Vibration behavior of functionally graded sandwich beam with porous core and nanocomposite layers

Hua Si,Daoming Shen,Jinhong Xia,Vahid Tahouneh 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.1

This paper presents the influence of carbon nanotubes (CNTs) waviness, aspect ratio, internal pores and graphene platelets (GPLs) on the vibrational behavior of functionally graded nanocomposite sandwich beams resting on two-parameter elastic foundations. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness of upper and bottom layers of the sandwich beam and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes’ effective aspect ratio as the filler content increases. The core of structure is porous and the internal pores and graphene platelets (GPLs) are distributed in the matrix of core either uniformly or non-uniformly according to three different patterns. The elastic properties of the nanocomposite are obtained by employing Halpin-Tsai micromechanics model. The equations of motion are derived based on Timoshenko beam theory and employing Hamilton’s principle. The problem is modeled using a semi-analytical approach composed of generalized differential quadrature method (GDQM) and series solution adopted to solve the equations of motion. Detailed parametric studies are carried out to investigate carbon nanotubes (CNTs) waviness, CNT aspect ratio, porosity coefficient, porosity distribution, graphene platelets (GPLs) distribution, Winkler foundation modulus, shear elastic foundation modulus and geometrical conditions on the vibrational behavior of the sandwich structure.

Effects of superimposed cyclic operation on corrosion products activity in reactor cooling system of AP-1000

Fiaz Mahmood,Huasi Hu,Guichi Lu,Si Ni,Jiaqi Yuan 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.4

It is essential to predict the radioactivity distribution around the reactor cooling system (RCS) duringobligatory cyclic operation of AP-1000. A home-developed program CPA-AP1000 is upgraded to predictthe response of activated corrosion products (ACPs) in the RCS. The program is written in MATLAB and ituses state of the art MCNP as a subroutine for flux calculations. A pair of cyclic power profiles weresuperimposed after initial full power operation. The effect of cyclic operation is noticed to be moreprominent for in-core surfaces, followed by the primary coolant and out-of-core structures. The resultshave shown that specific activity trends of 56Mn and 24Na promptly follow the power variations,whereas, 59Fe, 58Co, 99Mo and 60Co exhibit a sluggish power-following response. The investigationspointed out that promptly power-following response of ACPs in the coolant is vital as an instantradioactivity source during leakage incidents. However, the ACPs with delayed power-following responsein the out-of-core components are perceived to cause a long-term activity. The present results are foundin good agreement with those for a reference PWR. The results are useful for source term monitoring andoptimization of work procedures for an innovative reactor design

Study on the design and experimental verification of multilayer radiation shield against mixed neutrons and γ-rays

Hu, Guang,Hu, Huasi,Yang, Quanzhan,Yu, Bo,Sun, Weiqiang Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.1

The traditional methods for radiation shield design always only focus on either the structure or the components of the shields rather than both of them at the same time, which largely affects the shielding performance of the facilities, so in this paper, a novel method for designing the structure and components of shields simultaneously is put forward to enhance the shielding ability. The method is developed by using the genetic algorithm (GA) and the MCNP software. In the research, six types of shielding materials with different combinations of elements such as polyethylene (PE), lead (Pb) and Boron compounds are applied to the radiation shield design, and the performance of each material is analyzed and compared. Then two typical materials are selected based on the experiment result of the six samples, which are later verified by the Compact Accelerator Neutron Source (CANS) facility. By using this method, the optimal result can be reached rapidly, and since the design progress is semi-automatic for most procedures are completed by computer, the method saves time and improves accuracy.

Development of gradient composite shielding material for shielding neutrons and gamma ray

Guang Hu,Guang Shi,Huasi Hu,Quanzhan Yang,Bo Yu,Weiqiang Sun 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.10

In this study, a gradient material for shielding neutrons and gamma rays was developed, which consists of epoxy resin, boron carbide (B4C), lead (Pb) and a little graphene oxide. It aims light weight and compact, which will be applied on the transportable nuclear reactor. The material is made up of sixteen layers, and the thickness and components of each layer were designed by genetic algorithm (GA) combined with Monte Carlo N Particle Transport (MCNP). In the experiment, the viscosities of the epoxy at different temperatures were tested, and the settlement regularity of Pb particles and B4C particles in the epoxy was simulated by matlab software. The material was manufactured at 25 °C, the Pb C and O elements of which were also tested, and the result was compared with the outcome of the simulation. Finally, the material's shielding performance was simulated by MCNP and compared with the uniformity material's. The result shows that the shielding performance of gradient material is more effective than that of the uniformity material, and the difference is most noticeable when the materials are 30 cm thick.

Development of a novel reconstruction method for two-phase flow CT with improved simulated annealing algorithm

Yan, Mingfei,Hu, Huasi,Hu, Guang,Liu, Bin,He, Chao,Yi, Qiang Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.4

Two-phase flow, especially gas-liquid two-phase flow, has a wide application in industrial field. The diagnosis of two-phase flow parameters, which directly determine the flow and heat transfer characteristics, plays an important role in providing the design reference and ensuring the security of online operation of two-phase flow system. Computer tomography (CT) is a good way to diagnose such parameters with imaging method. This paper has proposed a novel image reconstruction method for thermal neutron CT of two-phase flow with improved simulated annealing (ISA) algorithm, which makes full use of the prior information of two-phase flow and the advantage of stochastic searching algorithm. The reconstruction results demonstrate that its reconstruction accuracy is much higher than that of the reconstruction algorithm based on weighted total difference minimization with soft-threshold filtering (WTDM-STF). The proposed method can also be applied to other types of two-phase flow CT modalities (such as X(𝛄)-ray, capacitance, resistance and ultrasound).

Measurement of undesirable neutron spectrum in a 120 MeV linac

Yan Yihong,Tan Xinjian,Weng Xiufeng,Zhang Xiaodong,Zhang Zhikai,Sun Weiqiang,Hu Guang,Hu Huasi 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.10

Photoneutron background spectroscopy observations at linac are essential for directing accelerator shielding and subtracting background signals. Therefore, we constructed a Bonner Sphere Spectrometer (BSS) system based on an array of BF3 gas proportional counter tubes. Initially, the response of the BSS system was simulated using the MCNP5 code. Next, the response of the system was calibrated by using neutrons with energies of 2.86 MeV and 14.84 MeV. Then, the system was employed to measure the spectrum of the 241AmeBe neutron source, and the results were unfolded by using the Gravel and EM algorithms. Using the validated system, the undesirable neutron spectrum of the 120 MeV electron linac was finally measured and acquired. In addition, it is demonstrated that the equivalent undesirable neutron dose at a distance of 3.2 m from the linac is 19.7 mSv/h. The results measured by the above methods could provide guidance for linac-related research.