Investigation of expanding-folding absorbers with functionally graded thickness under axial loading and optimization of crushing parameters

Chunwei Zhang,Limeng Zhu,Farayi Musharavati,Afrasyab Khan,Tamer A. Sebaey 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.6

In this study, a new type of energy absorbers with a functionally graded thickness is investigated, these type of absorbers absorb energy through expanding-folding processes. The expanding-folding absorbers are composed of two sections: a thin-walled aluminum matrix and a thin-walled steel mandrel. Previous studies have shown higher efficiency of the mentioned absorbers compared to the conventional ones. In this study, the effect of thickness which has been functionally-graded on the aluminum matrix (in which expansion occurs) was investigated. To this end, initial functions were considered for the matrix thickness, which was ascending/descending along the axis. The study was done experimentally and numerically. Comparing the experimental data with the numerical results showed high consistency between the numerical and experimental results. In the final section of this study, the best energy absorber functionally graded thickness was introduced by optimization using a thirdorder genetic algorithm. The optimization results showed that by choosing a minimum thickness of 1.6 mm and the exponential coefficient of 3.25, the most optimal condition can be obtained for descending thickness absorbers.

Application of Lagrangian approach to generate P-I diagrams for RC columns exposed to extreme dynamic loading

Zhang, Chunwei,Abedini, Masoud Techno-Press 2022 Advances in concrete construction Vol.14 No.3

The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damages. Therefore, it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, columns are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. Therefore, current research examines the effect of blast loads on the reinforced concrete columns via development of Pressure- Impulse (P-I) diagrams. In the finite element analysis, the level of damage on each of the aforementioned RC column will be assessed and the response of the RC columns when subjected to explosive loads will also be identified. Numerical models carried out using LS-DYNA were compared with experimental results. It was shown that the model yields a reliable prediction of damage on all RC columns. Validation study is conducted based on the experimental test to investigate the accuracy of finite element models to represent the behaviour of the models. The blast load application in the current research is determined based on the Lagrangian approach. To develop the designated P-I curves, damage assessment criteria are used based on the residual capacity of column. Intensive investigations are implemented to assess the effect of column dimension, concrete and steel properties and reinforcement ratio on the P-I diagram of RC columns. The produced P-I models can be applied by designers to predict the damage of new columns and to assess existing columns subjected to different blast load conditions.

Implementation of a Wireless Controlled Device with RGB Driving Based on FFT

Zhang Hong,Tian Chunwei,Lin Gaoya,Wang Hongbin 보안공학연구지원센터 2013 International Journal of Multimedia and Ubiquitous Vol.8 No.6

Research and Implementation of RGB-LED Mixed Light Matching along with Music Playing

Zhang Hong,Gao Xiaoshuang,Mohanmmed Obadi,Zhao Ruirui,Tong Jinrui,Tian Chunwei,Hu Zhiqiang 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.4

Synesthesia effect between music and color is a researching direction which is concerned much. The problem of mismatching between music playing and color had always existed in applications. On the basis of researching music and color, colors which are corresponding to various chords respectively are determined, and the frequency spectrum analysis on chords is performed. The real-time frequency domain transformation to time domain audio signal being played is carried out. The closest chord to audio signal being played can be identified via comparison between a chord spectrum and the spectrum of audio signal being played, and the color corresponding to the audio signal is determined. To improve the accuracy of recognition the method is investigated with which wavelet transform is adopted to de-noise processing of audio signal. Through tests on the audio experiment platform, color mixed effect test, optimization of the audio signal processing parameters, and processing time sequence scheming have been performed. A novel audio player is developed in application to realize the optimal RGB-LED mixed light which automatically presents matching color effect for arbitrary music being played. The research can reveal relationships between music and color from the perspective of frequency spectrum, promote the development of the color music, which has broad application prospects in urban landscape, stage lighting, and psychotherapy.

Study on the Application of Canola Oil and Cottonseed Oil in SolutionPolymerized Styrene-butadiene Rubber

Yuan Jing,Chunwei Zhang,Su Zhang,Guangyi Lin,Huidong Cao,Jiahui Wen,Zonglong Wang,Yuanyuan Niu,Zetao Lin 한국고분자학회 2023 폴리머 Vol.47 No.6

The application of vegetable oil-based softeners canola oil and cottonseed oil in Solution polymerized styrene-butadiene rubber (SSBR) system composites was investigated. The results showed that when the aromatic oil was replaced by 5 parts of vegetable oil-based softeners in equal amounts in the base formulation of SSBR system, the work-ing performance of the rubber was better, the tear strength and elongation at break were improved and the tensile strength was reduced; the vulcanization time of the rubber prepared with vegetable oil-based softeners was significantly reduced compared with that of aromatic oil; the glass transition temperature of the rubber was significantly reduced and the cold resistance and snow performance of the rubber were improved.

Elastic wave phenomenon of nanobeams including thickness stretching effect

Eyvazian, Arameh,Zhang, Chunwei,Musharavati, Farayi,Khan, Afrasyab,Mohamed, Abdeliazim Mustafa Techno-Press 2021 Advances in nano research Vol.10 No.3

The present work deals with an investigation on longitudinal wave propagation in nanobeams made of graphene sheets, for the first time. The nanobeam is modelled via a higher-order shear deformation theory accounts for both higher-order and thickness stretching terms. The general nonlocal strain gradient theory including nonlocality and strain gradient characteristics of size-dependency in order is used to examine the small-scale effects. This model has three-small scale coefficients in which two of them are for nonlocality and one of them applied for gradient effects. Hamilton supposition is applied to obtain the governing motion equation which is solved using a harmonic solution procedure. It is indicated that the longitudinal wave characteristics of the nanobeams are significantly influenced by the nonlocal parameters and strain gradient parameter. It is shown that higher nonlocal parameter is more efficient than lower nonlocal parameter to change longitudinal phase velocities, while the strain gradient parameter is the determining factor for their efficiency on the results.

The multi-axial strength performance of composite structural B-C-W members subjected to shear forces

Limeng Zhu,Chunwei Zhang,Xiaoming Guan,Brian Uy,Li Sun,Baolin Wang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.1

This paper presents a new method to compute the shear strength of composited structural B-C-W members. These B-C-W members, defined as concrete-filled steel box beams, columns and shear walls, consist of a slender rectangular steel plate box filled with concrete and inserted steel plates connecting the two long-side steel plates. These structural elements are intended to be used in structural members of super-tall buildings and nuclear safety-related structures. The concrete confined by the steel plate acts to be in a multi-axial stressed state: therefore, its shear strength was calculated on the basis of a concrete's failure criterion model. The shear strength of the steel plates on the long sides of the structural element was computed using the von Mises plastic strength theory without taking into account the buckling of the steel plate. The spacing and strength of the inserted plates to induce plate yielding before buckling was determined using elastic plate theory. Therefore, a predictive method to compute the shear strength of composited structural B-C-W members without considering the shear span ratio was obtained. A coefficient considering the influence of the shear span ratio was introduced into the formula to compute the anti-lateral bearing capacity of composited structural B-C-W members. Comparisons were made between the numerical results and the test results along with this method to predict the anti-lateral bearing capacity of concrete-filled steel box walls. Nonlinear static analysis of concrete-filled steel box walls was also conducted by using ABAQUS and the results agreed well with the experimental data.

Pore-scale study of in-situ surfactant flooding with strong oil emulsification in sandstone based on X-ray microtomography

Yun She,Chunwei Zhang,Mohammad Azis Mahardika,Anindityo Patmonoaji,Yingxue Hu,Shintaro Matsushita,Tetsuya Suekane 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-

This study presented a pore-scale investigation on the dynamic displacement of oil subjected to ex-situand in-situ surfactantflooding using X-ray microtomography. The ex-situ surfactant solution was preprepared,whereas the in-situ surfactant was generated directly with the chemical reaction inside porousmedia. The results showed that oil removal from the pore spaces relied on the combination of piston-like,pore-bodyfilling and a weak emulsification mechanism in the ex-situ system, whereas the in-situ systemwas dominated by a strong emulsification process. The threshold capillary pressure was decreasedsignificantly owing to interfacial tension reduction and wettability alteration, which enhanced the oilcluster mobilization. Therefore, the in-situ system produced the highest oil recovery efficiency of 86.9%compared with ex-situ system and waterflooding. The emulsifying ability was evaluated through oilcluster size distributions and their dynamic evolution. The networks or branches disappeared andemulsified into small oil ganglia and singlets, thereby leading to a significant decrease in the averageequivalent diameter. Finally, strong emulsification in the in-situ system was attributed to quick andprecise surfactant aggregation at the oil–water interface that induced blebbing, whereas the ex-situ casewas dominated by slow surfactant transport relying on advection and diffusion in theflow mainstream.

Design and Optimization of a Magnetic Coupling Structure with High Anti-offset for Wireless Power Transfer

Chen Long,Zhang Chunwei,Ben Tong,Nie Heng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

As the power transfer efficiency (PTE) is rapidly reduced due to the high offset between the transmitter and the receiver in the wireless power transfer (WPT) system, a Bidirectional Staggered Solenoid Structure (BSSS) with high anti-offset performance was proposed in this paper. Firstly, the factors that affect the PTE are analyzed by establishing a mathematical model of the magnetic coupling structure. Secondly, a parameter optimization method for the traditional flat solenoid coil (FSC) is proposed, which reduces the volume of the magnetic core without reducing the anti-offset ability. Then, the anti-offset performance of the optimized magnetic coupling structure is analyzed and compared with the square, the circle, and the DD (double D) coils structure by three-dimensional (3-D) finite element analysis (FEA). Finally, the anti-offset performance of the structure is verified by a S/S compensated WPT prototype. The PTE is still high when the power transfer distance (PTD) is 164 mm. When the offset distance in X and Y directions increases from 0 to 150 mm, PTE only decreases by 2.62% and 3.71%, respectively.

Thermal postbuckling of shear deformable multiscale hybrid composite beams

Arameh Eyvazian,Chunwei Zhang,Mohammad Alkhedher,Murat Demiral,Afrasyab Khan,Tamer A. Sebaey 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.4

This research is deal with thermal buckling and post-buckling of carbon nanotube/fiber/polymer composite beams. The beam is considered to be under uniform temperature rise. Firstly, the effective material properties of a two phase nanocomposite consisting of CNT and polymer are extracted. Then, the modified Chamis rule is utilized to obtain the equivalent thermo-mechanical properties of multiscale hybrid composite (MHC). Based on the first order shear deformation theory, Von-Karman type of geometrically nonlinear strain-deformation equations and also the virtual work rule, the equilibrium equations of a three phace composite beam are derived. Bifurcation buckling and also the thermal post-buckling is analysed using the generalized differential quadrature technique. In the thermal buckling phenomena, a linear eigenvalue problem is solved; however, due to the nonlinearity, the thermal postbuckling study is performed using an iterative displacement control strategy. After validation study, several novel results demonstrate the influences of length-to-thickness ratio, agglomeration of applied CNTs and fibers in the composite media and number and orientation of layers on the critical temperature and displacement loading path.