Repeated lateral impacts on steel grillage structures at room and sub-zero temperatures

Truong, Dac Dung,Shin, Hyun Kyoung,Cho, Sang-Rai Elsevier 2018 International journal of impact engineering Vol.113 No.-

<P><B>Abstract</B></P> <P>This paper presents experimental and numerical investigation results for the plastic response of steel grillages, represented by one longitudinal stiffener and two transverse stiffeners of stiffened plates, used on ships or offshore structures under repeated mass impacts. The repeated mass impact scenario adopted in this paper could represent the repetition of impacted loads on marine structures due to contact with ice floes and floating objects during service. Repeated impact tests on grillage models at room and sub-zero temperatures (−50 °C) were conducted by releasing a knife-edge striker using a drop testing machine. The ends of the grillage models were firmly fixed onto a strong bed with support fixtures. To evaluate the repeated impact performance of the tested models, permanent deflections were measured after each impact test. Additionally, numerical simulations were performed using the commercial software package ABAQUS/Explicit to predict the extent of damage to the tested models caused by repeated impacts. In the calculations, the material properties of tested models were used to determine the strain hardening and strain rate hardening model using the equations recently proposed by the authors. Also, a simple analytical approach has been proposed to predict the damage evolution of the grillage subjected to repeated mass impacts. Reasonable agreement was achieved between the predictions and test results. The results showed that when the structure was repeatedly impacted, permanent deflections of the grillage significantly increased with increasing impact force. The permanent deflections tended to have certain values when the number of impacts increased. Based on the numerical results (which were substantiated with the experimental results), further calculations were then carried out to examine impact responses in greater detail and assess the effects of variations in boundary conditions and strain rate definitions on the response of grillages to repeated mass impacts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Repeated mass impact tests were performed on four steel grillage structures at room and sub-zero temperatures for different kinetic energies. </LI> <LI> Deflection increments were reduced and contact force increased, but impact duration decreased with an increasing number of impacts. </LI> <LI> An analytical method has been developed in this study to predict the permanent deflections of grillage beam under repeated mass impact. </LI> <LI> There is reasonable agreement between the experimental results and predictions of the numerical and analytical analyses developed in this study. </LI> <LI> The effects of strain rate and boundary conditions on the impact responses of grillages were also numerically investigated. </LI> </UL> </P>

Determination of k0 factors of short-lived nuclides 46mSc and 110Ag for the k0-NAA

Truong Truong Son,Ho Van Doanh,Ho Manh Dung 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9

The k0-standardization neutron activation analysis method has successfully determined the mass fraction of elements of interest using around a hundred analytical radionuclides. However, several very short-lived nuclides with half-life less than 100 s have not been used at Dalat research reactor. One of the reasons is that the values of k0-factors of these nuclides are significantly different. Therefore, this work focused on re-determination and evaluation of k0-factors of very short-lived nuclides 110Ag (T1/2 ¼ 24 s) and 46mSc (T1/2 ¼ 18.75 s). The results of determination of the short-lived nuclides revealed that k0-factor of 110Ag is significantly difference between the existing data and the obtained results in this work. The evaluation of the k0-factors was done by using the obtained results for application of k0-NAA for NIST1566b and NIST-2711A standard reference materials

Response of low-temperature steel beams subjected to single and repeated lateral impacts

Truong, Dac Dung,Jung, Hae-Jung,Shin, Hyun Kyoung,Cho, Sang-Rai The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.6

This paper presents the experimental and numerical investigation results of the response of low-temperature steel (LT-FH32 grade steel) beams under repeated impacts at room temperature and a single impact at a sub-zero temperature. After conducting tensile tests at room and sub-zero, repeated impact tests were conducted on two clamped single-beam models at room temperature, and single-impact tests of two other clamped single-beam models were conducted at $-50^{\circ}C$. The single and repeated impact tests were conducted by releasing a knife-edge striker using a drop testing machine. The permanent deflection of the model measured after each impact gradually increased with increasing number of impacts. Under the reduced temperature, the permanent deflection of the models slightly decreased. The numerical analyses were also performed to predict the damage response of the tested single-beam models. A comparison of the numerical prediction with those of experiments showed quite reasonable agreement.

Permanent set evolution of aluminium-alloy plates due to repeated impulsive pressure loadings induced by slamming

Truong, Dac Dung,Shin, Hyun Kyoung,Cho, Sang-Rai Springer-Verlag 2018 Journal of marine science and technology Vol.23 No.3

Response of low-temperature steel beams subjected to single and repeated lateral impacts

Dac Dung Truong,Hae-Jung Jung,Hyun Kyoung Shin,Sang-Rai Cho 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.6

This paper presents the experimental and numerical investigation results of the response of lowtemperature steel (LT-FH32 grade steel) beams under repeated impacts at room temperature and a single impact at a sub-zero temperature. After conducting tensile tests at room and sub-zero, repeated impact tests were conducted on two clamped single-beam models at room temperature, and singleimpact tests of two other clamped single-beam models were conducted at 50 C. The single and repeated impact tests were conducted by releasing a knife-edge striker using a drop testing machine. The permanent deflection of the model measured after each impact gradually increased with increasing number of impacts. Under the reduced temperature, the permanent deflection of the models slightly decreased. The numerical analyses were also performed to predict the damage response of the tested single-beam models. A comparison of the numerical prediction with those of experiments showed quite reasonable agreement.

Response of steel plates to repeated impulsive pressure loadings induced by slamming

Dac Dung Truong,Byoungcheon Seo,Nyo Me Thet Naing,Hyun Kyoung Shin,Sang-Rai Cho 한국해양환경·에너지학회 2017 한국해양환경공학회 학술대회논문집 Vol.2017 No.10

Elasticity of Market Demand between Modes of Transport in Vietnam by Price and Income

Quang Dung Truong,Hai Quang Nguyen,Dang Khoa Tran 중앙대학교 경제연구소 2020 Journal of Economic Development Vol.45 No.1

This study aims to determine the demand elasticity of passenger and freight transport market between different modes of transport in Vietnam by income, by price and by the price of substitute mode of transport (cross price). Upon consideration of the theoretical basis and inheriting the results of previous studies, this study applies a non-linear model to estimate the elasticity coefficients of demand. The analysis of the data for a 16-year period from 2001 to 2016 in Vietnam shows that as a general rule, the average per capita income is a factor that positively influences the transport market demand of different modes of transport. Freight rates, as a general rule, have an opposite effect on passenger transportation by waterway, freight transportation by road, by waterway and by air. Demand is greatly affected by the cross price in the freight transportation by air. The outcome of the research serves as a basis to propose business implications for executive management to make appropriate policies for each mode of transport and to create harmonization of all modes of transport.

Synthesis of Nano Titanium Dioxide and Its Application in Photocatalysis

Truong Van Chuong,Le Quang Tien Dung,Dinh Quang Khieu 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

This paper presents a simple way to synthesize titaniumdioxide nanotubes by using a microwave- assisted reaction of TiO2 particles and NaOH solution. The main advantage of the introduction of microwave into the reaction system is the extremely rapid kinetics for synthesis. This method is simple and easy to reproduce. Structural and microstructural characterizations of titania nanotubes were accomplished using X-ray diffraction (XRD), scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM) techniques. The specific surface area was calculated using the Brunauer-Emmett-Teller model and was found to be 52 m2/g. A high photocatalysis of our TiO2 nanotubes was obtained. This paper presents a simple way to synthesize titaniumdioxide nanotubes by using a microwave- assisted reaction of TiO2 particles and NaOH solution. The main advantage of the introduction of microwave into the reaction system is the extremely rapid kinetics for synthesis. This method is simple and easy to reproduce. Structural and microstructural characterizations of titania nanotubes were accomplished using X-ray diffraction (XRD), scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM) techniques. The specific surface area was calculated using the Brunauer-Emmett-Teller model and was found to be 52 m2/g. A high photocatalysis of our TiO2 nanotubes was obtained.

Physical Layer Secrecy Performance of RF-EH Networks with Multiple Eavesdroppers

Truong, Tien-Vu,Vo, Nhan-Van,Ha, Dac-Binh,Tran, Duc-Dung The Korea Institute of Information and Commucation 2016 Journal of information and communication convergen Vol.14 No.3

In this study, we investigate the physical layer secrecy performance of RF energy harvesting (EH) networks over Rayleigh fading channels. The RF-EH system considered here consists of one power transfer station, one source, one destination, and multiple passive eavesdroppers. The source harvests energy from the power transfer station and transmits the information to the destination by using a time switching-based relaying protocol. The eavesdroppers try to extract the transmitted information without an active attack. By using the statistical characteristics of the signal-to-noise ratio (SNR), the exact closed-form expressions of the existence probability of the secrecy capacity and the secrecy outage probability are derived. Further, we analyze the secrecy performance of the system with respect to various system parameters, such as the location of the system elements and the number of eavesdroppers. Finally, the equivalent Monte Carlo simulation results are provided to confirm the correctness of our calculations.

Design, Modeling and Analysis of a PEM Fuel Cell Excavator with Supercapacitor/Battery Hybrid Power Source

Tri Dung Dang,Tri Cuong Do,Hoai Vu Anh Truong,Cong Minh Ho,Hoang Vu Dao,YU YINGXIAO,정은진,안경관 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.1

The objective of this study was to design and model the PEM fuel cell excavator with supercapacitor/battery hybrid power source to increase efficiency as well as eliminate greenhouse gas emission. With this configuration, the system can get rid of the internal combustion engine, which has a low efficiency and high emission. For the analysis and simulation, the governing equations of the PEM system, the supercapacitor and battery were derived. These simulations were performed in MATLAB/Simulink environment. The hydraulic modeling of the excavator was also presented, and its model implemented in AMESim and studied. The whole system model was built in a co-simulation environment, which is a combination of MATLAB/Simulink and AMESim software. The simulation results were presented to show the performance of the system.