To investigate the mechanical properties of tunnel lining concrete under different moderate-low strain rates after high temperatures, uniaxial compression tests in association with ultrasonic tests were performed. Test results show that the ultrasonic wave velocity and mass loss of concrete specimen begin to sharply drop after high temperatures of 600°C and 400°C, respectively, at the strain rates of 10‒5s‒1 to 10‒2s‒1. The compressive strength and elastic modulus of specimen increase with increasing strain rate after the same temperature, but it is difficult to obtain an evident change law of peak strain with increasing strain rate. The compressive strength of concrete specimen decreases first, and then increases, but decreases again in the temperatures ranging from room temperature to 800°C at the strain rates of 10‒5s‒1 to 10‒2s‒1. It can be observed that the strain-rate sensitivity of compressive strength of specimen increases with increasing temperature. In addition, the peak strain also increases but the elastic modulus decreases substantially with increasing temperature under the same strain rate.

Heating of steel or structural aluminum alloys at a speed of 2 to 50 K/min – characterizing the fire conditions – leads to a reduction in mechanical properties of the analyzed alloys. The limit of proportionality fp, real fy and proof f₀₂ yield limit, breaking strength fu and longitudinal limit of elasticity E decrease as the temperature increases. Quantitative evaluation of the thermal conversion in strengths of structural alloys is published in Eurocodes 3 and 9, in the form of dimensionless graphs depicting reduction coefficients and selected (tabulated) discrete values of mechanical properties. The author’s proposal for an analytical formulation of code curves describing thermal reduction of elasticity modulus and strengths of structural alloys recommended for an application in building structures is presented in this paper.

In the paper, the authors describe the method of reduction of a model of rotor system. The proposed approach makes it possible to obtain a low order model including e.g. non-proportional damping or the gyroscopic effect. This method is illustrated using an example of a rotor system. First, a model of the system is built without gyroscopic and damping effects by using the rigid finite element method. Next, this model is reduced. Finally, two identical, low order, reduced models in two perpendicular planes are coupled together by means of gyroscopic and damping interaction to form one model of the system. Thus a hybrid model is obtained. The advantage of the presented method is that the number of gyroscopic and damping interactions does not affect the model range.

The aim of the paper is to validate the use of measurement methods in the study of GFRP joints. A number of tests were carried out by means of a tensile machine. The studies were concerned with rivet connection of composite materials. One performed two series of tests for two different forces and two fibre orientations. Using Finite Element Method (FEM) and Digital Image Correlation (DIC), strain maps in the test samples were defined. The results obtained with both methods were analysed and compared. The destructive force was analysed and, with the use of a strain gauge, the clamping force in a plane parallel to the annihilated sample was estimated. Destruction processes were evaluated and models of destruction were made for this type of materials taking into account their connections, such as riveting.

The article is a continuation of the authors’ elaboration (Dąbrowski, Dziurdź, 2016). The aim of this continuation is to prove that a proposed way of modelling and using the coherent analysis to filter nonlinear disturbances is a useful technique in vibroacoustic diagnostics. The thesis was proved by solving the task of diagnosing the damage of the gear of the car gearbox on the basis of the measurement of mechanical vibrations and the noise in the engine chamber.

Studies were carried out to determine the effect of heat treatment parameters on the plastic properties of unalloyed ausferritic ductile iron,

such as the elongation and toughness at ambient temperature and at – 60 °C. The effect of austenitizing temperature (850, 900 and 950°C)

and ausferritizing time (5 - 180 min.) at a temperature of 360°C was also discussed. The next step covered investigations of

a relationship that is believed to exist between the temperature (270, 300, 330, 360 and 390 °C) and time (5, 10, 30, 60, 90, 120, 150, 180,

240 min.) of the austempering treatment and the mechanical properties of unalloyed ausferritic ductile iron, when the austenitizing

temperature is 950°C. The “process window” was calculated for the ADI characterized by high toughness corresponding to the EN-GJS800-10-RT

and EN-GJS-900-8 grades according to EN-PN 1564 and to other high-strength grades included in this standard. Low-alloyed

cast iron with the nodular graphite is an excellent starting material for the technological design of all the ausferritic ductile iron grades

included in the PN-EN-1624 standard. The examined cast iron is characterized by high mechanical properties stable within the entire range

of heat treatment parameters.

The cultivation of genetically modified crops has long been a contentious issue in the European Union. Now a group of biotech specialists and legal experts propose a mechanism to take the political edge out of the authorization process.

Robotics specialists observe nature carefully and try to recreate the complex motions performed by people and animals with ease. Locomotion and the ability to manipulate flexible objects are especially challenging, but progress is being made.

Prof. Małgorzata Kossut of the Nencki Institute of Experimental Biology talks about brain plasticity, the mechanisms of learning, and the mysteries of forgetfulness.

The results presented in this article are part of the research on fatigue life of various foundry alloys carried out in recent years in the Lukasiewicz Research Network – Institute of Precision Mechanics and AGH University of Science and Technology, Faculty of Foundry Engineering. The article discusses the test results obtained for the EN-GJS-600-3 cast iron in an original modified low-cycle fatigue test (MLCF), which seems to be a beneficial research tool allowing its users to evaluate the mechanical properties of materials with microstructural heterogeneities under both static and dynamic loads. For a comprehensive analysis of the mechanical behaviour with a focus on fatigue life of alloys, an original modified low cycle fatigue method (MLCF) adapted to the actually available test machine was used. The results of metallographic examinations carried out by light microscopy were also presented. From the analysis of the results of the conducted mechanical tests and structural examinations it follows that the MLCF method is fully applicable in a quick and economically justified assessment of the quality of ductile iron after normalizing treatment.

The increased cultivation of highbush blueberry in Poland has been paralleled with enhanced

damage to this crop by different pests and diseases, including soft scales. We have

carried out trials to assess methods for controlling soft scales of the genus Parthenolecanium

in highbush blueberry grown in open fields or under a plastic tunnel, with an approach

based on integrated pest management (IPM) principles. The reduction of Lecanium

scale population using alternative products, with mechanical mechanisms of action, was

similar to that achieved with treatments of different formulations of neonicotinyl-based

pesticides; sometimes they were even more effective on protected crops. Control programs

on plantations with a large population of Lecanium scales based on the application of these

alternative products in spring and at harvest time and chemical compounds in autumn resulted

in a very high efficacy and are considered the most suitable strategies to assure yields

without residues and a reduced impact on the environment.

In this article the structural and mechanical properties of grain refinement of Cu-Sn alloys with tin content of 10%, 15% and 20% using the KOBO method have been presented. The direct extrusion by KOBO (name from the combination of the first two letters of the names of its inventors – A. Korbel and W. Bochniak) method employs, during the course of the whole process, a phenomenon of permanent change of strain travel, realized by a periodical, two-sided, plastic metal torsion. Moreover the aim of this work was to study corrosion resistance. The microstructure investigations were performed using an optical microscope Olimpus GX71, a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM). The mechanical properties were determined with INSTRON 4505/5500 machine. Corrosion tests were performed using «Autolab» set – potentiostat/galvanostat from EcoChemie B.V. with GPES software ver. 4.9. The obtained results showed possibility of KOBO deformation of Cu-Sn casting alloys. KOBO processing contributed to the refinement of grains and improved mechanical properties of the alloys. The addition of tin significantly improved the hardness. Meanwhile, with the increase of tin content the tensile strength and yield strength of alloys decrease gradually. Ductility is controlled by eutectoid composition and especially δ phase, because they initiate nucleation of void at the particle/matrix interface. No significant differences in the corrosion resistance between cast and KOBO processed materials were found.

Magnesium alloys thanks to their high specific strength have an extensive potential of the use in a number of industrial applications. The most important of them is the automobile industry in particular. Here it is possible to use this group of materials for great numbers of parts from elements in the car interior (steering wheels, seats, etc.), through exterior parts (wheels particularly of sporting models), up to driving (engine blocks) and gearbox mechanisms themselves. But the use of these alloys in the engine structure has its limitations as these parts are highly thermally stressed. But the commonly used magnesium alloys show rather fast decrease of strength properties with growing temperature of stressing them. This work is aimed at studying this properties both of alloys commonly used (of the Mg-Al-Zn, Mn type), and of that ones used in industrial manufacture in a limited extent (Mg-Al-Sr). These thermomechanical properties are further on complemented with the microstructure analysis with the aim of checking the metallurgical interventions (an effect of inoculation). From the studied materials the test castings were made from which the test bars for the tensile test were subsequently prepared. This test took place within the temperature range of 20°C – 300°C. Achieved results are summarized in the concluding part of the contribution.

The study includes the results of research conducted on selected lead-free binary solder alloys designed for operation at high temperatures.

The results of qualitative and quantitative metallographic examinations of SnZn alloys with various Zn content are presented. The

quantitative microstructure analysis was carried out using a combinatorial method based on phase quanta theory, per which any

microstructure can be treated as an array of elements disposed in the matrix material. Fatigue tests were also performed using the

capabilities of a modified version of the LCF method hereinafter referred to in short as MLCF, which is particularly useful in the

estimation of mechanical parameters when there are difficulties in obtaining many samples normally required for the LCF test. The fatigue

life of alloys was analyzed in the context of their microstructure. It has been shown that the mechanical properties are improved with the

Zn content increasing in the alloy. However, the best properties were obtained in the alloy with a chemical composition close to the

eutectic system, when the Zn-rich precipitates showed the most preferred morphological characteristics. At higher content of Zn, a strong

structural notch was formed in the alloy because of the formation in the microstructure of a large amount of the needle-like Zn-rich

precipitates deteriorating the mechanical characteristics. Thus, the results obtained during previous own studies, which in the field of

mechanical testing were based on static tensile test only, have been confirmed. It is interesting to note that during fatigue testing, both

significant strengthening and weakening of the examined material can be expected. The results of fatigue tests performed on SnZn alloys

have proved that in this case the material was softened.

High-tin bronzes are used for church bells and concert bells (carillons). Therefore, beside their decorative value, they should also offer

other functional properties, including their permanence and good quality of sound. The latter is highly influenced by the structure of bell

material, i.e. mostly by the presence of internal porosity which interferes with vibration of the bell waist and rim, and therefore should be

eliminated. The presented investigations concerning the influence of tin content ranging from 20 to 24 wt% on mechanical properties of

high-tin bronzes allowed to prove the increase in hardness of these alloys with simultaneous decrease in the tensile and the impact

strengths (Rm and KV, respectively) for the increased tin content. Fractures of examined specimens, their porosity and microstructures

were also assessed to explain the observed regularities. A reason of the change in the values of mechanical properties was revealed to be

the change in the shape of α-phase crystals from dendritic to acicular one, and generation of grain structure related to the increased Sn

content in the alloy.

The results of examinations of the influence of titanium-boron inoculant on the solidification, the microstructure, and the mechanical

properties of AlZn20 alloy are presented. The examinations were carried out for specimens cast both of the non-modified and the

inoculated alloy. There were assessed changes in the alloy overcooling during the first stage of solidification due to the nuclei-forming

influence of the inoculant. The results of quantitative metallographic measurements concerning the refinement of the grain structure of

casting produced in sand moulds are presented. The cooling rate sensitivity of the alloy was proved by revealing changes in morphology of

the α-phase primary crystals. Differences in mechanical properties resulting from the applied casting method and optional inoculation were

evaluated.

The results of studies presented in this article are an example of the research activity of the authors related to lead-free alloys. The studies covered binary SnZn90 and SnZn95 lead-free alloys, including their microstructure and complex mechanical characteristics. The microstructure was examined by both light microscopy (LM) and scanning electron microscopy (SEM). The identification of alloy chemical composition in micro-areas was performed by SEM/EDS method. As regards light microscopy, the assessment was of both qualitative and quantitative character. The determination of the geometrical parameters of microstructure was based on an original combinatorial method using phase quantum theory. Comprehensive characterization of mechanical behavior with a focus on fatigue life of alloys was performed by means of the original modified low cycle fatigue method (MLCF) adapted to the actually available test machine. The article discusses the fatigue life of binary SnZn90 and SnZn95 alloys in terms of their microstructure. Additionally, the benefits resulting from the use of the combinatorial method in microstructure examinations and MLCF test in the quick estimation of several mechanical parameters have been underlined.

The paper, especially dealt with problems of reclamation of used furan sand, carried out in new, vibratory sand reclamation unit REGMAS

developed by researches from AGH-University of Science and Technology, Faculty of Foundry Engineering in Cracow (Poland).

Functional characteristics of reclamation unit as well as the results of reclamation of used sand with furfuryl resin are discussed in the

paper. The quality of reclaim was tested by means of the LOI and pH value, dust content in the reclaim and at least by the the quality of

the castings produced in moulds prepared with the use of reclaimed matrix.

Lead-free alloys containing various amounts of zinc (4.5%, 9%, 13%) and constant copper addition (1%) were discussed. The results of

microstructure examinations carried out by light microscopy (qualitative and quantitative) and by SEM were presented. In the light

microscopy, a combinatorial method was used for the quantitative evaluation of microstructure. In general, this method is based on the

phase quanta theory according to which every microstructure can be treated as an arrangement of phases/structural components in the

matrix material. Based on this method, selected geometrical parameters of the alloy microstructure were determined. SEM examinations

were based on chemical analyses carried out in microregions by EDS technique. The aim of the analyses was to identify the intermetallic

phases/compounds occurring in the examined alloys. In fatigue testing, a modified low cycle fatigue test method (MLCF) was used. Its

undeniable advantage is the fact that each time, using one sample only, several mechanical parameters can be estimated. As a result of

structure examinations, the effect of alloying elements on the formation of intermetallic phases and compounds identified in the examined

lead-free alloys was determined. In turn, the results of mechanical tests showed the effect of intermetallic phases identified in the

examined alloys on their fatigue life. Some concepts and advantages of the use of the combinatorial and MLCF methods in materials

research were also presented.

Ductile iron was quenched using two-variant isothermal transformation. The first treatment variant consisted of one-phase austenitization at a temperature tγ = 830, 860 or 900°C, cooling down to an isothermal transformation temperature of 300 or 400°C and holding from 8 to 64 minutes. The second treatment variant consisted of two-phase austenitization. Cast iron was austenitizied at a temperature tγ = 950°C and cooled down to a supercritical temperature tγ’ = 900, 860 or 830°C. Isothermal transformation was conducted under the same conditions as those applied to the first variant. Ferrite cast iron was quenched isothermally. Basic strength (Rp0.2, Rm) and plastic (A5) properties as well as matrix microstructure and hardness were examined. As a result of heat treatment, the following ADI grades were obtained: EN-GJS-800-8, EN-GJS-1200-2 and EN-GJS-1400-1 in accordance with PN–EN 1564:2000 having plasticity of 1.5÷4 times more than minimum requirements specified in the standard.

The paper presents the method of preparing a composite slurry composed of AlSi11 alloy matrix and 10 vol.% of SiC particles, as well as

the method of its high-pressure die casting and the measurement results concerning the tensile strength, the yield point, the elongation and

hardness of the obtained composite. Composite castings were produced at various values of the piston velocity in the second stage of

injection, diverse intensification pressure values, and various injection gate width values. There were found the regression equations

describing the change of mechanical properties of the examined composite as a function of pressure die casting process parameters. The

conclusion gives the analysis and the interpretation of the obtained results.

This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.