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1

Wykorzystanie zdolności pochłaniania energii do wyznaczania wytrzymałości resztkowych fibrokompozytów

Głodkowska Wiesława, Laskowska-Bury Joanna, Lehmann Marek

Materiały Budowlane

|

2023

|

nr 3

1--4

PL

W artykule omówiono sposób wyznaczania wytrzymałości resztkowych z wykorzystaniem zdolności pochłaniania energii przez fibrokompozyt. Badania przeprowadzono przez zginanie płyt o przekroju kwadratowym podpartych przegubowo na obwodzie. Określone w ten sposób wytrzymałości resztkowe cechują się znacznie mniejszym współczynnikiem zmienności niż wyznaczone wg PN-EN 14651:2007. Opisane badanie jest alternatywą dla 3-punktowego zginania belek i pozwala na wyznaczenie tej cechy z większą wiarygodnością.

EN

The article discusses the method of determining residual strength using the energy absorption capacity of fibrecomposite. The research was carried out by bending square cross-section plates simply supported at the perimeter. The residual strengths determined in this way are characterized by a much lower coefficient of variation than those determined using the normative method according to PN-EN 14651:2007. The described test is an alternative to 3-point bending of beams and allows to determine this feature with greater reliability.

2

Wpływ koloru pokrycia na funkcjonowanie dachu

Patoka Krzysztof

Materiały Budowlane

|

2022

|

nr 11

214--215

3

Dynamic impact compressive performance of expanded polystyrene (EPS)-foamed concrete

Yuan Chen, Wenhua Zhang, Lei Zhang, Wanting Zou, Yunsheng Zhang

Archives of Civil and Mechanical Engineering

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2022

|

Vol. 22, no. 4

art. no. e164, 2022

EN

The mechanical property and thermal insulation capacity of EPS concrete will be reduced due to the uneven distribution and float of EPS particles. In this study, an effective strategy for resolving these issues is provided. Physical foaming was mostly employed in this process to prepare foam and inject it into EPS concrete. Different EPS contents and particle sizes were used to make the 11 groups of novel EPS-foamed concrete specimens. The Split Hopkinson Pressure Bar (SHPB) was used to investigate the dynamic impact performance of the new EPS-foamed concrete. The dynamic increasing factor (DIF), peak stress, energy absorption capabilities, and stress–strain curves were all reviewed. The findings revealed that when the amount of EPS in the system increased, the peak stress fell and the energy absorption capacity gradually increased. The energy absorbed was increased by 7–8 times in comparison to specimens lacking EPS. Furthermore, the optimal EPS con-tent ranged between 30 and 40% by volume. The EPS particle size had a significant impact on the specimen strength under dynamic impact load when the density was the same. It was determined that the optimal distribution of EPS particle size was 3–5 mm, based on the test results and the degree of specimen damage. Under the dynamic impact with the best particle size, EPS-foamed concrete demonstrated a relevant excellent energy dissipation capability, with a maximum DIF of 9.16.

4

Structural Damage Characteristics of a Layer-to-Layer 3-D Angle-Interlock Woven Composite Subjected to Drop-Weight Impact

Qian Ma, Ke Wang, Shudong Wang, Yiwei Ouyang, Zhiqiang Lin, Wenfeng Shi, Limin Jin, Xianyan Wu

Autex Research Journal

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2021

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Vol. 21, no. 3

293--298

EN

The most attractive structural feature of the three-dimensional (3D) angle-interlock woven structure is that the straight weft yarns are bundled by the undulated warp yarns, which induces the overall good structural stability and a stable fabric structure. Thus the 3-D angle-interlock woven composite (3DAWC) prepared by the vacuum-assisted resin transfer molding (VARTM) curing process has excellent mechanical properties by using the fabric and epoxy resin as the reinforcement and matrix, respectively. The low-velocity impact damage properties of the composites under different drop-weight energies (70, 80, and 100 J) were tested experimentally. The load–displacement curves, energy–time curves, and the ultimate failure modes were obtained to analyze the performance of resistance to low-velocity impact, as well as the impact energy absorption effect and failure mechanism, especially the structural damage characteristics of the 3DAWC subjected to the low-velocity impact of drop weight. By analyzing the obtained experimental results, it is found that the fabric reinforcement is the primary energy absorption component and the impact energy mainly propagates along the longitudinal direction of the yarns, especially the weft yarn system, which is arranged in a straight way. In addition, as the impact energy increases, the energy absorbed and dissipated by the composite increases simultaneously. This phenomenon is manifested in the severity of deformation and damage of the material, i.e., the amount of deformation and size of the damaged area.

5

Energy absorption of the strengthened viscoelastic multi-curved composite panel under friction force

Shao Yunhong, Zhao Yang, Gao Jun, Habibi Mostafa

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

71--99

EN

This study investigated FG carbon nanotubes filled composites, which are promising metamaterials that can be useful in the energy absorption field. This structure can absorb energy through elastic deformation. For this issue, absorbed energy and dynamic stability analysis of the FG-CNTRC curved panel surrounded by a non-polynomial viscoelastic substrate using three-dimensional poroelasticity theory is investigated. For stability of the structure after vibrating, the viscoelastic substrate as the non-polynomial viscoelastic model is presented. The curved panel comprises multilayer carbon nanotubes (CNT) which are uniformly distributed in all layers of facing sheets; however, the system’s weight fraction alters for each layer through the thickness orientation. The influences of several parameters, such as Winkler–Pasternak parameters, span angle CNTs’ volume fraction, length to radius ratio, compressibility coefficient, friction coefficient, torsional parameter, initial axial stress, and damping factor on the dynamic responses of the FG-CNTRC curved panel surrounded by a non-polynomial viscoelastic substrate are investigated. The golden result of this paper is that the effect of radial stress on the energy absorption is hardly dependent on the value of the foundation parameters. As an applicable outcome in pertained applications, by increasing the compressibility, and friction coefficients, the composite shell's energy absorption decreases.

6

Compressive Property of an Auxetic-Knitted Composite Tube Under Quasi-Static Loading

Boakye Andrews, Raji Rafui King, Ma Pibo, Cong Honglian

Autex Research Journal

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2020

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Vol. 20, no. 2

101--109

EN

This research investigates the compressive property of a novel composite based on a weft-knitted auxetic tube subjected to a quasi-static compression test. In order to maximize the influence of the fiber content on the compression test, a Kevlar yarn was used in knitting the tubular samples using three different auxetic arrow-head structures (i.e. 4 × 4, 6 × 6 and 8 × 8 structure). A quasi-static compression test was conducted under two different impact loading speeds (i.e. 5 mm/min and 15 mm/min loading speed). The results indicate that the energy absorption (EA) property of the auxetic composite is highly influenced by the auxeticity of the knitted tubular fabric.

7

Neural Networks in Crashworthiness Analysis of Thin-Walled Profile with Foam Filling

Rogala Michał

Advances in Science and Technology. Research Journal

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2020

|

Vol. 14, no 3

93--99

EN

This article presents the numerical tests of thin-walled compressed columns with a square cross-section. The crush efficiency indicators were determined using the finite element method (Abaqus) and neural networks of MLP. The models had a constant circular trigger, with a diameter of 32 mm. During dynamic analysis, the samples were loaded with 1700 J. The numerical models were filled with aluminum foam from 40 mm to 180 mm every 20 mm. The study presents the conclusions for the thin-walled models with crushable foam.

8

Effect of Test Velocity on the Specific Energy Absorption under Progressive Crushing of Composite Tubes

Ryzińska Grażyna, Gieleta Roman

Advances in Science and Technology. Research Journal

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2020

|

Vol. 14, no 2

94--102

EN

The paper presents the results of the compression tests for carbon-epoxy composites in order to assess the amount of energy absorbed depending on the process velocity and content of axial fibres. Two types of prepreg (UD 200 g/m2 and woven 160 g/m2) were used to prepare the specimens with a diameter of 20 mm and a height of 34 mm. The specimens were subjected to compression under various speed conditions (static, dynamic and SHPB tests). The calculated specific energy absorption values showed a 50–60% decrease with increasing process velocity and depending on the type of specimens architecture. The highest energy values were absorbed by the specimens with the highest share of axial fibres in the sample.

9

Numerical Crush Analysis of Thin-Walled Aluminium Columns with Square Cross-Section and a Partial Foam Filling

Ferdynus Mirosław, Rogala Michał

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 3

144--151

EN

The article presents the results of numerical crush simulations of thin-walled structures with a square cross-section and partial filling with foamed material. The influence of the length of the filling on the values of the energy efficiency index was analysed. Four types of foamed material were subjected to numerical analysis. The research was conducted using FEM in Abaqus 6.14 program. The obtained results were presented in the following forms: load-shortening characteristics, tables and diagrams. The best energy absorbing properties are shown by models filled with aluminium and polyethylene terephthalate foam.

10

Tribological Tests and Impact Tests of Acrylic Polymers for Dental Prosthetics

Ryniewicz A. M., Ryniewicz W., Bojko Ł., Pałka P.

Tribologia

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2018

|

nr 4

89--95

EN

The clinical functionality of the prosthesis structure consists of creating the most convenient conditions without any traumatic effects of chewing forces on the substrate and adapting it to the individual biomechanical exclusions of the stomatognathic system (SS). When transferring functional loads, the optimization of tribological features and the ability to absorb energy is an important design and material parameter. The aim is to evaluate acrylic plastics intended for prostheses in terms of resistance to wear and resistance to movement in sliding contact within the environment of artificial saliva and their ability to absorb energy. Based on the analysis of the test results, it can be pointed out that Vertex is a good material for partial and complete dentures. Villacryl demonstrated similar properties, with Probase and Probase O being slightly worse. The appropriate mechanical parameters of the materials used in the prosthesis allow the production of thin plates that accurately reproduce the prosthetic substrate and improve the patient’s comfort of use through such a fit.

PL

Funkcjonalność kliniczna konstrukcji protezy polega na stworzeniu najdogodniejszych warunków bezurazowego oddziaływania sił żucia na podłoże oraz dostosowania jej do indywidualnych wymuszeń biomechanicznych US. Przy przekazywaniu obciążeń czynnościowych istotnym parametrem konstrukcyjno-materiałowym jest optymalizacja cech tribologicznych oraz zdolność do pochłaniania energii. Celem jest ocena tworzyw akrylowych przeznaczonych na protezy w zakresie odporności na zużycie i oporów ruchu w kontakcie ślizgowym w środowisku sztucznej śliny oraz ich zdolności do pochłaniania energii. Na podstawie analizy wyników badań można wskazać, że Vertex jest dobrym materiałem do wykonywania protez częściowych i całkowitych. Zbliżone do niego właściwości posiadał Villacryl, a nieco gorsze Probase i Probase O. Odpowiednie parametry mechaniczne materiałów stosowanych na protezy pozwalają na wykonanie cienkich płyt, które dokładnie odwzorowują podłoże protetyczne i poprzez takie dopasowanie poprawiają pacjentowi komfort użytkowania.

11

Experimental study of hybrid rubberized composite slabs

Subashree P., Thenmozhi R.

Archives of Civil Engineering

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2018

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Vol. 64, nr 4/II

21--29

EN

Rubberized concrete is made up of scrap tyre rubbers where the fine aggregate is partially replaced by it, as the waste rubber is being a threat to the environment. It is estimated that only 4% of the waste tyre is used in the application of civil engineering and also there is shortage of fine aggregates. The primary objective of this study is to investigate the preliminary concrete properties of M25 and M30 concretes. The fine aggregate is replaced by pre-treated crumb rubber with 10, 15 and 20 % of total weight. Various tests are conducted on the rubberized concrete specimens such as compressive strength, split tensile strength, flexural strength and slump test. The investigation is carried out to determine the impact load behavior of hybrid rubberized composite slabs. In addition 0%, 1%, 1.5%, and 2% of replacement of rubber fibers for total weight of coarse aggregate is also made. The specimen of size 300 mm x 300 mm x 50 mm thickness is subjected to drop hammer test to find its performance against the impact loads. The number of blows for the first crack and complete failure of slab was found and the characteristics were studied.

12

Rubber and magnetorheological fluid applied as the interlayer in composite armours against high-velocity loadings

Fras T., Fras L. J., Faderl N.

Diagnostyka

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2017

|

Vol. 18, No. 3

63--68

EN

Monolithic, homogenous ballistic shields consisting of a single thick, high-hardness and high-strength steel plate are rarely applied in modern combat vehicles. Currently, a popular armour concept is a multilayered shield since it is expected that the kinetic energy of a threat may be dissipated by transmission through materials with different properties and also by multiple interface reflections. Searching for a maximum ballistic protection at minimum weight inspires applications of various materials which complementary behaviour provides a high protective efficiency without excessive mass. The preliminary experimental investigation presented in the paper aimed to verify behaviour of two prototyped laminated armours under impacts of small-calibre projectiles (cal. 7.62). The main interest lied in impact properties of materials proposed as the intermediate layer. The first tested concept was a laminated steel armour with the 10 mm thick rubber interlayer. In the second armour, the intermediate layer consisted of a magnetorheological fluid.

13

Preliminary comparative static identification research on selected commercial auxetic fabrics

Klasztorny M., Szurgott P., Niezgoda T., Miedzińska D., Kiczko A.

Composites Theory and Practice

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2017

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R. 17, nr 2

59--66

EN

Preliminary comparative static identification experimental tests on four selected commercial auxetic woven fabrics were conducted in terms of the tensile test in the auxetic fibre direction. A new method of such tests was developed, based on capstan grips as well as on video-extensometer and extensometer techniques. The identification tests were carried out at temperatures of 20 and 180°C due to the intended use of auxetic fabric as a protective curtain against a shock wave induced by a gas explosion. The ultimate tension force per unit width of fabric, effective Poisson’s ratios in the fabric plane and in the transverse plane, as well as the absorbed energy were determined approximately. The auxetic fabric with the relatively best properties was selected.

PL

Przeprowadzono wstępne porównawcze statyczne doświadczalne testy identyfikacyjne czterech wybranych auksetycznych tkanin użytkowych w zakresie próby rozciągania w kierunku włókna auksetycznego. Została opracowana nowa metoda takich badań, wykorzystująca uchwyty kabestanowe, jak również wideotensometr i techniki tensometryczne. Testy identyfikacyjne prowadzono w temperaturach 20 i 180°C, ze względu na planowane zastosowanie materiału auksetycznego w postaci kurtyny ochronnej przeciw fali uderzeniowej wywołanej wybuchem gazu. Na podstawie testów określono graniczną nośność tkaniny, efektywne wartości współczynnika Poissona w płaszczyźnie tkaniny i w płaszczyźnie poprzecznej oraz energię absorbowaną. Wybrano tkaninę auksetyczną charakteryzującą się względnie najlepszymi właściwościami.

14

Anchoring principles of a new energy-absorbing expandable rock bolt

Wen Z., Jiang Y., Han Z., Yang S., Wang X.

Engineering Transactions

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2016

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Vol. 64, iss. 1

89--103

EN

The greater the mine, the harder stability control will be. And the conventional rock bolts do not adapt well to the severe rock stress conditions. An ideal bolt having a high resistance and large deformation should be developed. Based on the test results and theoretical study, this paper proposes an energy-absorbing expandable rock bolt, which consists of the bar, sleeve, bolt plate, nut, and bolt end. The anchoring mechanism and its efficiency were systematically analysed in the laboratory and in practice: the anchoring mechanism and supporting density, especially the quantitative relationship, were deduced under the Energy Balance Theory, that is, EB = 1 2 · n · F0 (u0 + 2∆u). As Compared with the conventional bolt and large deformation bolts, the new type of bolt could provide a larger constant resistance, even in the soft rock roadway with large squeezing deformation, the pulling force can be achieved by F = A · σ · f2, it mainly being generated by a normal stress acting on the pore surface. These characteristics are helpful in making the supported roadway safe. The amount of released energy during the large deforming process of the surrounding rock is expressed through conservation of energy, which can provide reference to the quantitative calculation of the bolt supporting system.

15

Effect of quadrilateral discontinuity size on the energy absorption of structural steel profiles

Estrada Q., Szwedowicz D., Majewski T., Martinez E., Rodriguez-Mendez A.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 2

186--193

EN

In this paper the effect of discontinuity size on energy absorption performance of steel square profiles is reported. The analysis consists of finite element simulations and experimental results of the compression strength of steel profiles with discontinuities. The discontinuities were placed at the mid span of the profiles in two walls opposite to each other. Square, rectangular and diamond initiators were evaluated at different scales. The numerical results determined the size intervals that present a good energy absorption performance in each case. Energy absorption capabilities were increased up to 12.54% with respect to a structure without discontinuities. Additionally, the peak load value (Pmax) was decreased 25.97% with the implementation of a diamond initiator. For structures with discontinuities with major axis close to the profile width, a buckling effect was observed. Finally, it was observed that the size of the initiators contributes to reduce the peak load (Pmax) value.

PL

W pracy przedstawiono analizę wpływu rozmiaru nieciągłości na pochłanianie energii przez stalowe profile o przekroju kwadratowym. Analiza przedstawia wyniki symulacji elementami skończonymi próby ściskania profili stalowych z nieciągłościami oraz porównanie z danymi eksperymentalnymi. Nieciągłości zostały usytuowane w środku profilu w dwóch przeciwległych ścianach. W pracy zostały przebadane nieciągłości o formach kwadratowych, prostokątnych i rombowych dla różnych wymiarów. Stwierdzono wzrost o 12,54% możliwości pochłaniania energii w porównaniu dla struktur bez nieciągłości. Dodatkowo, w przypadku nieciągłości rombowych stwierdzono spadek wartości siły maksymalnej (Pmax) o 25,97%. Zaobserwowano występowanie efektu wyboczenia dla nieciągłości rombowej gdy wymiar jej osi zbliża się do szerokości profilu. Zaobserwowano, ze rozmiar nieciągłości wpływa na redukcje wartości maksymalnego obciążenia oraz w tym samym czasie na obniżenie pochłanianej energii.

16

Badania energochłonności struktur wykonanych ze stopów magnezu

Kaczyński P., Bartczak B., Gronostajski Z., Polak S.

Rudy i Metale Nieżelazne Recykling

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2015

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R. 60, nr 12

699--706

PL

Artykuł przedstawia badania energochłonności cienkościennych struktur energochłonnych wykonanych ze stopu magnezu AZ31. Badany materiał pęka krucho podczas zginania w temperaturze otoczenia. Ten powszechnie znany problem utrudnia obróbkę plastyczną stopów magnezu i ich wykorzystanie w produkcji elementów energochłonnych. W pracy wykazano, iż zastosowanie odpowiedniego kształtu geometrycznego pozwala na kontrolę procesu dynamicznego zgniatania i aktywowanie nowego mechanizmu pochłaniania energii, jakim jest progresywne kruszenie.

EN

Magnesium is the eighth most common element on earth. Its content in the earth's crust is 2.1 %. Today, China produces about 80 % of magnesium worldwide. It is primarily used as: an alloying addition to aluminum castings (41 %), the material for castings and sheets (32 %), the material for desulfurization of steel alloys (14%) and for other purposes (14 %) [1]. Global demand for this element is expected to reach 1 270 000 tons, which is an increase of 42 % compared to 2015 [2]. Magnesium alloys are the third most commonly used material for the construction of the structural elements, right after steel alloys and aluminum alloys. Because density of magnesium equals to about ¼ of steel density and ⅔ of aluminum density it is one of the lightest metals. This allows for its use in the automotive industry, aerospace industry, power industry and other industries that pus special emphasis on construction weight reduction. A good example is the increased use of magnesium components by major automotive companies, including General Motors (GM), Ford, Volkswagen and Toyota [3÷10]. However, the weight of magnesium components in a typical family sedan car in North America equals only to 0.3 % of the total weight of the vehicle. The reason for this state is the problem with the plastic forming of magnesium elements and the behavior of the material during impact. Sheets made of magnesium alloys cracks brittle during bending. This material is considered to be unsuitable for the construction of energy-absorbing elements, which absorb energy by plastic folding. This study demonstrate that the use of appropriate geometric shape allows to control the dynamic crushing process and activation of a new mechanism which is progressive crushing.

17

Wpływ wytłaczania papierów higienicznych na ich właściwości fizyczne

Szewczyk W., Khadzhynova S., Pełczyński P.

Przegląd Papierniczy

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2015

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R. 71, nr 12

699--704

PL

W przypadku wyrobów wykonanych na bazie papierów higienicznych, w szczególności ręczników papierowych, wytrzymałość mechaniczna jest jedną z najważniejszych cech użytkowych. Właściwości fizyczne ręczników papierowych zależą od tych właściwości papierów higienicznych, z których je wykonano, ale ulegają zmianie w trakcie przetwarzania papierów, w szczególności na etapie wytłaczania. Ważnym parametrem opisującym ilościowo efekt wytłaczania jest względne pole powierzchni wytłoczeń. W niniejszym artykule przedstawiono wyniki badań wpływu tego parametru na następujące właściwości wyrobów z papierów higienicznych: wytrzymałość na rozciąganie, rozciągliwość, pochłanianie energii rozciągania oraz wytrzymałość na rozciąganie na mokro.

EN

Mechanical strength is one of the most important features for products made on the basis of tissue paper, in particular paper towels. Physical properties of paper towels depend on the physical properties of tissue paper from which they were made, but these properties are altered during paper processing, especially at the embossing stage. An important parameter describing the effect of embossing is the relative area of embossed surface. In this article the results of research on the impact of this parameter on the following properties of hygienic paper products are presented: tensile strength, stretch, tensile energy absorption and tensile wet strength.

18

Metoda i stanowisko do badania pochłaniania energii uderzenia poruszającego się obiektu przez przemysłowe hełmy ochronne

Baszczyński K.

Pomiary Automatyka Kontrola

|

2014

|

R. 60, nr 2

90--93

PL

Artykuł dotyczy problematyki badania parametrów ochronnych hełmów stosowanych w warunkach przemysłowych. Przedstawiono założenia do metody badania energii pochłanianej przez hełm ochronny podczas uderzenia poruszającego się obiektu. Zaprezentowano praktyczną realizację metody badań i zbudowane stanowisko. Scharakteryzowano jego konstrukcję i podstawowe parametry. Jego własności i zalety zostały ocenione na podstawie wyników badań wybranych typów hełmów ochronnych.

XX

The paper discusses the problems associated with testing protective parameters of helmets used in industrial environment. The disadvantages of the testing methods used to date, which do not allow predicting the helmet performance upon high-energy impact by a moving object, are presented. A new method of assessing impact energy absorbed by a helmet is proposed and assumptions for this method formulated. Practical implementation of the method as well as the developed test stand are presented. The stand allows measuring the force acting on a head form on impact inflicted by a falling object as well as the helmet deformation using a high speed digital camera. The software package designed to control the measuring instruments and to process the data recorded during the impact is described, with special emphasis on specialist software enabling description of the time course of helmet deformation using image identification methods. The presented method and stand were used for testing the selected types of protective industrial helmets. The obtained results indicate that the properties of such helmets fail to exceed significantly the minimal requirements specified in the relevant standards. The performed tests also demonstrate that the target parameters of the stand have been obtained and confirm that it is a unique tool enabling complex assessment of protective helmets, useful in particular for design and development of new construction solutions.

19

Systemy amortyzacji siłowników pneumatycznych

Dworzak S.

Pneumatyka

|

2014

|

Nr 1-2

26--29

PL

Pochłanianie energii przez siłowniki pneumatyczne jest ważnym ich zadaniem w złożonych systemach. Pomimo faktu, że siłowniki są znanymi od lat napędami, okazuje się, iż nadal możliwe jest ich udoskonalanie. Nowy system amortyzacji PPS firmy Festo jest rewolucyjnym rozwiązaniem, które sprawia, że siłowniki stają się jeszcze bardziej uniwersalne i prostsze w utrzymaniu. W niniejszym artykule zaprezentowano oferowane przez Festo systemy amortyzacji konstrukcyjnie związane z siłownikiem oraz omówiono nową samonastawialną amortyzację pneumatyczną PPS.

EN

Systems of depreciation in pneumatic actuators shock absorbing in pneumatic cylinders is an important task in complex systems. Despite of fact that this type of actuators is available for dozens of years it is still possible to make it operate better. Festo new PPS shock absorbing system is an innovative solution that makes pneumatic cylinders even more universal and easy to commission.

20

On the failure mode of resistance spot welded HSLA 420 steel

Pouranvari M.

Archives of Metallurgy and Materials

|

2013

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Vol. 58, iss. 1

67-72

EN

Failure mode of resistance spot welds (interfacial vs. pullout) is a qualitative measure of resistance spot weld performance. Considering adverse effect of interfacial failure mode on the vehicle crashworthiness, process parameters should be adjusted so that the pullout failure mode is guaranteed ensuring reliability of spot welds during vehicle lifetime. In this paper, metallurgical and mechanical properties of HSLA 420 resistance spot welds are studied with particular attention to the failure mode. Results showed that the conventional weld size recommendation of 4t0:5 (t is sheet thickness) is not sufficient to guarantee pullout failure mode for HSLA steel spot welds during the tensile-shear test. Considering the failure mechanism of spot welds during the tensileshear test, minimum required fusion zone size to ensure the pullout failure mode was estimated using an analytical model. Fusion zone size proved to be the most important controlling factor for peak load and energy absorption of HSLA 420 resistance spot weld.

PL

Tryb uszkodzenia zgrzein (pękanie na granicy faz a wyrywanie) jest jakościowa miara zachowania zgrzein. Biorąc pod uwagę niekorzystny wpływ uszkodzenia na granicy faz na odporność pojazdu na uderzenia, parametry zgrzewania powinny być ustawione tak, ze trybem uszkodzenia jest wyrywanie co gwarantuje niezawodność zgrzein w czasie eksploatacji pojazdu. W pracy, badane sa metalurgiczne i mechaniczne właściwości zgrzein stali HSLA 420 ze szczególnym uwzględnieniem trybu uszkodzenia. Wyniki próby rozciągania i ścinania wykazały, ze konwencjonalne zalecenie rozmiaru spoiny 4t0:5 (t - grubość) nie jest wystarczające, aby zapewnić ze trybem uszkodzenia jest wyrywanie. Biorąc pod uwagę mechanizm uszkodzenia zgrzein w czasie próby rozciągania i ścinania, minimalna wielkość strefy stopionej wymagana do zapewnienia, ze trybem uszkodzenia jest najbardziej istotnym czynnikiem decydującym o maksymalnym obciążeniu i pochłanianiu energii przez zgrzewana stal HSLA 420.