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Application of insulation padding in a heavy turbine guide vane casting

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Journal of Iron and Steel Research(International) 2017年第5期24卷 495-500页

作者： Jin-wu Kang Qing-xian Ma Chi Zhang Pei-chao Zhou Zhong-ren Liu Zu-liang Li Hao Zhang School of Materials Science and Engineering Key Laboratory for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084 China Department of Mechanical Engineering Key Laboratory for Advanced Materials Processing Technology Tsinghua University Beijing 100084 China Harbin Electric Machinery Co. Ltd. Harbin 150040 Heilongjiang China

To replace metal padding by insulation padding for castings can save the melt and reduce cleaning work of castings. The design of insulation padding was investigated. The equation of the modulus extension factor for insulation padding and the ratio of its thickness over the modulus of a casting were improved to deter- mine the thickness of insulation padding. The insulation padding was designed for a turbine guide vane casting weighing 3.5 t. A sound casting was obtained with 750 kg steel saved. On the other side, the cast- ing obviously expanded at the interface with the insulation padding, which is perhaps the reason that the use of insulation padding has been suspended for many years. To avoid the expansion of insulation pad- ding, a shielding layer made of a kind of material of good fire resistance was adopted to prevent the insula- tion layer from touching the melt. The shielding layer serves as a cushion of heat and expansion during so- lidification process so as to resist the expansion of castings and guarantee the feeding effect at the same time. Furthermore, insulation padding can be placed by a certain offset into the mold cavity so as to coun- teract the expansion of castings.

关键词： Heavy steel casting Insulation padding Metal padding modulus Expansion Shielding

CONTINUOUS STIFFNESS MODE NANOINDENTATION RESPONSE OF POLY(METHYL METHACRYLATE) SURFACES

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Chinese Journal of Polymer Science 2013年第8期31卷 1096-1107页

作者： T. Iqbal B.J. Briscoe S. Yasin P.F. Luckham Chemical Engineering Department University of Engineering & Technology Chemical Engineering Department Imperial College

Indentation is a comparatively simple and virtually nondestructive method of determining mechanical properties of material surfaces by means of an indenter inducing a localized deformation. The paper present experimental results of the load-displacement curves, the hardness and the elastic modulus data, and associated analysis for poly（methyl methacrylate）（PMMA） surfaces as a function of contact displacement. The experimental results include continuous stiffness indentations performed using constant loading rate and constant displacement rate experiments. The continuous stiffness indentation involves continuous calculation of a material stiffness, and hence hardness and elastic modulus of surfaces, during discrete loading-unloading cycles, as in a conventional indentation routine, and in a comparatively smaller time constant, The dependence of the compliance curves, the hardness, the elastic modulus and the plasticity index upon the imposed penetration depth, the applied normal load and the deformation rate are described. Tip area and load frame calibrations for the continuous stiffness indentation are also reported. The paper includes practical considerations encountered during indentation of polymers specifically at low penetration depths. The experimental results show a peculiarly harder response of PMMA surfaces at the submicron （near to surface） layers.

关键词： Nanoindentation PMMA Hardness modulus Continuous stiffness.

Theoretical study on damage bifurcation of unstable failure process of quasi-brittle materials

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中国有色金属学会会刊：英文版 2009年第S3期19卷 811-818页

作者：王忠昶赵德深杨庆 Key Laboratory for Prediction&Controlon Complicated Structure System of Education Department of Liaoning Province Dalian University Institute of Geotechnical Engineering School of Civil and Hydraulic EngineeringDalian University of Technology

To obtain the damage effect in the process of elasto-plasticity deformation of quasi-brittle materials, the isotropic damage loading-unloading function and damage variable were introduced to non-continuous bifurcation. The critical bifurcation orientation and its corresponding hardening modulus for quasi-brittle materials were derived considering the effect of stiffness degradation and volumetric dilatancy under the assumption of isotropic damage. The relationships of localized orientation angle and maximal hardening modulus dependent on degree of damage and initial Poisson's ratio of rock were explored. Comparative analyses were conducted to study the bifurcation of uniaxial tension-compression samples under the conditions of plane stress and plane strain. It is shown that as the initial Poisson's ratio or degree of damage increases, the localization orientation angle of the plane uniaxial compression sample tends to be initiated to decrease. However, the localization orientation angle of the plane uniaxial tension sample tends to be initiated to increase. The sum of orientation angle under tension and compression conditions is 90°. There are plane stress and plane strain cases of the maximum hardening modulus that is independent of the uniaxial compression and tension.

关键词： isotropic damage orientation of localization maximum hardening modulus bifurcation uniaxial sample

Dynamic properties of composite cemented clay

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2004年第3期5卷 60-67页

作者：蔡袁强梁旭 Institute of Geotechnical Engineering Zhejiang University Hangzhou Construction Committee

In this work, the dynamic properties of composite cemented clay under a wide range of strains were studied considering the effect of different mixing ratio and the change of confining pressures through dynamic triaxial test. A simple and practical method to estimate the dynamic elastic modulus and damping ratio is proposed in this paper and a related empirical normalized formula is also presented. The results provide useful guidelines for preliminary estimation of cement requirements to improve the dynamic properties of clays.

关键词： Composite cemented clay Dynamic triaxial test Dynamic elastic modulus Damping ratio

Delamination process in cross-ply UHMWPE laminates under ballistic penetration

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Defence Technology（防务技术） 2021年第1期17卷 278-286页

作者： Gen-lin Mo Qian-wen Ma Yong-xi Jin Wen-min Yan Zhong-xin Li Zhi-lin Wu Institute of Advanced Manufacturing Jiangsu UniversityZhenjiang212013China Key Laboratory of Transient Shock Beijing102202China Zhenjiang Hospital of Traditional Chinese Medicine 212013China School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China

Cross-ply unidirectional laminates made of ultra-high molecular weight polyethylene fibers are widely used as components of bullet-proof vests.To simulate the delamination process of the material under penetration,we constructed a numerical mechanical model,which was validated by tests using 7.6239 mm rifle bullets penetrating laminates of different thicknesses.The results show that the delamination region is essentially diamond-shaped.The simulated delamination region is in good agreement with the experimental data.It is found that the delamination region increases with the compression modulus along the fiber direction.The delamination region increases when the shear strength between the fabric layers decreases;However,it is little influenced by the normal strength.The delamination region of the front face of the laminate is little influenced by the failure strain of the material and the initial velocity of the bullet.The delamination region of the back face increases with the failure strain and decreases with the initial velocity.

关键词： proof process modulus

Effect of vertical stress rest period on deformation behaviour of unbound granular materials:Experimental and numerical investigations

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第1期11卷 172-180页

作者： Ali Alnedawi Kali Prasad Nepal Riyadh Al-Ameri Mohanad Alabdullah School of Engineering Deakin University

Repeated load triaxial test is used to assess the deformation behaviour of unbound granular materials(UGMs) in flexible road pavements. Repeated load pulse characteristics(i.e. shape, loading period and rest period) are the stress configurations used in the experimental set-up to simulate the passing axle loads. Some researchers and standard testing protocols suggest a rest period of varying durations after a loading phase. A thorough review of existing literature and practises has revealed that there is no agreement about the effect of the rest period of vertical stress pulse on the deformation behaviour of the UGMs. Therefore,the main objective of this study is to investigate the effect of repeated stress rest period on the deformation behaviour of UGMs experimentally. Experiments are conducted, both with and without rest period, using basalt and granite crushed rocks from Victoria, Australia. Furthermore, in order to gain insight into the effect of the rest period, finite element modelling is also developed. Both the experimental and modelling results show that the rest period has a noticeable effect on both resilient and permanent deformation behaviours of UGMs. It is, therefore, recommended to take extra precautions while adopting a particular standard testing protocol and to supplement the results by additional tests with different loading configurations.

关键词： Flexible pavement Unbound granular materials(UGMs) Repeated load triaxial test Resilient modulus Permanent deformation Finite element modelling

Experimental investigation of the degradation mechanism of silicone rubber exposed to heat and gamma rays

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High Voltage 2017年第2期2卷 92-101页

作者： Shugo Hanada Maki Miyamoto Naoshi Hirai Liuqing Yang Yoshimichi Ohki Department of Electrical Engineering and Bioscience Waseda University3-4-1 OhkuboShinjuku-kuTokyoJapan Research Institute for Materials Science and Technology Waseda University2-8-26 Nishi-WasedaShinjuku-kuTokyoJapan State Key Laboratory for Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anPeople's Republic of China Cooperative Major in Nuclear Energy Waseda University3-4-1 OhkuboShinjuku-kuTokyoJapan

Cable-grade silicone rubber was aged thermally or by combining heat and gamma-ray radiation,and resultant changes in chemical,thermal,mechanical and electrical properties were examined.The experimental results obtained in these analyses are clearly consistent with the mechanism that silicone rubber is degraded by forming cross-linked structures via formation of abundant siloxane bonds.With further progress of degradation,decomposition becomes dominant.Reflecting these mechanisms,mechanical properties deteriorate dramatically by losing elasticity.Both the real and imaginary parts of complex permittivity decrease,which is a contrastive difference from typical ageing behaviour of organic insulating polymers.In addition,both the elongation at break and indenter modulus are good indicators of degradation of silicone rubber.

关键词： rubber mechanism modulus

Finite Element Method on Shape Memory Alloy Structure and Its Applications

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Chinese Journal of Mechanical Engineering 2019年第5期32卷 125-135页

作者： Bo Zhou Zetian Kang Zhiyong Wang Shifeng Xue College of Pipeline and Civil Engineering China University of Petroleum(East China)

It is significant to numerically investigate thermo-mechanical behaviors of shape memory alloy(SMA)structures undergoing large and uneven deformation for they are used in many engineering fields to meet special requirements To solve the problems of convergence in the numerical simulation on thermo-mechanical behaviors of SMA structures by universal finite element software.This work suppose a finite element method to simulate the super-elasticity and shape memory effect in the SMA structure undergoing large and uneven deformation.Two scalars,named by phase-transition modulus and equivalent stiffness,are defined to make it easy to establish and implement the finite element method for a SMA structure.An incremental constitutive equation is developed to formulate the relationship of stress,strain and temperature in a SMA material based on phase-transition modulus and equivalent stiffness.A phase-transition modulus equation is derived to describe the relationship of phase-transition modulus,stress and temperature in a SMA material during the processes of martensitic phase transition and martensitic inverse phase transition.A finite element equation is established to express the incremental relationship of nodal displacement,external force and temperature change in a finite element discrete structure of SMA.The incremental constitutive equation,phase-transition modulus equation and finite element equation compose the supposed finite element method which simulate the thermo-mechanical behaviors of a SMA structure.Two SMA structures,which undergo large and uneven deformation,are numerically simulated by the supposed finite element method.Results of numerical simulation show that the supposed finite element method can effectively simulate the super-elasticity and shape memory effect of a SMA structure undergoing large and uneven deformation,and is suitable to act as an effective computational tool for the wide applications based on the SMA materials.

关键词： Shape memory alloy Incremental constitutive equation Finite element equation Phase-transition modulus Applications

Value of elastography point quantification in improving the diagnostic accuracy of early diabetic kidney disease

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World Journal of Clinical Cases 2019年第23期7卷 3945-3956页

作者： Qiu-Yun Liu Qi Duan Xiao-Hong Fu Li-Qian Fu Hong-Wei Xia Yong-Lin Wan Department of Ultrasound Naval Military Medical University Affiliated Gongli HospitalShanghai 200135Chi Department of Ultrasound Shanghai Hemujia HospitalShanghai 200336China Department of Nephrology Naval Military Medical University Affiliated Gongli HospitalShanghai 200135China

BACKGROUND Diabetic kidney disease(DKD)is a common complication of diabetes.The patient’s prognosis is poor once DKD progresses to advanced stage.Accurate diagnosis and timely treatment of early DKD are important for improving patient’s prognosis and reducing mortality.AIM To explore the value of elastography point quantification(ElastPQ)in improving the accuracy of early DKD diagnosis.METHODS A total of 69 patients with type 2 diabetes were recruited from Naval Military Medical University Affiliated Gongli Hospital.Patients were divided into early DKD group and medium DKD group according to pathological results and urinary albumin excretion rate(UAER).Another 40 patients with simple diabetes were included as the diabetes group.The baseline data,laboratory diagnostic indicators,and ultrasound indicators for each patient were recorded.The differences of the indicators in the three groups were compared.Multivariate logistic regression was used to analyze the influencing factors of the development from simple diabetes into early DKD and from early DKD into medium DKD.Receiver operating characteristic analyses of potential indicators in identifying early DKD and medium DKD,and early DKD and simple diabetes were established.RESULTS Multivariate logistic regression analysis showed that UAER(Pmodulus(YM)(P0.9].The accuracy of UAER(AUC=0.744),diabetes duration(AUC=0.757),and renocortical YM(AUC=0.782)for the diagnosis of early DKD and simple diabetes were limited.However,the combined diagnosis of UAER,diabe

关键词： Diabetic kidney disease Elastography point quantification Young's modulus Urinary albumin excretion rate Combined diagnosis Diabetes