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| 1 | A novel hybrid design method of lattice structure based on failure mode显示文摘Adjusting the mechanical properties of lattice structures is important for many modern application fields. In this paper, a new design method for hybrid multi-layer lattice structures was developed to improve the mechanical properties and energy absorption, by altering and suppressing the formation of the shear band. In these hybrids, all unit cells were divided into two parts:(i) diagonal unit cells and(ii) matrix unit cells. Four categories of unit cells were selected to construct the hybrid multi-layer structures. The compressive moduli, ultimate strengths, and energy absorption properties of the laser powder bed fusion(L-PBF)fabricated structures were assessed by experiments and finite element analysis(FEA). The results revealed the great impact of diagonal unit cells on the mechanical properties of the structures. Stronger diagonal unit cells than matrix unit cells led to hybrid structures with enhanced mechanical properties. Compared with a uniform body-centered cubic(BCC) lattice structure, the relative density of the lattice structure consisting of the weakest BCC matrix unit cells and strongest BFVC diagonal unit cells(coupling of BCC, FCC, and VC) exhibited an increase of 20%. The compressive modulus and ultimate strength of this structure rose by more than 200% and 90%, respectively. Two types of structures with specific properties were generated by hybrid design.The first displayed higher modulus, superior strength, and elevated specific energy absorption(SEA) but lower crash load efficiency(CLE). The second illustrated simultaneously higher SEA and elevated CLE. The present results provide a new insight for improving the load-bearing and energy absorption capacities of lattice structures. | Chuanlei Li Junfeng Qi Panding Wang Zeang Zhao Zhe Wang Hongshuai Lei Shengyu Duan | 2022 | Science China(Physics,Mechanics & Astronomy)2022，65，9： | 0 |
| 2 | Gradient carbonyl-iron/carbon-fiber reinforced composite metamaterial for ultra-broadband electromagnetic wave absorption by multi-scale integrated design显示文摘The demand of high-end electromagnetic wave absorbing materials puts forward higher requirements on comprehensive performances of small thickness,lightweight,broadband,and strong absorption.Herein,a novel multi-layer stepped metamaterial absorber with gradient electromagnetic properties is proposed.The complex permittivity and permeability of each layer are tailored via the proportion of carbonyliron and carbon-fiber dispersing into the epoxy resin.The proposed metamaterial is further optimized via adjusting the electromagnetic parameters and geometric sizes of each layer.Comparing with the four-layer composite with gradient electromagnetic properties which could only realize reflection loss(RL)of less than−6 dB in 2.0-40 GHz,the optimized stepped metamaterial with the same thickness and electromagnetic properties realizes less than−10 dB in the relevant frequency range.Additionally,the RL of less than−15 dB is achieved in the frequency range of 11.2-21.4 GHz and 28.5-40 GHz.The multiple electromagnetic wave absorption mechanism is discussed based on the experimental and simulation results,which is believed to be attributed to the synergy effect induced by multi-scale structures of the metamaterial.Therefore,combining multi-layer structures and periodic stepped structures into a novel gradient absorbing metamaterial would give new insights into designing microwave absorption devices for broadband electromagnetic protections. | Qian Zhou Tiantian Shi Bei Xue Shengyue Gu Wei Ren Fang Ye Xiaomeng Fan Wenyan Duan Zihan Zhang Lifei Du | 2023 | International Journal of Minerals,Metallurgy and Materials2023，30，6： | 0 |
| 3 | Adaptive enhancement design of triply periodic minimal surface lattice structure based on non-uniform stress distribution显示文摘The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this paper,an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties.Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS.One keeps the same relative density,and the other keeps the same of non-enhanced region thickness.Compared with the uniform lattice structure,the elastic modulus for the structure with the same relative density increases by more than 17%,and the yield strength increases by more than 10.2%.Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion(L-PBF)with 316L stainless steel to verify the proposed enhanced design.The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography(μ-CT)scans.The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli,ultimate strengths,and energy absorption capabilities than the homogeneous P-TPMS lattice structure. | Yijin ZHANG Bin LIU Fei PENG Heran JIA Zeang ZHAO Shengyu DUAN Panding WANG Hongshuai LEI | 2023 | Applied Mathematics and Mechanics(English Edition)2023，44，8： | 0 |
| 4 | Statistical static timing analysis for circuit aging prediction显示文摘Complementary metal oxide semiconductor(CMOS)aging mechanisms including bias temperature instability(BTI)pose growing concerns about circuit reliability.BTI results in threshold voltage increases on CMOS transistors,causing delay shifts and timing violations on logic circuits.The amount of degradation is dependent on the circuit workload,which increases the challenge for accurate BTI aging prediction at the design time.In this paper,a BTI prediction method for logic circuits based on statistical static timing analysis(SSTA)is proposed,especially considering the correlation between circuit workload and BTI degradation.It consists of a training phase,to discover the relationship between circuit scale and the required workload samples,and a prediction phase,to present the degradations under different workloads in Gaussian probability distributions.This method can predict the distribution of degradations with negligible errors,and identify 50%more BTI-critical paths in an affordable time,compared with conventional methods. | Duan Shengyu Zhai Dongyao Lu Yue | 2021 | The Journal of China Universities of Posts and Telecommunications2021，28，2： | 0 |
| 5 | Improved quadratic isogeometric element simulation of one-dimensional elastic wave propagation with central difference method显示文摘Two improved isogeometric quadratic elements and the central difference scheme are used to formulate the solution procedures of transient wave propagation problems. In the proposed procedures, the lumped matrices corresponding to the isogeometric elements are obtained. The stability conditions of the solution procedures are also acquired. The dispersion analysis is conducted to obtain the optimal Courant-FriedrichsLewy(CFL) number or time-step sizes corresponding to the spatial isogeometric elements.The dispersion analysis shows that the isogeometric quadratic element of the fourth-order dispersion error(called the isogeometric analysis(IGA)-f quadratic element) provides far more desirable numerical dissipation/dispersion than the element of the second-order dispersion error(called the IGA-s quadratic element) when appropriate time-step sizes are selected. The numerical simulations of one-dimensional(1D) transient wave propagation problems demonstrate the effectiveness of the proposed solution procedures. | Weibin WEN Shibin LUO Shengyu DUAN Jun LIANG Daining FANG | 2018 | Applied Mathematics and Mechanics(English Edition)2018，39，5： | 0 |
| 6 | An improved time integration scheme based on uniform cubic B-splines and its application in structural dynamics显示文摘A time integration algorithm for structural dynamic analysis is proposed by uniform cubic B-spline functions. The proposed algorithm is successfully used to solve the dynamic response of a single degree of freedom(SDOF) system, and then is generalized for a multiple-degree of freedom(MDOF) system. Stability analysis shows that, with an adjustable algorithmic parameter, the proposed method can achieve both conditional and unconditional stabilities. Validity of the method is shown with four numerical simulations.Comparison between the proposed method and other methods shows that the proposed method possesses high computation accuracy and desirable computation efficiency. | Weibin WEN Hongshuai LEI Kai WEI Baosheng XU Shengyu DUAN Daining FANG | 2017 | Applied Mathematics and Mechanics(English Edition)2017，38，6： | 0 |
| 7 | Optimizing hairy root production from explants of Phyllanthus hainanensis,a shrub used for traditional herbal medicine显示文摘Phyllanthus hainanensis is a shrub that has been used in traditional herbal medicine.It has great pharmaceutical potential for treating diseases such as cancer and diabetes.As a prerequisite for propagation of this species on a large scale,hairy roots in P.hainanensis were induced using Rhizobium rhizogenes and various factors affecting hairy root induction and growth evaluated.Seven factors were tested:(1)type of explant,(2)type of culture medium,(3)duration of pre-culture,(4)R.rhizogenes inoculum cell density,(5)duration of infection,(6)acetosyringone concentration in the culture medium,and(7)duration of incubation.The optimal protocol for hairy root induction and growth was:young shoots,pre-cultured in Y1 for 2 d,inoculated with R.rhizogenes broth with an OD600 of 0.6 for 20 min,and incubated for 3 d.Putative transgenic hairy roots were initially identified by morphology and then confirmed by polymerase chain reaction.Successful and optimal production of hairy roots is a critical prerequisite for industrial scale clonal propagation of P.hainanensis.Being able to cultivate the plant on a large scale will provide rapid and ready supply of the plant materials that can be used in herbal medicine and in scientific and industrial exploitation. | Zhaogui YAN Shengyu LIU Junlian ZHANG Guan HUANG Lijun DUAN Yaomei YE | 2020 | Frontiers of Agricultural Science and Engineering2020，7，4： | 0 |
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