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Structural optimization design of semi-rigid base asphalt pavement using modulus matching criterion and multi-indicator range analysis

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第1期11卷 131-159页

作者： Zhihao Yang Linbing Wang Dongwei Cao Yinghao Miao Hailu Yang China Airport Planning&Design Institute Co. Ltd.Beijing 101312China Department of Road and Urban Railway Engineering Beijing University of TechnologyBeijing 100124China National Center for Materials Service Safety University of Science and Technology BeijingBeijing 100083China School of Environmental CivilAgricultural and Mechanical EngineeringUniversity of GeorgiaAthensGA 30602USA China-Road Transportation Verification&Inspection Hi-Tech Co. Ltd.Beijing 100088China

Damage to semi-rigid base asphalt pavement is related to improper matching of the pavement structure moduli.This study mainly focused on the modulus matching of structural layers and the development of a pavement structure optimization method.First,the modulus loss of existing pavement structures was analysed,and a three-dimensional finite element model was established based on the existing pavement.Second,the influence of the modulus of each structural layer on the mechanical response indicators and fatigue life was analysed.Based on the results,a pavement structure design method using the smoothness of the stress-strain curve as the modulus matching criterion of the structural layers was proposed.And it was found that a strain convex point was present and that the stress mutation between the structural layers was significant when the modulus matching of the pavement structure was reasonable.Further,the evaluation indicators were divided into two groups,namely,mechanical indicators and fatigue life indicators.And it was proposed an optimized pavement structure design method based on modulus matching and multi-indicator range analysis.Finally,the optimal modulus combination of pavement structure was determined by this method.The research systematically studied the influence of the modulus of each structural layer on the mechanical response and fatigue life of the pavement,and proposed the concept and specific executive criteria of modulus matching for the first time.Meanwhile,it also provided an effective optimization method for pavement structure design.

关键词： stress-strain curve Modulus matching Structural optimization design Multi-indicator range analysis Fatigue life

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Enhanced plasticity of spontaneous coagulation cast oxide ceramic green bodies

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Journal of Advanced Ceramics 2024年第5期13卷 568-578页

作者： Juanjuan Wang Jin Zhao Junyan Mao Wenlong Liu Haohao Ji Jian Zhang Shiwei Wang State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

In the preparation of large-sized ceramics,the use of a green body with relatively high plasticity is crucial to minimize the risk of cracking during processing.To achieve this goal,glycerol and polyethylene glycol(PEG)were utilized as plasticizers in the shaping of green bodies of oxide ceramics through spontaneous coagulation casting(SCC).This study investigated the effects of plasticizers and particle sizes ranging from the submicron to nanoscale on the slurry viscosity,drying shrinkage of wet gels,and mechanical properties of green bodies.The plasticity of the green bodies was assessed by measuring the impact toughness and flexural stress‒strain curves.By incorporating an appropriate plasticizer,the peak width of the flexural stress‒strain curve for dried green bodies from particles of different sizes was nearly twice that without plasticizers,and the impact toughness was enhanced by approximately 71%,34%,and 41%when the particle size decreased from the submicron scale to the nanoscale(0.45μm,0.18μm,and 50 nm,respectively).The drilling test revealed that there was nearly no cracking around the holes in the green bodies with plasticizers.The plasticity mechanism of the green bodies was examined based on ultraviolet–visible(UV–Vis)spectroscopy and scanning electron microscopy(SEM).It was discovered that plasticizers might mitigate the brittleness of green bodies by adjusting the interactions between molecules and modifying the gel network properly.

关键词： green body plasticity plasticizer particle size impact toughness stress-strain curve

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Numerical simulation of the stress-strain curve and the stress and strain distributions of the titanium-duplex alloy

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Rare Metals 2008年第5期27卷 463-467页

作者： ZHAO Xiqinga ZANG Xinliang WANG Qingfeng Park Joongkeun YANG Qingxiang Key Laboratory of Metastable Materials Science ＆ Technology Yanshan University Qinhuangdao 066004 China Department of Materials Science and Engineering Korea AdvancedInstitute of Science and Technology Taejon 305-701 South Korea

The stress-strain curve of an α-β Ti-8Mn alloy was measured and then it was calculated with finite element method （FEM） based on the stress-strain curves of the single α and β phase alloys. By comparing the calculated stress-strain curve with the measured one, it can be seen that they fit each other very well. Thus, the FE model built in this work is effective. According to the above mentioned model, the distributions of stress and strain in the α and β phases were simulated. The results show that the stress gradients exist in both α and β phases, and the distributions of stress are inhomogeneous. The stress inside the phase is generally higher than that near the interface. Meanwhile, the stress in the α phase is lower than that in the β phase, whereas the strain in the α phase is higher than that in the β phase.

关键词： titanium alloy stress-strain curve numerical simulation finite element method

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Full-Range Compressive stress-strain curves for Cold-Formed 304 Stainless Steel Circular Hollow Sections After Exposure to Vacuum Brazing

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Acta Mechanica Solida Sinica 2018年第5期31卷 557-572页

作者： Bin Hu Yang Jin Lin-Zhi Wui Center for Composite Materials Harbin Institute of Technology Harbin 150001 China Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil Engineering Harbin Engineering University Harbin 150001 China

With the rapid development of microscale cellular structures, the small-diameter cold-formed welded stainless steel tubes have recently been used for creating the metallic lat- tice topologies with high mechanical properties. In this paper, to obtain the accurate material properties of the circular hollow section （CHS） under pure compression, a series of concentric compression tests are conducted on the millimeter-scale cold-formed 304 stainless steel circu- lar tubular stub columns after exposure to a vacuum brazing process. The tests cover a total of 18 small-diameter stub tubes with measured thickness-to-diameter ratios （t/D） from 0.023 to 0.201. A generalized three-stage nominal stress-strain model is developed for describing the compressive behavior of the post-brazing CHSs over the full strain range. This mechanical model is especially applicable to computer code implementation. Hence, an interactive computer pro- gram is developed to simultaneously optimize three strain hardening exponents （n1, n2, n3） in the expression of the model to produce the stress-strain curve capable of accurately replicating the test data. To further reduce the number of the model and material parameters on which this model depends, this paper also develops five expressions for determining the 2.5% proof stress （ap2）, n2, the ultimate compressive strength （σp3）, n3, and the ultimate plastic strain （p3%） for given experimental values of three basic material parameters （E0, σ0.01, σ0.2）. These expressions are validated to he effective for the CHSs with t/D 〉_ 0.027. The analytically predicted full-range stress-strain curves have generally shown close agreement with the ones obtained experimentally.

关键词： Compression test stress-strain curve Cold-formed 304 Stainless steel Circular hollow section （CHS） Post-brazing

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Plastic Flow Modeling of Ti-5 Al-2 Sn-2 Zr-4 Mo-4 Cr Alloy at Elevated Temperatures and High strain Rates

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Journal of Wuhan University of Technology(Materials Science) 2015年第3期30卷 611-616页

作者：王宝林 AI Xing 刘战强 LIU Jigang School of Mechanical &Automotive Engineering Qilu University of Technology Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of Education School of Mechanical Engineering Shandong University

The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.

关键词： Ti-5A1-2Sn-2Zr-4Mo-4Cr SHPB stress-strain curve high temperature high strain rate dynamic constitutive relationship

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Recrystallization of High Carbon Steel during High strain Rate

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Journal of University of Science and Technology Beijing 2001年第1期8卷 55-58页

作者： Di Tang, Qingwu Cai, Yueqin Li, Yumei Pu, Yuzhou Zhu National Engineering Rolling Center of University of Science & Technology Beijing, Beijing 100083, China Iron & Steel Research Inst. Maan Shan Iron and Steel Co. Ltd., Maan Shan 243000, China National Engineering Rolling Center Univ. of Sci. and Technology Beijing Beijing 100083 China

The recrystallization of high carbon steel during high temperature and high speed rolling has been studied by analyzing the stress-strain curves and the austenite grain size. Isothermal multi-pass hot compression at high strain rate was carried out by Gleeble-200D. The austenite grain size was measured by IBAS image analysis system. The results show that static recrystallization occurred at interpass time under pre-finish rolling, and at the finish rolling stage, due to the brief interpass time, static recrystallization can not be found.

关键词： high strain rate stress-strain curve recrystallization austenite grain

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Verification of Interpretation of Dynamic strain Aging for Intermediate Temperature Embrittlement in Ni-Bi Alloy

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Journal of Iron and Steel Research(International) 2015年第7期22卷 602-606页

作者： Wu-qiang YANG Min XU Ye MENG Lei ZHENG Xiao-dong MENG School of Materials Science and Engineering University of Science and Technology Beijing Henei Cisri Dekai Technology Company Limited

Intermediate temperature embritttement （ITE） is a general phenomenon in Ni alloys and recently was interpreted by dynamic strain aging （DSA）. The relationship between ITE and DSA was studied by a binary Ni-Bi alloy. The experimental alloy of well-controlled purity was produced by vacuum induction inching and then heat-treated properly. Tensile tests were performed at various tensile temperatures, and the elongation at fracture was used to indicate the ductility. In order to identify the mechanisms of fracture and ITE, fracture morphologies of the samples of low ductility were observed by scanning electron microscopy. According to the tensile ductility, Ni-Bi alloy shows an obvious embrittlement behavior in the intermediate temperature range （700--750℃ ）. However, the stress strain curves of Ni-Bi alloy and the fracture morphologies indicate that DSA does not exist over the whole temperature range. Based on the experimental results and literatures, the interpretation of DSA was then discussed and proved to be invalid for elucidating the general feature of ITE in Ni-Bi alloy and Ni-based superalloys.

关键词： intermediate temperature embrittlement Ni-Bi alloy dynamic strain aging stress-strain curve fracture morpbology

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Fabrication and compressive performance of plain carbon steel honeycomb sandwich panels

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Journal of University of Science and Technology Beijing 2008年第3期15卷 255-260页

作者： Yu＇an Jing Shiju Guo Jingtao Han Yufei Zhang Weijuan Li School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Liaoning Anshan 114044 China

Plain carbon steel Q215 honeycomb sandwich panels were manufactured by brazing in a vacuum furnace. Their characteristic parameters, including equivalent density, equivalent elastic modulus, and equivalent compressive strength along out-of-plane （z-direction） and in-plane （x-and y-directions）, were derived theoretically and then determined experimentally by an 810 material test system. On the basis of the experimental data, the compressive stress-strain curves were given. The results indicate that the measurements of equivalent Young＇s modulus and initial compressive strength are in good agreement with calculations, and that the maximum compressive strain near to solid can be up to 0.5-0.6 along out-of-plane, 0.6-0.7 along in-plane. The strength-to-density ratio of plain carbon steel honeycomb panels is near to those of Al alloy hexagonal-honeycomb and 304L stainless steel square-honeycomb, but the compressive peak strength is greater than that of Al alloy hexagonal-honeycomb.

关键词： steel honeycomb sandwich brazing compressive strength elastic modulus stress-strain curve

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Compressive behavior of hybrid steel-polyvinyl alcohol fiber-reinforced concrete containing fly ash and slag powder:experiments and an artificial neural network model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2021年第9期22卷 721-735页

作者： Fang-yu LIU Wen-qi DING Ya-fei QIAO Lin-bing WANG Qi-yang CHEN Department of Civil and Environmental Engineering Virginia Polytechnic Institute and State UniversityVirginia 24061USA Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationShanghai 200092China Department of Civil and Environmental Engineering University of Illinois at Urbana-ChampaignUrbana 61801USA

Understanding the mechanical behavior of hybrid fiber-reinforced concrete(HFRC),a composite material,is crucial for the design of HFRC and HFRC structures.In this study,a series of compression experiments were performed on hybrid steelpolyvinyl alcohol(PVA)fiber-reinforced concrete containing fly ash and slag powder,with a focus on the fiber content/ratio effect on its compressive behavior;a new approach was built to model the compression behavior of HFRC by using an artificial neural network(ANN)method.The proposed ANN model incorporated two new developments:the prediction of the compressive stress-strain curve and consideration of 23 features of components of HFRC.To build a database for the ANN model,relevant published data were also collected.Three indices were used to train and evaluate the ANN model.To highlight the performance of the ANN model,it was compared with a traditional equation-based model.The results revealed that the relative errors of the predicted compressive strength and strain corresponding to compressive strength of the ANN model were close to 0,while the corresponding values from the equation-based model were higher.Therefore,the ANN model is better able to consider the effect of different components on the compressive behavior of HFRC in terms of compressive strength,the strain corresponding to compressive strength,and the compressive stress-strain curve.Such an ANN model could also be a good tool to predict the mechanical behavior of other composite materials.

关键词： Experiments Artificial neural network(ANN) Hybrid fiber-reinforced concrete(HFRC) Compressive behavior stress-strain curve

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General Model of Fuzzy Plasticity

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Chinese Journal of Mechanical Engineering 2010年第4期23卷 496-504页

作者： ZHANG Chunliang ZHANG Liangchi School of Mechanical and Electrical Engineering Guangzhou University Guangzhou 510006 China School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney NSW 2052 Australia

The transition between the elastic and plastic states is sharp in the classical plasticity theory. To overcome this problem, many constitutive models, such as multi-yield-surface model and two-surface model, have been developed. However, these models can not represent the true deformation process in a material. In order to capture nonlinear hardening behavior and smooth transition from elastic to plastic state, a general model of fuzzy plasticity is developed. On the basis of the theory of fuzzy sets and TAKAGI-SUGENO fuzzy model, a fuzzy plastic model for monotonic and cyclic loadings in one dimension is established and it is generalized to six dimensions and unsymmetric cycles. The proposed model uses a set of surfaces to partition the stress space with individual plastic modulus. The plastic modulus between two adjacent surfaces is determined by a membership function. By means of a finite number of partitioning surfaces, the fuzzy plastic model can provide with a more realistic and practical description of the materials behavior than the classical plasticity model. The validity of the fuzzy plastic model is investigated by comparing the predicted and experimental stress-strain responses of steels. It was found that the fuzzy plasticity has the ability to handle many practical problems that cannot be adequately analyzed by the conventional theory of plasticity.

关键词： plasticity theory fuzzy model membership function plastic modulus stress-strain curve

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