Time filter

Source Type

Szymczak T.,Polish Motor Transport Institute | Kowalewski Z.,Polish Institute of Fundamental Technological Research
Archives of Metallurgy and Materials

The paper presents behaviour of materials under complex loading being combinations of torsion-reverse-torsion cycles superimposed on monotonic tensile deformation. The 2024 aluminium alloy, P91 steel and M1E copper were investigated under plane stress state using thin-walled tubular specimens. All tests were strain controlled and a total strain was less than 1%. An influence of torsion cycles on tensile characteristic was manifested by lowering of the proportional limit and yield point. This effect was increased with magnification of cyclic strain amplitude and in the case of copper a reduction of yield point was equal around 90%. A character of this effect was checked using the yield surface concept after each test. The papers also presents, variations of tangential hardening modulus and plastic strain energy dissipation. Source

In recent years, dynamic development of electric drives in automotive applications has been taking place. Electrically driven vehicles are considered to offer a possibility of solving the most important ecological problems posed by motorisation. The paper presents results of testing the energy consumption by an electric car in conditions corresponding to actual operation of such vehicles, i.e. at drive tests where urban, extra-urban, and traffic jam conditions were simulated. The disitance energy consumption and total vehicle efficiency were determined at drive tests. An energy consumption characteristic was determined in pseudorandom conditions of urban operation of the car, with employing the Monte Carlo method for this purpose. Source

Paper presents the results of pollutant emission tests from the self ignition engine in various states of its operation. Engine operating states were obtained on the engine test stand. The investigations were conducted in static and dynamic tests, both standard used in the type approval procedures as special ones, simulating specific engine operating conditions. The specific brake emission of carbon monoxide as well as those of hydrocarbons, nitrogen oxides and particulate matter, averaged during the tests, have been determined. The influence of the engine operating states on the pollutant emission of impurities has been evaluated. Very high sensitivity was established of the pollutant specific brake emission on the operating states of the engine, both static ones and dynamic. Source

The article is an attempt to find relationship between the implemented system of periodic technical inspections of vehicles and the number of road accidents, reliability of vehicles and road safety. The study utilises results of comparative tests, where the relationships and parameters could be directly observed for the cases with the system implemented and some without periodic technical inspections at all (for example: between the states of the USA, Australia and the research work conducted in Norway in the 90's). The analysis of results leads to unexpected conclusion that system of periodic technical inspections of vehicles does not have statistically signifcant effect on the number of accidents, including the number of road accidents involving fatalities. Source

Mocko W.,Polish Institute of Fundamental Technological Research | Mocko W.,Polish Motor Transport Institute
Materials and Design

This study analyses the influence of fatigue loading on the residual tensile properties of AISI 1045 steel. The fatigue tests were carried out under stress-controlled tensile loadings at a stress ratio equal to 0. The maximum applied stresses were within the range from 550 MPa to 790 MPa. An analysis of ratcheting strain and plastic strain amplitude evolution due to fatigue loading was performed on the experimental data. In the next stage of this study, the initial fatigue loadings were introduced. Two maximum stresses, 550 MPa and 750 MPa, and three cycle lengths, 25%, 50% and 75% of the total number of cycles required to fracture the material at a given stress, were used. The pre-fatigued specimens were subjected to tensile testing at strain rates from 10-4 to 100 s-1. A large number of fatigue cycles, equal to 75% of the fatigue life, induces material softening as well as a drop in elongation and a reduction of area. Pre-fatigue at maximum stress equal to 550 MPa results in the increase of the elastic limit and offset yield point as well. Both parameters reach almost constant value after number of cycles equal to 25 % of the fatigue life. The further increase in the number of cycles does not affect elastic limit and offset yield point in a clearly visible way. The increase of maximum stress of the initial fatigue loadings up to 750 MPa induces similar but stronger effect i.e. increase and stabilization of elastic limit and offset yield point values, however decrease of both parameters value is observed at large number of pre-fatigue cycles corresponding to 75% of the fatigue life. © 2014 Elsevier Ltd. Source

Discover hidden collaborations