Publications by authors named "Tomasz Sadowski"

10 Publications

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A Novel Approach by Spark Plasma Sintering to the Improvement of Mechanical Properties of Titanium Carbonitride-Reinforced Alumina Ceramics.

Molecules 2021 Mar 3;26(5). Epub 2021 Mar 3.

Łukasiewicz Research Network-Cracow Institute of Technology, Centre of Advance Manufacturing Technology, 73 Zakopianska St., 30-418 Cracow, Poland.

Ti(C,N)-reinforced alumina-zirconia composites with different ratios of C to N in titanium carbonitride solid solutions, such as Ti(C,N) (C:N = 30:70) and Ti(C,N) (C:N = 50:50), were tested to improve their mechanical properties. Spark plasma sintering (SPS) with temperatures ranging from 1600 °C to 1675 °C and pressureless sintering (PS) with a higher temperature of 1720 °C were used to compare results. The following mechanical and physical properties were determined: Vickers hardness, Young's modulus, apparent density, wear resistance, and fracture toughness. A composite with the addition of Ti(C,N)n nanopowder exhibited the highest Vickers hardness of over 19.0 GPa, and its fracture toughness was at 5.0 Mpa·m. A composite with the Ti(C,N) phase was found to have lower values of Vickers hardness (by about 10%), friction coefficient, and specific wear rate of disc (Ws) compared to the composite with the addition of Ti(C,N). The Vickers hardness values slightly decreased (from 5% to 10%) with increasing sintering temperature. The mechanical properties of the samples sintered using PS were lower than those of the samples that were spark plasma sintered. This research on alumina-zirconia composites with different ratios of C to N in titanium carbonitride solid solution Ti(C,N), sintered using an unconventional SPS method, reveals the effect of C/N ratios on improving mechanical properties of tested composites. X-ray analysis of the phase composition and an observation of the microstructure was carried out.
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http://dx.doi.org/10.3390/molecules26051344DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7959295PMC
March 2021

The Use of Neural Networks in the Analysis of Dual Adhesive Single Lap Joints Subjected to Uniaxial Tensile Test.

Materials (Basel) 2021 Jan 15;14(2). Epub 2021 Jan 15.

Department of Solid Mechanics, Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 38, 20-618 Lublin, Poland.

Adhesive bonding are becoming increasingly important in civil and mechanical engineering, in the field of mobile applications such as aircraft or automotive. Adhesive joints offer many advantages such as low weight, uniform stress distribution, vibration damping properties or the possibility of joining different materials. The paper presents the results of numerical modeling and the use of neural networks in the analysis of dual adhesive single-lap joints subjected to a uniaxial tensile test. The dual adhesive joint was created through the use of adhesives with various parameters in terms of stiffness and strength. In the axis of the overlap, there was a point bonded joint characterized by greater stiffness and strength, and on the outside, there was a bonded joint limited by the edges of the overlap and characterized by lower stiffness and strength. It is an innovative solution for joining technology and the influence of such parameters as the thickness of one of the adherends, the radius of the point bonded joint and the material parameters of both adhesive layers were analyzed. The joint is characterized by a two-stage degradation process, i.e., after the damage of the rigid adhesive, the flexible adhesive ensures the integrity of the entire joint. For numerical modeling, the Finite Element Method (FEM) and cohesive elements was used, which served as input data to an Artificial Neural Network (ANN). The applied approach allowed the impact of individual parameters on the maximum force, initiation energy, and fracture energy to be studied.
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http://dx.doi.org/10.3390/ma14020419DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7831007PMC
January 2021

Material Characterization of PMC/TBC Composite Under High Strain Rates and Elevated Temperatures.

Materials (Basel) 2020 Jan 1;13(1). Epub 2020 Jan 1.

Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 38, 20-618 Lublin, Poland.

Polymer matrix composites (PMC), despite their many advantages, have limited use at elevated temperatures. To expand the scope of their uses, it becomes necessary to use thermal barrier coatings (TBC). In addition to elevated temperatures, composite structures, and thus TBC barriers, can be exposed to damage from impacts of foreign objects. Therefore, before using the thermal barrier in practice, knowledge about its behavior under high-speed loads is necessary. The paper presents results for samples with the PMC/TBC system subjected to dynamic compression using a split Hopkinson pressure bar (SHPB). The substrate was made of CFRP (carbon reinforced polymer) with epoxy matrix and twill fabric. TBC was made of ceramic mat saturated by commercial hardener from Vitcas company. The tests were carried out at ambient temperature and elevated temperature-55 °C and 90 °C. Tests at ambient temperature were carried out for three pressure levels: 1, 1.5, and 2 bar. Only the pressure of 1 bar was used for the elevated temperature. Studies have shown that the limit load is 1 bar for ambient temperature. At 1.5 bar, cracks occurred in the TBC structure. Increased temperature also adversely affects the TBC barrier strength and it is damaged at a pressure of 1 bar.
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http://dx.doi.org/10.3390/ma13010167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981405PMC
January 2020

Characterization and validation of an in vivo confocal Raman spectroscopy led tri-method approach in the evaluation of the lip barrier.

Skin Res Technol 2020 May 9;26(3):390-397. Epub 2019 Dec 9.

proDERM Institute of Applied Dermatological Research GmbH, Hamburg, Germany.

Background/aim: It was the aim to establish and validate in vivo confocal Raman spectroscopy for characterization of the lip barrier in conjunction with transepidermal water loss (TEWL) and skin capacitance assessments. For the first time in vivo, barrier-relevant components of the lip (derived, natural moisturizing factors (NMFs) and ceramides are described.

Methods: In 32 healthy volunteers, a dental tongue fixation device was inserted to prevent both voluntary and involuntary lip moisturization during measurements. Seventeen individual parameters relating to water, ceramide, and NMF content were assessed via Raman spectroscopy. Additionally, corneometry and TEWL were measured. To give a guidance for the required volunteer group size of future lip barrier studies for all test parameters, coefficients of variation (CV) were calculated and plots showing the required sample size for a given percentage treatment effect.

Results: Raman spectroscopy assessed parameters on the lower lip comprehensively characterized the state of the lip barrier. Parameter variability was sufficiently low to corroborate changes in most parameters using relatively small study populations.

Conclusions: Lip skin is comparatively well hydrated. Biophysical measurement of the lip barrier function is a challenge, as unconscious licking of the lower lip has to be prevented. In vivo confocal Raman spectroscopy provides insightful parameters for the characterization of the lip barrier and sufficiently low inter-individual variability to assess relatively small parameter changes employing relatively few study subjects. Differences at the molecular level and at a high spatial resolution are detectable, and these insights might provide a breakthrough in the evaluation of lip barrier function and developing solutions for lip care.
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http://dx.doi.org/10.1111/srt.12814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317720PMC
May 2020

Three-Dimensional Free Vibration Analysis of Thermally Loaded FGM Sandwich Plates.

Materials (Basel) 2019 Jul 25;12(15). Epub 2019 Jul 25.

Department of Higher Mathematics, National Technical University 'Kharkiv Polytechnic Institute', 2 Kyrpychova Str., 61002 Kharkiv, Ukraine.

Using the finite element code ABAQUS and the user-defined material utilities UMAT and UMATHT, a solid brick graded finite element is developed for three-dimensional (3D) modeling of free vibrations of thermally loaded functionally gradient material (FGM) sandwich plates. The mechanical and thermal material properties of the FGM sandwich plates are assumed to vary gradually in the thickness direction, according to a power-law fraction distribution. Benchmark problems are firstly considered to assess the performance and accuracy of the proposed 3D graded finite element. Comparisons with the reference solutions revealed high efficiency and good capabilities of the developed element for the 3D simulations of thermomechanical and vibration responses of FGM sandwich plates. Some parametric studies are carried out for the frequency analysis by varying the volume fraction profile and the temperature distribution across the plate thickness.
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http://dx.doi.org/10.3390/ma12152377DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6696097PMC
July 2019

The Influence of Single Lap Geometry in Adhesive and Hybrid Joints on Their Load Carrying Capacity.

Materials (Basel) 2019 Jun 12;12(12). Epub 2019 Jun 12.

Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 38, 20-618 Lublin, Poland.

The manufacturing technology for adhesive joints is not yet fully optimized, as proved by a large number of papers that have been published in recent years. Future studies on innovative techniques for fabricating adhesive joints should investigate the influence of parameters such as: (1) The shape of adhesive protrusion, (2) lap dimensions, and (3) cohesive layer reduction in the most efforted regions of the joint. With the application of additional mechanical connectors (e.g., rivets, screws, and welds) in adhesive joints, new hybrid connections can be fabricated. The number of publications in this new field is still relatively small. To fill the gap, this paper presents the results of a numerical analysis of different single lap geometries in (1) pure adhesive and (2) hybrid joints. A total of 13 different models with the same surface area of the adhesive layer were considered. In the case of hybrid joints, the adhesive surface before the application of mechanical connectors was assumed to be the same in every tested case. The numerical analysis of pure adhesive and hybrid joints revealed that the differences in strength led to a 30% decrease in the load capacity of these joints. Therefore, when designing pure adhesive and hybrid joints, special attention should be paid to the shape of the lap between the joined elements.
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http://dx.doi.org/10.3390/ma12121884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6630626PMC
June 2019

Temperature Effects during Impact Testing of a Two-Phase Metal-Ceramic Composite Material.

Materials (Basel) 2019 May 17;12(10). Epub 2019 May 17.

Lublin University of Technology, PL-20-618 Lublin, Poland.

Metal-ceramic composite (MCC) materials can be used for manufacturing high-responsibility structures such as jet engines or cutting tools. One example of these materials is a two-phase wolfram carbide (WC) and cobalt (Co) composite. This MCC is a combination of hard WC grains with a Co metallic ductile binder. The resulting microstructure is a combination of two phases with significantly different mechanical behaviors. In this study, we investigate impact conditions, starting with an illustrative example of the Taylor impact bar where-although the process is very rapid-the equivalent plastic strain and temperature are higher in the adiabatic solution than those in the coupled solution. On exposing the WC/Co composite with a metallic binder to impact loading, heat is generated by plastic deformation. If the process is fast enough, the problem can be treated as adiabatic. However, a more common situation is that the process is slower, and the heat is generated in the ductile metallic binders. As a result, the associated grains are heated due to the conduction effect. Consequently, the process should be treated as coupled. When the impact is applied over a short time period, maximum temperatures are significantly lower if the process is analyzed as coupled rather than as adiabatic. The grains are immediately affected by temperature increase in the binders. Therefore, the heat conduction effect should not be omitted.
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http://dx.doi.org/10.3390/ma12101629DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566361PMC
May 2019

The Influence of TBC Aging on Crack Propagation Due to Foreign Object Impact.

Materials (Basel) 2019 May 8;12(9). Epub 2019 May 8.

Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 38, 20-618 Lublin, Poland.

While a plane is maneuvering before take-off and landing, some solid particles (e.g. sand, dust, soil) may get into the engine with air. A vast majority of them are stopped by the compressor blades, but the smaller ones can get into a hot part of the engine and cause erosion. A pneumatic laboratory work station was built in order to investigate the impact of foreign object damage (FOD) particles with a diameter of 4 mm. Cylindrical samples with a diameter of 30 mm were used, each having a thermal barrier coating (TBC) deposited by the air plasma spray (APS) method with the application of yttria-stabilized zirconia (YSZ). Sample aging was performed for four ranges: 48, 89, 185, and 353 h at the temperature of 1000 °C. After aging, samples were subjected to impacts made with different energies. Various damage images were captured depending on the aging time and impact velocity. Numerical studies led to the determination of how the incidence angle of a foreign object and the blade temperature affected the number of elements that became damaged during impact. It was found that impacts perpendicular to the surface were the most dangerous, while heating the blade to the operating temperature resulted in a 27% decrease in the number of elements damaged during impact when compared to the cold blade.
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http://dx.doi.org/10.3390/ma12091488DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6540608PMC
May 2019

Large-scale human skin lipidomics by quantitative, high-throughput shotgun mass spectrometry.

Sci Rep 2017 03 7;7:43761. Epub 2017 Mar 7.

Lipotype GmbH, Dresden, Germany.

The lipid composition of human skin is essential for its function; however the simultaneous quantification of a wide range of stratum corneum (SC) and sebaceous lipids is not trivial. We developed and validated a quantitative high-throughput shotgun mass spectrometry-based platform for lipid analysis of tape-stripped SC skin samples. It features coverage of 16 lipid classes; total quantification to the level of individual lipid molecules; high reproducibility and high-throughput capabilities. With this method we conducted a large lipidomic survey of 268 human SC samples, where we investigated the relationship between sampling depth and lipid composition, lipidome variability in samples from 14 different sampling sites on the human body and finally, we assessed the impact of age and sex on lipidome variability in 104 healthy subjects. We found sebaceous lipids to constitute an abundant component of the SC lipidome as they diffuse into the topmost SC layers forming a gradient. Lipidomic variability with respect to sampling depth, site and subject is considerable, and mainly accredited to sebaceous lipids, while stratum corneum lipids vary less. This stresses the importance of sampling design and the role of sebaceous lipids in skin studies.
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http://dx.doi.org/10.1038/srep43761DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5339821PMC
March 2017

Measuring lipid packing of model and cellular membranes with environment sensitive probes.

Langmuir 2014 Jul 30;30(27):8160-6. Epub 2014 Jun 30.

Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.

The extent of lipid packing is one of the key physicochemical features of biological membranes and is involved in many membrane processes. Polarity sensitive fluorescent probes are commonly used tools to measure membrane lipid packing in both artificial and biological membranes. In this paper, we have systematically compared eight different probes to measure membrane lipid ordering. We investigated how these probes behave in small unilamellar liposomes, phase-separated giant unilamellar vesicles, cell-derived giant plasma membrane vesicles, and live cells. We have tested the order sensitivity of a variety of measurable parameters, including generalized polarization, peak shift, or intensity shift. We also investigated internalization and photostability of the probes to assess probe potential for time-lapse live cell imaging. These results provide a catalogue of properties to facilitate the choice of probe according to need.
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http://dx.doi.org/10.1021/la501226vDOI Listing
July 2014
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