Wyniki wyszukiwania - BazTech

1

Research on the design and simulation of frontal collision assessment of a truck with emergency vehicle suppression system

Vu Hai Quan, Tran Quang Tam, Nguyen Anh Ngoc, Le Hong Quan, Hoang Khai Hung

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2025

|

z. 128

295--309

EN

In response to the growing threat of vehicle-ramming attacks targeting critical infrastructure such as airports, government facilities, and public gathering spaces, this study focuses on the design and simulation of a direct frontal collision between a heavy truck and an emergency vehicle barrier using the Finite Element Method (FEM). The simulation model is developed to replicate realistic impact conditions, allowing detailed analysis of the barrier’s structural behavior under extreme loads, including deformation patterns, stress distribution, and energy absorption capacity. Material properties, contact interactions, and boundary constraints are carefully defined to enhance simulation accuracy. The results reveal that an optimally designed barrier with reinforced structures and effective energy-dissipating features can significantly reduce damage and vehicle intrusion, thereby improving overall protective performance. This confirms the crucial role of FEM-based simulation in the early design phase of physical security systems, offering a cost-effective and predictive approach to evaluating and optimizing barrier effectiveness before real-world deployment.

2

Mechanical energy absorption capacity of the porous Ti-6AI-4V alloy under quasi-static and dynamic compression

Markovsky Pavlo E., Janiszewski Jacek, Stasiuk Oleksandr O., Savvakin Dymitro G., Oryshych Denys V., Dziewit Piotr

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2025

|

Vol. 73, nr 1

art. no. e151959

EN

Porous materials are extremely efficient in absorbing mechanical energy in different applications. In the present study, porous materials based on the Ti-6(wt.%)Al-4V alloy were manufactured with the use of two different powder metallurgy methods: i) blended elemental powder approach using titanium hydride (TiH2) as well as V-Al master alloy powders and ii) using hydrogenated Ti-6-4 pre-alloyed powder. The powder compacts were sintered with additions of ammonium bicarbonate as a pore-holding removable agent. The emission of hydrogen from hydrogenated powders on vacuum sintering and the resulting shrinkage of powder particles permitted the control of the sintering process and the creation of anticipated porous structures. Mechanical characteristics were evaluated under quasi-static and dynamic compressive loading conditions. Dynamic compression tests were performed using the direct impact Hopkinson pressure bar technique. All investigations aimed at characterizing the mechanical energy-absorbing ability of the obtained porous structures. The anticipated strength, plasticity, and energyabsorbing characteristics of porous Ti-6-4 material were evaluated, and the possibilities of their application were also discussed. Based on the obtained results, it was found that porous Ti-6-4 material produced with a blended elemental powder approach showed more promising energy absorption properties in comparison with pre-alloyed powder.

3

Exploring the potential: auxetic metamaterials as core elements in buckling restrained braces

Basri Hamza, Ras Abdelouahab, Hamdaoui Karim, Wielgos Piotr

Archives of Civil Engineering

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2025

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Vol. 71, nr 3

325--338

EN

Buckling restrained braces (BRBs) are now widely used in different seismic zones as lateral resisting systems due to their quasi-symmetric and stable cyclic behavior. These systems are capable of dissipating the energy of severe lateral loads while protecting the integrity of other components of the structure. The material selection for these damper components as the inner core element requires high ductility, low strength increase, and high energy dissipation ability. Therefore, designing BRB steel cores using auxetic metamaterials has been recently investigated and suggested in the field of structure protection. The behavior of these metamaterials is characterized by a negative Poisson’s ratio (NPR) and unique mechanical characteristics, including their shear resistance and high ability for energy absorption. In this paper, we seek to investigate the effect of auxetic behavior on the dissipative performance of BRB under cyclic loading. Two different types of BRB were numerically designed and modeled using the finite element program Abaqus. The numerical analysis results show stable hysteresis behavior in both specimens and good stress distribution along the inner auxetic core. In addition, a parametric study was conducted to further investigate the effect of the gap size between the auxetic core and the concrete encasement. The cyclic performance of a buckling restrained brace with an auxetic perforated core was assessed, and the outcomes of this numerical analysis provide a reasonable basis for applying an auxetic core in the field of structure protection.

PL

Stężenia z ograniczonym wyboczeniem (Buckling Restrained Braces BRB) są obecnie szeroko stosowane w różnych strefach sejsmicznych jako boczne systemy nośne ze względu na ich quasisymetryczne i stabilne zachowanie cykliczne. Systemy te są w stanie rozproszyć energię dużych obciążeń poprzecznych, chroniąc jednocześnie integralność innych elementów konstrukcji. Wybór materiału na te elementy tłumika jako element rdzenia wewnętrznego wymaga wysokiej ciągliwości, niskiego wzrostu wytrzymałości i dużej zdolności rozpraszania energii. Dlatego też w ostatnim czasie badano i sugerowano projektowanie rdzeni stalowych BRB z wykorzystaniem metamateriałów auksetycznych w dziedzinie ochrony konstrukcji. Zachowanie tych metamateriałów charakteryzuje się ujemnym współczynnikiem Poissona (negative Poisson’s ratio NPR) i unikalnymi właściwościami mechanicznymi, w tym odpornością na ścinanie i dużą zdolnością do pochłaniania energii. W tym artykule staramy się zbadać wpływ zachowania rdzenia auksetycznego na wydajność rozpraszającą BRB pod obciążeniem cyklicznym. Zaprojektowano numerycznie i zamodelowano dwa różne typy BRB przy użyciu programu elementów skończonych Abaqus.Wyniki analizy numerycznej wskazują na stabilne zachowanie histerezy w obu próbkach i dobry rozkład naprężeń wzdłuż wewnętrznego rdzenia auksetycznego. Ponadto przeprowadzono badanie parametryczne w celu dalszego zbadania wpływu rozmiaru szczeliny pomiędzy rdzeniem auksetycznym a obudową betonową. Oceniono cykliczną wydajność stężenia z ograniczonym wyboczeniem z auksetycznym perforowanym rdzeniem, a wyniki tej analizy numerycznej stanowią uzasadnioną podstawę do zastosowania rdzenia auksetycznego w dziedzinie ochrony konstrukcji.

4

Numerical studies of the energy absorption capacities and deformation mechanisms of 2D cellular topologies

Majdak Mateusz, Baranowski Paweł, Małachowski Jerzy

Archives of Civil and Mechanical Engineering

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2024

|

Vol. 24, no. 2

art. no. e111, 2024

EN

This paper investigates the energy absorption capacities of selected cellular topologies under quasi-static loading conditions. Twenty topologies with nearly identical relative densities belonging to 4 groups were examined: honeycomb, re-entrant, bioinspired and chiral. The topologies were modeled using an experimentally validated numerical ABSplus model and subsequently subjected to in-plane uniaxial compression tests. The findings revealed the topologies with the most favorable energy absorption parameters and the main deformation mechanisms. The topologies were classified by mechanism, and a parametric study of basic material properties, namely modulus of elasticity, yield stress, and ductility, was performed for a representative topology from each mechanism. The results indicated that the honeycomb group topologies were characterized by the largest average absorbed energy, and yield stress was found to have the greatest impact on energy absorption efficiency regardless of the main deformation mechanism.

5

Numerical simulation on progressive failure of yielding support material for squeezing tunnel

Ci Xiang, Liu Xinyu, Tan Xianjun, Yang Diansen, Tian Hongming, Chen Weizhong

Archives of Civil and Mechanical Engineering

|

2024

|

Vol. 24, no. 1

art. no. e9, 2024

EN

Yielding support is effective in controlling excessive deformation of soft rock in squeezing tunnel engineering, and the developed polyethylene (PE) pipe filled with foamed concrete is a good choice serving as a yielding support. To deal with distortions brought on by significant mesh deformations and to enhance visualization, a numerical simulation method based on finite element method-smoothed particle hydrodynamics coupling (FEM-SPH) is adopted taking into account the progressive failure of PE pipes filled with foamed concrete (FC-PE) during deformation. By simulating the gradual failure of foamed concrete through smooth particle flow and the wrapped PE pipe using the finite element method, the damage process of the filled pipe has been examined. Comparison with experimental results demonstrates the superiority of the proposed model in terms of computational efficiency and accuracy, investigating the impact of several critical variables on the energy absorption capabilities of FC-PE, as well as setting pertinent evaluation indicators based on practical engineering application conditions. Additionally, numerical results demonstrate that the frictional characteristics between PE pipe and foamed concrete have little effects on the deformation energy absorption properties. The numerical results also demonstrate that the FC-PE’s diameter has a positive impact on both the energy absorption efficiency and the usage efficiency, while thicker FC-PE having a lower energy absorption efficiency.

6

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

Lisowska Aleksandra, Sanecki Henryk, Szkoda Maciej

Transport Problems

|

2023

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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.

7

Energy absorption, free and forced vibrations of flexoelectric nanocomposite magnetostrictive sandwich nanoplates with single sinusoidal edge on the frictional torsional viscoelastic medium

Chu C., Shan L., Al‑Furjan M. S. H., Farrokhian A., Kolahchi R.

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 4

art. e223, 1--28

EN

Most studies on the nanoscale mainly focus on regular rectangular nanoplates, but according to the synthesis of nanostructures, the dynamic response of non-rectangular nanoplates is noticeable and there are not many works on these complex nanostructures. This work presents energy absorption, and forced and free vibrations of sandwich non-rectangular nanoplates with a single sinusoidal edge resting on a fractional torsional viscoelastic medium. The nanostructure is made from alumina reinforced by graphene platelets (GPLs) as a core covered by the flexoelectric and magnetostrictive materials as top and bottom layers, respectively. The consideration of size effects is derived from the innovative theory of local/nonlocal phenomena in a two-phase context. The Halpin-Tsai micromechanical and Kelvin–Voigt models are applied for the effective characteristics of the material in the nanocomposite layer and structural damping, respectively. Based on Hamilton’s principle and refined zigzag theory (RZT), the coupled electro-magneto-mechanical equations of motion are gained and analyzed by Galerkin’s and Newmark’s procedures. The effects of different components, including factors related to both the nonlocal and local phase fractions, the volume fraction of GPLs, various elastic mediums, electric field, structural damping, magnetic field, piezoelectric and flexoelectric effects on the absorption of energy, and forced and free vibrations of the sandwich nanostructure. Numerical simulations demonstrate that optimal energy absorption occurs when the flexoelectric factor is set to zero and the piezoelectric constant is non-zero but of opposite polarity. Additionally, it is concluded that when the coefficient of the local phase fraction is zero, increasing the nonlocal factor has more influence on the energy absorption and vibration of the nanostructure.

8

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

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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.

9

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.

10

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.

11

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.

12

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.

13

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.

14

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 %.

15

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

|

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.

16

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.

17

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

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2016

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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.

18

Impact behaviour of spot-welded thin-walled frusta

Kotełko M., Mołdawa A.

Acta Mechanica et Automatica

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2016

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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.

19

Niestacjonarny pomiar termowizyjny absorpcji wiązki laserowej przez porowate materiały budowlane

Marynowicz A.

Fizyka Budowli w Teorii i Praktyce

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2015

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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.

20

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

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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.