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1

Strength Analysis Aspects of Psyllium/Thermoplastic Starch Films under Impact Loading Conditions

Beer-Lech Karolina, Kołodziej Paweł, Skic Anna, Branco Ricardo

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

385--393

EN

Tensile test under quasi-static loads conditions is usually used to determine the mechanical strength of thermoplastic starch films. This kind of test does not fully illustrate the load conditions for packaging films, which, under the conditions of use, are succumb to dynamic loads. Thus, the aim of the study was to present the possibilities of using a patented soft tissues measurement testing station to analyze the mechanical strength of thermoplastic starch (TPS) films under impact loading conditions. Two groups of film specimens containing the addition of psyllium husks (TPS/PH) and psyllium flour (TPS/PF) were used for the measurements. The casting method was applied, and glycerol was used as a plasticizer. Microstructure of the specimen surface was analyzed by stereoscopic microscopy. Specimens with the addition of psyllium flour had a more uniform microstructure. The maximum breaking forces obtained during impact tests for these films were 5 times higher than specimens containing psyllium seed husk. The same behaviour was found with respect to stresses with average values of 48.6 MPa for TPS/PF and 20.2 MPa for TPS/PH. Moreover, research confirms usefulness of patented soft tissues measurement testing station to analyse the mechanical strength of thermoplastic starch films.

2

Effect of foot pronation during distance running on the lower limb impact acceleration and dynamic stability

Xiang Liangliang, Gu Yaodong, Wang Alan, Mei Qichang, Yu Peimin, Shim Vickie, Fernandez Justin

Acta of Bioengineering and Biomechanics

|

2022

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Vol. 24, no. 4

21--30

EN

Foot pronation is not an isolated factor influencing lower limb functions. Exploring gait variability and impact loading associated with the foot posture are crucial for understanding foot pronation-related injury mechanisms. This study aimed to evaluate how foot posture affects impact loading and running variability during running. Methods: Twenty-five male participants were recruited into this study. Pressure under the foot arch, acceleration and marker trajectory were recorded in the right limb for each runner after 1, 4, 7 and 10 km running, respectively. Linear mixed effects models were used to analyze the statistical difference of the data. Results: FPI-6 has significantly increased after the 10 km running ( p < 0.01). For the tibial acceleration, peak resultant acceleration after 10 km running was significantly increased than after 4 km running ( p = 0.02). At the dorsum of the foot, the short-time largest Lyapunov exponent (LyE) after 10 km running decreased 0.28 bit/s compared with LyE after 7 km running ( p = 0.03). In the tibia, LyE after 4 km and 10 km running was decreased significantly ( p < 0.01 and p = 0.01). Conclusions: The foot was significantly pronated at the middle and at the end of running. Foot pronation during distance running increased the distal tibia peak impact acceleration but did not increase running instability.

3

Dynamic characteristics study on the two-stage safety valve used on hydraulic support under impact loading

Zhao Guochao, Wang Hui, Song Yuning, Zhang Changshuai

Journal of Theoretical and Applied Mechanics

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2020

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Vol. 58 nr 3

623--635

EN

A two-stage linkage safety valve for hydraulic support is presented. Considering the hydraulic support is impacted, dynamic simulation of the column circuit with the two-stage safety valve subject impact loading was carried out, and the dynamic characteristics of the two- -stage safety valve with different impact forms were studied. A rapid impact loading test rig was built to test the two-stage safety valve sample under impact loading. Simulation and experimental results indicate that the two-stage safety valve has high sensitivity and good unloading performance, it can realize fast and large flow unloading of the hydraulic support under different impact forms and pressures.

4

Dynamic mechanical characteristics of filling layer self-compacting concrete under impact loading

Li Ning, Long Guangcheng, Fu Qiang, Song Hao, Ma Cong, Ma Kunlin, Xie Youjun, Li He

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 3

851--861

EN

Filling layer self-compacting concrete (FLSCC) is a key construction material in China Rail Track System (CRTS) III slab ballastless track and its resistance to impact loading is of great importance to the service security of high-speed train. In this paper, the dynamic mechani-cal characteristics of FLSCC under impact loading were investigated with a split Hopkinson pressure bar (SHPB) at strain rates ranging from 101 s_1 to 102 s_1. Results show that the compressive strength, peak strain, elastic modulus and toughness ratio of FLSCC all increase with strain rate. The increase factors of compressive strength (DIFc) and strain (DIFe) of FLSCC increase linearly with decimal logarithm of strain rate. The elastic modulus (Ed) and toughness ratio (TR) increase linearly with strain rate. Self-compacting concrete (SCC) shows greater strain rate effect than normal concrete (NC). However, FLSCC presents lower strain rate effect but better toughness performance than normal SCC. The incorporation of large content of SP and VMA provides FLSCC with higher porosity, which makes it possess excellent dynamic mechanical performance.

5

Composite material components damaged by impact loading: a methodology for the assessment of their residual elastic properties

Belingardi G., Cavatorta M. P., Paolino D. S.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 87, nr 1

18--24

EN

Purpose: Detection and evaluation of damage due to impact or fatigue loading in components made by composite materials is one of the main concern for automotive engineers. We focus on damage due to impact loading on long fibre, plastic matrix composite, as they represent one of the most interesting development solution for automotive components toward lightweight structure that in turn means reduction of fuel consumption and of Green House Gas emissions. Design/methodology/approach: An innovative simplified methodology is proposed, based on the impact and repeated impact behaviour of composite material, for the evaluation of the induced damage and of material residual elastic properties. The investigated composite laminate is made of eight twill-wave carbon fabrics impregnated with epoxy resin. The methodology consists of two phases: at first the identification of the impact response. Composite plates have been impacted at different energy levels and residual elastic properties measured through standard tensile tests. The relationship between impact energy and residual elastic properties is obtained. Then the exploration impact load is identified, large enough to give a well-defined picture of the suffered damage but soft enough to do not induce further damage in the composite laminate. Findings: This exploration impact test and the Damage Index (DI) value, as interpretation key, leads to a prediction of the local residual elastic properties in the damaged area. The proposed methodology has been validated on plate specimens. A strict correlation is found between the predicted and the actual residual elastic properties of the damaged composite plate. Practical implications: Subsequently it has been applied to a composite beam, with a omega shape transverse section, that can be considered as a demonstrator for a typical beam used in the car body frame. Originality/value: A selection on the following alternatives will be possible: a – don’t care the damage is not affecting the structure performance; b – repair is needed but will be sufficient; c – substitute the damaged component as soon as possible.

6

Impact behaviour of safety shoe high strength steel parts

Peixinho N., Mendonça J.

Engineering Transactions

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2018

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Vol. 66, iss. 2

175--185

EN

This study presents results on the dynamic response of safety toe cap models made of high-strength steel. The structural response to impact loading conditions under normative requirements was properly related to tap the potential of lightweight design for significant reduction of thickness. A fully martensitic steel grade was selected, and numerical models were used to study extensive plastic deformation and strain-rate dependence. Material properties were modelled using the Cowper-Symonds models. The numerical simulation was developed using ANSYS explicit dynamics software and was compared to an experimental standard testing of final prototypes. The numerical modelling approach analysed different friction models seeking to better describe collapsing behaviour. A local stiffening toe cap model with high energy absorption efficiency was validated.

7

Analiza przełomów udarowych połączeń klejowych blokowych

Komorek A., Chojnacki K.

Technologia i Automatyzacja Montażu

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2017

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nr 4

21--26

PL

W artykule zaprezentowano wyniki analizy rodzaju zniszczenia oraz prawidłowości przełomów udarowych połączeń klejowych. W testach stosowano metodykę badania udarności z wykorzystaniem próbek blokowych, w których spoina klejowa jest niszczona przez udarowe obciążenia ścinające. Testy przeprowadzano za pomocą młota wahadłowego, dedykowanego do badań połączeń klejowych. Maksymalna energia wahadła stosowanego w badaniach wynosiła 15 J. Do określenia udarności badanych połączeń wykorzystano zależność wg której energia zużyta do oderwania górnego elementu próbki w takim teście, czyli energia wytrącona przez wahadło jest miarą wytrzymałości udarowej połączenia klejowego. Elementy próbek zostały wykonane ze stali S235 lub stopu aluminium 2017A. Do klejenia próbek wykorzystano żywicę epoksydową Epidian 57 z utwardzaczem Z1 lub klej Loctite 3421. Rezultaty badań wskazują, że spoiny klejowe wykonane obydwoma z badanych klejów cechują się zniszczeniem o charakterze kohezyjno-adhezyjnym. Wprowadzane elementy dystansowe w postaci nici nie wpływają na udarność badanych połączeń. Makroskopowa analiza spoin o małej grubości nie pozwala wnioskować jednoznacznie o charakterze zniszczenia spoin.

EN

The article presents the results of the analysis of the damage type and the regularity of adhesive joints impact fracture. The experimental testing was conducted with a pendulum hammer designed to examine adhesive joints. Tests of block samples were carried out according to the Standard ISO 9653. The maximum energy of the pendulum used in the investigation equaled 15 J. In order to determine the impact strength of the examined connections, we used a dependency according to which the energy used to detach the upper element of the sample in such a test, that is the energy lost by the pendulum, is the measure of impact strength of the adhesive joint. The adherends were made of steel S235 or an aluminum alloy 2017A. In order to bond the samples, we used Epidian 57 epoxide resin with Z1 hardener or Loctite 3421 adhesive. The results of the experimental investigation indicate that adhesive joints made of both of the tested adhesives are characterized by cohesive-adhesive damage. Placed in joints spacers of the sewing threads form do not affect the impact strength of the tested adhesive joints. Macroscopic analysis of low-thickness joints does not make it possible to conclude clearly about the nature of joint fracture.

8

Strain energy method for determining dynamic yield stress in Taylor’s test

Włodarczyk E., Sarzyński M.

Engineering Transactions

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2017

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Vol. 65, iss. 3

499--511

EN

This paper presents a theoretical method for determining dynamic yield stress of metals. The method is based on conversion of the part initial kinetic energy of a metal rod striking a rigid target into the energy of elastic and plastic-strain deformation at selected period ts. By means of this method, a theoretical simple algebraic formula has been derived for determining the dynamic yield stress of metals loaded by the Taylor direct impact experiment (Taylor DIE). This formula gives the results comparable with experimental data.

9

The selected aspects of the research into impact loading of adhesive joints in błock samples - comparison of different ways of applying the load

Komorek A., Godzimirski J.

Problemy Eksploatacji

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2016

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no. 4

77--91

EN

The research described in this article, relates to the survey methodology of błock bonded joints, dealing with one of its aspects. The authors have decided to check experimentally what impact on the results of the tests has the manner (direction) of applying the load and whether it is possible to compare the results obtained on two different research devices. Experimental studies have been completed with numerical calculations of the test cases. The research was carried out with impact dropping tools - Gabaldini Impact 25 and with a special machine designed to test adhesive joints. The energy used to tear off the upper part of the specimen, that is the energy lost by the dropping device, is the measure of the strength of impact loading of an adhesive bond. The sample elements were made of steel S235. The samples were examined using two different machines, however the applied hands allowed conducting an examination on both devices with samples of the same geometry. In order to bond the samples, the authors used Epidian 57 epoxide resin with Zł hardener. The results of experimental testing indicate that the impact strength of adhesive joints can be compared only if the research was carried out on the same test machine. Also, the direction of the load applied to the sample has a significant impact on the obtained results, as confirmed in the numerical calculations.

PL

Opisane w artykule badania odnoszą się do metodyki badań udarowych połączeń klejowych blokowych i rozpatrują jeden z jej aspektów. Autorzy postanowili sprawdzić eksperymentalnie, jaki wpływ na wyniki badań ma sposób (kierunek) przyłożenia obciążenia do próbki oraz czy można porównywać wyniki uzyskane na dwóch różnych urządzeniach badawczych. Badania eksperymentalne uzupełniono obliczeniami numerycznymi badanych przypadków. Badania przeprowadzano przy pomocy młotów wahadłowych - Galdabini Impact 25 oraz dedykowanego do badań połączeń klejowych. Energia zużyta do oderwania górnego elementu próbki, czyli energia wytracona przez wahadło, jest miarą wytrzymałości udarowej połączenia klejowego. Elementy próbek zostały wykonane ze stali S235. Próbki badano z wykorzystaniem dwóch różnych maszyn, jednak zastosowane uchwyty pozwoliły prowadzić badania na obydwu urządzeniach z zastosowaniem próbek o takiej samej geometrii. Do klejenia próbek wykorzystano żywicę epoksydową Epidian 57 z utwardzaczem Zł. Wyniki badań eksperymentalnych wskazują, że wytrzymałość udarową połączeń klejowych można porównywać, tylko jeżeli badania prowadzono na tej samej maszynie badawczej. Również kierunek przyłożenia obciążenia do próbki wywiera istotny wpływ na uzyskiwane wyniki, co potwierdzono także w obliczeniach numerycznych.

10

An analysis of the effect of impact loading on the destruction of vascular structures in the brain

Ratajczyk M., Sąsiadek M., Będziński R.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

21--31

EN

Subdural hematomas are one of the frequent complications of head injuries. Such hematomas result from exceeding the border strength values of bridging veins. Subdural haemorrhages are life-threatening and are a frequent cause of considerable pathologies. Traffic participants and also soldiers who participate in armed conflicts are the most vulnerable to head injuries. Although hematomas have been studied for many years the mechanism of hematoma formation has not been fully clarified as yet. In the paper, the effort of brain tissue structures due to the propagation of shock wave was analyzed. Particular attention was paid to the deformation ability and changes in the energy of bridging veins. This research was concerned with changes in mechanical properties of these veins in the frontal, parietal and occipital regions of the brain. For the present research the authors have constructed finite element models of brain tissue fragments and conducted numerical studies taking into account the boundary conditions arising from violent overloads that result from combat operations. As a result of the numerical analysis conducted, critical values of strain and stress have been obtained. The analysis showed high diversity in the properties of the different regions of the brain tissue. The studies carried out by the authors rendered it possible to assess the effort of the tissue structures of veins in connection with mechanical parameters, including geometrical parameters, in particular in relation to the likelihood of hematoma formation.

11

Rozkłady nacisków powierzchniowych jabłek przy obciążeniach udarowych

Stopa R., Komarnicki P., Młotek M.

Inżynieria Rolnicza

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2013

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R. 17, nr 3, t. 1

363--374

PL

Przedstawiono wyniki pomiarów nacisków powierzchniowych jabłek odmiany Ligol przy pomocy systemu Tekscan w warunkach obciążeń udarowych. Wyznaczono warstwice i rozkłady nacisków w dwóch wzajemnie prostopadłych kierunkach dla dwóch wariantów obciążenia różniących się energią zderzenia jabłka z powierzchnią oporową. Wyznaczono średnie wartości wielkości mierzonych podczas testu i przeprowadzono dla nich analizę statystyczną. Ustalono, że wzrost energii zderzenia wpływa na wartość i rozkład maksymalnych nacisków w miejscu styku jabłka z powierzchnia oporową. Wykazano, że w centralnej strefie styku nastąpiły odkształcenia plastyczne tkanki jabłka w wyniku jej uszkodzenia objawiające się niskimi wartościami nacisków powierzchniowych. Maksymalne wartości nacisków powierzchniowych znajdują się w strefie granicznej powierzchni styku.

EN

Results of measurements of surface pressure of Ligol apples with the use of Tekscan system in impact loading conditions were presented. Contour lines and distribution of pressure in two mutually perpendicular directions for two variants of loading differing with the energy of apple collision with the area of resistance were determined. Average values measured during the test were determined and statistical analysis was carried out for them. It was determined that the growth of collision energy influences the value and distribution of maximum pressures in the area of the apple contact with the area of resistance. It was proved that in the central contact zone, plastic deformations of the apple tissue occurred as a result of its damage appearing with low values of surface pressure. Maximum values of surface pressure are in the border zone of the contact area.

12

Dynamiczne zachowanie się metalowego pręta ze wzmocnieniem potęgowym uderzającego w sztywną tarczę. Cz. 2, Analiza mechanicznych charakterystyk wyżarzonego pręta miedzianego Cu-ETP

Włodarczyk E., Sarzyński M.

Biuletyn Wojskowej Akademii Technicznej

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2013

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Vol. 62, nr 1

61-78

PL

Dokonano teoretycznej i eksperymentalnej analizy mechanicznych parametrów miedzianego (Cu-ETP) pręta uderzającego w nieodkształcalną tarczę. W tym celu przeprowadzono na kilku prętach testy Taylora z różnymi początkowymi wartościami prędkości uderzenia, zawartymi w przedziale (60 m/s < U < 220 m/s). Ponadto wykorzystano analityczne rozwiązanie tego problemu zamieszczone w pracy [1]. Wartości parametrów badano podczas przebiegu procesu zderzenia i po jego zakończeniu. Różnice między teoretycznymi i eksperymentalnymi wartościami badanych parametrów zmieniają się wraz ze wzrostem prędkości uderzenia, w wymienionym wyżej przedziale, od kilku do kilkunastu procent. Zatem w tym zakresie prędkości uderzenia pominięcie wpływu szybkości odkształcenia na dynamikę badanego miedzianego pręta, w celu uzyskania analitycznego rozwiązania problemu, jest dopuszczalne.

EN

The theoretical and experimental analysis of some of mechanical parameters of annealed copper (Cu-ETP) rod, striking a rigid target, has been carried out. For this purpose, the Taylor impact tests on some the rods at various values of impact velocity contained in the range, 60 m/s < U < 220 m/s were performed. Furthermore, presented in paper [1] the analytical solution of the Taylor impact problem has been used. The parameters of the rods were studied during the impact and post-impact. Differences between theoretical and experimental values of the tested parameters of the rod increase from several to over dozen per cent together with increase in the impact velocity in the range of 60 m/s < U < 220 m/s. So, in the range values of the velocity U, the influence of a strain rate on dynamics of the studied copper rod can be neglected.

13

Analiza procesów deformacyjno-naprężeniowych w bryle gruntowej badanej płytą dynamiczną ZFG-01

Gosk W.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2011

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z. 58, nr 3/II

31-38

PL

W pracy opisano analizę zachowania bryły gruntu piaszczystego poddanej badaniu za pomocą lekkiej płyty dynamicznej ZFG-O1. Przeprowadzono identyfIkację dynamicznego modułu sztywności podłoża gruntowego w oparciu o profIl przyspieszeń zarejestrowany podczas testu udarowego. Założono, że nieliniowość ośrodka będzie wyrażona zmienną w czasie wartością dynamicznego modułu sztywności. IdentyfIkacja została przeprowadzona z uwagi na proces na podstawie autorskiego programu obliczeniowego umożliwiającego opis falowy zachowania się walcowej bryły gruntu.

EN

The paper presents an analysis of the behavior of sandy soil solid tested by means of ZFG-O1 light drop tester. The dynamic stiffness modulus of the ground was identified on the basis of recorded acceleration during impact test. It was assumed that nonlinearity of the ground was described by time-dependent values of the dynamic stiffness modulus. The identification was carried out by an original calculation program which enabled the description of wave propagation in cylindrical soil solid.

14

Weight function for a crack in an orthotropic medium under normal impact loading

Mukherjee S., Das S.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 4

915-928

EN

The paper deals with the investigation of an elastodynamic response of an infinite orthotropic medium containing a central crack under normal impact loading. Laplace and Fourier integral transforms are employed to reduce the dimensional wave propagation problem to the solution of a pair of dual integral equations in the Laplace transform plane. These integral equations are then reduced to integral differential equations which have been solved in the low frequency domain by method of iteration. To determine time dependence of the parameters, these equations are inverted to yield the dynamic stress intensity factor (SIF) for normal point force loading. These results have been used to obtain the SIF at the crack tip which corresponds to the weight function for the crack under normal loading. Analytical expressions of the weight function are used to derive SIF for polynomial loading. Numerical results of normalized SIF for a large normalized time variable and for different concentrated point force loading at an arbitrary location of the crack surface have been calculated for different orthotropic materials. In the present paper, a numerical Laplace inversion technique is used to recover the time dependence of the solution. Finally, the results obtained are displayed graphically.

15

Konstrukcja dynamicznego wykresu naprężenie-odkształcenie (σ-ε) na podstawie trwałych odkształceń pręta obciążonego udarowo

Włodarczyk E., Janiszewski J.

Biuletyn Wojskowej Akademii Technicznej

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2006

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Vol. 55, nr 4

191-208

PL

Opracowana przez G. I. Taylora, Th. Karmana i Ch. A. Rachmatulina teoria propagacjifal sprężysto-plastycznych w ośrodkach ciągłych wymaga stosowania dynamicznego związku naprężenie-odkształcenie (σ-ε). Związek ten różni się istotnie od statycznego wykresu σ-ε. W związku z tym opracowano wiele metod otrzymywania dynamicznej zależności σ-ε. W niniejszym artykule dokonano przeglądu niektórych metod konstrukcji dynamicznej zależności σ-ε, opartych na trwałych odkształceniach cylindrycznego pręta metalowego uderzającego prostopadle z odpowiednią prędkością w nieodkształcalną przegrodę. W metodach tych wykorzystuje się analityczne rozwiązanie problemu oddziaływania centrowanej fali obciążenia (fali Reimanna) z odbitą od swobodnego końca pręta falą odciążenia silnej nieciągłości. Taki układ fal generowany jest w metalowym pręcie podczas zderzenia z nieodkształcalną przegrodą. Okazuje się, że trwałe (plastyczne) odkształcenia pręta, powstałe podczas procesu zderzenia, pozwalają skonstruować dynamiczny wykresσ-ε dla materiału, z którego jest on wykonany.

EN

The theory of Taylor, Karman's, and akhmatulin's on elastic-plastic waves propagation in continuous media requires application of dynamical stress-strain relation. In fact, this relation is different from static stress-strain curve. Therefore, some methods for the dynamic stress-strain plot performance were elaborated. The survey of the construction methods of the dynamical stress-strain plot on the basis of plastic strain of the impact loaded bar has been presented here. Analytical solution of the problem of interaction of the centered Rimann's wave with an unloading wave of strong discontinuity, reflected from free end of the bar, was used. Such waves system is generated in the metal bar during its striking with a rigid target. It turned out, that plastic strain of the bar, produced during the impact, allows for constructing the dynamic stress-strain curve for bar material.

16

On importance of imperfections in plastic strain localization problems in materials under impact loading

Glema A., Łodygowski T.

Archives of Mechanics

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2002

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Vol. 54, nr 5-6

411-423

EN

The work is the continuation of Professor Piotr Perzyna achievements in the description and analysis of the phenomenon of plastic strain localization. The ductile materials under impact loading are in focus of interest. In particular, the influence of initial imperfections on the final pattern of localization is elaborated. The computer simulations were performed in the environment of ABAQUS program.

17

Porušovanie liatiny s gul'ôčkovym grafitom

Koniečna R., Zaharová B.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2000

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Vol. 263, z. 63

73-78

18

Analiza konstrukcji ochronnych maszyn roboczych poddanych obciążeniom udarowym

Rusiński E., Karliński J.

Problemy Maszyn Roboczych

|

2000

|

Z. 15

27-38

PL

W artykule zaprezentowano dotychczasowe wyniki prac nad nieliniowymi zagadnieniami mechaniki. Dotyczą one modelowania zjawisk udarowych. Obiektem badań są konstrukcje ochronne maszyn roboczych. Przedstawiono podstawy teoretyczne określające charakterystyki materiałowe i ich wykorzystanie w metodzie elementów skończonych. Porównano różne modele zachowania się materiału w przypadku obciążenia udarowego oraz zaprezentowano przykłady liczbowe.

EN

In the paper selected problems occurring in analysis of nonlinear model of impact phenomena were presented. The material characteristics and their application in finite element method were discussed. Various models of material behavior under impact loading were compared and numerical examples were shown.