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.

CRASHWORTHINESS OPTIMIZATION OF TAPERED UD-CFRP TUBE ACCOUNTING FOR MULTIPLE LOADING PANGLES

Chen Yisong,Zhu Guohua,Wang Zhen 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.4

Tapered composite energy-absorbing components have superior advantages in weight reduction and crashworthiness improvement subjected to oblique compressions compared to straight structures. This study investigated the crashworthiness characteristics of uni-directional carbon fiber reinforced plastic (UD-CFRP) tubes under various loading angles, and further provided the guidance on multi-objectives optimization for UD-CFRP tubes accounting for multiple loading cases. The crashworthiness characteristics of straight UD-CFRP tubes subjected to three compressive angles (0°, 10° and 20°) were firstly explored experimentally, and results indicated that energy-absorbing capacity of samples decreased with the loading angles increasing due to changes in deformation behaviors. The multi-layer finite element modes (FEMs) were developed and validated, and simulations found that internal energy (IE) of intra-CFRP layer and inter-cohesive layer, friction energy decreased with the increase in loading angles. Parametric studies indicated crashworthy performances of UD-CFRP samples under multiple loading angles can be further improved by adjusting the tapered angle or wall thickness. Consequently, the synthetic special energy absorption (SEAβ), synthetic peak crushing force (PCFβ) and mass of tapered tube were optimized accounting for three different loading groups. Compared to baseline sample, the SEAβ was improved by 14 %, while the PCFβ and mass were reduced by 30.2 % and 19 %, respectively.

Progress in Adsorption-Enhanced Hydrogenation of CO2 on Layered Double Hydroxide (LDH) Derived Catalysts

Xin Fang,Chuang Chen,He Jia,Yingnan Li,Jian Liu,Yisong Wang,Yanli Song,Tao Du,Liying Liu 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.95 No.-

It is acknowledged as a promising strategy to reduce excessive CO2 emissions by catalytic conversion tovalue-added chemicals, in which layered double hydroxide (LDH) derived catalysts play essential roles. Inthe present review, latest progresses were summarized to gain insights on this issue. LDH-derivedcatalysts can be prepared via various methods and possess favorable characteristics of reversibletopotactic transformation for further development. Compared to conventional catalysts, they showspecific advantages in specific surface area, metal element dispersion and active site distribution. Despiteof distinguished LDH-derived catalysts applied in CO2 reduction reactions to methane, methanol,hydrocarbons, etc., state-of-art LDH-derived catalysts consisted of catalyst-adsorbent synergistic systemare recently constructed to employ the surface CO2 adsorption boundary layer to increase the CO2 partialpressure near active sites for hydrogenation. The overall catalytic performance is thus promoteddramatically. Accordingly, the strategy of adsorption-enhanced hydrogenation is expected to facilitatethe industrialization of CO2 hydrogenation and is instructive for catalyst design in future.

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.

Laparoscopic Sacrocolpopexy Plus Colporrhaphy With an Small Intestine Submucosa Graft Versus Total Pelvic Floor Reconstruction for Advanced Prolapse: A Retrospective Cohort Study

Junyan Wang,Xiaojuan Wang,Keqin Hua,Yisong Chen 대한배뇨장애요실금학회 2019 International Neurourology Journal Vol.23 No.2

Purpose: Transvaginal mesh (TVM) results in a greater anatomic cure but more complications. We aimed to compare laparoscopic sacrocolpopexy (LSC) plus colporrhaphy with the small intestine submucosa (SIS) graft versus TVM for advanced pelvic organ prolapse (POP). Methods: Patients with advanced POP who underwent LSC plus colporrhaphy with the SIS graft or TVM at a center between September 2015 and November 2016 were studied. Anatomical outcomes were evaluated using POP quantification. Functional outcomes related to POP and sexual life were evaluated using the Pelvic Floor Distress Inventory (PFDI-20) and the Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Questionnaire (PISQ-12). Data regarding surgical procedures and patient demographic variables were recorded. Chi-square and Student t -tests were used for 2 independent samples. Results: A total of 76 patients were enrolled in this study with 26 patients in the LSC plus colporrhaphy with the SIS graft group (group A) and 50 patients with TVM group (group B). All patients in both groups demonstrated significant improvement in anatomical outcomes (P<0.05) after surgery. PFDI-20 scores were significantly improved 12 months after operation in both groups (P<0.001). PISQ-12 scores were significantly improved in patients after surgery, especially patients in group A (P<0.001). Mesh exposure occurred in both groups as follows: 8 patients (30.7%) in group A and 5 patients (10%) in group B. Conclusions: Even though both surgeries showed excellent results for subjective and objective outcomes, the use of an SIS graft might increase the exposure of polypropylene mesh. We do not recommend LSC plus colporrhaphy with the SIS graft for advanced multiple-compartments prolapse.

Tetragonal zirconia based ternary ZnO-ZrO2-MOx solid solution catalysts for highly selective conversion of CO2 to methanol at High reaction temperature

Xin Fang,Yunting Xi,He Jia,Chuang Chen,Yisong Wang,Yanli Song,Tao Du 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.88 No.-

Catalytic conversion of CO2 to methanol has attracted increasing interests as a promising strategy forreducing excessive CO2 emissions. However, the methanol selectivity drops rapidly with elevatedtemperature due to enhanced CO synthesis using conventional catalysts, which hiders its application. Herein, ZnO-ZrO2 solid solution catalysts (SSCs) were prepared with different methods and modified byadding extra metal, i.e., Al, Cr, Fe or Mg. As-prepared SSCs were characterized and tested in reaction. Theresults show that prepared ZnO-ZrO2 SSCs possess similar chemical compositions but different crystals,morphologies and pore systems, among which the C-ZZ synthesized by co-precipitation exhibits theoptimal property. After doping, the basic crystal of tetragonal ZrO2 can be retained and ternary ZnO-ZrO2-MOx SSCs are successfully prepared. There come dramatic improvements in overall catalyticperformance. Specifically, the 3Mg-C-ZZ SSC, at 3.0 MPa and GHSV of~2000 h 1, maintains a considerablemethanol selectivity of 81.5 % even at 320 C. Prepared catalysts present remarkable superiorities toconventional copper-based catalysts especially at high reaction temperatures, which endures thempromising applications in coupling conversion of CO2 to valuable chemicals with the intermedia ofmethanol.

Conductively coupled flexible silicon electronic systems for chronic neural electrophysiology

Li, Jinghua,Song, Enming,Chiang, Chia-Han,Yu, Ki Jun,Koo, Jahyun,Du, Haina,Zhong, Yishan,Hill, Mackenna,Wang, Charles,Zhang, Jize,Chen, Yisong,Tian, Limei,Zhong, Yiding,Fang, Guanhua,Viventi, Jonathan National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.41

<P>Materials and structures that enable long-term, intimate coupling of flexible electronic devices to biological systems are critically important to the development of advanced biomedical implants for biological research and for clinical medicine. By comparison with simple interfaces based on arrays of passive electrodes, the active electronics in such systems provide powerful and sometimes essential levels of functionality; they also demand long-lived, perfect biofluid barriers to prevent corrosive degradation of the active materials and electrical damage to the adjacent tissues. Recent reports describe strategies that enable relevant capabilities in flexible electronic systems, but only for capacitively coupled interfaces. Here, we introduce schemes that exploit patterns of highly doped silicon nanomembranes chemically bonded to thin, thermally grown layers of SiO2 as leakage-free, chronically stable, conductively coupled interfaces. The results can naturally support high-performance, flexible silicon electronic systems capable of amplified sensing and active matrix multiplexing in biopotential recording and in stimulation via Faradaic charge injection. Systematic in vitro studies highlight key considerations in the materials science and the electrical designs for high-fidelity, chronic operation. The results provide a versatile route to biointegrated forms of flexible electronics that can incorporate the most advanced silicon device technologies with broad applications in electrical interfaces to the brain and to other organ systems.</P>