Determination of the Causes of Copper Wires Beads after Fire in Vehicles

An electrical installation that simulates an automobile DC power supply system with a voltage of 12 V has been created. An experimental simulation of a short circuit at currents up to 400 A on copper multi-wire and single-wire conductors under normal environmental conditions is carried out. The copper wires beads were annealed in a furnace at temperatures from 700 to 1000 °C for 20, 40 and 60 minutes. Metallographic analysis of copper wires beads was carried out. The temperatures and times that of at which the signs of short circuit and overcurrent are destroyed has been revealed. Obtained results contribute to improvement evidence’s researching in the fire investigation of motor vehicles electrical wiring after a fire. Keywords: Arc beads, Copper, Metallographic analysis, Electrical Short Circuit, Wires.

Problems in the investigation of fires of motor vehicles

The article pays great attention to the causes of fires that occur in motor vehicles. Statistical data indicate that fires that occurred in motor vehicles consistently occupy the second place in terms of quantity and material damage after fires that occurred in residential buildings. The investigation of fires related to the ignition of motor transport itself is quite complex. The article analyzes the causes of fires in motor vehicles. Some manufacturing defects of modern cars have been investigated. The statistics of fires in Russia are analyzed and presented. Certain features and directions of investigations of this category of criminal cases are considered.

Warm sheet metal forming of energy-absorbing elements made 7075 aluminum alloy in the hardened state T6

The article covers experimental research on the forming of products made of 7075 aluminum alloy. This aluminum alloy grade is characterized by high strength, but due to its low formability in T6 temper, its use in the stamping processes of complex structural elements is limited. The authors have manufactured a U-shaped element at an elevated temperature and determined the optimal parameters of the process. Conventional heating of the sheet and shaping it at the temperature of 100 and 150 °C allowed to obtain a product of high strength similar to the T6 state, above 540 MPa. Due to the excessive springback of the sheet during forming, these products were characterized by a large deviation of the shape geometry, exceeding the allowable values of + / − 1 mm. Only the use of an alternative method of heating the sheet to temperatures of 200 and 240 °C (between plates at 350 °C, heating time 2 min, heating rate 1.8 °C/s) allowed to obtain a product that meets both the strength and geometric requirements. The determined optimal process’ parameters were later transferred to the stamping process of elements of a more complex shape (lower part of the B-pillar). The sheet was heated up and formed in the previously pre-heated tools. In the subsequent series of tests, the heating method and the blank’s temperature were being analyzed. In the case of the foot of the B-pillar, it was necessary to lower the initial blank temperature to 200 °C (heating in a furnace with a temperature of 340 °C, heating speed 0.5 °C/s). The appropriate combination of the process parameters resulted in the satisfactory shape deviation and reaching the product’s strength comparable to the strength of the material in as-delivered T6 temper. Using electron microscopy, it was verified that the structure of the finished product contained particles MgZn2 that strongly strengthen the alloy. The obtained results complement the data on the possibility of using 7075 aluminum alloy to produce energy-absorbing elements of motor vehicles.

Effect of Lane Narrowing Implemented on an Urban Dual Carriageway on Speed Reduction and Acoustic Environment

The on-going growth in the use of motor vehicles leads to a number of traffic safety problems. Therefore, various traffic calming measures are applied to increase traffic safety in built-up areas. Lane narrowing is one of the techniques used to influence the perception of drivers and make them slow down. With this in mind, the authors conducted traffic volume and speed counts before and after installation of the lane narrowing treatment, covering 100 passing vehicles, at an intersection between an urban dual carriageway and an estate street where over a dozen fatal accidents occurred in the recent years. Traffic noise was also measured, both before and after lane narrowing. The traffic count data were analysed to show speed reduction by ca. 15 km/h, yet in all cases still above 50 km/h, which is the speed limit applicable to built-up areas in Poland. The analysis of the “before” and “after” noise maps showed only minor changes to the distribution of noise. The locations of these changes to the acoustic environment depended on the speed and volume of traffic and, much more importantly, on the topography of the surrounding area, the existing roadside layered landscape and the type of planted vegetation. The detailed analyses of the analysed parameters demonstrated that sustainable design of traffic calming measures on urban dual carriageways must consider not only the desired speed reduction but also the surrounding landscape and the local topography.

Diagnosis of Gasoline Injection Engine and Fault Tolerant Control

The paper presents some considerations regarding the diagnosis and control of a gasoline injection engine for motor vehicles. The growing importance of diagnosis is highlighted in the conditions in which the practice has shown that there are always some faults, the fault being defined as a deviation of a parameter or a variable from its nominal value. Here are some solutions used in the gasoline injection engine, related to fault tolerant control. It is exemplified by treating the air pressure control system admitted in the engine cylinders of the Audi A6 car, targeting the pressure sensor in the intake manifold. Keywords: motor vehicle, diagnosis, fault tolerant control (FTC), PID controller, fuzzy logic, control reconfiguration