Effects of Brain Mechanical Properties on Child Head Responses under Linear Load

Shihai Cui,Yue Chen,Haiyan Li,Lijuan He,Shijie Ruan 대한의용생체공학회 2016 Biomedical Engineering Letters (BMEL) Vol.6 No.2

Purpose It is usually difficult to obtain the accurate mechanicalproperties of pediatric brain and skull because of the absenceof pediatric cadaver experiments. The goal of this work is todiscuss how different brain mechanical properties influencepediatric head response. Methods A validated finite element model of a 3-year-oldchild head with detailed anatomical structures was used toparametrically investigate the effects of mechanical propertieson child head. Taguchi orthogonal method was adopted todecrease the numbers of the simulation under direct impactload. Results With the increase of the skull elastic modulus, thecoup pressure decreases significantly (P < 0.001) whereasthe contrecoup pressure (P < 0.001) and maximum vonMises stress of skull (P < 0.001) increase significantly. Withthe increase of the short-time shear modulus of brain tissue,maximum shear stress of brain tissue (P < 0.001) increasessignificantly whereas the maximum principal strain (P < 0.01)decreases significantly. Conclusions Both Elastic modulus of skull and linearviscoelastic material parameters of brain tissues have statisticallysignificant effects on impact responses of child head. Differentmaterial parameters can lead to a great difference on impactresponses of child head.

A study of the corrosion resistance of a micro-arc oxidation coating on a cast aluminum-copper alloy

Shihai Cui,Jianmin Han,Weijing Li,Xiangyang Xu,Yuanfu Liu 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating. Protective coatings have been successfully prepared on a high strength aluminum-copper alloy ZL205 using a micro-arc oxidation (MAO) method. The influence of the oxidation time and current density on the thickness and corrosion resistance of MAO coatings has been studied. The thickness of MAO coating increases linearly with an increase of oxidation time. When the oxidation time is shorter than 20 minutes, the coating improves the corrosion resistance of ZL205 alloy quickly with an increase of oxidation time, which is confirmed by 5% salt spray test. When the oxidation time is longer than 20 minutes, the corrosion resistance of the MAO coating increases slowly with an increase of oxidation time. For a fixed oxidation time, the thickness of the MAO coating increases with an increase of current density and the corrosion resistance can also be improved. SEM and XRD analysis show that the surface morphology and phase of the MAO coating change with an increase of the oxidation time, which results in different corrosion resistance of the MAO coating.

The microstructure and corrosion resistance of micro-arc oxidation coatings on SiCp/A356 composites

Shihai Cui,Jianmin Han,Weijing Li,강석봉,이정무 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

Micro-arc oxidation (MAO) coatings were prepared on a SiCp/A356 composite. The microstructure and phase composition of the coatings on the SiCp/A356 composite were examined by XRD and SEM methods. It was found that there were two layers in the coating, a dense layer which was mainly composed of crystalline α-Al2O3 and a loose layer which consisted of γ-Al2O3 and mullite. The coating was well bonded to the SiCp/A356 substrate. The corrosion behavior of the coated and uncoated SiCp/ A356 composites was evaluated with a salt spray test and a potentiodynamic polarization technique. The results of the salt spray test showed that the coating could improve the corrosion resistance of SiCp/A356 by 11 times. The corrosion potential was shifted significantly in the anodic direction and the corrosion current density of the coated SiCp/A356 composite was reduced.

Design and Implementation of a Time-frequency Analysis System for Non-stationary Vibration Signals Using Mixed Programming

Miaozhong Sun,Shihai Cui,Yuanli Xu 보안공학연구지원센터 2014 International Journal of Hybrid Information Techno Vol.7 No.6

At present, in the feature extraction of non-stationary vibration signals, many time-frequency analytic methods have emerged to meet the further need of non-stationary signal analysis such as Wavelet Transform (WT), Short Time Fourier Transform (STFT), Wigner-Ville Distribution (WVD), Empirical Mode Decomposition (EMD), Ensemble Empirical Mode Decomposition (EEMD) and so on. However, these time-frequency analysis methods can only be carried out on Matlab platform and the processes are of low efficiency, bringing a lot of inconvenience in signal analysis because they can not run on Windows system independently. According to the defects, a novel method of mixed programming which combines Matlab with Delphi based on COM (component Object Model) module technology is proposed to design a time-frequency analysis system for non-stationary vibration signals assembling fourteen methods. The advantages of two languages are shared with each other. In design of the system, a combined method which combines two or three analytic methods is put forward for relational analytic modules to make the analytic results more perfect and clearer, like WAVELET-FFT, EMD-WVD etc.. This paper uses the EMD-WVD combined method as an example to present the programming thoughts and processes. The effectiveness of the system is validated using a simulation signal and an experimental signal. The system can be executed separated from MATLAB environment.

Solidification simulation of a SiCp/Al disk brake casting

Zhiyong Yang,Jianmin Han,Shihai Cui,강석봉,이정무 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

A SiCp/Al composite disk brake casting for a high-speed application is produced using an adjustable vacuum pressure casting method specially developed for the production of SiCp/Al composite castings with complex structure. Feeding path during the solidification process of the disk brake casting is investigated by solidification simulation with a ProCAST code and checked by measurement of cooling curves. The simulation results match well with the measured cooling curves, which shows that the results of solidification simulation can be well used for a SiCp/Al composite casting production. With the help of solidification simulation, it is easy to establish a suitable feeding path that is the key technology for producing sound castings with the adjustable vacuum pressure casting method. Different casting plans with gating systems and chills are simulated and an improved casting plan for the disk brake casting is proposed based on the research presented in this paper. The casting quality is checked and confirmed by X-ray inspection and destructive inspection, which shows that the casting has few internal defects.

Research on the method for producing complex SiCP/Al composite disk brake castings

Han Jianmin,Sha Zhensong,Li Weijing,Cui Shihai,Wang Jinhua 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4

The casting properties of a SiCP/Al composite are analyzed in this paper and the methods for producing complex castings of SiCP/Al composite disk brake together with their difficulty are discussed. An adjustable vacuum pressure casting method is established on the basis of a normal adjustable pressure casting method. The SiCP/Al composite disk brake casting is made with the established method. The results show that the adjustable vacuum pressure casting is a successful casting method for producing SiCP/Al composite castings of large dimensions and complex structures, which gives few defects as confirmed by Xray real- time image system. The casting properties of a SiCP/Al composite are analyzed in this paper and the methods for producing complex castings of SiCP/Al composite disk brake together with their difficulty are discussed. An adjustable vacuum pressure casting method is established on the basis of a normal adjustable pressure casting method. The SiCP/Al composite disk brake casting is made with the established method. The results show that the adjustable vacuum pressure casting is a successful casting method for producing SiCP/Al composite castings of large dimensions and complex structures, which gives few defects as confirmed by Xray real- time image system.