Browsing by Subject "strength"

Now showing 1 - 9 of 9

Access status: Open Access ,
Assessment of integrity of operating gas pipelines
(Wydawnictwa AGH, 2018) Ładecki, Bogusław; Matachowski, Filip; Bednarz, Stanisław
Gas pipelines that have been in operation for many years require supervision, taking into account the places and conditions of their usage. The currently applicable normative regulations do not fully determine the scope of the integrity control of such gas pipelines. The standards provide general guidelines for monitoring corrosion phenomena in pipelines, allowing the use of simplified strength patterns based on a flat state of stress, in actuality, real objects usually have complex three-dimensional structures. Such an approach may be a reason for committing significant errors in determining the state of stresses and strains in the construction of pipelines, which is a significant problem in assessing the integrity of pipelines (when combined with the lack of a formulation of the appropriate admission criteria). This paper presents a methodology for assessing the integrity of pipeline structures operating at ambient temperatures based on conducting comprehensive measurements of wall thickness defects (in connection with performing necessary defectoscopy tests). The results of these measurements and non-destructive tests are the basis for the analysis of stress strength and MES deformation based on the verified real geometry as well as the method of supporting the pipelines. The information obtained on this basis regarding the pipeline structure areas of the highest efforts is the basis for selecting the critical areas of pipeline construction for which they should be repaired or modernized, or a monitoring program should be developed using non-destructive tests.
Access status: Open Access ,
Casting of Al-Si alloys in the full-mould technology - process conditions
(2014) Mocek, Jan; Zych, Jerzy; Krubnik, Łukasz
A review of various technologies using expendable casting patterns made of expanded polystyrene is given in the paper. The results of our own investigations on implementing this technology at the pilot-plant scale - for the art castings series - were presented. The results of tests of materials and moulds applied in the full-mould technology were shown. Gas evolution tendencies of expanded polystyrenes and protective coatings were estimated. Gas evolutions were described as functions of the polystyrene heating temperature. The tests of protective coatings used in this technology were performed and strength (Rm), permeability (P), and gas evolution tendency of these coatings assessed. New solutions developed by the team of researchers were applied in testing coating strength, permeability, and the gas evolution tendency of expanded polystyrene. A good correlation between the results of coating properties and the obtained casting quality was found. Coatings, which were characterised by higher strengths and better permeability, allowed us to produce castings without surface or inner faults.
Access status: Open Access ,
Designing folding wall box pallets
(2014) Wolny, Stanisław; Ładecki, Bogusław; Matachowski, Filip
Designing of modern box pallets with folding walls, which are used for example to transport tires, requires fulfilment of a number of performance requirements. Such pallets, adapted to be moved by forklifts, are stored or transported without loading with walls folded, and during operation they are put together in the piles of a few pieces and braced by the transport belts. Difficult operating conditions are related to necessity to provide resistance of construction of a pallet or their pile on: bending, piling, stability, hitting in case of a free-fall, lifting by forklift, as well as the resistance to horizontal strokes by both edges and legs. In order to meet the above mentioned requirements, it is necessary to implement the relevant tensile FEM analyses, which are then reviewed by the relevant experimental testing. The paper discuss the requirements specified by standards for designing of the above mentioned pallets and presents FEM results in the process of pallets' designing.
Access status: Open Access ,
Problems with rectification of hoist supports on the example of a semi-portal bridge-crane with a lattice structure
(2014) Ładecki, Bogusław; Matachowski, Filip
The long period and conditions of operation are the cause of various types of severe damage to cranes used in the steelworks industry. Among the more dangerous and difficult to eliminate crane damage types, there is excess durable deflection of its supports from vertical axis. The object of the study is the semi-portal grab bridge-crane with steel lattice structure, for which deflection of a fixed support was detected that several times exceeded permissible values. For this crane, rectification was performed aimed at bringing fixed supports to the vertical line by stabilisation of the corrected location of the bearing structure of the crane using additional angle braces. The analysis of periodical geodetic measurements of the crane structure showed insufficient effect of the rectification, whereas loss of stability of some rods in the fixed support was detected. The study involved the FEM strength analysis of the crane, which revealed that the applied rectification method caused redistribution of forces in the rods of the fixed support, resulting in the loss of stability of some rods of the support, thus questioning the effectiveness of the rectification method applied.
Access status: Open Access ,
Testowanie zgodności parametrów wytrzymałościowych betonu
(Wydawnictwa AGH, 2009) Kohutek, Zdzisław B.
This article presents the principles of samples collecting and of appointing of concrete strength. It describes the procedures and criteria of conformity testing under norm PN-EN 206-1. Numerical examples along with groups of overlapping and non-overlapping consecutive results have also been contained in its contents. Final remarks explain the consequences of new defectiveness risk ratio. This article and the item [6] from bibliography bring the complete set of publications concerning the assessment of concrete properties conformity to an end.
Access status: Open Access ,
Wpływ cyklicznego nasłoneczniania na przebicie statyczne wybranych geosyntetyków
(Wydawnictwa AGH, 2011) Cholewa, Mariusz; Lupa, Marcin
The paper presents results of tests of the static punch strength of chosen geosynthetics subjected to cycles of insolation amounting to 100 hours. Three geotextiles (GW-1: of knitted continuous filaments, GW-2: of welded continuous filaments and GW-3: of stitched continuous filaments), three geonets (GS-1: of the density of 16 openings per 1 cm2, GS-2: of the density of 1 opening per 1 cm2, GS-3: of the density of 1.0 openings per 1 cm2) and three geomembrans (GM-1: 0.3 mm thick, GM-2: 1.0 mm thick and GM-3 1.5 mm thick,) were used for the tests. The tests of punch shear were conducted in accordance with a method described in the standard PN-EN ISO 12236. For each of the nine materials, the results of tests of so called »fresh« and insolated samples were compared. It was shown that the influence of solar radiation received during 100 hours do not cause weakening geonets and geomembrans. It were only geotextiles that showed decreasing of strength value.
Access status: Open Access ,
Wytrzymałość na przebicie geosyntetycznych przesłon uszczelniających
(Wydawnictwa AGH, 2011) Cholewa, Mariusz; Job, Robert
The paper presents results of punch strength tests of protecting and sealing geosynthetics. Six types of geotextiles of different thickness and basis weight were chosen as protecting materials, two types of geomembrans of different thickness and one type of bentonit mat represented sealing materials. The tests were carried out separately for a set of the geotextiles and the geomembranes and for a set of the geotextiles, geomembranes and the bentonit mat. The measurements were taken according to the standard: PN-EN 14574. The results of the tests showed, that the punch strength of the set geomembrane + geotextile increases in proportion to the thickness of the materials and ranges from 0.73 to 2.62 kN in the dry test and from 0.76 to 2.88 kN while testing hydratised samples. Whereas the punch force of the set geotextile + geomembrane + bentonit mat ranges between 1.48 and 5.19 kN depending on the type of geomembrane and geotextile.
Access status: Open Access ,
Zmienność wytrzymałościowa piaskowców godulskich z Brennej w warunkach jednoosiowego ściskania
(Wydawnictwa AGH, 2010) Łukasiak, Dominik
The paper presents characteristics of Godula Sandstones from Brenna on base of uniaxial compressive strength. Analysed influence paleostress and zones of airing of rocky massifs on rocks from Brenna Glebiec quarry.
Access status: Open Access ,
Моделирование влияния скорости горных работ на прочность пород и устойчивость выработки
(Wydawnictwa AGH, 2010) Ivanov, Aleksej; Sdvižkova, Elena Aleksandrovna; Šašenko, Oleksandr Mikolajovič
Research results of rock mass strength depending on rate of mining are presented in the article. The connection between rock mass failure (in situ measurements) and the destruction of rock samples (laboratory tests) is shown. The statistical model considering change of rock mass strength depending on loadingrate effect is resulted. The phenomenological failure criterion is developed taking into account the created statistical model. This criterion is used at numerical simulations of rock mass stress strain state. Outcomes of numerical modelling for »workings - rock mass - longwall« system are presented. Failure zones in rock mass at various working speed and the various coalface spaces are resulted as well.