Wyniki wyszukiwania - Biblioteka Nauki

1

Effects of Range and Mode on Lifting Capability and Lifting Time

100%

Lee T. H.

International Journal of Occupational Safety and Ergonomics

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2012

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tom Vol. 18, No. 3

387--391

EN

This study examined the effects of 3 lifting ranges and 3 lifting modes on maximum lifting capability and total lifting time. The results demonstrated that the maximum lifting capability for FK (from floor to knuckle height)was greater than that for KS (from knuckle height to shoulder height) or FS (from floor to shoulder height. Additionally, asymmetric lifting with initial trunk rotation decreased maximum lifting capability compared with symmetric lifting or asymmetric lifting with final trunk rotation. The difference in total lifting time between KS and FS was not significant, while FK increased total lifting time by ~20% compared with FS even though the travel distance was 50% shorter.

2

Joints of steel sandwich structures

100%

Kozak J.

Polish Maritime Research

|

2021

|

tom nr 2

128--134

EN

Steel sandwich structures are perceived as alternatives to single-skin welded structures in the shipbuilding industry due its advantages like significant reduction of mass in relation to typical single skin structure. However, beside problems with their strength properties itself, applications in real structures requires of solving the problem of joining, both for connection sandwich to sandwich as well as sandwiches to single-shell structures. Proper design of joints is connected with some factors like lack of attempt to interior of panel, introduction of additional parts and welds with completely different stiffness. In the paper the results of laboratory fatigue tests of selected joints as well as numerical calculation of stressed for different kind of joints of sandwich structures are presented. As result of calculations optimisation of geometry for selected joints is performed.

3

Comparative analysis of welded and adhesive joints strength made of acid-resistant stainless steel sheets

100%

Rudawska A. , Pawlak P. , Miturska I. , Stančeková D. , Chyra M.

Advances in Science and Technology. Research Journal

|

2017

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tom Vol. 11, no 4

97--102

EN

The article presents the selected results of strength tests on the effectiveness of bonding high-alloy steel 1.4310. Sheet steel is one of the materials that are difficult to activate energy. Effective joining of it is difficult, requires selection of the appropriate bonding technology. The paper focuses on the comparative tests of shear strength of one-single lap welded and bonded joints. The welding process was performed on 3 groups of samples TIG welding and argon, where the variable value of the welding process was current: 60A, 70A, 80A. The adhesion process was performed in 6 groups of samples which differed in the method of surface preparation and the type of the adhesive. Adhesive joints were made by using adhesive of epoxy resin and a hardener: Epidian 61/TFF at a mass ratio of 100:22 and Epidian 61/IDA at a mass ratio of 100:40. As a way of surface preparation applied 3 different, but simplified and environmentally friendly methods of surface preparation: degreasing with using cleaner Loctite 7061, abrasive machining with P320 and degreasing and grinding with abrasive T800 and degreasing were used. Make joints and curing the adhesive joints were carried out at ambient temperature. Analyzed the joints were tested destructive – which set out the shear strength, in accordance with DIN EN 1465 on the testing machine Zwick / Roell Z150. Based on the results of the research it was found that better results were obtained for the maximum welded joints, but this result was similar to the maximum value of the strength of the adhesive bond.

4

Alluvial deposits as a subsoil and material for basic hydro-technical constructions

100%

Wierzbicki J. , Stefaniak K.

Journal of Ecological Engineering

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2015

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tom Vol. 16, nr 5

176--182

EN

The article presents an analysis of geotechnical parameters of the alluvial deposit (the areas of the Vistula and Warta river valleys) with a view to using the soil as an earth construction material and as a foundation for buildings constructed on the grounds tested. Strength and deformation parameters of the subsoil tested were identified by the CPTU (cone penetration test) and DMT (flat dilatometer test) methods, as well as by the vane test (VT). The article includes the analysis of overconsolidation process of the soil tested and a formula for the identification of the overconsolidation ratio OCR. Equation 4 reflects the relation between the undrained shear strength and plasticity of the silts analyzed and the OCR value. The analysis resulted in the determination of the Nkt coefficient, which might be used to identify the undrained shear strength of both sediments tested. On the basis of a detailed analysis of changes in terms of the constrained oedometric modulus M0, the relations between the said modulus, the liquidity index and the OCR value were identified. Mayne’s formula (1995) was used to determine the M0 modulus from the CPTU test. The usefulness of the alluvial deposit as an earth construction material was analysed after their structure had been destroyed and compacted with a Proctor apparatus. In cases of samples characterized by different water content and soil particle density, the analysis of changes in terms of cohesion and the internal friction angle proved that these parameters are influenced by the soil phase composition. On the basis of the tests, it was concluded that the most desirable shear strength parameters are achieved when the silt is compacted below the optimum water content.

5

Wpływ czynników konstrukcyjnych i technologicznych na wytrzymałość klejowych połączeń czopowych walcowych wykonanych ze stopu AlSi7Mg0,3 i kompozytu epoksydowo-szklanego

100%

Zielecki W. , Perłowski R.

Technologia i Automatyzacja Montażu

|

2014

|

tom nr 1

47--50

PL

W pracy przedstawiono analizę wpływu czynników konstrukcyjnych i technologicznych na wytrzymałość klejowych połączeń czopowych walcowych wykonanych ze stopu AlSi7Mg0,3 i kompozytu epoksydowo-szklanego. Z zastosowanych trzech kompozycji klejowych Loctite Hysol 9514, Araldite 2014, Epidian 57 + PAC najwyższą wytrzymałość na ścinanie 40 – 41 MPa zapewniła kompozycja Loctite Hysol 9514 o grubości 0,15 mm. Jedynie dla kompozycji Epidian 57 + PAC alodynowanie powierzchni otworu tulei spowodowało wzrost wytrzymałości na ścinanie badanych połączeń o 5 – 40%.

EN

The paper presents an analysis of the impact of structural and technological factors on strength of the adhesive cylindrical joints made of alloy AlSi7Mg0,3 and the epoxy-glass composite. The three adhesive compositions are used: Loctite Hysol 9514, Araldite 2014, Epidian 57 + PAC, highest shear strength 40 – 41 MPa assured composition of Loctite Hysol 9514 with a thickness of 0,15 mm. Only the composition Epidian 57 + PAC chromating surface of the bushing hole caused an increase of shear strength in examined connections about 5 – 40%.

6

Porosity, porous structure and strength of polymer concretes

100%

Slopkova K.

Prace Naukowe Instytutu Budownictwa Politechniki Wrocławskiej. Konferencje

|

1999

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tom Vol. 75, nr 26

167-172

EN

An article dealing with the problems of porosity and their relation to polymer concrete strengths, refers to the above problems in the following sequence: analysis of the dependence among porosity, pore structure and polymer concrete composition strengths; expression of porosity and pore structure as the function of binder content; influence of pore size on polymer concrete strengths.

PL

Praca traktuje o problemie porowatości i o wpływie tego parametru na wytrzymałość betonu żywicznego, biorąc pod uwagę następujące etapy: analizę zależności występujących w cesze porowatości, strukturę porowatości jako funkcję zawartości spoiwa, a następnie wpływ wymiarów porów na wytrzymałość betonu żywicznego.

7

Wpływ sztywności ośrodka skalnego na zmiany stanu naprężeń w otoczeniu skrzyżowania wyrobisk korytarzowych

100%

Majcherczyk T. , Małkowski P.

Przegląd Górniczy

|

2001

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tom T. 57, nr 12

34-42

PL

Artykuł zawiera analizę wyników obliczeń numerycznych dla modelu przestrzennego skrzyżowania dwóch wyrobisk korytarzowych. Autorzy przedstawili wnioski w zakresie rozkładu naprężeń ax i az oraz zmiany wartości współczynnika koncentracji naprężeń w różnych odległościach od skrzyżowania dla trzech wartości modułu sprężystości liniowej.

EN

He paper contains an analysis of the numerical calculations results for the spatial model of a crossing of two narrow workings. The Authors present conclusions referring to the distribution of the stresses ax, and az as well as variation of the value of the stress 9 concentration coeficient at different distances from the crossing for three values of the module of linlear elasticity.

8

Rules of proper and safe conducting altitude training as part of the shaping athletes’ stamina abilities

100%

Ambroży T. , Wieczorek T. , Mucha D.

Kultura Bezpieczeństwa. Nauka – Praktyka – Refleksje

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2016

|

tom 24(24)

46-73

EN

The aim of study is to present rules of training in mountain conditions relating to the planning of training programs. The review of literature allows us to understand the course of physiological changes during acclimatization in mountains and it also helps us to distinguish human responses in acute phase from responses during subsequent processes of adaptation. The benefits of preparation which are results of training in the mountains are as follows: increased transport of oxygen to the muscles, improvement of the blood functions associated with the transport of oxygen, increased aerobic capacity, which affects the growth of buffering ability of muscles and blood.

9

Doświadczalna weryfikacja obliczeń wytrzymałościowych metalowej uszczelki typu 2-delta

100%

Krasiński M. , Trojnacki A.

Przegląd Mechaniczny

|

2011

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tom nr 2

15-24

PL

W pracy przedstawiono wyniki badań doświadczalnych metalowej wysokociśnieniowej uszczelki typu B. Badania przeprowadzono w warunkach montażowych, bez obciążenia połączenia ciśnieniem roboczym. Na wewnętrznej, cylindrycznej powierzchni uszczelki mierzono odkształcenia obwodowe i osiowe przy użyciu tensometrów oporowych. Po odciążeniu zmierzono szerokość strefy kontaktu plastycznie odkształconej powierzchni roboczej uszczelki. Zostały również wykonane badania materiałowe uszczelek oraz gniazd. Wyniki pomiarów porównano z obliczeniami analitycznymi, wykonanymi na podstawie uproszczonego powłokowego modelu uszczelki. W analitycznym opisie strefy kontaktu uszczelki z gniazdem uwzględniono plastyczne odkształcenia uszczelki. Dodatkowo została wykonana numeryczna weryfikacja pomiarów i obliczeń analitycznych za pomocą obliczeń MES, w których uwzględniono nieliniowe własności materiałów połączenia oraz tarcie na powierzchni kontaktu.

EN

There were presented results of experimental investigations of metallic high-pressure gasket type B. Experiments were conducted in assembling conditions, without apply a operating pressure to the joint. There were measured circumferential and axial deformations at the internal, cylindrical area of the gasket with the use of resistance extensometers. After unloading, width of contact area of plastically deformed working area of the gasket was measured. Material tests of gaskets and seats were performed. Experimental results were compared with the numerical results, which took into account simplified shell model of the gasket. In analytical description of contact area between gasket and the seat, plastic deformation of the gasket was considered. Additionally, numerical verification of experimental tests and analytical approach were performed using FEM calculations, which took into account nonlinear properties of applied materials and friction at the contact area.

10

Doświadczalna weryfikacja obliczeń wytrzymałościowych metalowej uszczelki typu B

100%

Szybiński B. , Trojnacki A.

Przegląd Mechaniczny

|

2011

|

tom nr 7-8

50-57

11

Influence of pitting corrosion on strength of steel ships and offshore structures

100%

Jakubowski M.

Polish Maritime Research

|

2011

|

tom nr 4

54-58

EN

The present paper deals with the influence of pitting corrosion on mechanical properties of mild and low alloy steels and strength of steel structures under static and quasi-static loads. Pitting corrosion is a very important phenomenon that influence local strength of ship hull members. The present paper is based mainly on Japanese publications. Analyzing the standard tensile diagrams one can see that that pitting corrosion reduces the load corresponding to yield stress (YS) and, even more markedly, tensile strength UTS, reduces almost to zero plastic flow strains at YS load level and dramatically reduces the total elongation to fracture. Nominal UTS load for uniformly corroded specimens is higher than that for pitted specimens at the same average thickness loss. The strength related to the true fracture surface area (i.e. reduced by pits, taking into account real path of the crack through the pits) is almost independent of the thickness loss and is almost the same as for uniform thickness loss. For wide specimens the tensile strength depends mainly on the local deformation ability, and the maximum loading ability for large members, predicted on the base of the total true fracture surface area, can be overestimated. Concept of equivalent thickness loss for plates under bending and compression and for more complex structural models as well as relation between the average and the equivalent thickness losses has been presented. Approach based on degree of pitting (ratio of pitted area to total plate surface area) has been shown as a real and more convenient than the approach based on the thickness loss.

12

Influence of the thickness of joined elements on lap length of aluminium alloy sheet bonded joints

100%

Rudawska A.

Advances in Science and Technology. Research Journal

|

2015

|

tom Vol. 9, nr 27

35--44

EN

This work features the results of experimental research in determining the limiting length of the bonded single-lap joint of materials of the same thickness, different thicknesses and of hybrid systems of different aluminium alloy sheets. The length of the bonded lap joint is just one of the structural features, critical to the strength of bonded joints, this length depending on the thickness and type of the bonded elements. In the case of single-lap bonded joints there is a limiting lap length exceeding of which should not increase the strength of such joints. This is why the length of a bonded lap joint is critical in terms of strength and application concerns. The length of the lap is not always reflected in practice due to simplification of the analytical relations. What is required is experimental verification of the derived theoretical relations. The tested materials are aluminium alloy sheets, widely used in the machinery, aviation and construction industries.

13

Effect of Surface Abrasive Treatment on the Strength of Galvanised Steel Sheet Adhesive Joints

100%

Miturska-Barańska I. , Rudawska A. R.

Advances in Science and Technology. Research Journal

|

2022

|

tom Vol. 16, no 1

75--84

EN

The aim of this study was to determine the effect of abrasive treatment as a method of surface preparation on the strength of adhesive joints made of galvanised steel sheet. The subject of experimental investigations were adhesive joints of samples made of galvanised steel sheet DX51, 0.7 mm thick. The surfaces of the samples were abraded with coated abrasive tools of grain sizes P120, P180, P220, P400 and P600, and then degreased with PIKKO extraction solvent. The surface properties in terms of roughness and 3D surface topography were examined using a Hommel-Etamic T8000 RC120-400. The adhesive joints were made using Epidian 53 epoxy resin adhesive composition and IDA curing agent in a 100:40 weight ratio. Samples of single-lap adhesive joints were tested for strength on a Zwick/Roell Z150 testing machine, in accordance with the PN - EN 1465:2009 standard. The tests showed that the samples mechanically processed with an abrasive tool of P220 gradation show the best strength properties. Adhesive joints, in which the surface of the joined elements was mechanically processed with an abrasive tool of P120 gradation, obtained negative results. The obtained test results were subjected to further statistical analysis. The Shapiro-Wilk test was used to assess the normality of the distribution. Then, the non-parametric Kruskal-Wallis test and the median test were applied, which showed that there were no significant differences in the results obtained between the adhesive joints whose surfaces were prepared with P220 and P400 abrasive paper, i.e. both methods of surface preparation can be considered as the most favourable among those analysed during the adhesive bonding of DX51 galvanised sheets.

14

The impact of polymer raw materials from the recycling process on the strength of connectors in non structural applications

100%

Nowoświat A. , Knap P.

Architecture Civil Engineering Environment

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2016

|

tom Vol. 9, no. 2

93--104

EN

Waste materials have become a serious problem in many branches of industry, including also civil engineering. The amount of waste generated in civil engineering is still growing, and therefore, the application of recycling in the construction industry is highly justified. In the present paper we demonstrate the effects resulting from the application of polymer raw materials from the recycling process. It particularly involves the recycling of raw materials from polypropylene applied in the production of plastic connectors and their impact on the load-bearing efficiency of fixing elements. The research combinesalso material characteristics and the properties of the investigated connectors. The research tests carried out on the connectors consisted in the assessment of their load-bearing capacity at fixing places in a base made of concrete class C20/25 or from solid ceramic brick.

PL

Odpady stanowią duży problem w różnych gałęziach przemysłu, w tym również budownictwie. Ilość odpadów w budownictwie stale rośnie. Dlatego też zasadnym jest stosowanie recyklingu w branży budowlanej. W niniejszej pracy wykazano wpływ jaki niesie ze sobą zastosowanie surowców polimerowych z recyklingu. W szczególności z recyklingu surowców z polipropylenu, zastosowanych w produkcji łączników na nośność zamocowań. Powiązano również cechy materiałowe z właściwościami badanych łączników. Badania łączników polegały na ocenie ich nośności przy zamocowaniach w podłożu z betonu klasy C20/25 lub cegły ceramicznej pełnej.

15

Koncepcja i obliczenia wytrzymałościowe prasy do brykietowania trocin

100%

Lewandowski T. , Malcher K. , Przybyłek G. , Słomski W. , Stefurak W.

Przegląd Mechaniczny

|

2008

|

tom nr 10

44-48

PL

Przedstawiono fragmenty prac koncepcyjnych oraz modelowo-obliczeniowych zrealizowanych przez zespól z Politechniki Warszawskiej i firmę WroPol Engineering przy projekcie hydraulicznej maszyny do brykietowania trocin z otwartą komorą prasowania. W ramach projektu wykonano modele 3D urządzenia oraz przeprowadzono obliczenia wytrzymałościowe wybranych newralgicznych elementów maszyny.

EN

The paper presents the parts of designing and modeling - calculating works conducted by the group of scientists from Wrocław University of Technology and company WROPOL ENGINEERING at the project of hydraulic machinę for sawdust briquetting with the open pressing chamber. Wilhin the framework of project the 3D models of machinę were elaborated as well as the strength calculations of selected crucial elements of the machinę were conducted.

16

Węzły kompozytowe struktur nośnych w świetle badań wytrzymałościowych

100%

Dębski D. , Dębski M. , Gołoś K. , Osiński Z.

Zeszyty Naukowe Politechniki Białostockiej. Mechanika

|

2001

|

tom Z. 24

PL

W pracy przedstawiono nowe, alternatywne rozwiązanie połączeń (węzłów) struktur nośnych, w postaci węzłów kompozytowych, w świetle badań wytrzymałościowych wykonanych na węzłach izolowanych. W ograniczonym zakresie wykorzystano tu wyniki badań wykonanych w ramach projektu badawczego (Dębski i inni, 1999) finansowanego przez Komitet Badań Naukowych oraz prac prowadzonych nad nowym samolotem sportowym DEKO-9 Magic.

EN

A new, alternative solution of structures joints, based on composite connections is presented as well as results of strength tests. Some of results have been obtained during research project financed by State Committee for Scientific Research and when designing new sport airplane DEKO-9 Magic.

17

Multilevel Models for the Analysis of Angle-Specific Torque Curves with Application to Master Athletes

100%

Carvalho H. M.

Journal of Human Kinetics

|

2015

|

tom 49

|

nr 1

25-35

EN

The aim of this paper was to outline a multilevel modeling approach to fit individual angle-specific torque curves describing concentric knee extension and flexion isokinetic muscular actions in Master athletes. The potential of the analytical approach to examine between individual differences across the angle-specific torque curves was illustrated including between-individuals variation due to gender differences at a higher level. Torques in concentric muscular actions of knee extension and knee extension at 60°·s-1 were considered within a range of motion between 5°and 85° (only torques “truly” isokinetic). Multilevel time series models with autoregressive covariance structures with standard multilevel models were superior fits compared with standard multilevel models for repeated measures to fit anglespecific torque curves. Third and fourth order polynomial models were the best fits to describe angle-specific torque curves of isokinetic knee flexion and extension concentric actions, respectively. The fixed exponents allow interpretations for initial acceleration, the angle at peak torque and the decrement of torque after peak torque. Also, the multilevel models were flexible to illustrate the influence of gender differences on the shape of torque throughout the range of motion and in the shape of the curves. The presented multilevel regression models may afford a general framework to examine angle-specific moment curves by isokinetic dynamometry, and add to the understanding mechanisms of strength development, particularly the force-length relationship, both related to performance and injury prevention.

18

Testing of Rounded Valley Aggregate in Concrete Mix in Comparison with Crushed Limestone Aggregate

100%

Sarireh M. K.

Advances in Science and Technology. Research Journal

|

2022

|

tom Vol. 16, no 1

282--293

EN

Round valley aggregate RVA is a natural source of aggregate that is found in Tafila in Jordan. For current research, RVA from Al-Hasa valley was considered for testing with crushed limestone aggregate (CLA) from Karak and Tafila sources. 39 samples were collected through the valley at the joint with the lake of Al-Tanour Dam in Tafila. Samples of RVA and CLA were tested and concrete mix at 15, 20, and 25 MPa. ANOVA analysis was conducted to test means’ differences in aggregate and concrete properties. Results showed that RVVA has no significant difference in means’ properties. While RVA has significant differences when with CLA from Karak and Tafila. Results of ANOVA showed that there is a significant difference in the properties of fresh and hardened concrete for 15 and 25 MPa concrete grades. While significant difference is neglected for 20 MPa concrete grade. Consequently, RVA can be used for concrete mix as CLA.

19

Analysis of the Influence of the Mould Temperature in the Weld Line Areas on Strength of the Injection Mouldings

100%

Humienny R. , Postawa P. , Kalwik A.

Archives of Metallurgy and Materials

|

2022

|

tom Vol. 67, iss. 1

325--331

EN

The weld lines that occur in injection mouldings are critical areas on which depends on the strength of the mouldings. The flow of the material in the injection mould takes place through the gate and then gradually in the mould cavity. Depending on the shape of the formed object, the weld line may or may not occur. In the case of spreading of plastic streams or bypassing obstacles in the form of cores in the mould, the joining lines run down. Most often, the strength of the moulded part is the lowest in these areas and the resulting lines can cause cracking. The aim of the research presented in the publication was to evaluate the properties of particular parts of mouldings obtained from an experimental injection mould equipped with 4 weld line areas. The tests were performed using the method of thermal analysis by Dynamic Mechanical Analysis DMA. Tensile tests were performed on the parts with weld areas and the maximum crack force was determined. The morphology of the obtained fractures was observed using an optical microscope.

20

Strength of abs parts produced by fused deposition modelling technology – a critical orientation problem

100%

Górski F. , Wichniarek R. , Kuczko W. , Zawadzki P. , Buń P.

Advances in Science and Technology. Research Journal

|

2015

|

tom Vol. 9, nr 26

12--19

EN

Numerous experimental studies, including experiments performed by the authors, have shown that the part orientation during layer deposition has a very strong in-fluence on final strength of a product manufactured by additive Fused Deposition Technology. The paper presents the results of tensile, bending and impact strength tests performed on samples of various orientations, made out of ABS material using FDM technology. The results of these tests allowed discovering a unique phenomenon – with the changing orientation, not only the values of strength indexes change, but macroscopic material behavior under load as well. The transition between a “yield point” and “brittle” material usually happens in a certain range of orientation values, named a critical orientation by the authors. The paper indicates supposed ranges of critical orientation for various types of loads