The possibility of traffic accident reconstruction using event data Recorders: A review

Uređaji za beleženje podataka koriste se u svrhu istraga saobraćajnih nesreća više od 20 godina. Neke zemlje su zakonski regulisale njihovu primenu i validan su dokaz u istragama i rekonstrukcijama. Međutim, uređaji za beleženje se koriste kao izvor informacija, a ne kao baza podataka na osnovu kojih je moguće rekonstruisati događaj. Istraživanja samo pomoću uređaja za beleženje još uvek nisu moguća zbog određenih pojava, kao i zbog konstruktivnih karakteristika uređaja. Naučnici iz Japana i Poljske testirali su tačnost podataka iz uređaja i na osnovu njih izvršili rekonstrukcije udesa. Oba tima su utvrdila da je rekonstrukciju moguće izvesti samo u jednostavnim situacijama, poput pravolinijskog udara jednog vozila u drugo. Kada je u udaru više učesnika, ili je udaru prethodio neki manevar, nije moguće utvrditi šta se zaista dogodilo. Neophodan je dalji razvoj ovih uređaja, kako bi se povećala njihova efikasnost prilikom rekonstrukcije saobraćajnih nezgoda.Event Data Recorders (EDRs) have been used for the purpose of investigating traffic accidents for more than 20 years. Some countries have regulated their application by law, and they are a valid evidence during investigations and reconstructions. However, recording devices are used as a source of information, not as a database from which it is possible to reconstruct the event. Investigations using only recording devices are still not possible due to the some phenomena that exist, and due to the constructional features of the devices. Scientists from Japan and Poland tested the accuracy of the data from the devices and performed reconstructions of accidents. Both teams have established that it is possible to perform reconstruction only in simple situations, such as a straight-line crash of one vehicle into another. When there are several participants in a crash, or a crash was preceded by a maneuver, it is not possible to determine what really happened. Further development of data recording devices is necessary, in order to increase their efficiency during the reconstruction of traffic accidents

The possibility of traffic accident reconstruction using event data Recorders: A review

Uređaji za beleženje podataka koriste se u svrhu istraga saobraćajnih nesreća više od 20 godina. Neke zemlje su zakonski regulisale njihovu primenu i validan su dokaz u istragama i rekonstrukcijama. Međutim, uređaji za beleženje se koriste kao izvor informacija, a ne kao baza podataka na osnovu kojih je moguće rekonstruisati događaj. Istraživanja samo pomoću uređaja za beleženje još uvek nisu moguća zbog određenih pojava, kao i zbog konstruktivnih karakteristika uređaja. Naučnici iz Japana i Poljske testirali su tačnost podataka iz uređaja i na osnovu njih izvršili rekonstrukcije udesa. Oba tima su utvrdila da je rekonstrukciju moguće izvesti samo u jednostavnim situacijama, poput pravolinijskog udara jednog vozila u drugo. Kada je u udaru više učesnika, ili je udaru prethodio neki manevar, nije moguće utvrditi šta se zaista dogodilo. Neophodan je dalji razvoj ovih uređaja, kako bi se povećala njihova efikasnost prilikom rekonstrukcije saobraćajnih nezgoda.Event Data Recorders (EDRs) have been used for the purpose of investigating traffic accidents for more than 20 years. Some countries have regulated their application by law, and they are a valid evidence during investigations and reconstructions. However, recording devices are used as a source of information, not as a database from which it is possible to reconstruct the event. Investigations using only recording devices are still not possible due to the some phenomena that exist, and due to the constructional features of the devices. Scientists from Japan and Poland tested the accuracy of the data from the devices and performed reconstructions of accidents. Both teams have established that it is possible to perform reconstruction only in simple situations, such as a straight-line crash of one vehicle into another. When there are several participants in a crash, or a crash was preceded by a maneuver, it is not possible to determine what really happened. Further development of data recording devices is necessary, in order to increase their efficiency during the reconstruction of traffic accidents

Contribution to the investigation of the influence of tire non-uniformity on the lateral tire characteristics

Tire models are widely used in research in the field of vehicle dynamics and noise, and especially in the simulation of their movement under the action of forces and moments. In general case, we distinguish theoretical models defined on the basis of tire construction and empirical or semi-empirical models based on experimental tests. In addition, a combination of these two types of models can also produce tire models. In practice, there is a very wide range of mathematical tire models defined using finite element analysis, by approximation of polynomials of different degrees, by approximation of magic formula, etc. In this paper, an attempt is made to calculate non-stationary lateral characteristics of tires on the basis of experimental stationary lateral characteristics, using two-parameter higher level polynomials. This polynomials define the tire lateral characteristics, and take into account their non-uniformity. More specifically, the lateral characteristics are approximated as a function of the dynamic change of the slip angle, radial load due to tire non-uniformity and time

Toughness of ferritic reactor steel in transition-temperature region

Tema ove doktorske disertacije je feritni reaktorski čelik 20MnMoNi 55, konkretno njegova žilavost u području prelaznog temperaturnog režima najviše zbog njegove primene u ekstremnim uslovima, odnosno niskim temperaturama. Ispitivanja su urađena na C(T) uzorcima različitih dimenzija i tempraturama -60 i -90℃, sa ciljem dobijanja krivih verovatnoća loma cepanjem ispitivanih manjih C(T) epruveta i predikcije ponašanja većih uzoraka na ispitnim temperaturama statističkim metodama (konkretno, Vejbulovom raspodelom) obrade dobijenih rezultata. Kumulativnim raspodelama verovatnoće loma cepanjem i predikcijama ponašanja većih uzoraka u funkciji parametra mehanike loma Jc direktno je prikazan uticaj veličine uzoraka na integritet konstrukcije izrađene od ovog materijala i njegovu sposobnost ili težnju ka žilavom ili krtom lomu usled prisustva prsline. Pored šire slike ponašanja feritnog reaktorskog čelika 20MnMoNi 55 na ispitnim temperaturama -60℃ i -90℃ preko parametara Jc i drugih analiziranih relavantnih parametara, ovom disertacijom pružen je dodatni uvid uticaja dinamičkog opterećenja pripremljenih uzoraka na dobijene rezultate preko plastične zone oko vrha prsline i analizom rasipanja dobijenih rezultata. Dobijene su i analizirane određene zakonitosti uočenih pojava, poput potencijalne temperaturne zavisnosti Vejbulovih parametara kumulativne raspodele za C(T)50 uzorke na dvema ispitnim temperaturama. Skaliranjem određenih eksperimentalnih rezultata ispitivanja dobijena je empirijska zakonitost u cilju analize uticaja veličine geometrijski sličnih C(T) uzoraka na temperaturi -60℃. Cilj skaliranja je sveobuhvatno predviđanje ponašanja uzoraka većih dimenzija na osnovu ispitivanja manjih.The topic of this doctoral thesis is ferritic reactor steel 20MnMonNi 55, i.e. its toughness in transition-temperature region, tipically used in application for structures working at low temperature. Tests were performed on the C(T) specimens with different geometry and on -60 and -90℃ in order to get cleavage fracture probabilities curves of small specimens and to predict behavior of the larger ones at specific temperatures. Method used for probability prediction is Weibull statistic method of results processing. The cumulative distributions of cleavage fracture probability, as well as obtained behaviour predictions of the larger specimens in the function of fracture mechanics parameters Jc, show the influence of specimen size effect on the integrity of real structure made of this steel, and its ability and tendency towards ductile or brittle fracture in the presence of the crack. In addition, experimental testing in this thesis provided a broad picture of ferritic reactor steel 20MnMoNi 55 behavior at temperatures -60℃ and -90℃ by analyzing Jc and other relevant parameters. This dissertation provides additional insight into the influence of dynamic loading via specimens pre-cracking and plastic strain around the specimen crack tip by analyzing the obtained scattered results and parameters. Certain relations of observed phenomena were analyzed and discussed, such as the potential temperature dependence of the Weibull parameters of the cumulative distribution for C(T)50 specimes at two temperatures. By scaling of certain experimental results with the aim of determining of size effect of geometrical similar C(T) specimens, the empirical relation for temperature of -60℃ was obtained. The goal of scaling is to comprehensively predict the behavior of larger specimens based on the examination of smaller ones

The effect of exploitation conditions on the damage of a roller reducer toothed shaft and its repair

This paper describes repair method of the toothed shaft of roller reducer located in Steelworks Smederevo facility, as well as the effects of exploitation conditions that have led to damage i.e. shaft fracture. After more than 15 years of in-service exploitation the shaft fracture has occurred at the bearing position. The fracture occurred due to blocking on the roller driven by this shaft. In order to restore the working capabilities of the shaft, the repair welding procedure has been established. Additional difficulties during establishing repair procedure were caused by the fact that the base material of the shaft was unknown, so certain assumptions were made (e.g. assumption of base material). Application of repair welding has resulted in significant direct and indirect savings in comparison to the purchasing of a new shaft

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

Integrity assessment of ammonia storage tank by non-destructive testing

Ammonia is a very dangerous fluid, and it is so important that its storage tanks are safe. Fusion welded joints (in further text: welded joints) are the 'weakest' location in some structures, in this case - tanks, and the detection of defects in welded joints during manufacture is also very important, since defects may cause failure with catastrophic events. NDT techniques that have been performed on welded joints show insight into the quality of the performed welding technique, and results imply whether tanks are safe to be put into exploitation. Three different methods are used for testing: visual, penetrant, and ultrasonic (in this case a new method is used). The first two methods show no irregularities, but third NDT method shows the necessity for tank repair. All of these tests are performed in accordance with relevant standards that are discussed, as well as the used NDT methods in general, with their ability and restrictions

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

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