Research on the Influence of Processing Parameters on the Specific Tensile Strength of FDM Additive Manufactured PET-G and PLA Materials

Fused deposition modeling (FDM) is one of the most accessible additive manufacturing (AM) technologies for processing polymeric materials. It allows processing most of thermoplastic polymers, with polyethylene terephthalate glycol-modified (PET-G) and polylactic acid (PLA). AM parts tend to display anisotropic behavior because of layer-by-layer fabrication and various technological parameters that can be set for 3D print, so it is hard to predict and analyze how the manufactured parts would behave under load. This research presents results of classic tensile strength tests performed on 57 PET-G specimens and 57 PLA specimens manufactured with varying technological parameters such as: printing temperature, print orientation, layer height, and infill percentage. Afterward, a comparative analysis is performed, proposing specific tensile strength (STS) as a benchmark to determine how 3D printed parts strength is varying due to beforementioned parameters, eliminating bias induced by varying weight of specimens. The biggest relative increase of UTS and the biggest relative decrease of STS was noted for variable infill percentage (increasing infill—PLA: 37.27% UTS increase and 30.41% STS decrease; PET-G: 24.42% UTS increase and 37.69% STS decrease). The biggest relative increase of STS between examined parameters was observed for both materials as the printing temperature was increased (27.53% for PLA and 12.69% for PET-G). Similar trends in STS changes were observed for both materials. Obtained data shows which FDM AM parameters are the most important to obtain the biggest UTS of manufactured parts, and those do not overlap with parameters needed to obtain optimal strength-to-weight ratio

Badania wpływu kształtu powierzchni roboczej walców na efekty pracy prasy walcowej praca doktorska /

Tyt. z ekranu tytułowego.Praca doktorska. Akademia Górniczo-Hutnicza im. Stanisława Staszica (Kraków), 2010.Zawiera bibliogr.Dostępna także w wersji drukowanej.Tryb dostępu: Internet.Stan wiedzy w zakresie scalania materiałów drobnoziarnistych w prasie walcowej, rozwoju jej konstrukcji, znaczenie, badania, doskonalenie procesu scalania materiałów drobnoziarnistych w prasie walcowej, doskonalenie konstrukcji pras walcowych, podstawowe kształty powierzchni roboczej elementów formujących, badania procesu brykietowania koncentratu miedzi w prasie walcowej, opis instalacji doświadczalnej, metodyka badań, charakterystyka materiałów użytych do badań, przygotowanie materiału do brykietowania, badanie wilgotności materiału, przebieg procesu brykietowania, pomiar poboru mocy prądu przez silnik układu napędowego prasy walcowej, badanie wytrzymałości brykietów na zrzut, na ściskanie, badania eksperymentalne procesu brykietowania koncentratu miedzi w prasie walcowej z grawitacyjnym układem podawania materiału, program badań eksperymentalnych, badania z wymuszonym podawaniem materiału, badania symulacyjne wpływu objętości brykietów na wartość nacisku jednostkowego w procesie brykietowania koncentratu miedzi, program symulacji komputerowej procesu brykietowania, wyznaczenie zmienności jednostkowego oporu zagęszczania, określenie zmienności współczynnika tarcia zewnętrznego, dobór geometrii powierzchni roboczej elementów formujących prasy, badania procesu scalania wodorotlenku wapnia w prasie walcowej, badanie podatności scalonego materiału na granulowanie dwustopniowe, badania eksperymentalne procesu brykietowania wodorotlenku wapnia, procesu kawałkowania, metoda doboru elementów formujących prasy walcowe

Analysis of the Temperature Distribution on the Surface of Saddle-Shaped Briquettes Consolidated in the Roller Press

The unit pressure in the fine-grained material consolidation process in the roller press can reach over hundred MPa and is a parameter which results, among other things, from the properties of the consolidated material and the compaction unit geometry. Its value changes depending on the place on the molding surface. Generating different pressure on the surface of briquettes makes their compaction different. One’s own and other researchers’ experience shows that, in the case of exerting high pressure on the merged fine-grained material, the higher unit pressure exerted on the material, the higher temperature of the consolidated material is. The temperature distribution on the surface of the briquettes can testify the locally exerted pressure on the briquette. The stress distribution in the briquetting material is still a subject of research. The article includes thermography studies of the briquetting process of four material mixtures. Thermal images of briquettes were taken immediately after they left the compaction zone as well as forming rollers. The obtained thermograms and temperature variability at characteristic points of the surface of briquettes were analyzed. The correlation between the temperature distribution and the stress distribution in the briquettes was determined

The Method of Calculating Ploughshares Durability in Agricultural Machines Verified on Plasma-Hardened Parts

Reliability consists of four components: failure-less operation, maintainability, durability, and preservation ability. For different machines and different conditions of operation, different combinations of these properties, and differences in how they are balanced and proportioned are essential. For tractors, the most important aspect of reliability is maintainability, while for agricultural machines, durability is most important. Using the example of a ploughshare, the issue of increasing the durability has been studied; a method for calculating the durability of a ploughshare for various types of soils has been described. The use of plasma hardening of the surface of a 65G-steel ploughshare has been proposed; the effectiveness of plasma hardening of soil-cutting parts and its economic feasibility have been proved. Due to hardening to a depth of 1–1.8 mm, the service life of parts increases by 2–3 times; moreover the downtime of expensive machine-tractor units for replacing worn-out parts is reduced

Use of the Finite Element Method in the Prediction of Stresses and Strains in Roller Press Frames

In the article the design solutions for the roller presses have been characterized. On this basis, several roller press models were selected, their CAD models were prepared and then the loads have been put on the roller press frames and other components of the presses. The results of a stress and strain analyses have been done using the finite element method. A comparison of individual solutions are presented. On the basis of the analysis performed, the construction of the considered object are rated and solutions aimed at improving the existing solutions are presented

The use of thermography to determine the compaction of a saddle-shaped briquette produced in an innovative roller press compaction unit

The unit compacting pressure in the fine-grained material consolidation process in the roller press can reach >100 MPa and is a parameter that results, among other things, from the properties of the consolidated material and the compaction unit geometry. Achieving the right pressure during briquetting is one of the factors that guarantee the proper consolidation and quality of briquettes. The distribution of the temperature on the surface of the briquettes correlates with locally exerted pressure. The present work aimed to analyse the bri-quetting process of four fine-grained materials in a roller press equipped with saddle-shaped briquette-forming rollers based on images ob-tained from the thermography conducted immediately after their consolidation. The tests were carried out in a roller press that was equipped with forming rollers of 450-mm diameter and having a cavity with a volume of 4 cm3, as described by patent PL 222229 B1. Two mixtures of hydrated lime with 9.1 wt% and 13.0 wt% water, a mixture of scale and a mixture of electric arc furnace (EAF) dust were used for the tests. In most mixtures, the highest temperatures were achieved in the middle-upper part of the briquettes. The briquettes from the EAF dust mixture heated locally the most on the surface up to 37.7 °C. The difference between the maximum briquette temperature and the ambient temperature was 20.2 °C

The Thermographic Analysis of the Agglomeration Process in the Roller Press of Pillow-Shaped Briquettes

When the briquetting process of fine-grained material takes place in the roller press unit, the pressure reached is over a hundred megapascals. This parameter is a result, among other factors, of the geometry of a compaction unit and also the properties of the consolidated material. The pressure of the unit is not constant and the changes in value depend on a given place on the molding surface. By the process of generating different types of pressure on the surface of briquettes, their compaction is different as well. The distribution of temperature on the surface of the briquettes may determine the pressure used locally on them. Nevertheless, the distribution of stress in the briquetting material is still a subject of scientific study. However, it is known that the pressure exerted on the briquette is different for different compaction systems. The article includes authors’ further thermography studies on the classical pillow-shaped briquetting process (instead of the saddle-shaped ones that were previously conducted) of four materials (calcium hydroxide and water mixture, mill scale, charcoal fines and starch mixture, as well as a mixture of EAFD, scale, fine coke breeze, molasses, and calcium hydroxide). Immediately after the briquettes left the compaction zone, thermal images were taken of them, as well as forming rollers. Thermograms that were obtained and the variability of temperature at characteristic points of the surface of pillow-shaped briquettes were analyzed. They showed differences in temperature on the surface of briquettes. In all four cases, the highest briquette temperatures were recorded in their upper part, which proves their better densification in this part. The temperature differences between the lower and upper part of the briquettes ranged from 1.8 to 9.7 °C, depending on the mixture

Modelling of the Fine-Grained Materials Briquetting Process in a Roller Press with the Discrete Element Method

By using the Altair® EDEM™ software, which implements the discrete element method, modelling and further study of the processes occurring in the roller press’s deformation area were carried out. It was shown that the discrete element method makes it possible to accurately describe the phenomena occurring in the area of roller press deformation compared with the finite element method. Models of material compaction in a roller press are developed using calcium hydroxide (slaked lime) and copper ore concentrate. The developed model makes it possible to determine the process’s energy parameters and the material’s compaction characteristics, taking into account the characteristics of its constituent particles. It was shown that discrete element modelling could be used effectively to create roller presses that provide rational characteristics of the briquetting process, taking into account the properties of the material being briquetted and the operating modes of the equipment. The results of the studies provided the basis for the applicability of the development of the discrete element method for describing the phenomena occurring in roller presses and accelerating the design of press equipment and briquetting technological processes

The Role of Chemical Composition of High-Manganese Cast Steels on Wear of Excavating Chain in Railway Shoulder Bed Ballast Cleaning Machine

The main task for a ballast bed is to transmit the sleeper pressure in a form of stress cone to the subsoil, provide proper drainage and resist the sleeper displacement. Poorly maintained ballast could severely limit the maximum speed capacity and create further problems with the structural integrity, possibly leading to a complete failure of a given rail line. To prevent the unwanted corollaries, the ballast bed has to be periodically cleaned with an appropriate machinery. In this paper the authors investigated the effect of the chemical composition on the physical properties of the ballast excavating chains made of high-manganese steels. The authors focused on the wear mechanism, work hardening ability and hardness in the cross-sections areas. A microstructure analysis was performed as well, and observations revealed divergent morphology of precipitations at the grain boundaries, which influenced the size of austenite grains. The deformation twins formed as a result of operation were noticed in the samples. Research has shown that less carbon and chromium reduces the hardness of cast steel, and it specifically affects the ability to strain hardening. The authors explained the role of adjustments in chemical composition in the operational properties of high-manganese cast steels. It has been shown in the paper that different chemical compositions affect the properties of the alloys, and this causes different types of wear. The high content of chromium increases the hardness of materials before and after plastic deformation hardening, which in the conditions of selector chains results in greater dimensional stability during wear of holes in pin joints and will be more susceptible to abrasive wear in the presence of dusts from the ballast than creep