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Strength Analysis Aspects of Psyllium/Thermoplastic Starch Films under Impact Loading Conditions

Beer-Lech Karolina, Kołodziej Paweł, Skic Anna, Branco Ricardo

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

385--393

EN

Tensile test under quasi-static loads conditions is usually used to determine the mechanical strength of thermoplastic starch films. This kind of test does not fully illustrate the load conditions for packaging films, which, under the conditions of use, are succumb to dynamic loads. Thus, the aim of the study was to present the possibilities of using a patented soft tissues measurement testing station to analyze the mechanical strength of thermoplastic starch (TPS) films under impact loading conditions. Two groups of film specimens containing the addition of psyllium husks (TPS/PH) and psyllium flour (TPS/PF) were used for the measurements. The casting method was applied, and glycerol was used as a plasticizer. Microstructure of the specimen surface was analyzed by stereoscopic microscopy. Specimens with the addition of psyllium flour had a more uniform microstructure. The maximum breaking forces obtained during impact tests for these films were 5 times higher than specimens containing psyllium seed husk. The same behaviour was found with respect to stresses with average values of 48.6 MPa for TPS/PF and 20.2 MPa for TPS/PH. Moreover, research confirms usefulness of patented soft tissues measurement testing station to analyse the mechanical strength of thermoplastic starch films.

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Effect of non-zero mean stress bending-torsion fatigue on fracture surface parameters of 34CrNiMo6 steel notched bars

Macek Wojciech, Szala Mirosław, Trembacz Jarosław, Branco Ricardo, Costa José

Production Engineering Archives

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2020

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Vol. 26, Iss. 4

167--173

EN

Modern methods of testing materials require the use of the latest technologies and combining measurement and calculation methods. It is important to find a quantitative way of describing, among other things, the failures so that it can help to design with high accuracy. This paper studies loading orientations on crack shape and fracture surface changes. The advantage of the entire fracture surface method is simplicity and applicability in studies on other materials, shapes and loadings. A higher values of fracture surface parameters (Sx, Vx) was observed in failure specimens with lower σ/τ (B/T) ratios. It has been observed that largest crack lengths with a small number of cycles occur for loading combinations different then B=T. As well as analyzed surface parameters Sx, Vx, are higher for larger number of cycles to crack initiation (Ni) values.

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Mechanical Properties and Sliding Wear Resistance of Suspension Plasma Sprayed YSZ Coatings

Łatka Leszek, Szala Mirosław, Macek Wojciech, Branco Ricardo

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

307--314

EN

In this work, the yttria stabilised zirconia ZrO2 + 8 wt% Y2 O3 (YSZ) coatings were studied. The coatings were manufactured by using a relatively new method based on liquid feedstock, called suspension plasma spraying (SPS). The main aim of the study was to investigate the influence of one of the fundamental process parameters, stand-off distance, on the YSZ coating mechanical properties, namely adhesion, cohesion, hardness, and dry sliding wear resistance. Moreover, the coating surface morphology and microstructure were investigated. Despite the fact that in the SPS method, the heat flux into the substrate is much higher than in conventional atmospheric plasma spraying (APS), for the stand-off distances as short as 40 mm, the structure has not been damaged by thermal stresses. The results revealed that shorter spray distance leads to obtaining the coatings characterised by higher cohesion and adhesion to the substrate as well as higher hardness and resistance to sliding wear. The wear mechanism of both YSZ coatings relies on the adhesive mode, which is intensified by severe coating material delamination.