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tensile test AND PHYSICAL MODEL OF NiTi SHAPE MEMORY ALLOY

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Transactions of Nanjing University of Aeronautics and Astronautics 2004年第4期21卷 267-271页

作者： HUZi-li WANGXin-wei XIONGKe AeronauticalScienceKeyLaboratoryforSmartMaterialsandStructures NUAA29YudaoStreetNanjing210016P.R.China

The tensile stress-strain curves of NiTi wires are obtained by tensile experiments under different heat treatments. A phenomenological physical model based on hysteresis element method is developed to describe the experimentally determined stress-strain curves of shape memory alloy (SMA) wires. Numerical simulations are made. Simulation results show that：(1) a series of unusual changes on physical and mechanical properties of SMA wires occur when martensitic, especially R (rhombohedral) phase transformation emerge. The stress-strain relation of SMA wires is highly non-linear; (2) there are no notable yielding phenomena before NiTi wires are broken; (3) numerical results obtained by the physical model are in good agreement with experimental data.

关键词： SMA tensile test physical model numerical simulation constitutive relation

A METHOD TO QUANTIFY CRAZING DEFORMATION BY tensile testS FOR POLYSTYRENE/POLYOLEFIN ELASTOMER IMMISCIBLE BLENDS

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Chinese Journal of Polymer Science 2007年第4期25卷 387-392页

作者：方征平 Institute of Polymer Composites Zhejiang University

A method to quantify crazing deformations by tensile tests for polystyrene （PS） and polyolefin elastomer （POE） blends was investigated. The toughness of PS/POE blends, reflected by the Charpy impact strength, increased with the content of POE. SEM micrographs showed the poor compatibility between PS and POE. In simple tensile tests, it is very easy to achieve the ratio of crazing deformation, i.e. K by measuring the size changes of samples. The K values decreased with increasing the content of POE, and the deformations of PS/POE blends were dominated by crazing. The plots of the change of volume （△V） against longitudinal variation （△I） showed a linear relationship, and the slope of lines decreased with the content of POE. Measuring samples at the tensile velocities of 5 mm/min, 50 mm/min, and 500 mm/min respectively, the K values kept unchanged for each PS/POE blends.

关键词： Crazing deformation Shear yielding deformation tensile test Polystyrene (PS) Polyolefin elastomer (POE) Blend.

Probing into the Yield Plateau Phenomenon in Commercially Pure Titanium During tensile tests

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 701-709页

作者： Xiaohui Shi Zuhan Cao Zhiyuan Fan Ruipeng Guo Junwei Qiao College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan030024China

To explain the intrinsic mechanism of the yield plateau phenomenon in commercially pure titanium,the tensile behaviors of commercially pure titanium specimens after 91.6%cryorolling and subsequent annealing at 280℃,335℃,450℃and 600℃have been *** results show that the yield plateau phenomenon is a result of dislocation behaviors controlled by grain size and thus only exists within a given range of mean grain size.αgrain boundaries are the main dislocation multiplication sources of commercially pure ***-grained microstructure could offer numerous dislocation multiplication locations during *** the applied stress is above the yielding strength,dislocations multiply rapidly and the mobile dislocation density is *** retrieve the imposed strain rate,the mean dislocation velocity is bound to be ***,it takes time for them to interact with each *** a result,the movement of dislocations is hardly blocked and the deformation could continue at a nearly constant applied ***,the so-called yield plateau behavior presents in the tensile *** disappearance of yield plateau phenomenon in coarse-grained and ultrafi ne-grained microstructures is attributed to the quick realization of the mutual interactions among dislocations at the initial stage of tensile test.

关键词： Yield plateau Commercially pure titanium tensile test Grain size Dislocation

Experimental investigations of the functional morphology of dragonfly wings

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Chinese Physics B 2013年第8期22卷 738-745页

作者： H. Rajabi A. Darvizeh Department of Mechanical Engineering Faculty of Engineering The University of GuilanRasht Iran

Nowadays, the importance of identifying the flight mechanisms of the dragonfly, as an inspiration for designing flapping wing vehicles, is well known. An experimental approach to understanding the complexities of insect wings as organs of flight could provide significant outcomes for design purposes. In this paper, a comprehensive investigation is carried out on the morphological and microstructural features of dragonfly wings. Scanning electron microscopy （SEM） and tensile testing are used to experimentally verify the functional roles of different parts of the wings. A number of SEM images of the elements of the wings, such as the nodus, leading edge, trailing edge, and vein sections, which play dominant roles in strengthening the whole structure, are presented. The results from the tensile tests indicate that the nodus might be the critical region of the wing that is subjected to high tensile stresses. Considering the patterns of the longitudinal corrugations of the wings obtained in this paper, it can be supposed that they increase the load-bearing capacity, giving the wings an ability to tolerate dynamic loading conditions. In addition, it is suggested that the longitudinal veins, along with the leading and trailing edges, are structural mechanisms that further improve fatigue resistance by providing higher fracture toughness, preventing crack propagation, and allowing the wings to sustain a significant amount of damage without loss of strength.

关键词： dragonfly wings SEM tensile test nodus longitudinal corrugation

Quasi-Situ Characterization of Deformation in Low-Carbon Steel with Equiaxed and Lamellar Microstructure Treated by the Quenching and Partitioning Process

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Acta Metallurgica Sinica(English Letters) 2020年第12期33卷 1657-1665页

作者： Pengfei Gao Weijian Chen Feng Li Beijia Ning Zhengzhi Zhao Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation Beijing 100083China

The relationship between microstructure morphology and mechanical properties of the low-carbon steel(Fe-0.20 C-2.59 Mn-2.13 Si)treated by diff erent intercritical annealed quenching and partitioning(Q&P)processes was investigated through interrupted tensile tests plus quasi-situ electron backscatter diff raction *** show that size and distribution of retained austenite(RA)directly aff ect the sequence of deformation induced martensitic *** strain increases,the equiaxed RA grains wrapped by ferrite transform fi rst,followed by the equiaxed and fi lm-like RA grains adjacent to *** with traditional intercritical annealed Q&P steel with equiaxed structure,the steel with quenching pretreatment contains uniform lamellar structure and the relatively fi lm-like type of RA,leading to the higher yield strength,tensile strength,and elongation,as well as the steady increase in dislocation density upon straining.

关键词： Steel Quenching and partitioning Austenite Martensitic transformation Electron backscatter diffraction(EBSD) tensile test

Stress corrosion cracking behavior of PH13-8Mo stainless steel in Cl^- solutions

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Journal of Iron and Steel Research International 2017年第3期24卷 282-289页

作者： Qiang Yu Chao-fang Dong Jian-xiong Liang Zhen-bao Liu Kui Xiao Xiao-gang Li Corrosion and Protection Center Institute of Advanced Materials and Technology University of Science and Technology Beijing Beijing 100083 China Institute for Special Steel Central Iron and Steel Research Institute Beijing 100081 China

The stress corrosion cracking（ SCC） behavior of PH13-8Mo precipitation hardening stainless steel（ PHSS） in neutral NaCl solutions was investigated through slow-strain-rate tensile（ SSRT） test at various applied potentials. Fracture morphology,elongation ratio,and percentage reduction of area were measured to evaluate the SCC susceptibility. A critical concentration of 1. 0 mol / L neutral NaCl existed for SCC of PH13-8Mo steel. Significant SCC emerged when the applied potential was more negative than -0. 15 VSCE,and the SCC behavior was controlled by an anodic dissolution（ AD） *** the applied potential was lower than -0. 55 VSCE,an obvious hydrogen-fracture morphology was observed,which indicated that the SCC behavior was controlled by hydrogen-induced cracking（ HIC）.Between -0. 15 and -0. 35 VSCE,the applied potential exceeded the equilibrium hydrogen evolution potential in neutral NaCl solutions and the crack tips were of electrochemical origin in the anodic region; thus,the SCC process was dominated by the AD mechanism.

关键词： Stress corrosion cracking PH13-8Mo precipitation hardening stainless steel Neutral NaCl solution Slow-strain-rate tensile test Applied potential

MECHANICAL PROPERTIES OF HYBRID GLASS/SUGAR PALM FIBRE REINFORCED UNSATURATED POLYESTER COMPOSITES

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Chinese Journal of Polymer Science 2013年第10期31卷 1394-1403页

作者： S.M.Sapuan H.Y.Lok M.R.Ishak S.Misri Department of Mechanical and Manufacturing Engineering Universiti Putra Malaysia43400 UPM Serdang Selangor Malaysia Institute of Advanced Technology (ITMA) Universiti Putra Malaysia43400 UPM Serdang Selangor Malaysia Institute of Tropical Forestry and Forest Products (INTROP) Universiti Putra Malaysia43400 UPM SerdangSelangor Malaysia Faculty of Engineering and Technology Multimedia UniversityJalan Ayer Keroh Lama75450 Bukit Beruang Melaka Malaysia Department of Aerospace Engineering Universiti Putra Malaysia43400 UPM Serdang Selangor Malaysia

A research has been carried out to investigate the mechanical properties of composites made by hybridizing sugar palm fibre （Arenga pinnata） with glass fibre into an unsaturated polyester matrix. Hybrid composites of glass/sugar palm fibre were fabricated in different weight ratios of strand mat glass fibres ： sugar palm fibres 4：0, 4：1, 4：2, 4：3, 4：4, and 0：4. The hybrid effects of glass and sugar palm fibre on tensile, flexural and impact properties of the composites were evaluated according to ASTM D5083, ASTM D790 and ASTM D256 respectively. Results have been established that properties of hybrid glass/sugar palm composites such as tensile strength, tensile modulus, elongation at break, toughness, flexural strength, flexural modulus and impact strength are a function of fibre content. The failure mechanism and the adhesion between fibres/matrix were studied by observing the scanning electron micrographs of impact fracture samples. In general, the incorporation of both fibres into unsaturated polyester matrix shows a regular trend of increase in the mechanical properties.

关键词： tensile test Flexural test Impact test Hybrid composite Sugar palm fibre.

Mechanical properties and surface characteristics of SiC fibers irradiated by swift heavy ions

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Nuclear Science and Techniques 2022年第9期33卷 37-47页

作者： Li-Qing Zhang Chong-Hong Zhang Chen-Chun Hao Guo-Dong Hu Zheng-Dong Feng Yong-Jian Tang Wen-Kun Zhu Jian-Yang Li Qing Huang Southwest University of Science and Technology Mianyang 621010China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingbo 315201China

SiC fibers were irradiated by 414.4-MeV^(112)Sn^(27.3+)ions to different fluences(5.0×10^(12),6.0×10^(13),1.6×10^(14),and 1.92×10^(15)ions/cm^(2)).^(112)Sn^(27.3+)deposited its energy mainly via electron energy loss and passed through the SiC ***,the mechanical properties and surface characteristics of fibers were studied using a specific single filament tensile test and field emission scanning electron *** revealed that the carbon concentration on the fiber surface increased while the silicon concentration ***,the addition of oxygen was found to correlate with an increase in ion ***,the fiber surface morphology of the least fluence(5.0×10^(12)ions/cm^(2))irradiated specimen displayed no obvious changes and its diameter was slightly *** successive increases of ion fluence,large grains/bubbles on the fiber surface first appeared and then disappeared,and the diameter of fibers evidently ***,at the highest fluence(1.92×10^(15)Sn ions/cm^(2))irradiated specimen,some fibers were brittle *** a result,the mean tensile strength and the average elastic modulus of the fibers generally decreased with respect to the ion *** degradation mechanisms of mechanical properties of SiC fibers under irradiation are discussed in detail.

关键词： SiC fibers Swift-heavy-ion irradiation FE SEM tensile test

Spring-back deformation in tube bending

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International Journal of Minerals,Metallurgy and Materials 2009年第2期16卷 177-183页

作者： Da-xin E Hua-hui He Xiao-yi Liu Ru-xin Ning School of Materials Science and Engineering Beijing Institute of Technology Beijing 100081 China

The spring-back of a bending metal tube was studied through extensive experiments and finite element method （FEM） analysis. An approximate equation for the spring-back angle of bending was deduced. It is noted that the mechanical properties of the material （in a tubular form） are quite different from those found in the standard tensile tests （when the materials are in bar forms）. This is one of the major reasons that result in the discrepancies in the outcomes of experimental study, FEM calculations, and spring-back analysis. It is therefore of crucial importance to study the mechanical properties of the materials in their tubular forms. The experiments and FEM simulations prove that the spring-back angle is significantly affected by the mechanical properties of the materials. The angle decreases accordingly with plastic modulus, but changes inversely with the hardening index and elastic modulus The spring-back angle is also affected by the conditions of tube deformation： it increases accordingly with the relative bending radius but changes inversely with the relative wall thickness. In addition, the spring-back angle increases nonlinearly with the bending angle.

关键词： tube bending spring-back finite element simulation tensile test