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Dynamic compressive and splitting tensile response of unsaturated polyester polymer concrete material at different curing ages

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CONSTRUCTION AND BUILDING MATERIALS 2018年 177卷 477-498页

作者： Chen, De Liu, Feng Yang, Fei Jing, Lin Feng, Wanhui Lv, Jianbing Luo, Qingzi Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510006 Guangdong Peoples R China Southwest Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Sichuan Peoples R China Jinan Univ Moe Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

The present study performed quasi-static and dynamic compressive and splitting tensile tests on unsaturated polyester polymer concrete (UPPC) at four different curing ages (6 h, 3 days, 7 days, and 28 days). We examined a total of 136 specimens, specifically 24 cubic specimens and 12 cylindrical specimens for quasi-static tests and 45 cylinders and 55 FBD specimens for dynamic compressive and tensile tests, respectively. The experimental results indicated that UPPC exhibited rapid strength enhancement in the early stages of curing, and the natural curing condition-treated cubic specimens exhibited 6-h compressive and splitting tensile strengths of 40 MPa and 6.5 MPa, respectively, which was almost the 50-60% of the 28-day strengths. The UPPC is also sensitive to the strain rate, such that both the compressive and splitting tensile strengths exhibited significant increases following an increase in the strain rate. Conversely, the strain rate sensitivity decreased with the curing age. We deemed the CEB-FIP equation for normal cement concrete to be inadequate for estimating the strain rate sensitivity of UPPC. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： UPPC Curing age SHPB Flattened Brazilian disc Dynamic increase factor

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Computer Transient Simulation for Dual In-Line Package through Finite Element Analysis and ANASYS Software

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Journal of Physics: Conference Series 2021年第1期2033卷

作者： Wei Su Wenhao Luo Xianshan Dong Si Chen Agam Tomar Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia

The reliability of the DIP package is studied by numerical simulation. Firstly, the DIP package, fixture and metal steel are modeled. Based on this, variable thickness papers are laid on the sample. According to the experiment, corresponding excitation and boundary condition are set. Then, the transient analysis result of DIP package is obtained through numerical simulation. The results show the relation of different thickness papers and acceleration-time curve, which provides a beneficial reference for the optimization of DIP packing.

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Wave Soldering Coupled Thermal-mechanical Simulation of Multi-layer Ceramic Capacitors

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IOP Conference Series: Earth and Environmental Science 2021年第4期632卷

作者： Wei Su Wenhao Luo Junkui Li Renhuai Liu MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou 510632 China. Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou 510610 China. School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China

In this paper, the thermal-mechanical coupling finite element analysis of MLCC wave soldering with heat conduction and heat convection is calculated, and the steady-state temperature field and transient temperature field as well as the stress distribution of MLCC are obtained. Using the finite element analysis method of indirect thermal-mechanical coupling, the stress analysis is carried out with the temperature field as the boundary condition, and the thermal-structural coupling model is established. By analyzing the thermal stress of MLCC, the weak parts sensitive to thermal stress are determined, which provides a useful reference for solving the reliability problem of MLCC wave soldering.

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Experimental study on dynamic split tensile properties of rubber concrete

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CONSTRUCTION AND BUILDING MATERIALS 2018年 165卷 675-687页

作者： Feng, Wanhui Liu, Feng Yang, Fei Li, Lijuan Jing, Lin Guangdong Univ Technol Sch Civil & Transportat Engn Guangzhou 510006 Guangdong Peoples R China Jinan Univ Moe Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China Southwest Jiaotong Univ State Key Lab Tract Power Chengdu 610031 Sichuan Peoples R China

Static and dynamic split tensile tests were conducted on rubber concrete with varied volume fractions of rubber particles that replaced fine aggregate (10%, 20%, 30%, 40%, and 50%, named as RC10, RC20, RC30, RC40, and RC50, respectively). The flattened Brazilian disc specimens were applied to determine the tensile properties and energy absorption capabilities under high strain rate by an SHPB (Split Hopkinson Pressure Bar) and medium strain rate by a drop-hammer testing machine. With a high-speed camera, the crack growth of specimens in the SHPB and drop-hammer impacting tests was observed and validated. The experimental result of five rubber concretes and one normal concrete without rubber particles was obtained, and the strain-rate effect on tensile strength of rubber concretes and normal concrete was confirmed. For high strain rate, RC10, RC20 and RC30 were sensitive to strain rate dependence, but rate dependence of RC40 and RC50 was lower than normal concrete. RC30 exhibited the most sensitivity and excellent energy absorption capability in static and dynamic tests. Excessive rubber content did not continually increase the toughness of the concrete under dynamic loadings. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Dynamic split tensile test Rubber concrete Flattened Brazilian disc (FBD) Energy absorption capability

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Harmonic Response Analysis for Ball Grid Array Package Using Computer Finite Element Simulation

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Journal of Physics: Conference Series 2021年第1期2033卷

BGA package is selected as the research object in this paper. Workbench (finite elemental analysis tool in ANSYS) is used for harmonic response analysis. The author lays several paper sheets on the sample and builds the finite element model of clamp, ceramic and metal plate. Then, the model analysis is carried out. Based on this, it is converted to harmonic response analysis. According to the results, the author has found that there is no relation between the number of paper sheets and acceleration-frequency result. It promotes the development of electronic packaging reliability.

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Sensing and Exploiting Static Femto-Newton Optical Forces by a Nanofiber with White-Light Interferometry

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ACS PHOTONICS 2018年第8期5卷 3205-3213页

作者： Yu, Jianhui Chen, Liheng Dong, Huazhuo Liu, Xingyu Huang, Hankai Qiu, Weiqia Huang, Shiqing Zhu, Wenguo Lu, Huihui Tang, Jieyuan Xiao, Yi Zhong, Yongchun Luo, Yunhan Zhang, Jun Chen, Zhe Jinan Univ Guangdong Higher Educ Inst Key Lab Optoelect Informat & Sensing Technol Guangzhou 510632 Guangdong Peoples R China Jinan Univ Guangdong Prov Key Lab Opt Fiber Sensing & Commun Guangzhou 510632 Guangdong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

Optical force determines the fundamental process of momentum exchange between light and matter. However, owing to the weak mechanical effect of the optical force and relatively large stiffness of optomechanical devices, pico-Newton (10(-12) N) optical force is required to manipulate micro/nanoparticles and the optical response of optical devices. It is still extremely challenging to sense static femto-Newton (fN) optical forces and exploit such forces to actuate micro-optical devices. Here, using a tapered nanofiber (TNF) with a high mechanical efficiency of 2.13 nm/fN, a sensitive and cost-effective scheme is demonstrated to generate, sense, and exploit fN optical force. Strong light coupling from the TNF to a glass substrate can result in a fN repulsive optical force, which can induce a TNF deformation of up to 425.6 nm. Such a large deformation allows white-light interferometry to detect a fN static optical force (5.2 fN). Moreover, the high optomechanical efficiency (15.6 nm/mu W) allows us to all-optically control the signal power at values ranging from 0.09 to 17.1 mu W with only microwatt pump power, which paves the way toward microwatt and fN-optical-force optomechanical devices.

关键词： femto-Newton optical force all-optical control linear momentum exchange nanofiber white-light interferometry optomechanics

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Direct Writing Supercapacitors Using a Carbon Nanotube/Ag Nanoparticle-Based Ink on Cellulose Acetate Membrane Paper

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POLYMERS 2019年第6期11卷 973-973页

作者： Guan, Xipeng Cao, Lin Huang, Qin Kong, Debin Zhang, Peng Lin, Huaijun Li, Wei Lin, Zhidan Yuan, Hong Jinan Univ Key Lab Disaster Forecast & Control Engn Sch Mech & Construct Engn MOE Guangzhou 510632 Guangdong Peoples R China Jinan Univ Inst Adv Wear & Corros Resistant & Funct Mat Guangzhou 510632 Guangdong Peoples R China

In this work, we present a cellulose acetate membrane flexible supercapacitor prepared through a direct writing method. A carbon nanotube (CNT) and silver (Ag) nanoparticle were prepared into ink for direct writing. The composite electrode displayed excellent electrochemical and mechanical electrochemical performance. Furthermore, the CNT-Ag displayed the highest areal capacity of 72.8 F/cm(3). The assembled device delivered a high areal capacity (17.68 F/cm(3)) at a current density of 0.5 mA/cm(2), a high areal energy (9.08-5.87 mWh/cm(3)) at a power density of 1.18-0.22 W/cm(3), and showed no significant decrease in performance with a bending angle of 180 degrees. The as-fabricated CNT/Ag electrodes exhibited good long-term cycling stability after 1000 time cycles with 75.92% capacitance retention. The direct writing was a simple, cost-effective, fast, and non-contact deposition method. This method has been used in current printed electronic devices and has potential applications in energy storage.

关键词： Ag CNT flexible supercapacitor electrode polymer conductive film cellulose acetate membrane

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Numerical Simulation of Random Vibration Analysis for Ball Grid Array Package

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IOP Conference Series: Earth and Environmental Science 2021年第3期769卷

作者： Wenhao Luo Wei Su Xianshan Dong Zhenhua Nie Agam Tomar MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China School of Mechanics and Construction Engineering Jinan University Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia Perth Australia

This paper uses ANSYS Workbench (a finite element analysis software) to simulate BGA ceramic packing. The author models fixture, ceramic and metal steel. Then different thickness papers are laid on the BGA product. By random vibration analysis, the natural frequency and mode of the sample are obtained. According the results, the author discusses the relationship between different thickness papers and PSD-frequency curve. It provides a benefit instruction for the design of BGA packing.

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Application of Matlab to Data Processing of Buckling Experiments

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IOP Conference Series: Materials Science and engineering 2020年第1期746卷

作者： Jiahui Zhou Peng Yang Jie Sun Chenyu Shi Jianghong Xue School of Mechanics and Construction Engineering Jinan University Key Lab of Disaster Forecast and Control in Engineering Ministry of Education Guangzhou 510632 Guangdong China

In this paper, matlab programs were written to efficiently process the experiment data for buckling and post-buckling of delaminated composite beams. In the experiments, data collected from 810 Material Test System (MTS) and from dial indicator were sampled at different frequencies, thus were not matched with each other in time. To solve this problem matlab programs were developed. It shows that using the developed program, the experiment data from the two testing systems are corresponding and truly reflect the changes of mechanical parameters in the buckling and post-buckling process of specimens in the experiments.

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Coupling effects of finite rotation and strain-induced anisotropy on monotonic and cyclic failure of metals

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ACTA MECHANICA 2018年第12期229卷 4963-4975页

作者： Wang, Yu-Sen Zhan, Lin Xi, Hui-Feng Xiao, Heng Shanghai Univ Shanghai Inst Appl Math & Mech Yanchang Rd 149 Shanghai 200072 Peoples R China Jinan Univ Coll Mech & Construct Engn Guangzhou 510632 Guangdong Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

New finite-strain elastoplastic constitutive equations are proposed toward a direct approach for simulating both monotonic and cyclic failure effects of metals. Novelties in several respects are incorporated in these new equations: (a) No yield conditions need be imposed, and therefore smooth transition from an elastic to a plastic state may be ensured without involving strong discontinuities in elastoplastic tangent moduli;(b) Complex forms of usual elastoplastic equations assuming the loading-unloading conditions may be substantially simplified in a more realistic sense of representing elastoplastic behavior of metals;(c) Failure effects in a broad case of multi-axial loading conditions may be automatically predicted as inherent constitutive features, without involving any additional variables and any ad hoc failure criteria;and (d) A new evolution equation for the back stress is introduced for effective characterization of both hardening and softening effects associated with strain-induced anisotropy. A simultaneous simulation of monotonic and cyclic failure effects of metal tubes under torsional loadings is for the first time presented for both free- and fixed-end torsion with finite rotation. Results are obtained for coupling effects of finite rotation and strain-induced anisotropy. Model predictions compare well with experimental data.

关键词： Metals

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