Browsing by Subject "fatigue"

Now showing 1 - 4 of 4

Access status: Open Access ,
Al 6082 and Al 7075 alloys under the modified low-cycle fatigue test
(2016) Maj, Maria; Piekło, Jarosław
This paper discusses the possibility of assessing the quality of materials in terms of their mechanical properties as determined by a modified low-cycle fatigue test applied in these studies. The developed computer program adapted to the needs of an MTS universal testing machine is described, as are the details of an algorithm used by this program. The compatibility of test results obtained by the two methods (i.e., the standard low-cycle fatigue test [LCF] and its modified original version [MLCF]) has been demonstrated on the samples of selected non-ferrous metals alloys.
Access status: Open Access ,
Analiza przyczyn powstawania pęknięć zmęczeniowych w konstrukcji bębna pędnego maszyny wyciągowej
(Wydawnictwa AGH, 2005) Cichociński, Andrzej; Ładecki, Bogusław
Still in use today there are some hoisting mining machines with motion wheels, the construction of which uses ri-gid 'U' shaped diaphragms to connect side disks. In such wheels periodically, after servicing, fatigue cracks are being found. The authors performed strength analysis done by the finite elements method, and verified its results using appropriate tensammetric measurements. The measurements and analyses performed confirmed that direct cause of the fatigue cracks in the barrels is over-rigidity of the structure due to stiff diaphragms joining the wheel disks. Based on this, recommendations were issued regarding modernization of motion wheels in the discussed ho-isting machines.
Access status: Open Access ,
Ocena zasobu trwałości zmęczeniowej ustrojów nośnych maszyn podstawowych górnictwa odkrywkowego
(Wydawnictwa AGH, 2011) Alenowicz, Jerzy; Onichimiuk, Marek; Wygoda, Marian
Specificity of operation and construction of opencast mining basic machines has been presented in the paper. Regulations of load carrying structures dimensioning and existing inconveniences have been discussed. Reasons of fatigue fracturing in these structures have been indicated. Previous assessment methods of fatigue life resources based on research have been presented. Description and operational scheme of a system of constant monitoring of load carrying structure effort of opencast mining basic machines has been placed. Advantages resulting from system implementation in current exploitation of machines have been given. Possibilities of system implementation in brown coal opencast mines have been discussed.
Access status: Open Access ,
Significance of rivet flexibility for load transfer in lap joints
(2010) Skorupa, Małgorzata; Machniewicz, Tomasz; Korbel, Adam; Skorupa, Andrzej
Presented in this paper are results of an experimental investigation on the rivet flexibility and load transmission in a riveted lap joint representative for the aircraft fuselage. The test specimens consisted of two aluminium alloy Alclad sheets joined with three rows of rivets. Rivet flexibility measurements have been performed under constant amplitude fatigue loading using several methods including two novel optical techniques developed by the present authors. The axial forces in the sheets required to determine the rivet flexibility have been derived from strain gauge measurements. In order to eliminate the effect of sheet bending the strain gauges have been bonded at the same locations on the outside and faying surface of the sheet. Variations of the rivet flexibility during the fatigue loading as well as the dependence of the rivet flexibility and load transmission on the rivet squeeze force have been studied. The experiments enabled to evaluate the usefulness of various techniques to determine the rivet flexibility. It was observed that although the measured flexibility was identical for both outer rivet rows, the load transfer through either of these rows was different. Previous experimental results of the authors suggest that the non-symmetrical load transfer distribution through the joint is associated with large differences between the rivet hole expansion in the sheet adjacent to the driven rivet head and the sheet under the manufactured head. It has been concluded that commonly used computation procedures according to which the load transfer is only related to the rivet flexibility may lead to erroneous results.