Wyniki wyszukiwania - BazTech

1

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

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

Archives of Civil and Mechanical Engineering

|

2022

|

Vol. 22, no. 4

art. no. e164, 2022

EN

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

2

Dynamic strength and accumulated plastic strain development laws and models of the remolded red clay under long-term cyclic loads: laboratory test results

Li J., Chen S., Jiang L.

Polish Maritime Research

|

2015

|

S 1

89--94

EN

The dynamic strength and accumulated plastic strain are two important parameters for evaluating the dynamic response of soil. As a special clay, the remolded red clay is often used as the high speed railway subgrade filling, but studies on its dynamic characteristics are few. For a thorough analysis of the suitability of the remolded red clay as the subgrade filling, a series of long-term cyclic load triaxial test under different load histories are carried out. Considering the influence of compactness, confining pressure, consolidation ratio, vibration frequency and dynamic load to the remolded red clay dynamic property, the tests obtain the development curves of the dynamic strength and accumulated plastic strain under different test conditions. Then, through curve fitting method, two different hyperbolic models respectively for the dynamic strength and accumulated plastic strain are built, which can match the test datum well. By applying the dynamic strength model, the critical dynamic strength of the remolded red clay are gained. Meanwhile, for providing basic datum and reference for relevant projects, all key parameters for the dynamic strength and accumulated plastic strain of the remolded red clay are given in the paper.

3

Odporność dynamiczna kotwi górniczych

Pytlik A.

Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie

|

2015

|

nr 4

28--35

PL

W artykule przedstawiono metodykę badań pozwalającą symulować pracę kotwi mocowanych w górotworze punktowo lub odcinkowo, która jest bliższa modelowi tąpnięcia wynikającego z ruchu bardzo dużych mas górotworu z prędkością początkową udaru mas skalnych. Przedstawiono również przykładowe wyniki badań odporności dynamicznej kotwi strunowych, analizę ich pracy przy obciążeniu dynamicznym oraz porównanie pracy kotwi przy różnych wartościach prędkości udaru, energii oraz pędu.

EN

The essential issue in mines of Upper Silesian Coal Basin the roof support’s stability in mining excavations operating in conditions of dynamic loads caused by mining works is. The most common is a chock support whereas an anchored chock support is used mainly for reinforcement. In order to evaluate dynamic resistance of various mining anchors, Central Mining Institute has developed research methodology that allows to simulate momentum of large rock masses dynamically loading an anchor. The test enables to evaluate a mechanical part of the anchor: a rod, a washer and a nut; as well as the anchor attached to a previously adjusted test roll filled with concrete or cement-mineral binder with high compressive strength. The research includes measurement of parameters such as dynamic strength of forces tearing the anchor off or causing the deformation of anchors, which influence the stability level of the roof support. Knowledge of these parameters may be useful while developing a design of an individual anchored chock support or a reinforced chock support. The article presents research methodology that enables to simulate operation of anchors mounted pointwise or section wise in rock mass. The methodology is similar to a model of mining tremor caused by movement of large rock mass with initial velocity of impact mass. The article also includes test results of dynamic support of string anchors and an analysis of their operation while dynamically loaded. Moreover, the research covered comparison of anchors operation with various velocities of impact mass, energy or momentum.

4

Wyznaczanie dynamicznych i zmęczeniowych wytrzymałości materiałów

Stolarski A.

Inżynieria i Budownictwo

|

2012

|

R. 68, nr 5

273-274

PL

Przedstawiono dwa nowe sposoby wykorzystania kryterium Campbella w celu modelowania dynamicznych i zmęczeniowych wytrzymałości materiałów konstrukcyjnych: stali i betonu. Pierwszy z nich dotyczy uproszczonego modelowania dynamicznego zachowania stali. Drugi sposób dotyczy wyznaczania zmęczeniowej wytrzymałości stali i betonu.

EN

Two new methods of application of the Campbell’s criterion to modelling the dynamic and fatigue strengths of structural materials: steel and concrete were presented in the paper. First of them relates to simplified modelling the dynamic behaviour of steel. Second method relates to determination the fatigue strengths of steel and concrete.

5

Dynamic strength of vitreous bond grinding wheels made of microcrystalline alumina type sol-gel.

Słowiński B., Fiks W.

Advances in Manufacturing Science and Technology

|

2006

|

Vol. 30, nr 1

101-110

EN

Summary The paper presents the results of investigations on the dynamic strength of vitreous bond grinding wheels made of microcrystalline alumina type sol-gel subject to a bursting test. A developed statistical model, giving consideration to the effect of abrasive-grain size, structure, hardness and concentration of microcrystalline sintered alumina SC in the binder material of these tools, has been discussed.

PL

W pracy przedstawiono wyniki badań wytrzymałości dynamicznej ściernic ceramicznych z mikrokrystalicznego korundu spiekanego typu SC, poddawanych próbie rozrywania. Do opracowania wyników wykorzystano model statystyczny, uwzględniający wpływ rozmiarów ziarna ściernego, struktury, twardości oraz zawartości korundu SC w ścierniwie tych narzędzi na ich prędkość graniczną. Na podstawie analizy wyników badania stwierdzono, że wytrzymałość dynamiczna na rozrywanie ściernic z mikrokrystalicznego korundu spiekanego SC zależy w sposób statystycznie istotny od wszystkich uwzględnionych parametrów budowy narzędzi. Największą jednak i jednoznaczną tendencję oddziaływania obserwowano tylko dla rozmiarów ziarna ściernego. Im mniejszy rozmiar ziarna ściernego, tym większą wytrzymałością dynamiczną charakteryzuje się ściernica.