This paper examined the cyclic deformation behaviour of multiphase low-carbon steel that was subjected to austempering heat treatments at four temperatures (190 °C, 230 °C, 275 °C, and 315 °C) below the martensite start temperature (Ms = 353 °C). The tests were conducted at room temperature, under fully reversed strain-controlled conditions, with strain amplitudes in the range 0.5–1.0%. The microstructure was observed by transmission electron microscopy, and the fracture surfaces were examined by scanning electron microscopy. The steel had a bainite/martensite microstructure, with increasing bainite content for higher austempering temperatures. Irrespective of the tested conditions, it strain-hardened during the first two cycles and then, strain-softened until failure. The austempering temperature did not significantly affect the stress-based, strain-based and energy-based relationships. However, lower austempering temperatures slightly improved the fatigue performance.
Analiza wewnętrznej struktury szkieletu pian węglowych (Reticulated Vitreous Carbon, RVC), przeprowadzona za pomocą mikrotomografii komputerowej, nie pozwoliła w sposób jednoznaczny określić w jakim stopniu ich struktura jest nieciągła. Dlatego, w celu dokładniejszej obserwacji zastosowano elektronową mikroskopię skaningową oraz optyczną. Wykonano również mikroprzekroje plazmą ksenonu i ablację laserową. Ponadto przeanalizowano topografię powierzchni przełomu szkieletu pian RVC. Na podstawie przeprowadzonych badań stwierdzono, że szkielet pian RVC nie wykazuje wewnętrznej porowatości.
EN
The analysis of the internal structure of RVC foams (Reticulated Vitreous Carbon) skeleton carried out by computed microtomography, did not allow to unambiguously determine to what extent their structure is discontinuous. Therefore, for more accurate observation, scanning electron microscopy and optical microscopy were used. Micro-cuts with Xenon plasma and laser ablation were also done. In addition, the topography of the breakthrough surface of the RVC foam skeleton was analyzed. On the basis of the conducted tests, it was found that the RVC foam skeleton does not show internal porosity.
This article presents selected aspects connected to work safety, related to production facilities in Poland, where production lines are installed as new, or transferred from other locations. The author focuses on ensuring work safety from the moment the decision of is made by company authorities, through the transfer of all production means and their commissioning to a regular production stage. The article contains the review of legislation, literature on technology transfer as well as researches and experiences of the author gained during his cooperation with international companies from the industries like food, energy, automotive and others.
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This paper presents the results of a study into the stress-based fatigue life calculation algorithm applied to cyclic and random multiaxial proportional and non-proportional loading. This method for high-cycle fatigue, covers both infinite and finite life region, and is based on a critical plane approach combined with rain flow cycle counting and linear damage accumulation. Algorithm based on the method for equivalent scaling of the normal stress in material planes in dependence on the stress state, proposed by Gaier and Danbauer. For analysis the calculated fatigue lives are compared to the experimental results for steel S355 under proportional and non-proportional bending with torsion.
The paper presents a solution of the control system for fatigue test stand MZGS-100 PL, comprising the integrated Real-Time controller based on FPGA (Field-Programmable Gate Array) technology with LabVIEW software. The described control system performs functions such as continuous regulation of speed induction motor, measuring strain of the lever machine and the test specimen, displacement of the polyharmonic vibrator, as well as the elimination of interferences, overload protection and emergency stop of the machine. The fatigue test stand also allows to set the pseudo-random history of energy parameter W(t).
PL
W pracy przedstawiono rozwiązanie układu sterowania maszyny zmęczeniowej MZGS-100PL, w oparciu o zintegrowany sterownik czasu rzeczywistego NI cRIO-9074 z oprogramowaniem Lab-VIEW w technologii FPGA. Przedstawiony układ sterowania umożliwia płynną regulację prędkości obrotowej silnika indukcyjnego, pomiar odkształceń dźwigni maszyny i badanej próbki, przemieszczenie wibratora poliharmonicznego, jak również eliminację zakłóceń oraz zabezpieczenie przed przeciążeniem i zatrzymanie awaryjne maszyny. Zaprezentowany system mechatroniczny do wyznaczania energetycznych charakterystyk zmęczeniowych materiałów przy zginaniu i skręcaniu pozwala na wyznaczanie energetycznych charakterystyk zmęczeniowych materiałów (Wa-N) przy obciążeniach cyklicznych oraz generowanie obciążeń pseudolosowych (poliharmonicznych).
The paper presents a review and comparison of energy-based fatigue models under uniaxial random loading. Fatigue life was calculated and compared with experimental results for choosing materials and types of loading.
The paper presents structure and principles of operation of the fatigue test stand for specimens subjected to polyharmonic proportional bending and torsion MZGS- 100 PL and show three options of digital control systems. Showned options of mechatronics systems based on data acquisition board Daqboard/2000, NI PXI-6259 in LabVIEW environment and programmable logie controller SAIA PCD2.
This paper presents solutions steerage system with still MZGS 100 PL machine. Machine MZGS 100 PL is used to research fixedness and loads. Steerage is possible realization of loads cyclic blocks about different amplitudes.
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Ogólny opis budowy i zasady działania maszyny do badań zmęczeniowych materiałów przy zmiennoamplitudowym zginaniu i skręcaniu oraz opis czterech układów do jej sterowania. Przedstawione warianty cyfrowych układów sterowania zawierają kartę pomiarową AMBEX z oprogramowaniem w języku C++, karty pomiarowe Daqboard/2000 i NI PXI-6259 z oprogramowaniem LabVIEW oraz sterownik PLC SAIA PCD2 i zostały użyte w systemie mechatronicznym, bazującym na maszynie zmęczeniowej typu MZGS-100 PL.
EN
General description and operating principles of a material fatigue testing machine under bending and torsion loads of varying amplitude are supplemented with descriptions of four versions of its control system.
The system is able to give rotational speed, and this feature joined with the polyharmonic vibrator (spacing and a number of weights at the disk edges) allows to obtain more options of sequence of loadings generated by the machine stand MZGS 100 PL. The measuring system uses the sensor of displacements and the tensometric bridge, so it is possible to measure strains [epsilon](t) and stresses [sigma](t) in the tested specimen. Control and measurements are performed in the LabVIEW environment with the Data Acqusition Board Daqboard/2000.
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