DESIGN OPTIMIZATION OF THIN-WALLED CIRCULAR TUBULAR STRUCTURES WITH GRADED THICKNESS UNDER LATER IMPACT LOADING

Fengxiang Xu,Xiaojin Wan,Yisong Chen 한국자동차공학회 2017 International journal of automotive technology Vol.18 No.3

In order to improve the crashing performance under lateral impact scenario, a thin-walled circular tube with functionally graded thickness (FGT) is introduced with its superior performance in this paper. The wall thickness of the FGT tubual structure is graded along the axial direction. Based on the assumed graded thickness function, several important parameters (such as the graded exponent, the tube diameter and yield stress) are selected and their effects on dynamic energy absorption characteristics are discussed. The analyzed results show that the FGT has better crashworthiness in special energy absorption (SEA) and crash force efficiency (CFE) than uniform thickness (UT) tube. Then, the optimization design is further employed to obtain the Pareto fronts of the graded configuration under lateral impact loading. Note that the specific energy absorption (SEA) and crashing force efficiency (CFE) are regarded as the objectives, and the grading exponent, yield stress and diameter are defined as the design variables. The surrogate model with the best accuracy is chosen by error analysis for improving the accuracy of optimization process. Thus, the optimal solution is reasonably obtained and analyzed. The optimal results indicate that the FGT structures have significant potential applications into vehicle body especially under later impacting event.

High-order Compact Gas-kinetic Scheme for Flow Simulation

Fengxiang Zhao,Kun Xu 한국전산유체공학회 2022 한국전산유체공학회 학술대회논문집 Vol.2022 No.10

DISCRETE OPTIMIZATION DESIGN OF TAILOR-WELDED BLANKS (TWBs) THIN-WALLED STRUCTURES UNDER DYNAMIC CRASHING

Yisong Chen,Fengxiang Xu,Suo Zhang,Kunying Wu,Zhinan Dong 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.2

Tailor-welded blanks (TWBs) thin-walled structures have been widely applied in field of automotive and construction due to their significant advantages in saving weight and improving crashworthiness. To further understand and improve crashing performance of TWB structures, this paper conducts parametric analysis and optimization design on TWB thin-walled tubes. Firstly, the numerical model of dynamic crashing event of different TWB tubes is derived from physical experiments. The parametric analysis results show that the material and thickness combinations have significant effects on the crashing performance. The energy-absorbed characteristics and deformed modes of TWBs are superior to those of tubes with uniform thickness. Then, two optimization cases of TWB tubes are presented through analysis of mean (ANOM) and updating orthogonal array, in which the thickness property and material types are considered as design variables. The results demonstrated that the performances of the optimized structure are much better than those of the initial counterpart.

Measurement of Intra-Fraction Displacement of the Mediastinal Metastatic Lymph Nodes Using Four-Dimensional CT in Non-Small Cell Lung Cancer

Suzhen Wang,Jianbin Li,Yingjie Zhang,Wei Wang,Fengxiang Li,Tingyong Fan,Min Xu,Qian Shao 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.4

Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy. Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy.

Investigation on the forming quality and hardness of hollow filter rods using water vapor forming method

Sanwen Peng,Gang Ouyang,Xiangwei Cao,Ning Hou,Guangyuan Yang,Fei Yan,Fengxiang Xu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.6

In this work, we describe experimental water vapor forming of hollow filter rods. The morphology, microstructure and mechanical property of hollow filter rods were carefully investigated. The forming mechanism of hollow filter rods was also discussed. The results demonstrated that a well-formed product was successfully obtained under the best process parameters. The circumference means of tested samples can be mainly determined by water vapor pressure and plasticizer concentration. However, the roundness of hollow filter rods depended on cellulose tow content. The occurrence of surface fuzzing and bending deflection was largely as the result of incomplete curing effect while the emergence of intermittent formation may rely on the tow feed volume during the forming process. The acceptable hardness of hollow filter rods was up to 92.27 % in the experiments. An improvement in hardness was mainly attributive to crisscrossing three-dimensional structures formed inside the filter rod. A model consisting of the diffusion stage, crosslinking stage and solidifying stage was proposed to illustrate the formation of filter rods.

Facile and Effective Preparation of the Lotus Leaf-based Adsorbent by Exposing Cellulose Nanocrystal for Waste Water Treatment and Air Purification

Huiyu Yang,Ke Liu,Xin Liu,Yaling Wang,Keshuai Liu,Fengxiang Chen,Bo Deng,Weilin Xu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2

One substantial plant waste, lotus leave was fabricated into lotus leave powder with different diameters by ball milling. The surface morphology, chemical composition, particle size, porosity parameters, crystal structure, and wettabilityof lotus leaf powders (LLPs) were analyzed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), laser particle size analysis, N2 adsorption/desorption, X-ray diffraction (XRD) analysis, and water contact angle (WCA) analysis, respectively. The results showed that the micro- and nanoscale waxy papilla structures on the surface of the lotus leaf were gradually destroyed by mechanical forces along with extended balling time. Accompanied re-exposing of -OH affluent cellulose nanocrystals (CNCs) was proved by HR-TEM, XRD, and FTIR. FTIR also revealed a hydroxyl to carboxyl transition on the surface of CNCs. Both the re-exposure of CNCs and thereof chemical structure transition after ball millingmade the LLP a good candidate for pollutant adsorbent for dye, formaldehyde, and heavy metal ions.