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Modeliranje i analiza trajnosti kompozitnih konstrukcija izloženih morskom okolišu
No full textThe experimental part of this research was developed, based on samples of epoxy/glass and polyester/glass composites in the form of standardized coupons, with various fiber orientation layout configurations submerged under the sea for an extended period of time (6, 12 and 24 months) in order to enable the assessment of the influence of the prolonged exposure to the sea on the mechanical properties of the material. Numerical finite element analysis (FEA) tensile test and three-point bending simulations on the coupon geometry indicated that the ultimate uniaxial tensile strength (UTS) is the most important parameter for the characterization of the structural mechanical behavior of the material. This parameter value variations were measured experimentally after each period of exposure to the sea and compared with obtained numerically values. The research results showed that all submerged specimens have exhibited an increase in mass due to water absorption and growth of adhering algae and marine microorganisms. Furthermore, various levels of reduction in ultimate tensile strength (UTS), depending on the fiber layout configurations, were observed. Significant changes in the matrix material structure were noticed in the areas where marine organisms and microorganisms adhered to and were embeded, effectively creating “voids” in the matrix material. Numerical analysis and simulations were conducted during the “wet” coupons’ submersion periods, yielding in a predictive model for the long-term behavior of composites in real marine environment. The model was then verified by comparison with the results of experimental tensile tests. Additionally, the usage of composites as a repair material in process equipment and structural elements made from different materials, was verified. The research showed the importance of environmental degradation of mechanical properties of composite materials in the real marine environment. The findings of this ii research could improve the technical regulations of classification societies for composite marine structures exposed to the marine environment during their service life and expand their application in this industrial sector. The design process of such structures can be further optimized by incorporating the material degradation prediction model proposed here.Eksperimentalni dio ovog istraživanja izveden je na standardiziranim uzorcima (kuponima) kompozitnih materijala izvedenih od kombinacije epoksidne i poliesterske smole kao matrice, te različito orijentiranih staklenih vlakana kao ojačavala uronjenima u more na duge periode od 6, 12 i 24 mjeseca. Svrha eksperimenta je procjena utjecaja duljeg izlaganja uzoraka moru na mehanička svojstva materijala. Numeričko modeliranje i simulacije vlačnog testa i savijanja u tri točke, primjenom metode konačnih elemenata (MKE) na odabranoj geometriji uzoraka pokazali su da je krajnja aksijalna vlačna čvrstoća (engl. Ultimate Tensile Strength, UTS) najvažniji parametar potreban za ispravnu karakterizaciju strukturno-mehaničkog ponašanja materijala. Promjene vrijednosti ovog parametra mjerene su eksperimentalno (vlačni test) nakon završetka navedenih vremenskih perioda izloženosti moru, te su uspoređivane sa vrijednostima dobivenima numeričkom analizom. Rezultati istraživanja pokazali su da su svi uronjeni uzorci imali povećanu masu zbog adsorpcije vode i rasta morskih algi i mikroorganizama koji su se vezali na površini materijala. Nadalje, zamijećene su različite razine smanjenja vlačne čvrstoće materijala za različite konfiguracije usmjerenja slojeva staklenih vlakana. Značajne promjene u strukturi materijala matrice uočene su u područjima vezanja algi i drugih morskih organizama na površini i prodora mikroorganizama u matricu, čime su u biti stvorene "praznine" u materijalu matrice. Numerička analiza i simulacije, provedene tijekom perioda uranjanja uzoraka, rezultirale su stvaranjem prediktivnog modela dugotrajnog ponašanja kompozita uslijed izloženosti stvarnom morskom okolišu. Model je provjeren usporedbom rezultata sa vrijednostima dobivenim eksperimentalnim vlačnim testovima. Povrh svega navedenog, ispitana je i potvrđena mogućnost uporabe kompozitnih materijala za popravke procesne opreme i konstrukcijskih elemenata izvedenih od drugačijih materijala. iv Provedeno istraživanje ukazalo je na važnost degradacije mehaničkih karakteristika kompozitnih materijala uslijed dugotrajne izloženosti morskome okolišu. Nalazi ovog istraživanja mogu poslužiti za poboljšanje tehničkih propisa i standarda klasifikacijskih društava predmetnih za kompozitne pomorske konstrukcije koje su u svom životnom vijeku izložene negativnim utjecajima morskog okoliša čime bi se omogućila šira primjena ovakvih materijala u pomorstvu. Proces projektiranja takvih konstrukcija može se dodatno optimizirati uključivanjem ovdje predloženog modela predviđanja degradacije materijala
Analytical Research of the Container Ships Cargo Area Fires in the Period From 2010 to 2020
No full textContainer transport by sea has almost doubled in the last decade. Accordingly, container ships’ size has increased significantly, and the latest container ships carry up to 24000 Twenty-foot Equivalent Units (TEU). In the near future, the appearance of container ships with a capacity of 25000 TEUs can be expected on the market, because the design is already available. It is known that 10-12% of transported containers contain International Maritime Dangerous Goods (IMDG) cargo. The above stated reasons directly impact the frequency of container ship fires in cargo spaces. According to the Insurance Companies, fires occur on average every two months, and this is a growing problem of container transport by sea. In this paper, 23 fires in the cargo area, either in cargo holds or on deck, were analysed. The analysis results determined the most common causes of fires and have shown that the current fire protection systems on container ships are ineffective. It is unacceptable that firefighting systems’ inefficiency results in the loss of human lives, abandonment of vessels, environmental pollution, and extensive property losses related to cargo and ship structure. Due to all the above, it is necessary to continuously work on new regulatory and technical solutions to improve the fire safety of cargo areas on container ships
Analytical Research of the Container Ships Cargo Area Fires in the Period From 2010 to 2020
No full textContainer transport by sea has almost doubled in the last decade. Accordingly, container ships’ size has increased significantly, and the latest container ships carry up to 24000 Twenty-foot Equivalent Units (TEU). In the near future, the appearance of container ships with a capacity of 25000 TEUs can be expected on the market, because the design is already available. It is known that 10-12% of transported containers contain International Maritime Dangerous Goods (IMDG) cargo. The above stated reasons directly impact the frequency of container ship fires in cargo spaces. According to the Insurance Companies, fires occur on average every two months, and this is a growing problem of container transport by sea. In this paper, 23 fires in the cargo area, either in cargo holds or on deck, were analysed. The analysis results determined the most common causes of fires and have shown that the current fire protection systems on container ships are ineffective. It is unacceptable that firefighting systems’ inefficiency results in the loss of human lives, abandonment of vessels, environmental pollution, and extensive property losses related to cargo and ship structure. Due to all the above, it is necessary to continuously work on new regulatory and technical solutions to improve the fire safety of cargo areas on container ships
Building a stereo audio amplifier using operational amplifier TDA2003
No full textTema ovog završnog rada jest izrada stereo audio pojačala korištenjem operacijskog pojačala TDA2003. U radu je prikazano postavljanje uvjeta sklopa, izrada tiskane pločice, sastavljanje potrebnih komponente za rad pojačala i eksperimentalna analiza rada sklopa. Izrada tiskane pločice i cijelog sklopa je prikazana u web programu EasyEDA.In this paper creation of a stereo audio amplifier using TDA2003 operational amplifier iz presented. The paper presents the setting of circuit conditions, production of a printed circuit board, assembly of necessary components for amplifier operation and experimental analysis of circuit operation. The production of the printed circuit board and the entire assembly is shown in the EasyEDA web program
Failure diagnosis of piston compressors
No full textTeme obuhvaćene ovim radom su: načelo rada klipnog kompresora, važnost u brodskom sustavu, mogući kvarovi i dijagnostika. Klipni kompresor jedan je od strojeva koji imaju iznimnu važnost na brodu s dizel motornom propulzijom. Teme u prvom dijelu rada su posvećene pojmovima dijagnostika kvarova održavanju te osnovnim podjelama klipnih kompresora. U nastavku rada objašnjeni su popratni sustavi i dijelovi koji omogućuju rad klipnog kompresora. Na kraju rada objašnjeni su najčešći kvarovi, njihova dijagnostika te ujedno i otklanjanje navedenih kvarova.The topics covered in this thesis are: operation of a reciprocating piston compressor importance in the ships system possible malfunctions and diagnostics. Reciprocating piston compressor is one of the most important devices on ship powered by internal combustion engine. First part of this thesis is dedicated to the concepts of diagnostic, system maintenance and basic classification of reciprocating piston compressor. In the continuation are explained the accompanying systems and parts which enable the operation of the piston compressor. Last part of the paper is used to explain most common failures and possible ways to fix them
Ultrasonic distance meter
No full textPrvi ultrazvučni mjerač udaljenosti stvoren je 1959. godine od strane Satomure. U praksi danas postoje četiri temeljne vrste ultrazvučnih mjerača; doppler, radar, ultrazvučna stezaljka te ultrazvučni odašiljač razine. Svi ultrazvučni mjerači udaljenosti rade tako što odašilju zvučni val na frekvenciji iznad raspona ljudskog sluha. Pritom koriste sondu za slanje impulsa i primanje eha, a senzor određuje udaljenost do cilja mjerenjem vremenskih intervala između slanja i primanja ultrazvučnog impulsa. Ultrazvučni mjerači udaljenosti prikladni su za detekciju blizine do deset metara i pružaju višestruka mjerenja raspona u sekundi. Njih odlikuje niska razina potrošnje energije te činjenica da oni mogu raditi u mnogim uvjetima okoline. Za izradu uobičajenog ultrazvučnog mjerača udaljenosti koristi se step down transformator, elektrolitički kondenzator, diode, otpornik, mikrokontroler, kristalni oscilator te ultrazvučni senzor. Prednosti ultrazvučnih mjerača udaljenosti su sposobnost mjerenja prozirnih objekata, uključujući površinu vode te nisku nabavnu cijenu. Ipak, ultrazvučni mjerači udaljenosti najbolje rade u praznim sobama ili na otvorenom, imaju vrlo nisku točnost te im je ograničena upotreba u inženjerskim aplikacijama. Za daljnja istraživanja se preporuča dodatno istraživanje ove tematike.The first ultrasonic distance meter was created in 1959 by Satomura. In practice today, there are four basic types of ultrasonic meters; doppler, radar, ultrasonic clamp and ultrasonic level transmitter. All ultrasonic rangefinders work by emitting a sound wave at a frequency above the range of human hearing. They use a probe to send the pulse and receive the echo, and the sensor determines the distance to the target by measuring the time intervals between sending and receiving the ultrasonic pulse. Ultrasonic rangefinders are suitable for detecting proximity up to ten meters and provide multiple range measurements per second. They are characterized by low energy consumption and the fact that they can work in many environmental conditions. A step down transformer, electrolytic capacitor, diode, resistor, microcontroller, crystal oscillator and ultrasonic sensor are used to make the usual ultrasonic distance meter. The advantages of ultrasonic distance meters are the ability to measure transparent objects, including the water surface, and the low purchase price. However, ultrasonic rangefinders work best in empty rooms or outdoors, have very low accuracy, and are limited in use in engineering applications. For further research, additional research on this topic is recommended
LNG risks
No full textPovećanjem količine tereta namijenjenog za prijevoz morem povećava se i broj brodova u opticaju i broj radnih procesa. Rezultat tomu je povećanje frekventnosti nesreća. Provedbom adekvatne procjene rizika, nastoji se smanjiti frekventnosti, a ujedno i posljedice nastalih nesreća. Procjena rizika, kao takva, veoma je kompleksna i treba biti izvedena temeljito od strane stručnog vodstva. U ovom diplomskom radu naglasak je stavljen na analizu nesreća specifičnih za brodove namijenjene prijevozu ukapljenog prirodnog plina te određivanje vjerojatnosti i posljedice za navedene nesreće. Kompleksnost sustava brodova za prijevoz ukapljenog prirodnog plina zahtjeva detaljnu procjenu rizika i pomni odabir metoda kojima će se izvršiti analiza rizika. Stoga, uz navedeno u ovom diplomskom radu objašnjene su i metode analize rizika i generalni pomorski rizici.Increasing the amount of cargo intended for transport by sea increases the number of ships in circulation and the number of work processes. The result is an increase in the frequency of accidents. By conducting an adequate risk assessment, we strive to reduce the frequency and consequences of accidents. Risk assessment as such is very complex and should be carried out to the end by expert management. In this diploma thesis, the emphasis is placed on the analysis of accidents specific to ships intended for the transport of liquefied natural gas and determining the probability and consequences of these accidents. The complexity of the liquefied natural gas ship system requires a detailed risk assessment and careful selection of methods to perform the risk analysis. Therefore, in addition to what is stated in this thesis, the methods of risk analysis and general maritime risks are also explained
Influence of turbo-blower on main engine operation
No full textU radu je opisano turbo-puhalo (TP), princip rada TP te utjecajem na rad dvotaktnog sporookretnog dizelskog brodskog motora. Opisana je fizička konstrukcija samog turbo-puhala te način na koji njegov rad doprinosi radu glavnog motora. Također je pojašnjena pojava pumpanja turbo-puhala. Objašnjen je indikatorski dijagram kao vrlo važan segment današnje dijagnostike kvarova te praćenja rada brodskog motoraIn this paper the turbo blower is described as well as working principle and its effects to the two-stoke slow-speed marine diesel engine. Physical construction of a turbo blower is described and the effect of it`s performance on the performance of the main engine, also the phenomenon of the turbo-blower surge is described. Indicator diagram is presented as well because of it`s importance in today`s malfunction diagnostics and monitoring of the marine engine
Sound controlled robot TI-RSLK MAX
No full textU ovom radu razrađen je mobili robot čije se upravljanje izvodi pomoću zvuka. Najprije su opisani senzori koji se koriste u mobilnoj robotici. Potom su pojašnjeni upravljački programi pomoću kojih se upravlja senzorima i aktuatorima. Nabrojani su i prikazani neki od aktuatora koji se koriste kod mobilnih robota. Za potrebe izrade ovog rada testirani su senzori zvuka na dva načina kako bi se spojili ispravni senzori. Na samom kraju izvedena je analiza upravljanja mobilnim robotom pomoću zvuka.In this paper, a mobile robot is developed whose control is performed using sound. First, the sensors used in mobile robotics are described. Then the software drivers used to control the sensors and actuators are explained. Some of the actuators used in mobile robotics are listed and shown. For the purposes of this paper, sound sensors were tested in two ways to connect the correct sensors. At the very end, an analysis of the control of the mobile robot by sound was performed
Analysis of the influence of different types of stainless steel welds on tensile stress and agressive acid atmosphere
No full textOvaj rad daje pregled odabira tehnika zavarivanja ovisno o potrebama elemenata koji se zavaruju. Navesti će se važnost odabira odgovarajućih dodatnih materijala prilikom zavara te korištenje ispravne zaštitne atmosfere prilikom izrade zavara. Ukratko će se opisati pojedine tehnike i svojstva nehrđajućih čelika. U praktičnom dijelu izraditi će se 7 epruveta koje će se podvrgnuti vlačnom testu te izlagati utjecaju kiselina. Jedna epruveta će biti izrađena iz komada dok su ostale polovice epruveta zavarivane elektrolučnim tehnikama. Praktični dio rada bazirati će se na prikazivanju razlika između tehnika u strukturi zavara te čvrstoći zavara.This thesys will provide an overview of the selection of welding techniques depending on the needs of the elements to be welded. The importance of selecting appropriate additional materials during welding and the use of the correct protective atmosphere during welding will be stated. Techniques and properties of stainless steels will be briefly described. In the practical part, 7 test samples will be made, which will be subjected to a tensile test and exposed to the influence of acids. One test sample will be made from one piece, while the other halves of the test samples are welded using electric arc techniques. The practical part of the work will be based on showing the differences between the welding techniques in the structure of the weld and the strength of the weld