Janusz Lisiecki

Estimation of Measurement Uncertainty

Estimation of Measurement Uncertainty The paper presents rules for evaluation of measurement uncertainty. It includes the list of definitions for basic terms that are associated with the issue and explains how to evaluate the measurement uncertainty for well-defined physical parameter that is considered as the measured. Next, the method for evaluation of measurement uncertainty is exhibited on the examples when measurement uncertainty is estimated for verification of a micrometer as well as evaluated for basic reliability parameters.

Flexible Auxetic Foams - Fabrication, Properties and Possible Application Areas

Flexible Auxetic Foams - Fabrication, Properties and Possible Application Areas The paper presents a review of worldwide literature related to auxetic materials manufactured on the basis of the flexible polyurethane foam. Properties of auxetic foams are discussed with account taken of raw materials and fabrication methods applied. Due to their negative value of the Poissons ratio the properties demonstrated by auxetic foams are totally different from those of polyurethane foam that has been used so far. Application examples of these new foams are specified with account taken of their physical and chemical parameters but the particular attention is paid to possible use as vibration damping materials in automotive industry and transportation systems.

ZL-130TCII Fracture Markers Solution for Full-Scale Fatigue Test

ZL-130TCII Fracture Markers Solution for Full-Scale Fatigue Test In the context of PZL-130TC-II full-scale fatigue test, several strategies of fatigue loadings that create fracture surface markings were considered. One block of spectrum is made of 200 flights. By reordering those flights, a block which should create a fracture marker, was developed. It was very important that reordering the load spectrum or adding overloads or underloads did not change spectrum severity. Pilot tests of aluminium alloys specimens were carried out to finalise appropriate marker intervals before commencing full-scale tests. The experiment was conducted with the MTS machine with 810.23 system. The results and conclusions are presented within this paper.

Modyfikacja mnk do opisu krzywych propagacji pęknięć zmęczeniowych

Modyfikacja MNK do Opisu Krzywych Propagacji Pęknięć Zmęczeniowych W pracy przedstawiono wyniki modyfikacji metody najmniejszych kwadratów (MNK) poprawiającej dopasowanie równania NASGRO do opisu prędkości propagacji pęknięć zmęczeniowych da/dN. Modyfikacja dotyczy w szczególności wszelkich przypadków aproksymacji danych, gdy zakres wartości jednej ze zmiennych znacznie (np. o kilka rzędów wielkości) różni się od zakresu wartości innych zmiennych. Zobrazowano wpływ poszczególnych parametrów na przebieg i możliwości dopasowania ww. równania do danych doświadczalnych. Ze względu na dużą elastyczność w opisie przebiegów doświadczalnych da/dN=f(δK) równanie NASGRO znalazło szerokie zastosowanie praktyczne i jest aktualnie uznawane za najlepiej opisujące tę zależność.

Modification of the Least-Squares Method for Description of Fatigue Crack Propagation

Modification of the Least-Squares Method for Description of Fatigue Crack Propagation The paper presents the results obtained after modification of the least-squares method (LSM) intended to improve the correlation between the NASGRO equation and description of fatigue crack growth da/dN. In particular, the modification refers to all the cases when data approximation is to be carried out and value of one variable substantially differs (e.g. by several magnitude orders) from the range of values adopted by other variables. The attention is focused on illustrating the impact of individual parameters onto the course and possibility to match the aforementioned equation to experimental data. Due to high flexibility for description of experimental functions da/dN=f(δK) the NASGRO equation can be widely applied in practice and is deemed as the best tool to describe the foregoing relation.

Modification of the Equation for Description of Wöhler's Curves

Modification of the Equation for Description of Wöhlers Curves The paper presents the way to modify the equation σ = f(2Nf) in order to improve the fit of experimental results from High Cycle Fatigue tests. In particular, the study deals with introduction of the 5-parameter exponential equation that enables better fit of the full Wöhlers curve to experimental data within the range of stress at the level of fatigue threshold as well as approximation to the quasi-static range and Low Cycle Fatigue tests for the highest stress values. It is illustrated how individual parameters affect the procedure and possibility to match the aforementioned equation to experimental data.

Elastyczne Pianki Auksetyczne - Wytwarzanie, Właściwości I Potencjalne Zastosowania

Elastyczne Pianki Auksetyczne - Wytwarzanie, Właściwości I Potencjalne Zastosowania W artykule dokonano przeglądu literatury światowej dotyczącej materiałów auksetycznych na bazie elastycznej pianki poliuretanowej. Przedstawiono właściwości pianek auksetycznych w zależności od rodzaju zastosowanych surowców wyjściowych i metod otrzymywania. Ze względu na ujemny współczynnik Poissona pianki auksetyczne są materiałami o odmiennych właściwościach użytkowych w stosunku do dotychczas stosowanych pianek poliuretanowych. Podano przykłady zastosowań pianek w zależności od ich właściwości fizyko-mechanicznych. Szczególną uwagę zwrócono na zastosowania pianek auksetycznych jako materiałów tłumiących w motoryzacji i transporcie.

INVESTIGATIONS OF SOME PROPERTIES OF MATERIAL SAMPLES TAKEN FROM THE AIRCRAFT WITHDRAWN FROM SERVICE

Investigations of Some Properties of Material Samples Taken from the Aircraft Withdrawn from Service Materials used in aircraft structures have (should have) certificates confirming their quality. Nowadays, in majority of cases, the symbols of materials used in construction of aircraft give detailed information about their mechanical properties. This general material data is gathered in the widely available engineering material data bases. In the case of materials used in Polish aviation several decades ago, there is no reliable material data crucial for crack propagation estimation or fatigue life estimation among others. Examinations conducted in many different research institutes are not systematized and are not gathered in a remotely accessible data base. As aging aircraft are concerned, the influence of service time (often exceeding thirty years) on the overall material properties is a very important factor. It may be too crude estimation to use standard material properties when it comes to aging aircraft fleet. Some experimental works concerning this topic are published from time to time and they are always very welcome. In the Air Force Institute of Technology experimental tests were carried out to determine some specific properties of the materials used in the PZL-130 Orlik aircraft structure. The samples were obtained from aircraft withdrawn from service. This enabled estimating the difference in material properties over time. The following tests were conducted during the experiments: - fatigue tests (crack propagation examination) - static tests. The analyzed material was taken from the central upper part of the aircraft wing. The experiment was conducted with the MTS machine with the 810.23 system.

Strength Testing and Analysis of Fatigue Crack Growth in Selected Aircraft Materials

Strength Testing and Analysis of Fatigue Crack Growth in Selected Aircraft Materials The study has been intended to determine the most essential mechanical and fatigue properties as well as impact strength of the 30HGSNA steel, to gain own data on the above-mentioned characteristics of materials to be used further on in numerical analyses of life estimates of aeronautical structural components. The scope of the study comprised the following assignments: - determination of the most fundamental mechanical properties and impact strength of materials - low-cycle fatigue testing and evaluation of the Manson-Coffin curves - high-cycle fatigue testing and evaluation of the Wöhler curves - investigation into fatigue crack growth rates at constant and variable load-cycle amplitudes (determination of curves da/dN = f(ΔK, R), coefficients in Paris and NASGRO equations, coefficients in the Wheeler models of delay, the value of Kth(R)) - crack toughness testing under the plane-state-of-strain conditions at room temperature (determination of the KIc(R)). The strength/fatigue testing was carried out in the Laboratory for Materials Strength Testing of the AFITs Division for Aeronautical Systems Reliability and Safety, the lab being accredited by the Polish Centre for Accreditation (Accreditation Certificate No.: AB 430).

Selected Problems of Measurement Uncertainty — Part 1@@@Wybrane Zagadnienia Niepewności Pomiaru - CZ. 1

The rules for evaluation of measurement uncertainty are presented in this paper. It includes the list of definitions for basic terms that are associated with the issue and explains how to evaluate the measurement uncertainty for well-defined physical parameters that are considered as the measurands (part 1). Next, the methods for evaluation of measurement uncertainty are exhibited on the examples when measurement uncertainty is estimated for verification of a micrometer as well as evaluated for basic reliability parameters (part 2). WYBRANE ZAGADNIENIA NIEPEWNOŚCI POMIARU – CZ. 1 Sylwester Klysz1,2, Janusz Lisiecki1 1 Zaklad Niezawodności i Bezpieczenstwa Techniki Lotniczej Instytut Techniczny Wojsk Lotniczych w Warszawie 2 Katedra Materialow Funkcjonalnych i Nanotechnologii Uniwersytet Warminsko-Mazurski w Olsztynie Slowa kluczowe: niepewnośc pomiaru, niepewnośc typu A i typu B, bląd pomiaru, rozklad normalny i prostokątny, budzet niepewności.