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Mocko W.,Polish Motor Transport Institute | Kowalewski Z.L.,Polish Institute of Fundamental Technological Research
Applied Mechanics and Materials | Year: 2011

The paper presents constitutive model of the aluminium metal matrix composite reinforced by a silicon carbide. Developed equation includes an empirically estimated term which takes into account softening effects of the composite due to reinforcement damages at a large strain. Experimental investigation of the aluminium based MMCs reinforced by silicon carbide of volume fraction equal to 0%, 10%, 20% and 30% were carried out. Tests were conducted at wide range of strain rates and large magnitudes of strains. Comparison between experimental and predicted data shows that the elaborated model may be applied for composite materials in computer simulations of large deformations. © (2011) Trans Tech Publications.

Mocko W.,Polish Institute of Fundamental Technological Research | Mocko W.,Polish Motor Transport Institute | Kowalewski Z.L.,Polish Institute of Fundamental Technological Research | Kowalewski Z.L.,Polish Motor Transport Institute
Kovove Materialy | Year: 2013

This paper presents the assembly of the miniaturised direct impact compression test method (MDICT) developed at the Institute of Fundamental Technological Research at the Polish Academy of Sciences (IFTR PAS). Additionally, this method was used to investigate the mechanical properties of tantalum at the strain rate of 8 × 105 s-1. To analyse the phenomena occurring during the tests, a numerical model of the testing stand was developed and validated. The finite element (FEM) model was expanded to estimate the sources of error achieved in the results using the analytical methods. The effects related to friction, inertia, specimen ratio, adiabatic heating, stress equilibration and strain rate on the stress-strain characteristic observed before and after the analytical correction were discussed.

Szymczak T.,Polish Motor Transport Institute | Kowalewski Z.,Polish Institute of Fundamental Technological Research | Brodecki A.,Polish Motor Transport Institute
Materials Today: Proceedings | Year: 2016

The paper concerns numerical and experimental investigations carried out for determination of an influence of holes on material behaviour under monotonic tension. The 40Cr steel commonly applied in automotive and power plant branches of industry was tested. The analysis was performed by the use of analytical and Finite Element Method calculations. It enabled identification of stress concentration/maximum stress versus hole diameter relationships, and the HMH stress distribution. Full-field contactless Digital Image Correlation (DIC) system was used for capturing the effective strain variations from the beginning of test up to specimen fracture. It enabled us to indicate the most important stress concentrator, and moreover, distribution of the HMH effective strain in 2D coordinate system. A comparison of tensile characteristic obtained by means of smooth and perforated specimens showed 70% reduction of yield point and 50% lowering of elongation as an effect of the artificial defects introduced. © 2016.

Mocko W.,Polish Institute of Fundamental Technological Research | Mocko W.,Polish Motor Transport Institute
Materials and Design | Year: 2014

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.

Mocko W.,Polish Motor Transport Institute | Brodecki A.,Polish Motor Transport Institute
Materials and Design | Year: 2015

In this paper, the application of the Rusinek-Klepaczko relation to describe the constitutive behaviour of Ti6Al4V titanium alloy with an HCP crystalline structure was proposed. The calibration of model coefficients was carried out on the basis of tensile tests. To obtain true stress-strain curves at quasi-static and dynamic loading conditions, the optical field measurement method was applied to determine the history of specimen cross-sections at the necking point. The outline of the specimen was tracked by virtual strain gauges implemented in TEMA Motion software. Adiabatic characteristics obtained at high strain rates using a pre-tension Hopkinson bar were corrected into quasi-isothermal using an analytical approach. Subsequently, a visco-plastic model calibrated using introduced methodology was validated using the finite element method. Engineering stress-strain curves, calculated using ABAQUS software incorporating the Rusinek-Klepaczko model, showed good agreement with experimental data at both quasi-static and dynamic deformation regimes. Moreover, numerical analysis of tensile tests shows that the strain, temperature and stress triaxiality distribution is non-homogenous in specimen cross-sections perpendicular to the loading direction. The value of the strain, temperature and stress triaxiality also depends on the strain rate. © 2015 Elsevier Ltd.

Chlopek Z.,Polish Motor Transport Institute
Archives of Transport | Year: 2014

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.

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.

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.

A tachograph which belongs to the group of ORD devices is the oldest recorder (On Board Recording Devices), and the duty of taking it was led into the USA already in 1939. In order to solve all these problems, they led with Directive of Advice No. 2135/98 from 24 September 1998 of the August of 2004 from the beginning of in the area of the European Union, new type of registering setting up in the road transport-digital tachograph. In order to make it impossible to abuse, a complex system of keys was applied cryptological and of certificates, saved in grating and devices, letting for explicit determining entitlements of users and authenticities of data, cards and devices. In spite of using the most modern keys and securing systems, with respect to elements of the system of digital tachographs a lot of modus operandis were observed so that they registered wrong sizes. The European Union took right action in order to prevent, nevertheless they must be implemented into the everyday life. This paper includes information about level of manipulation of digital tachograph and their elements, ways of manipulation of digital tachograph and future ways of counteracting manipulations. Copyright © 2013 SAE International and Copyright © 2013 SIAT, India.

Rostek E.,Polish Motor Transport Institute
Solid State Phenomena | Year: 2015

The article presented the processes of pyrolysis and gasification of biomass leading to the preparation of liquid hydrocarbon fractions in the synthesis of Fischer-Tropsch and processes HTU. Preliminary thermogravimetric testing of biomass samples was conducted on the STA 449 F3 Jupiter® coupled with the gases analyzer – spectrometer QMS 403 Aëolos. These studies were carried out for samples of cereal straw, crushed to a state of dry dust. The temperature regime provided that the samples were heated to the temperature of 750 °C at the heating rate of 10 K/min. Gases (nitrogen, argon or carbon dioxide) were used with flow rates of 60 mL/min. The results, along with discussion, are presented in graphs-TG curves and mass spectrum. © (2015) Trans Tech Publications, Switzerland.

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