shown. The
solar cells obtained with these materials have similar or even larger efficiency
as those including multiple A-cations, but are much more thermally stable, up
to 3500 h at 85 °C for a perovskite with a bandgap of 1.64 eV. With optimized
thickness, record efficiency of >19% and semitransparent devices with stabilized
power output in excess of 17% are achieved
Utilization of Construction and Demolition Mix Waste in the Fired Brick Production: The Impact on Mechanical Properties
Get PDFThe European Green Deal, which emphasizes zero-waste economies, and waste recycling
in construction and building materials, has arisen due to significant worldwide needs for solid waste recovery and usage. This ambitious study focuses on recycling mixed construction and demolition (C&D) waste into burnt bricks and investigating the influence of firing temperature. While pursuing its objectives, this is dependent on raw material characterization and burnt-brick product quality assessment. The recycling of mixed C&D waste is explored by mixing the waste into two soil types (alluvial and laterite) in ratios ranging from 5% to 45% at three firing temperatures (700 °C, 850 °C and 900 °C). The utilization of mixed C&D waste in amounts of 10% at 700 °C and 25% at 850 °C and 900 °C fulfilled the Indian standard. Although a fire at 700 °C results in less optimal waste utilization, it is beneficial and recommended for reducing the carbon footprint and energy use. Additional mineralogical and microstructural analyzes are performed on the optimal fired samples.
The study’s findings are promising for sustainable resource usage, reducing carbon footprint, and
reducing waste disposal volume. This research is a big step toward the Sustainable Development
Goals of the United Nations and a circular economy
Analiza modela upravljanja kvalitetom ispitivanja šipova
Get PDFU radu je prikazan sadržaj predloženog dokumenta Elaborata ispitivanja šipova i jasnije
su razjašnjene aktivnosti koje su obuhvaćene ovim dokumentom. Na primeru objekta Ušće 2
demonstrirana je primena jednog dela rešenja o ispitivanju šipova, a što bi se našlo u samom
elaboratu. Analizirane su količine (obim) ispitivanja šipova po tipovima testova i analizirane su
aktivnosti u okviru svakog pojedinačnog testa. Naglašeno je da je potrebna bolja saradnja na
relaciji projektant, izvođač i nadzora prema ispitivaču šipova
Type of precipitation and durations of sediment exposure as important weathering factors
No full textA diversity of factors, led by lithology, weathering, and erosion processes, plays a significant role in the formation and future of badland terrains. Then on previous observations it can be concluded that surface flow processes are the first trigger of erosion and that intense soil erosion combined with rapid and deep weathering are tightly connected to high erosion rates.
Since climate change presents a global issue that gains increasing attention and due to the complexity of the interactions and processes that are a part of general badlands origin and evolution, a weathering experiment on badland sediments from China was conducted. Explaining temporal changes, the impact of different precipitation types and its durations of exposure on sediments during weathering processes, as well as its impact on leachate ions behaviour are the aims behind this experiment.
Red clayey siltstone and mudstone badland sediments selected for the laboratory experiment were organized in four sets that included three different samples, making a total of 12 treated samples. Based on field climate data, in laboratory conditions samples were exposed to rain, acid rain, snow, and acid snow through fifteen daily cycles. Leachate was collected after each cycle and its volume, pH, electrical conductivity (EC), and ion concentrations were measured and analysed from the leachate. Changes occurring on the surface of the sample were observed through photographs taken at the end of each cycle.
Based on obtained results it can be said that the main differences occur when comparing rain and snow treatments generally. Temporal, cyclic changes were, to a certain extent, noticed through sediment decay. More importantly, durations of sediment exposure to precipitation proved to be crucial for weathering processes of tested siltstones and mudstones, having exclusion and ionic forces - ion exchange chromatography as dominant chemical processes