This paper presents different aspects of pressure vessel safety in the scope of industrial safety, focused to the chemical industry. Quality assurance, including application of PED97/23 has been analysed first, followed shortly by the risk assessment and in details by the structural integrity approach, which has been illustrated with three case studies. One important conclusion, following such an approach, is that so-called water proof testing can actually jeopardize integrity of a pressure vessel instead of proving it. [Projekat Ministarstva nauke Republike Srbije, br. TR 174004 i br. TR 33044]

The development of a modern motor vehicle is aimed at improving the performance in the fi eld of dynamics (both longitudinal and lateral), economy, safety and ergonomic characteristics. Special attention is paid to passenger comfort. Torsional oscillations in transmission cause longitudinal vibrations of the vehicle, depending on inertial parameters, as well as on stiffness and damping of the transmission. Taking into account the complexity of the problem, it is estimated that it is useful to analyse the impact of the transmission design parameters on the longitudinal (fore and aft) vibrations of freight motor vehicle. For this purpose, the dynamic simulation method was used, and the analysis of the infl uence of certain constructive parameters on the longitudinal oscillations of the vehicle was performed using the sensitivity function.

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.

Product warranty is a powerful marketing tool, but it always involves additional costs to the manufacturer. This paper deals with the warranty cost analysis for one type of passenger car batteries. Costs were calculated for three variants of fully renewing combination free replacement and pro-rata policy and for different warranty parameters. After choosing the price range for the product, a market research was performed to determine which warranty policy customers recognize as most favourable to them. Obtained results are guideline for the manufacturer to choose the warranty that minimizes the costs and maximizes the profit.

Original scientific paper This paper focuses on the identification of failure causes of a bolted joint used for the bedding of a primary column of an aerial platform. The tests conducted to determine chemical composition and mechanical properties have confirmed the 12.9 grade of the bolts. Also, mechanical properties tests and metallographic examination did not indicate any hidden defects caused by heat treatment (e.g. decarburisation etc.). On the other hand, visual and metallographic examination of cross-section as well as electron microscope scanning confirmed fatigue fracture of the bolts. Therefore, further analyses were done to check the dimensioning and the installation of the bolts. The effects on stress states in the bolts are presented from the standpoint of rated operating regimes, stiffness of joined elements, lubrication conditions of thread surfaces and temperature incompatibility between the bolts and elements being joined. Pre-tightening torque value incompatible with lubrication conditions was found to be the main factor that led to high stress values that initiated and later intensified the fatigue process which ended in fatigue failure of the bolts. Keywords: bolted joint lubrication; failure of bolts with high mechanical propertiesAnaliza otkaza vijčanog spoja stupa platforme za rad na visini Izvorni znanstveni članak U radu se razmatra problematika identifikacije uzroka otkaza vijčanog spoja uležištenja osnovnog stupa platforme za rad na visinama. Ispitivanja provedena kako bi se odredio kemijski sastav i mehanička svojstva, potvrdila su da se radi o vijcima kvalitete 12.9. Također, ispitivanja mehaničkih svojstava i metalografska ispitivanja nisu navodila ni na kakve skrivene kvarove uzrokovane toplinskom obradom (npr. razugljičenje itd.) S druge strane, visualno i metalografsko ispitivanje poprečnog presjeka kao i ispitivanje elektronskim mikroskopom potvrdili su lom vijaka uzrokovan zamorom. Zato su dalje analize bile usmjerene na utvrđivanje adekvatnosti dimenzioniranja i ugradnje predmetnih vijaka. U radu su predstavljeni utjecaji na naponsko stanje vijaka sa stanovišta nominalnih radnih režima, krutosti elemenata u spoju, uvjeta podmazanosti površina navoja i temperaturne nekompatibilnosti vijaka i elemenata koji se spajaju. Zaključeno je da je neusklađenost primijenjenog momenta prethodnog pritezanja vijaka s uvjetima podmazanosti površina navoja bila od dominantnog značaja za pojavu povišenih naponskih stanja u materijalu vijaka, koji su inicirali i intenzivirali zamorni proces, odnosno zamorni otkaz vijaka. Ključne riječi: podmazanost vijčanog spoja; otkaz vijaka visokih mehaničkih svojstava