Wyniki wyszukiwania - BazTech

1

Simulation method for measuring the impact energy of rail vehicles equipped with a soft absorber

Lisowska Aleksandra, Sanecki Henryk, Szkoda Maciej

Transport Problems

|

2023

|

T. 18, z. 3

15--28

EN

This paper presents a simulation method for testing the energy absorbed by the absorption systems of rail vehicles equipped with a soft absorber. The method makes it possible to verify the actual behavior of the absorption system during the impact of two vehicles. The first part of this paper describes the structural elements of a railway vehicle performing the function of an energy absorber during an impact according to the EN 15227 standard. A soft absorber, the so-called honeycomb, is analyzed in detail. It is a multicellular structure often used in rail vehicles due to its properties of controlled deformation. The literature review describes the research conducted on this element. The analytical part of this paper describes a general mathematical model of a rail vehicle collision according to Scenario 1, in which the collided vehicles are of the same type, and Scenario 2 for vehicles of different types. A computational impact simulation for the two scenarios has been carried out using the specialist software Mathcad, and the results are presented in graphs. The paper ends with conclusions presenting the application possibilities of the developed tool.

2

Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

Talebi S., Hedayati R., Sadighi M.

Archives of Civil and Mechanical Engineering

|

2021

|

Vol. 21, no. 3

231--245

EN

Closed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

3

Mechanical performances of metal-polymer sandwich structures with 3D-printed lattice cores subjected to bending load

Liu Zhaobing, Chen Hantang, Xing Shuaiqi

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

368--384

EN

In this article, we propose a new class of metal-polymer architected sandwich structures that exhibit different mechanical behaviors. These lightweight sandwich structures have been made of aluminum face sheets and 3D-printed lattice cores with 2D (Bi-grid, Tri-grid, Quadri-grid and Kagome-grid) and 3D (face-centered cubic-like and body-centered cubic-like) topologies. Finite element simulation and experimental tests were carried out to evaluate mechanical performances of the proposed sandwich structures under quasi-static three-point bending load. Specifically, the damage-tolerant capability, energy absorption and failure mechanisms of these sandwich structures were investigated and evaluated through a combination of analytical, numerical and experimental methods. It is found that sandwich structures with 3D face and body-centered cubic-like cores can provide more excellent flexural stiffness, strength and energy absorption performance. These enhanced mechanical features could be further explained by a so-called ‘Stress Propagation’ mechanism through finite element analysis (FEA) that can facilitate sandwich structures with 3D cores, especially body-centered cubic-like one, to transfer bending loads from central lattice units across neighboring ones more efficiently than 2D cores. Furthermore, core cracking is the main failure mode for the proposed sandwich structures, which is primarily caused and dominated by bending-induced tensile stress followed by shear stress. It is worth mentioning that our findings provide new insights into the design of novel lightweight sandwich composites with tailored mechanical properties, which can benefit a wide variety of high-performance applications.

4

Głowica do nanoszenia mieszanki elastomerowej na taśmę w linii technologicznej

Kozioł Stanisław, Matecki Krzysztof, Samborski Tomasz, Zbrowski Andrzej, Bąba Grzegorz

Technologia i Automatyzacja Montażu

|

2019

|

nr 2

18--24

PL

W Instytucie Technologii Eksploatacji została zaprojektowana i wykonana prototypowa głowica dozująca elastomery termoplastyczne w specjalnie zaprojektowanej linii technologicznej, wytwarzającej kompozyty tkaninowo-elastomerowe. Głowica umożliwia dozowanie elastomeru na przemieszczający się materiał, wyrównywanie naniesionej warstwy lub tworzenie warstw nieciągłych - przepuszczalnych dla pary wodnej lub powietrza. W urządzeniu zastosowano ogrzewanie dozowanego medium za pomocą olejowego przewodu grzewczego lub elektrycznych elementów grzejnych z regulacją temperatury. Opracowana konstrukcja zapewnia możliwość zmiany kierunku przepływu podłoża w linii technologicznej, precyzyjną regulację grubości warstwy, automatyczną realizację ruchów ustawczych i serwisowych oraz bezpieczną obsługę. Firma BOCHEMIA, wykorzystując głowicę w zbudowanej w ramach realizowanego projektu linii technologicznej, opracowała innowacyjne rozwiązania w zakresie technologii wytwarzania wielofunkcyjnych kompozytów zawierających innowacyjne materiały wykazujące właściwości absorbujące energię, umożliwiające tłumienie uderzeń oraz właściwości wodoszczelne, grzybobójcze i bakteriobójcze.

EN

The prototype of a dispensing head of thermoplastic elastomers was designed and construct-ed at the Institute for Sustainable Technologies for a purpose-built manufacturing line for producing textile-elastomer composite glues. The elastomer dispensing head enables the transfer of the elastomer onto the moving material; it evens out the applied layer or creates discontinuous layers which are permeable for water vapour or air. The device heats the medium being dispensed using an oil heated conduit or electric heating elements with temperature control. This design is capable of changing the flow direction of the substrate in the manufacturing line, regulating a precise layer thickness, automatically executing setup and maintenance, and safe handling. Using the dispensing head constructed as part of project developing the manufacturing, the BOCHEMIA company has developed innovative solutions for manufacturing technologies of multifunctional composites of innovative materials which exhibit the following properties: energy absorbing (which provided impact absorption properties), fungicidal, and bactericidal.

5

Badania materiałów spodowych obuwia dla osób powyżej 60 lat

Czaplicki Zdzisław, Olejniczak Zbigniew, Serweta Wioleta

Przegląd Włókienniczy - Włókno, Odzież, Skóra

|

2019

|

nr 5

30--32

PL

W artykule przedstawiono analizę porównawczą materiałów spodowych, z jakich wykonywane są spody obuwia dla osób 60+. Przy wyborze tych materiałów uwzględniono ich dostępność na rynku oraz wykorzystywanie przez producentów obuwia. Badano pięć różnych materiałów podeszwowych wykonanych na bazie polichlorku winylu, kauczuku termoplastycznego i poliuretanu. W badanych próbkach określono m. in. takie parametry jak odporność na ścieranie, twardość, elastyczność, absorpcję energii i współczynnik tarcia (odporność na poślizg). Stwierdzono, że najlepsze wyniki uzyskały próbki wykonane na bazie polichlorku winylu.

EN

This paper presents the comparative analysis of the sole materials for the shoes sole used by the persons over 60th+. The choice of materials was considered their accesability on the market and application by the shoes manufactures. Five different sole materials manufactured on the basis of polyvinyl chloride (PVC), thermoplastic rubber and polyurethane were investigated. During the investigations the following parameters were determined: resistance to abrasion, hardness, elasticity, energy absorption and friction coefficient (resistance for slide). It was stated that the best results were obtained the specimens produced on the basis of polyurethane.

6

Sposoby redukcji efektu miejskiej wyspy ciepła

Kleszczewska Katarzyna

Inżynieria i Budownictwo

|

2019

|

R. 75, nr 3

116--118

PL

Omówiono przyczyny powstawania i wpływ miejskich wysp ciepła oraz strategie zmierzające do redukcji temperatury w skupiskach ludności. Skupiono się przede wszystkim na technologiach związanych z nawierzchnią, zmierzających do zmniejszenia magazynowania przez nie ciepła i obniżenia temperatury powierzchni.

EN

The paper describes the causes and impact of urban heat islands and promotes strategies for lowering temperatures in population concentration. Main focus is concentrated on pavement technologies tend to store less heat and may have lower surface temperatures.

7

A parametric study of the mechanical behavior of nested multi tube structures under quasi-static loading

Chahardoli S., Alavi Nia A., Asadi Mehrdad

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 4

943--957

EN

Mechanical behavior of nested aluminum structures under lateral and quasi-static loadings has been investigated in current paper. These structures consist of two nested tubes in which the inner tube is located vertically in the horizontal outer tube. The research has been done numerically and experimentally. In the numerical section, the LS-DYNA software has been used while experimental results are implemented to validate the FE outcome. The well correlated numerical results show that increasing the diameter of the inner tube leads to a decrease in the maximum force and the specific energy absorption. Later, employing the optimization by response surface method in Minitab software, the energy absorber's characteristics has been optimized and introduced as new set of specifications. High crush force efficiency is the main criterion in current research.

8

Rdzenie konstrukcji kompozytowych z pianek półsztywnych do zastosowań w tarczach ochronnych dla strażaków

Ryszkowska J., Leszczyńska M., Auguścik M., Bryśkiewicz A., Półka M., Kukfisz B., Wierzbicki Ł., Aleksandrowicz J., Szczepkowski L., Oliwa R.

Polimery

|

2018

|

T. 63, nr 2

125—133

PL

Przedmiotem badań były półsztywne pianki poliuretanowe zaliczane do grupy materiałów absorbujących energię, zastosowane do wytwarzania elementów konstrukcji tarcz ochronnych dla strażaków. W celu zwiększenia odporności pianek na działanie ognia modyfikowano je dodatkiem grafitu ekspandującego i Fyrol PNX. Otrzymano pianki trudnopalne, o zmniejszonej zapalności i ograniczonej ilości wydzielanego dymu, wykazujące zdolność do pochłaniania 12–19 % energii uderzenia. Wprowadzenie do wytwarzanej kompozycji piankowej odpadu gumowego pozwoliło na obniżenie ceny pianek o ok. 25 %.

EN

The subject of the paper are semi-rigid polyurethane foams. They belong to a group of energy-absorbing materials, which have been used for manufacture of structural components of protecting shields for firefighters. In order to increase the fire resistance of the foams they were modified by addition of expandable graphite and Fyrol PNX. As a result, flame retardant foams have been obtained, with reduced flammability and limited amount of smoke emission, having an ability to absorb impact energy in the amount of 12–19 %. By introducing a rubber waste during the manufacture of foam composition, the price of foams was reduced by about 25 %.

9

Crushing behavior of kenaf fiber/wooden stick reinforced epoxy hybrid "green”composite elliptical tubes

Alkateb M., Sapuan S. M., Leman Z., Jawaid M., Ishak M. R.

Polimery

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2018

|

T. 63, nr 6

436--443

EN

In this paper, an investigation on crushing behavior of kenaf fiber/wooden stick reinforced epoxy hybrid composite elliptical tubes is presented. Kenaf fiber reinforced epoxy elliptical composite tubes, unsupported and supported by wooden sticks (4, 6 and 8), were fabricated using hand lay-up process. The crushing tests were performed at a constant speed of 20 mm/s to explore the potential effect of wooden sticks on the specific energy and mechanical behavior of kenaf fiber reinforced epoxy composite elliptical tubes. As a result of the study, it was found that the load carrying capacities of kenaf fiber reinforced epoxy composite tubes were gradually increased with the number of wooden sticks. Generally, the investigation showed that kenaf fiber reinforce depoxy composite elliptical tubes supported by wooden sticks demonstrated superior specific energy absorption and crashworthiness compared to the composite tubes unsupported. Further, the results also revealed that all specimens have failed in longitudinal failure modes. In this regard, an elliptical composite tube supported by 8 wooden sticks exhibited the best energy absorption capability.

PL

Przedstawiono wyniki badań odporności na zgniatanie eliptycznych rur wykonanych metodą laminowania ręcznego z hybrydowych kompozytów żywicy epoksydowej z włóknami kenafu, wzmacnianych 4, 6 lub 8 prętami drewnianymi. Testy zgniatania prowadzono przy stałej szybkości 20 mm/s, w celu oceny potencjalnego wpływu wzmacniających prętów drewnianych na energię właściwą oraz właściwości mechaniczne kompozytów. Stwierdzono, że zdolność do przenoszenia obciążeń przez rury kompozytowe zwiększała się ze wzrostem liczby prętów wzmacniających. Badania wykazały, że wzmocnienie prętami drewnianymi rur eliptycznych z kompozytów żywicy epoksydowej z włóknami kenafu wpływa na zwiększenie zdolności absorpcji energii oraz odporności na zderzenia. Wszystkie próbki ulegały zniszczeniu w kierunku wzdłużnym. Największą zdolność pochłaniania energii wykazywała rura kompozytowa wspierana przez 8 prętów drewnianych.

10

Odporność na przebicia materiałów kompozytowych

Kyzioł L.

Autobusy : technika, eksploatacja, systemy transportowe

|

2018

|

R. 19, nr 6

540--543, CD

PL

Konstrukcjom, które przenoszą obciążenia dynamiczne i których odporność decyduje o życiu i bezpieczeństwie człowieka stawia się szczególne wymagania. Wymagania dotyczą zarówno sfery materiałowej jak i konstrukcyjnej. To z kolei zmusza do poszukiwania optymalnych metod obliczeniowych, z uwzględnieniem nieliniowości, tak geometrycznej jak i fizycznej, wynikającej z konfiguracji struktury konstrukcji. Przykładem są różne konstrukcje balistyczne (osłony balistyczne), które są uderzane pociskami w których skumulowana jest ogromna energia. W takim przypadku uderzenie w tarczę (osłonę) pociskiem można rozpatrywać jako obciążenie spowodowane uderzeniem masą. Matematycznie zjawiska obciążeń przy dużych szybkościach odkształceń opisuje się różnymi modelami. Aparat matematyczny jest dość złożony ponieważ wymagana jest duża liczba „współczynników”, ponadto uzyskane wyniki badań nie zawsze są powtarzalne i ma na to wpływ wiele czynników. W pracy zaprezentowano wyniki przestrzeliwania tarcz wielowarstwowych z materiałów kompozytowych pociskami kalibru 7,62 mm. Tarcza składała się z trzech warstw, warstwy zewnętrzne stanowiły okładziny stalowe lub aluminiowe, warstwę wewnętrzną stanowiło drewno naturalne lub modyfikowane. Próbki w kształcie tarcz były o średnicy 50 mm i różnej grubości. Wyniki badań pozwoliły ocenić wpływ modyfikacji drewna na jego odporność na przebicia.

EN

For structures that carry dynamic loads, the requirements are imposed for safety reasons. The requirements apply to both materials and construction. This requires searching for optimal calculation methods, including geometric and physical nonlinearity, which are results from the construction of the structure. An example is various ballistic structures (ballistic shields), which are hit by bullets in which huge energy is accumulated. In this case, the hitting in the shield with a bullet can be considered as a load due to mass impact. Loads at high strain rates are described by various mathematical models. The mathematical model is complex because a large number of "coefficients" is required, moreover, the obtained test results are not always repeatable. The paper presents the results of shooting multilayer plates with composite materials with 7.62 mm caliber bullets. The shield consisted of three layers, the outer layers were steel or aluminum, the inner layer was natural or modified wood. The samples had the shape of a shield and were 50 mm in diameter and of different thickness. The results of the research allowed to assess the impact of wood modification on its puncture resistance.

11

The approach to mining safety improvement: Accident analysis of an underground machine operator

Karliński J., Ptak M., Działak P., Rusiński E.

Archives of Civil and Mechanical Engineering

|

2016

|

Vol. 16, no. 3

503--512

EN

This paper presents the numerical approach to the safety and ergonomics issues regarding the biomechanics of the mining machine operator. Based on actual accidents, the authors analyzed the current requirements for protective structures in regard to operator safety aspects. The study found that the current type-approval tests do not examine phenomena related to typical accidents in underground mines, such as rock bursts resulting in thill uplift, lateral rock tosses, or cover caving. In many cases it may result in severe or fatal injuries of the mining machine operators. Thus, the authors incorporate a precise human model into operator safety tests and conducted numerical simulations by the use of the coupled Finite Element and MulitBody codes. To mitigate the injuries, the state-of-the-art seat absorber was implemented underneath a typical operator's seat. The device was designed to dissipate the kinetic energy during the process of rapid floor uplift and immediate velocity change from the cab to gallery roof impact. In order to compare the energy-dissipating capabilities of the absorber two approaches were selected for the same boundary conditions: a standard seat and seat with absorber mounted in the cab during the impact. The cab initial velocity was the main variable during the simulations. Finally, the injury criteria for the standard seat and the new approach with the energy-absorbing device were collated and contrasted.

12

Impact behaviour of spot-welded thin-walled frusta

Kotełko M., Mołdawa A.

Acta Mechanica et Automatica

|

2016

|

Vol. 10, no. 4

280--284

EN

In the paper the dynamic response of thin-walled, spot-welded prismatic frusta subjected to axial impact load is investigated. The parametric study into the influence of several parameters on the energy absorption capability, expressed by some crashworthiness indicators is performed, using Finite Element simulations. FE model is validated by experimental results of quasi-static and dynamic (impact) tests. Results of initial study concerning influence of spot welds are presented. Some conclusions are derived from the parametric study into the influence of frustum angle and wall thickness upon the energy absorption capability.

13

Niestacjonarny pomiar termowizyjny absorpcji wiązki laserowej przez porowate materiały budowlane

Marynowicz A.

Fizyka Budowli w Teorii i Praktyce

|

2015

|

T. 7, nr 2

51--56

PL

W pracy zaproponowano sposób pomiaru absorpcji promieniowania lasera czerwonego przez dwa różne porowate materiały budowlane. Do niestacjonarnego pomiaru temperatury na powierzchni próbki ogrzewanej promieniem lasera wykorzystano kamerę termowizyjną. Zaproponowane podejście, oparte na zastosowaniu prostego aparatu optymalizacyjnego, pozwala wyznaczyć poszukiwane parametry z dobrą dokładnością.

EN

The method of the red laser beam absorption description by selected porous building materials was proposed. The transient temperature measurements were performed with the use of infrared camera equipment during laser induced heating-up of the samples surface. The proposed approach utilizes simple optimization technique and gives possibility for a good estimation of the investigated parameters.

14

Application of halloysite in fabrication of composite materials for energy absorption

Głuszek M., Antosik A., Żurowski R., Szafran M.

Composites Theory and Practice

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2015

|

R. 15, nr 2

61--65

EN

This work is devoted to the development of the composition as well as analysis of the rheological properties of shear thickening fluids (STF) based on pure halloysite (mineral from aluminosilicates group; H) and silica (SF14) doped halloysite dispersed in various organic liquids. The objective of this study was to form an intelligent composite using aluminosilicate tubes to dissipate energy and verify the applicability of the final suspensions to produce liquid armor. Halloysite is considered cheaper and more environmental friendly than pure SiO2 for STF production. Herein, we present studies concerning the effects of the molecular weight of poly(propylene glycol) (PPG) and modified aluminosilicate by mixing in ethanol with a carrier fluid. We also report that the fabrication of STF with silica doped halloysite leads to novel organic/inorganic composite materials with unprecedented protection properties. By analyzing the results obtained from the study, it was concluded that the liquids with modified halloysite as a dopant of 1, 3, 5 and 10 vol.% solid phase had a higher viscosity than the reference liquid based only on nanosilica. The fluid with the most favorable rheological properties is the slurry based on nanosilica with 1 vol.% halloysite (previously mixed with EtOH and PPG 725) dispersed in a poly(propylene glycol) of 725 g/mol molecular weight. The maximum shear thickening value of this liquid equaled 557 Pa·s at a shear rate of 7.8 s‒1. In the final step of the research, a knife penetration resistance test was performed. It was observed that the protective properties of p-aramid fabrics interleaved with STF based on pure SF14 powder and doped with halloysite are comparable. Thus, synthetic nanosilica can be partially replaced.

PL

W artykule przedstawiono wyniki badań nad opracowaniem składu cieczy zagęszczanych ścinaniem na bazie haloizytu (minerału z grupy glinokrzemianów; H) i krzemionki (SF14) domieszkowanej haloizytem zdyspergowanych w wybranych cieczach organicznych oraz ich charakterystykę reologiczną. Głównym celem badań było otrzymanie inteligentnego kompozytu, który wykorzystywałby częściowo rurkowy kształt cząstki haloizytu do rozpraszania energii, oraz sprawdzenie możliwości wdrożenia uzyskanych zawiesin do produkcji materiałów absorbujących energię, np. ciekłych pancerzy. Powszechnie jako fazę stałą stosuje się syntetyczną i drogą krzemionkę. Z uwagi na aspekt ekonomiczny i ekologiczny autorzy dokonali próby zastąpienia SiO2 naturalnym glinokrzemianem, którego zasoby w Polsce oceniane są na około 10÷12 mln ton. W pracy przedstawiono wpływ masy molowej glikolu polipropylenowego (PPG) stosowanego jako dyspergent oraz modyfikacji powierzchni ziaren fazy stałej poprzez mieszanie z etanolem i PPG na właściwości reologiczne zawiesin. Artykuł zawiera również wyniki badań nad otrzymaniem cieczy zagęszczanych ścinaniem na bazie nanokrzemionki z udziałem haloizytu jako domieszki do opracowania materiału kompozytowego do ochrony ciała człowieka. Analizując otrzymane rezultaty, stwierdzono, iż ciecze z dodatkiem 1, 3, 5 i 10% obj. modyfikowanego haloizytu charakteryzowały się wyższymi lepkościami niż próbka referencyjna oparta tylko na SiO2. Najlepsze właściwości reologiczne wykazuje zawiesina z dodatkiem 1%obj. glinokrzemianu (wcześniej poddanego procesowi modyfikacji powierzchni) zdyspergowanego w glikolu polipropylenowym o masie molowej 725 g/mol (PPG 725). Maksimum zagęszczania ścinaniem tej zawiesiny wynosiło 557 Pa·s przy szybkości ścinania 7,8 s‒1. W ostatniej fazie badań przeprowadzono testy odporności na uderzenia ostrzem. Zaobserwowano, iż materiały kompozytowe na bazie mat z włókien p-aramidowych przekładanych cieczami zagęszczanymi ścinaniem zarówno z SF14, jak i krzemionką z dodatkiem glinokrzemianu zapewniają porównywalne funkcje protekcyjne. Wykazano zatem, że syntetyczna nanokrzemionka może być częściowo zastąpiona haloizytem.

15

Evaluation of phenomenological model parameters using density dependent laws for prediction of mechanical response of cellular materials

Butt H. S. U., Xue P., Hou B.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2015

|

Vol. 63, nr 1

181–191

EN

Cellular materials have found wide-spread attention in structural applications involving impact energy absorption. The choice of the most suitable density of a cellular material, for a particular impact application, is based on its mechanical response, which may be obtained through experimental tests and/or models. A current study is focused on prediction of a mechanical response of a wide range of densities of a cellular material using available experimental data of very few densities. Best fitting-parameters of four selected phenomenological models, to fit the available experimental response of three distinct aluminum foam densities, are evaluated. The relationship between the best-fitting parameters and density of the foam is established by using two types of functions. The first function is based on a power law relationship between each parameter and foam density ρ, while the second function assumes each parameter as a linear combination of ρn and ρ, where n is any real number. The former function is found reasonable in the cases of both parameter interpolation and extrapolation while the latter is found reasonable for a parameter interpolation only. The findings of a current study emphasize for a conscious approach during selection of density dependent laws for phenomenological model parameters to avoid any erroneous or misleading design decision.

16

Axial splitting of empty and foam-filled circular composite tubes – An experimental study

Rezaei B., Niknejad A., Assaee H., Liaghat G. H.

Archives of Civil and Mechanical Engineering

|

2015

|

Vol. 15, no. 3

650--662

EN

This paper studies the effects of polyurethane foam-filler on the axial splitting process of circular composite tubes under the axial quasi-static loading, experimentally. A shear mode of failure in circular composite tubes is initiated by crushing the tube onto a conical die to absorb the energy. The effects of conical die angle, number of fiber fabric layers, resin type and also, diameter and fiber fabric type of the tubes on axial load, energy absorption and specific absorbed energy by the structure are studied. Experimental results show that the polyurethane foam-filler increases energy absorption capability by the tubes. Also, it is found that in the investigated domain, composite tubes with smaller diameters are better energy absorbers, comparing with the composite tubes with larger diameters. Experiments show that foam-filled circular tubes under the axial compression in the splitting process works as good energy dissipater.

17

Experimental and Numerical Investigation on Compression Orthotropic Properties of Spruce Wood in Axial and Transverse Loading Directions

Zhong W, Rusinek A., Jankowiak T., Huang X., Abed F.

Engineering Transactions

|

2014

|

Vol. 62, iss. 4

381–-401

EN

Compression tests on spruce wood in axial, radial and tangential directions have been performed using an INSTRON hydraulic machine. Spruce elastic mechanical properties and plastic deformation behaviour are presented. Experimental results allow to demonstrate different spruce failure modes: fibers buckling and collapsing are noticed under axial compression whereas, fibers slippage and delamination are the main failure modes under compression loading in radial and tangential directions. Spruce energy absorption efficiency and ideality energy absorption efficiency in the three loading directions are also analyzed. Representative volume element (RVE) model is adopted assuming transverse isotropic behavior to simulate wood microstructure in all directions. It was shown that micro-cell arrangement leads to wood macromechanical property spatial anisotropy. Porosity and hole shape effects on simulation results are estimated by RVE models with hexagon, circle, pentagon and square holes.

18

Comparison of Energy Absorption Properties of High Nitrogen Austenitic Steel and Cast Alloy Determined Using Low Velocity Perforation Test

Moćko W.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 1

65--69

EN

The results of energy absorbing analysis of VP159 austenitic steel and LH556 cast alloy were presented in this article. The assessment was carried out on the basis of drop-weight tower perforation test at impact energy equal to 500J and striker velocity equal to 12,5 m/s. Moreover, the basic mechanical properties of both tested materials were estimated in order to calibrate coefficients of the Johnson-Cook visco-plasticity model and Johnson-Cook damage initialization criterion as well. Subsequently, both models were applied for the finite element method simulation of perforation process. The reasonable agreement between measured and calculated shape of energy absorption curves were obtained for steel and cast alloy as well.

PL

W pracy przedstawiono wyniki analizy zdolności do pochłaniania energii blach wykonanych ze stali austenitycznej typu VP159 oraz staliwa LH556. Ocenę przeprowadzono wykorzystując test przebijania wykonany z użyciem młota opadowego przy energii uderzenia 500J i prędkości iglicy równej 12,5 m/s. Dodatkowo wyznaczono także charakterystyki mechaniczne obu materiałów. Na tej podstawie dokonano kalibracji modelu lepko-plastyczności Johnsona-Cooka oraz oszacowano kryterium inicjalizacji uszkodzenia Johnsona-Cooka. Następnie modele zostały wykorzystane do symulacji procesu przebijania z użyciem MES. Zarówno dla stali jak i staliwa uzyskano dobrą zgodność pomiędzy zmierzonymi i obliczonymi krzywymi pochłaniania energii.

19

Preliminary Investigation on the Ballistic Limit of Ultra High Molecular Weight Polyethylene Unidirectional Coated Fabric System

Ahmad M. R., Hassim N., Ahmad W. Y. W., Samsuri A., Yahya M. H. M.

Fibres & Textiles in Eastern Europe

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2013

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Vol. 21, no. 3 (99)

89--94

EN

This paper reports an investigation on the ballistic impact performance of high strength unidirectional (UD) fabrics UHMWPE coated with natural rubber latex (NRL). The effects of adding calcium carbonate in the NRL on the ballistic impact were also studied. Several NRL coated UD fabrics were assembled together with neat UD fabrics in a 12-ply fabric system. The ballistic limit and energy absorption of the fabric systems were determined. Results of the ballistic limit test showed that the NRL coated UD fabrics gave some positive effects in enhancing the ballistic impact performance of the fabric systems in comparison with all-neat fabric systems. Several mechanisms of energy absorption were observed on the fabric systems which include burn marks, fibre stretching, fibre pull-out, shearing, delamination of fabric plies for completely penetrated fabric systems and a punched-out effect on the back ply of partially penetrated fabric systems.

PL

Badania dotyczyły efektu uderzenia pocisku w balistyczny pakiet wykonany z pokrywanych naturalną gumą tkanin typu UD wykonanych z polietylenu o ultra wysokiej masie cząsteczkowej. Dodatkowo badano wpływ dodania węglanu wapnia do kauczuku naturalnego. W pakietach składano tkaniny powlekane i niepowlekane w systemy zawierające do 12 warstw. Określano limit balistyczny i energię absorpcji uzyskanych pakietów. Wyniki badań wskazują, że powlekanie warstw gumą naturalną daje pozytywne efekty poprawiając zachowanie pakietu na uderzenie pocisku. Obserwowano pojawianie się przypalenia pakietów, rozciąganie włókien, wyciąganie włókien, ścinanie, delaminację pakietów aż do całkowitej penetracji wszystkich warstw systemu.

20

An experimental study on rate sensitivity of J-integral and its evaluation by small punch test for TRIP steel

Shi L., Iwamoto T., Hashimoto Sh.

Engineering Transactions

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2013

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Vol. 61, iss. 2

119--136

EN

Recently, much attention has been paid to TRIP steel since it indicates both high ductility and strength by strain induced martensitic transformation. This transformation allows TRIP steel to oﬀer larger energy absorption than other steel at the same strength level. Therefore, it is expected to be applied to automobiles as security components that absorb energy upon collision. To produce the best performance of TRIP steel, the J-integral of TRIP steel should be investigated with respect to a various deformation rates for an evaluation of energy absorption. In the present study, the three point bending (3B) test is conducted for investigating the Jintegral until the crack growth of TRIP steel. Then, in order to determine the energy absorption characteristic by the J-integral value at various locations in the components of TRIP steel, the size of the specimen should be very small. Thus, an SP test is introduced and conducted by using the newly established apparatus based on the SHPB method. By using the result of the SP test in conjunction with the result of a 3B test, the evaluation of the J-integral of TRIP steel subject to various deﬂection rates is attempted. The correlation between the J-integral and the equivalent fracture strain of the SP test for TRIP steel is challenged to be redeﬁned.