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Denisa Cihlářová, Ivan Fencl, Silvia Cápayová and Petr Pospíšil

Abstract

The purpose of asphalt binder as a significant binder in road constructions is to permanently bind aggregates of different compositions and grain sizes. The asphalt binder itself does not have suitable adhesiveness, so after a period of time, bare grains can appear. This results in a gradual separation of the grains from an asphalt layer and the presence of potholes in a pavement. Adhesion promoters or adhesive agents are important and proven promoters in practice. They are substances mainly based on the fatty acids of polyamides which should increase the reliability of the asphalt’s binder adhesion to the aggregates, thus increasing the lifetime period of the asphalt mixture as well as its resistance to mechanical strain. The amount of a promoter or agent added to the asphalt mixture is negligible and constitutes about 0.3% of the asphalt’s binder weight. Nevertheless, even this quantity significantly increases the adhesive qualities of an asphalt binder. The article was created in cooperatation with the Slovak University of Technology, in Bratislava, Slovakia, and focuses on proving the new AD2 adhesive additive and comparing it with the Addibit and Wetfix BE promoters used on aggregates from the Skuteč - Litická and Bystřec quarries.

Open access

S. Pysz, R. Żuczek, J. Piekło and M. Maj

Abstract

The ecological meanings clearly indicates the need of reducing of the concentration of the CO2 in the atmosphere, which can be accomplished through the lowering of the fuel consumption. This fact implies the research for the new construction solutions regarding the reduction of the weight of vehicles. The reduced weight of the vehicle is also important in the case of application of the alternative propulsion, to extend the lifetime of the batteries with the reduction of recharge cycles. The use of cast alloy AlZnMgCu compliant of plastic forming class 7xxx alloy, are intended to significantly reduce the weight of the structures, while ensuring high strength properties. The wide range of the solidification temperature, which is more than 150°C, characterizes this alloy with a high tendency to create the micro and macro porosity. The study presents the relationship between the cooling rate and the area of occurrence and percentage of microporosity. Then the results were linked to the local tensile strength predicted in the simulation analysis. The evaluation of the microporosity was performed on the basis of the CT (computed tomography) and the analysis of the alloy microstructure. The microstructure analysis was carried out on test specimen obtained from the varying wall thickness of the experimental casting. The evaluation of the mechanical properties was prepared on the basis of the static tensile test and the modified low cycle fatigue test (MLCF).

Open access

J. Słowik, A. Drotlew and B. Piekarski

Abstract

The main aim of this study was to examine the compression-induced state of stress arising in castings of the guide grates during operation in pusher-type furnaces for heat treatment. The effect of grate compression is caused by its forced movement in the furnace. The introduction of flexible segments to the grate structure changes in a significant way the stress distribution, mainly by decreasing its value, and consequently considerably extends the lifetime of the grates. The stress distribution was examined in the grates with flexible segments arranged crosswise (normal to the direction of the grate compression) and lengthwise (following the direction of force). A regression equation was derived to describe the relationship between the stress level in a row of ribs in the grate and the number of flexible segments of a lengthwise orientation placed in this row. It was found that, regardless of the distribution of the flexible segments in a row, the stress values were similar in all the ribs included in this row, and in a given row of the ribs/flexible segments a similar state of stress prevailed, irrespective of the position of this row in the whole structure of the grate and of the number of the ribs/flexible segments introduced therein. Parts of the grate responsible for the stress transfer were indicated and also parts which play the role of an element bonding the structure.

Open access

Dirk Althaus, Andreas Braasch, Marco Schlummer and Arno Meyna

Regarding the Importance of the Mileage Distribution for Reliability Prognoses in Automotive Industry

In automotive industry there are few information about the load of a car in use. Therefore, the available data needs to be used and looked at carefully. Data that is nearly always available is the time in field, given by the date of registration and the date when failure occurred, and the driving distance. The driving distance can be used to describe the load of a car because in most cases the operating time is not known. This data can be used to calculate the mileage distribution of a car, which contains much additional information for safety and reliability analysis. Furthermore, it is useful to adopt testing routines and lifetime distances that are written down in specifications.

Open access

Gabriela Lajčáková and Jozef Melcer

Abstract

The knowledge of the development with time of the strain and stress states in pavement structures is needed in the solution of various engineering tasks as the design fatigue lifetime reliability maintenance and structure development. The space computing model of the truck TATRA 815 is introduced. The pavement computing model is created in the sense of Kirchhof theory of the thin slab on elastic foundation. The goal of the calculation is to obtain the vertical deflection in the middle of the slab and the time courses of vertical tire forces. The equations of motion are derived in the form of differential equations. The assumption about the shape of the slab deflection area is adopted. The equations of the motion are solved numerically in the environment of program system MATLAB. The dependences following the influence of various parameters (speed of vehicle motion, stiffness of subgrade, slab thickness, road profile) on the pavement vertical deflections and the vertical tire forces are introduced. The results obtained from the plate computing model are compared with the results obtained by the FEM analysis. The outputs of the numerical solution in the time domain can be transformed into a frequency domain and subsequently used to solve various engineering tasks.

Open access

J.A. Słowik, A. Drotlew and B. Piekarski

Abstract

The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression) and lengthwise (parallel to the direction of compression), was examined. The compression process was simulated using SolidWorks Simulation program. Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate flexibility has only the quantity and orientation of segments (crosswise / lengthwise), while the exact position of segments changes the grate flexibility by less than 1%.

Open access

Anita Tarbuk, Ana Marija Grancarić and Mirna Šitum

Abstract

The incidence of skin cancer is increasing by epidemic proportions. Basal cell cancer remains the most common skin neoplasm, and simple excision is generally curative. On the other hand, aggressive local growth and metastasis are common features of malignant melanoma, which accounts for 75% of all deaths associated with skin cancer. The primary cause of skin cancer is long exposure to solar ultraviolet radiation (UV-R) crossed with the amount of skin pigmentation and family genetics. It is believed that in childhood and adolescence, 80% of UV-R gets absorbed while in the remaining, 20 % gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Reducing the exposure time to sunlight, using sunscreens and protective textiles are the three ways of UV protection. Most people think that all the clothing will protect them, but it does not provide full sun screening properties. Literature sources claim that only 1/3 of the spring and summer collections tested give off proper UV protection. This is very important during the summer months, when UV index is the highest. Fabric UV protection ability highly depends on large number of factors such as type of fiber, fabric surface, construction, porosity, density, moisture content, type and concentration of dyestuff, fluorescent whitening agents, UV-B protective agents (UV absorbers), as well as nanoparticles, if applied. For all of these reasons, in the present paper, the results of UV protecting ability according to AS/NZS 4399:1996 will be discussed to show that standard clothing materials are not always adequate to prevent effect of UV-R to the human skin; and to suggest the possibilities for its improvement for this purpose enhancing light conversion and scattering. Additionally, the discrepancy in UV protection was investigated in distilled water as well as Adriatic Sea water.

Open access

Kamila Kustroń

Abstract

The paper proposes a selected key issues in the efficient formation of the airframe structure. The issues of concern design lifetime, manufacturing, command of the durability proposed in the accelerated tests and management of sustainability in the operation. A key importance is of the creating a durability of the airframe, which affects to choice materials and construction solutions. A key problem is modeling the system of exploitation and the inclusion of all the factors influencing the persistence in the aspect of aviation regulatory requirements. A key area influencing the prevention after air accidents, causes by loss of structural coherence of the airframe macroscopic structure. A key importance is the use of accelerated durability testing. A key issue is to determine if the concept of durability and viability are separate or similar in characteristics of durability. The key is to determine the diamonds of quality. A key importance is attributed to diagnostics, including integrated to airframe structure, defining a continuous condition of the aircraft through research pre-fault symptoms. These studies provide the knowledge which determines prevention activities.

Open access

Leszek Ułanowicz

1966. Ułanowicz L.: Identification of technical condition of the fluid power transmission on the basis of variation-related description of structural parameters. "Scientific Problems of Machines Operation and Maintenance" ("Zagadnienia Eksploatacji Maszyn"), z. 1 (145), vol. 41, 2006. Ułanowicz L.: Outline of the method for prediction of lifetime achieved by avionic hydraulic drives operated under real field conditions. "Journal of Kones Powertrain and Transport" 2009, vol. 16, no. 2

Open access

Leszek Ułanowicz

1966. Ułanowicz L.: Identification of technical condition of the fluid power transmission on the basis of variation-related description of structural parameters. "Scientific Problems of Machines Operation and Maintenance" ("Zagadnienia Eksploatacji Maszyn"), z. 1 (145), vol. 41, 2006. Ułanowicz L.: Outline of the method for prediction of lifetime achieved by avionic hydraulic drives operated under real field conditions. "Journal of Kones Powertrain and Transport" 2009, vol. 16, no. 2