Wyniki wyszukiwania - BazTech

1

Experimental study on SHPB cyclic impact of rubber-cement composite with different confine modes

Yang Rongzhou, Xu Ying, Chen Peiyuan, Cheng Lin, Ding Jinfu, Fu Hongxin

Archives of Civil Engineering

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2023

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Vol. 69, nr 2

517--534

EN

To promote the application of rubber-cement composites as the main bearing structure and key components in practical engineering under frequent dynamic disturbances, in this work, the split Hopkinson pressure bar (SHPB) cyclic impact tests of rubber-cement composite specimens with four different confine modes were carried out in which the impact load increased sequentially. The relationship between average strain rate, ultimate strain and impact times and the relationship between peak stress, damage energy, ultimate strain and incident energy were analyzed. The results showed that the appropriate confine reinforcement treatment can make rubber-cement composite give full play to its deformation ability when it was completely damaged. Carbon fiber-reinforced polymer (CFRP) sheet and steel cylinder can work together with the rubber-cement composite matrix to resist impact load, which effectively improves the structural strength, damage fracture energy, and cyclic impact resistance of the rubber-cement composite. Finally, based on the effect difference of confine modes, the simplified plane force models of rubber-cement composite specimens with four different confine modes were established, which clearly revealed the completely different impact resistance mechanism of the rubber-cement composites with different constraints under cyclic impact loading.

2

Preparation of the non-cohesive soil sample and calibration of the pneumatical launcher in the dynamic soil test SHPB

Sobczyk Kamil, Kruszka Leopold, Grązka Michał, Chmielewski Ryszard, Rekucki Ryszard

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2022

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Nr 1

16--27

EN

The paper analyzes the problem of initial compaction of a non-cohesive soil sample on the example of dry silty sand samples. Two different compaction methodologies were used: I) dynamic compaction - using split Hopkinson pressure bar and II) vibration compaction - using a vibrating shaker. A better result of the compaction process was obtained for dynamic compaction with an initial pressure value of 0.5 bar (small difference in the result - both methods obtained comparable results). The paper also includes a numerical analysis of the calibration of the pneumatic launcher in the Matlab environment on the basis of the system of difference equations. The calibration process was carried out in the initial pressure range from 0.5 to 3.0 bar for three different variants of the barprojectile length: 100 mm, 200 mm and 250 mm and compared with the experimental analysis - the results were consistent.

3

Experimental study on dynamic stability of rubber-cement composites by SHPB and high-speed slicing

Yang Rongzhou, Xu Ying, Chen Pei Yuan

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

319--334

EN

Improper disposal of waste tires will not only bring environmental impact and safety risks but also cause a serious waste of resources. In the field of civil engineering materials, waste tire particles are used as a substitute for non-renewable aggregates to produce flexible rubber-cement composites (RCC). To explore the high-speed slicing stability of RCC, this test took normal cement mortar (NCM) and rubber cement mortar (RCM) as research objects. The SHPB tests with the same impact energy level and the high-speed slicing tests with a slice thickness range of about 1.4 mm ~ 4.4 mm were carried out. The results showed that NCM and RCM showed different stability differences in the process of high-speed slicing. In the case of ensuring the integrity of the slice, the minimum thickness of the slice can be better decreased with the increase of the rubber content. Finally, from the perspectives of split Hopkinson pressure bar (SHPB) test results and mesoscopic structure states, the essential reason for ensuring the stability of high-speed slicing lied in the improvement of rubber particles (dominant role) and pores on material deformation and flexible energy dissipation.

4

Structural effects and real strain‑rate effects on compressive strength of sustainable concrete with crumb rubber in split Hopkinson pressure bar tests

Feng Wanhui, Chen Baiyu, Tang Yunchao, Wei Wenbo, He Weiming, Yang Yongmin

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 3

art. no. e136

EN

The dynamic increase factor (DIF) of the concrete material strength, obtained using a split Hopkinson pressure bar (SHPB), includes structural effects that do not precisely reflect the real strain-rate effect of concrete. To further clarify the real strain-rate effects of rubberised concrete (RC), an experimental investigation regarding the dynamic compressive response of ordinary concrete (NC) and RC with three rubber contents (10%, 20%, and 30%) was performed in this study. Additionally, based on a dynamic constitutive model, i.e., the Karagozian and Case (K&C) concrete model, numerical SHPB tests were conducted using the LS-DYNA software. According to the experimental results, all parameters of the K&C model were discussed, and the damage factors were modified to satisfy the mechanical properties of RC. After validating the numerical model, it was observed that the experimental DIF included the inertial enhancement and the real DIF. Moreover, because rubber particles effectively reduce the density and improve the deformation capacity of concrete, the real strain-rate effect of RC was found to be more rate-sensitive than that of NC by analysing the radial stress distribution. In addition to lateral inertia, another external source, namely, the interface friction between the specimen and bars, which can produce lateral confinement, was further studied. It was found that interface friction significantly contributes to lateral confinement; however, as the strain rate increased, the impact generally decreased. Finally, the mechanism of the strain-rate effect of RC was clarified.

5

Projekt koncepcyjny modernizacji stanowiska dzielonego pręta Hopkinsona

Sarzyńska Katarzyna

Przegląd Mechaniczny

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2021

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nr 6

11--15

PL

Celem pracy było opracowanie projektu koncepcyjnego modernizacji stanowiska dzielonego pręta Hopkinsona, który umożliwi prowadzenie badań materiałów inżynierskich w podwyższonych temperaturach. W ramach niniejszej publikacji dokonano analizy istniejącego w Zakładzie Technologii i Eksploatacji Uzbrojenia WAT stanowiska dzielonego pręta Hopkinsona, SHPB (Split Hopkinson Pressure Bar) do badań materiałów w warunkach dynamicznego obciążenia. Następnie sformułowano założenia modernizacji stanowiska oraz opracowano wstępny projekt stanowiska SHPB do badań materiałów w podwyższonych temperaturach. Efektem końcowym pracy jest wirtualny model 3d zmodernizowanego stanowiska SHPB.

EN

The aim of the work was to develop a conceptual design for modernization stand of the Split Hopkinson Pressure Bar (SHPB) to research engineering materials in high temperatures. First step was to analyze stand, which is located at the Faculty of Mechatronics, Armament and Aerospace, Military University of Technology, for material tests in dynamic loading conditions. Then the assumptions for the modernization stand of SHPB were formulated. A preliminary design of the SHPB stand was developed for testing mate- rials at elevated temperatures. The final effect of this work is 3D model of modernized stand which is able to preparing experiment in dynamic loading conditions in high temperatures.

6

Quasi-Static and Dynamic Mechanical Properties of a Ti-6Al-4V Titanium Alloy Produced Using Unconventional Manufacturing Methods

Sarzyńska Katarzyna J., Paszkowski Robert

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2021

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Vol. 12, Nr 4 (46)

69--82

EN

The purpose of this paper was to determine the mechanical properties of a Ti-6Al-4V titanium alloy produced by traditional CIP (Cold Isostatic Pressing) and by LENS (Laser Engineered Net Shaping), an additive manufacturing process. A reference material, being a commercial Ti-6Al-4V alloy, was also tested. The strength test specimens were produced from a high-quality, Grade 5 titanium powder. Each specimen had its density, porosity, and hardness determined. Compression curves were plotted for the tested materials from the strength test results with static and dynamic loads. These tests were performed on an UTS (Universal Testing Machine) and an SHPB (Split Hopkinson Pressure Bar) stand. The test results obtained led to the conclusion that the titanium alloy produced by CIP had lower strength performance parameters than its commercially-sourced counterpart. The LENS-produced specimens outperformed the commercially-sourced alloy both in static and dynamic load conditions.

PL

Celem niniejszej pracy było wyznaczenie właściwości mechanicznych stopu tytanu Ti-6Al-4V wytworzonego metodą klasycznej metalurgii proszków CIP (ang. Cold Isostatic Pressing) oraz przy użyciu przyrostowej technologii wytwarzania LENS (ang. Laser Engineered Net Shaping). Badaniom poddano także komercyjny stop Ti-6Al-4V jako materiał referencyjny. Próbki do badań wytrzymałościowych przygotowano z wysokiej jakości proszku stopu tytanu gatunku 5. Dla wykonanych próbek materiałowych wyznaczono gęstość, porowatość, a także określono twardość. Ponadto, wyznaczono krzywe ściskania dla badanych materiałów na podstawie rezultatów testów wytrzymałościowych w warunkach statycznego i dynamicznego obciążenia. Wykorzystano do tego celu uniwersalną maszynę wytrzymałościową (UTS, ang. Universal Testing Machine) oraz stanowisko dzielonego pręta Hopkinsona (SHPB, ang. Split Hopkinson Pressure Bar). Na podstawie otrzymanych wyników badań stwierdzono, iż stop tytanu uzyskany metodą klasycznej metalurgii proszków charakteryzuje się niższymi parametrami wytrzymałościowymi od jego komercyjnego odpowiednika. Próbki wykonane technologią LENS cechują się wyższymi parametrami w porównaniu ze stopem komercyjnym zarówno w statycznych jak również dynamicznych warunkach obciążenia.

7

Experimental investigation of dynamic behavior of silty sand

Chmielewski Ryszard, Kruszka Leopold, Rekucki Ryszard, Sobczyk Kamil

Archives of Civil Engineering

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2021

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Vol. 67, nr 1

481--498

EN

The paper includes experimental research using the Split Hopkinson Pressure Bar to determine dynamic compression curves and strength dynamic parameters to depend on the strain rate and moisture for silty sand soil samples. Those experiments are oedometric type based in a rigid confining cylinder. Samples of silty sand with fine a fraction content were taken for the study. To ensure sufficiently uniaxial strain of the tested material, the soil samples were placed in properly prepared casings made of duralumin for the needs of the tests. Thanks to the use of measuring strain gauges on the initiating and transmitting bars, as well as the casing, the nature of the loading pulse was obtained, which was then subjected to the process of filtration and data processing to obtain the nature of the incident, reflected and transmitted wave. During the above dynamic experiments with the representative of silty sand soils, it was observed that its dynamic compaction at a high strain rate is different than in the case of the Proctor test. This is due to higher compaction energy, which additionally changes the grain size by destroying the grains in the structure. The paper presents the results of particle size distribution analysis for two different types of soil samples - this type of analysis is unique. Hence experiments should be further continued for such soils with different granulations and various moisture using, for example, Hopkinson measuring bar technique to confirm for other silty sand soils that are often subgrade of various engineering objects.

PL

Artykuł obejmuje edometryczne badania eksperymentalne z wykorzystaniem techniki pręta Hopkinsona do określenia zarówno dynamicznego zachowania jak i zmian struktury dla próbek wybranego ośrodka gruntowego o różnej wilgotności poddanych oddziaływaniu dynamicznemu. Do badania wzięto piasek pylasty (siSa) o zawartości frakcji drobnych fi+fπ = 20,46%. W celu zapewnienia wystąpienia jednoosiowego stanu odkształcenia badanej próbki gruntu umieszczono ją w odpowiednio przygotowanej duraluminiowej osłonie pierścieniowej. Dzięki zastosowaniu tensometrów pomiarowych na prętach inicjującym oraz transmitującym, jak również osłonie zarejestrowano różne impulsy, które następnie poddano procesowi filtracji i obróbki danych, tak aby otrzymać obrazy propagacji sprężystych fal w prętach pomiarowych i w osłonie. Wykorzystując odpowiednie równania oraz zależności zmodyfikowanej metody Kolsky'ego dla trójwymiarowego stanu naprężenia w badanej próbce określono eksperymentalne zależności charakteryzujące zachowanie się próbek gruntu o różnej wilgotności: naprężenie ϭ(t), odkształcenie ε(t) oraz prędkość odkształcenia έ(t) w funkcji czasu. Na tej podstawie uzyskano krzywe ściskania dynamicznego dla różnej wilgotności próbek gruntu pylastego z określonymi wartościami początkowego dynamicznego edometrycznego modułu oraz lokalnych maksymalnych naprężeń plastycznych i odpowiadających im odkształceń. Podczas powyższych eksperymentów dynamicznych z próbkami gruntów typu piasku pylastego zaobserwowano, że jego dynamiczne zagęszczenie przy dużej szybkości odkształcania jest inne niż w przypadku testu Proctora. Wynika to z większej energii zagęszczania, która dodatkowo powoduje zmianę uziarnienia poprzez niszczenie ziaren w strukturze. W pracy przedstawiono wyniki analizy zmian uziarnienia dla dwóch różnych rodzajów próbek gruntu - tego typu analizy są unikalne. W związku z tym należy kontynuować eksperymenty dla takich gruntów o różnych granulacjach i różnej wilgotności, stosując technikę prętów pomiarowych Hopkinsona, w celu potwierdzenia opisanego zjawiska w innych gruntach typu piasku pylastego, które często są podłożem gruntowym dla różnych obiektów inżynieryjnych.

8

Dynamic splitting tensile performance of new and old concrete after high temperature treatment

Cao Hai

Archives of Civil Engineering

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2021

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Vol. 67, nr 4

79--89

EN

In order to study the dynamic splitting tensile properties of new and old concrete after high temperature treatment, the effects of different impact velocities and temperatures on failure modes, dynamic splitting strength and energy absorption of new and old concrete were analyzed by impact dynamic splitting tensile test use of variable cross-section Φ 74 mm split Hopkinson pressure bar apparatus. The results show that: Impact velocity and temperature not only affect the dynamic splitting strength of new and old concrete bonding specimens, but also affect the failure modes and degree of breakage. The dynamic splitting strength of new and old concrete increases with the increase of impact velocity, but the increase rate decreased with the increase of temperature. The dynamic splitting strength first increases slowly and then decreases dramatically with the increase of temperature. In the dynamic splitting test of new and old concrete, the energy absorption increases with the increase of impact velocity and decreases with the increase of temperature.

9

The concept of experimental research on the behavior of sand cover material for protective shelters for civilians

Kruszka Leopold, Chmielewski Ryszard, Sobczyk Kamil

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2020

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Nr 1

1--6

EN

The article proposes the concept of experimental dynamic tests of aggregate behavior - sand used as a material for covering temporary protective shelters for the population and civil defense. These shelters are part of the construction shielding infrastructure useful in crisis situations. Laboratory tests of loose soil, including sand, with impact loads are based on the Split Hopkinson Pressure Bar using a clamp. The work describes both this experimental method and the original laboratory stand for impact tests based on a pneumatic launcher with a projectile - bar. This position was built at the Institute of Civil Engineering of the Military University of Technology taking into account the requirements of generally applicable legal provisions. Examples of preliminary experimental research on the behavior of selected aggregate - dry sand under dynamic load - are presented.

10

Numerical study of dynamic behaviors of concrete under various strain rates

An H. M., Liu L.

Archives of Civil Engineering

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2019

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Vol. 65, nr 4

21--36

EN

As the dynamic behavior of the concrete is different from that under static load, this research focuses on the study of dynamic responses of concrete by simulating the split Hopkinson pressure bar (SHPB) test. Finite element code LS-DYNA is used for modeling the dynamic behaviors of concrete. Three continuous models are reviewed and the Holmquist-Johnson-Cook model (HJC) is introduced in detail. The HJC model which has been implemented in LS-DYNA is used to represent the concrete properties. The SHPB test model is established and a few stress waves are applied to the incident bar to simulate the dynamic concrete behaviors. The stress-strain curves are obtained. The stress distributions are analyzed. The crack initiation and propagation process are described. It is concluded that: the HJC model can modeling the entire process of the fracture initiation and fragmentation; the compressive of the concrete is significantly influenced by the strain rates.

11

Study on constitutive model and deformation mechanism in high speed cutting Inconel718

Hao Zhao Peng, Li Ji Ning, Fan Yi Hang, Ji Fang Fang

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

439--452

EN

The nickel-based alloy Inconel718 is a multi-component complex alloy. There exists complex cutting deformation, higher cutting temperature, higher cutting force and formation of serrated chip in the machining process. However, the formation time of every saw tooth unit in serrated chip is very short. It is difficult to use traditional method to analyze the chip at any time. Simulation analysis, integrated with the experimental results, was used to study the whole process of cutting deformation. The Johnson–Cook (JC) constitutive model of Inconel718 under high speed and high strain rate is established through split Hopkinson pressure bar (SHPB) test. The finite element method was used to study the deformation process. Combining the analysis of metallographic pictures which were obtained in the cutting experiment, the plastic behavior evolution of material in the cutting zone is deeply studied to further reveal the forming mechanism of serrated chip. The results showed that the local temperature in the cutting zone increased rapidly. The appearance of thermal softening of materials led to the change of stress distribution in the cutting zone. The thermoplastic shear instability further appeared which resulted in the shear localization, subsequently leading to the uneven deformation of chip and then serrated chip formed.

12

Assessment of Mechanical Properties of Laser Beam Welded Joints Made of Steel Strenx S700MC Subjected to High Impact Load

Prochenka P., Makowska K., Janiszewski J.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2018

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Vol. 62, No. 2

51--60

EN

The article assesses the strength and ductility of laser welded joints made of steel Strenx S700MC. The assessment was based on tests results concerning the material structure, hardness as well as quasi-static and dynamic tensile tests. The dynamic tests were performed using the tensile split Hopkinson pressure bar technique and strain rates of 103 s-1. The obtained results revealed that the strength of joints under quasi-static and dynamic tensile test conditions were high and similar, yet their ductility significantly deteriorated under the impact load.

PL

W artykule dokonano oceny wytrzymałości i ciągliwości złączy spawanych laserowo wykonanych ze stali Strenx S700MC na podstawie wyników badań struktury, rozkładu twardości oraz quasi-statycznej i dynamicznej próby rozciągania. Badania dynamiczne na rozciąganie z szybkością odkształcania rzędu 103 s-1 wykonano za pomocą techniki dzielonego pręta Hopkinsona. Uzyskane wyniki wykazały, że o ile wytrzymałość złączy w warunkach quasi-statycznego i dynamicznego rozciągania jest wysoka i zbliżona, to ich ciągliwość znacząco pogarsza się pod wpływem udarowego obciążenia.

13

Wpływ wkładek formujących na profil fali sprężystej propagującej się w długich prętach

Kochanowski K.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2014

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Vol. 5, Nr 4 (18)

45-58

PL

W artykule zaprezentowano wyniki badań doświadczalnych wpływu wkładek formujących na kształt fal sprężystych propagujących się w prętach zastosowanych w układzie badawczym techniki dzielonego pręta Hopkinsona (SHPB). Analizy przeprowadzono dla wkładek wykonanych z blachy miedzianej i pręta miedzianego dla sześciu różnych grubości oraz dla różnych szybkości uderzenia pręta wymuszającego. Zaprezentowane w artykule wyniki wskazują, iż jeśli zastosowana wkładka jest zbyt gruba, to nie pozwala ona na uzyskanie impulsu obciążenia próbki gwarantującego stałą szybkość odkształcenia. Natomiast zastosowanie zbyt cienkiej wkładki dla zadanej prędkości uderzenia nie powoduje zmniejszenia oscylacji impulsu wymuszającego. Wyniki badań dowodzą, że stosowanie wkładek formujących daje duże możliwości w kształtowaniu fali wymuszającej.

EN

The article presents the experimental results of impact of the wave shapers on the shape of elastic waves propagating through the bars used in split Hopkinson pressure bar technique. Analyses were performed for the wave shapers made of copper sheet and the copper rod for six different thicknesses and for different speeds of the striker bar. Results presented in this article show that if the wave shaper is too thick, it does not allow for obtaining pulse load of the specimen that ensures a constant speed of deformation. However, using too thin wave shaper for a given impact velocity does not decrease oscillations. The results show that the use of wave shaper gives the big opportunities for shaping the elastic wave.

14

Dynamiczne badania wytrzymałościowe drewna w obniżonych i podwyższonych temperaturach

Kruszka L.

Biuletyn Wojskowej Akademii Technicznej

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2004

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Vol. 53,nr 11-12

87-96

PL

W pracy przedyskutowano wyniki dynamicznych badań wytrzymałościowych trzech rodzajów drewna konstrukcyjnego: brzozy, sosny i osiki podczas monotonicznego i cyklicznego ściskania w temperaturach: pokojowej, podwyższonej i w obniżonej. Wycięte walcowe próbki były obciążane wzdłuż i w poprzek włókien oraz pod różnymi kątami do tych włókien. Drewniane próbki były badane bez i z obejmą stalową, tj. w jednoosiowym stanie naprężenia lub odkształcenia. Dodatkowo, drewniane płyty-próbki były umieszczone pomiędzy prętami pomiarowymi SPHB w celu uzyskania zależności naprężenie-odkształcenie w realnych warunkach ograniczenia poprzecznych deformacji masą materiału. Badania dynamiczne zostały zrealizowane z wykorzystaniem metody dzielonego pręta Hopkinsona na ściskanie (SPHB) przy szybkości odkształcenia 10³ s⁻¹.

EN

The dynamic strength testing results of three kinds of the structural woods, i.e. birch, pine and aspen in a monotonic and cyclic compression at room temperature as well as in lowered and elevated temperatures are discussed in this paper. The cut out cylindrical specimens were loaded along and across the fibers of the woods as well as at the other angles of cutting out from the wooden materiaIs. The wooden disk specimens were tested with and without a steel rigid jacket, i.e. in the both the unaxial strain and the stress states. Additionally, the wooden plate-specimens were placed between measuring the bars of SPHB in order to obtain the stress-strain dependence in the real confined condition of lateral deformation by the material mass. Dynamic examinations are realized using the split Hopkinson pressure bars (SPHB) method at the strain rates about 10³ s⁻¹.