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Effect of flow stress—strain relation on forming limit of 5754O aluminum alloy 被引量:3
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作者 王海波 万敏 阎昱 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第10期2370-2378,共9页
A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain (forming limit diagram made up of limit strain) of 5754O aluminum allo... A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain (forming limit diagram made up of limit strain) of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal. 展开更多
关键词 aluminum alloy forming limit sheet metal flow stress—strain relation inhomogenous deformation
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Constitutive relation of weakly anisotropic polycrystal with microstructure and initial stress 被引量:7
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作者 Mojia Huang Hua Zhan Xiuqiao Lin Hai Tang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2007年第2期183-198,共16页
Man (Nondestr Test Eval 15:191-214, 1999) derived the constitutive relation of a weakly-textured orthorhombic aggregate of cubic crystallites with effects of microstructure and initial stress. In this paper, a comp... Man (Nondestr Test Eval 15:191-214, 1999) derived the constitutive relation of a weakly-textured orthorhombic aggregate of cubic crystallites with effects of microstructure and initial stress. In this paper, a computational expression on the integration ∫SO(3) Q^× D^1m0dg is given. Then, by means of the computational expression, the general constitutive relation of a weakly-textured anisotropic polycrystal with the consideration of microstructure and initial stress is derived. As special cases of our general constitutive relation, two constitutive relations are given for an isotropic polycrystal and a weakly-textured anisotropic aggregate of cubic crystallites. The acoustoelastic tensor of the reference cubic crystal is derived to determine the material constants of the polycrystal. Two examples are given for understanding the physical meaning of the texture coefficients and the constitutive relations. 展开更多
关键词 Generalconstitutive relation of weakly-textured polycrystal .Microstructure Initial stress .Cubic crystallites
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Impacts of high temperature,relative air humidity,and vapor pressure deficit on the seed set of contrasting maize genotypes during flowering
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作者 Xin Dong Baole Li +8 位作者 Zhenzhen Yan Ling Guan Shoubing Huang Shujun Li Zhiyun Qi Ling Tang Honglin Tian Zhongjun Fu Hua Yang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第9期2955-2969,共15页
Heat stress is a major constraint to current and future maize production at the global scale.Male and female reproductive organs both play major roles in increasing seed set under heat stress at flowering,but their re... Heat stress is a major constraint to current and future maize production at the global scale.Male and female reproductive organs both play major roles in increasing seed set under heat stress at flowering,but their relative contributions to seed set are unclear.In this study,a 2-year field experiment including three sowing dates in each year and 20 inbred lines was conducted.Seed set,kernel number per ear,and grain yield were all reduced by more than 80%in the third sowing dates compared to the first sowing dates.Pollen viability,silk emergence ratio,and anthesis-silking interval were the key determinants of seed set under heat stress;and their correlation coefficients were 0.89^(***),0.65^(***),and-0.72^(***),respectively.Vapor pressure deficit(VPD)and relative air humidity(RH)both had significant correlations with pollen viability and the silk emergence ratio.High RH can alleviate the impacts of heat on maize seed set by maintaining high pollen viability and a high silk emergence ratio.Under a warming climate from 2020 to 2050,VPD will decrease due to the increased RH.Based on their pollen viability and silk emergence ratios,the 20 genotypes fell into four different groups.The group with high pollen viability and a high silk emergence ratio performed better under heat stress,and their performance can be further improved by combining the improved flowering pattern traits. 展开更多
关键词 MAIZE pollen viability silk emergence heat stress relative humidity
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Effect of Coarse Aggregate Size on and Crack Opening in Normal and Relationship between Stress High Strength Concretes 被引量:4
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作者 Jun ZHANG Qian LIU Lin WANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第5期691-700,共10页
Fine and coarse aggregates play an important role in the fracture of concrete. However, quantitative information available on the effect of the coarse aggregate size on the fracture properties of concrete is still lim... Fine and coarse aggregates play an important role in the fracture of concrete. However, quantitative information available on the effect of the coarse aggregate size on the fracture properties of concrete is still limited. In the present paper, the effect of coarse aggregate size (single grade of 5~10, 10~16, 16~20 and 20~25 mm) on stress-crack opening (σ-w) relation in normal and high strength concretes (compressive strength of 40 and 80 MPa, respectively) was studied. The investigation was based on three-point bending tests implemented by fictitious crack analysis. The result shows that coarse aggregate size and cement matrix strength significantly influence the shape of σ-w curve. For a given total aggregate content, in normal strength concrete, smaller size of aggregate leads to a high tensile strength and a sharp stress drop after the peak stress. The smaller the coarse aggregate, the steeper the σ-w curve. By contrast, in high strength concrete, the effect of aggregate size on σ-w relation almost vanishes. A similar σ-w relation is obtained for the concrete except for the case of 20~25 mm coarse aggregate size. The stress drop after the peak stress is more significant for high strength concrete than that for normal strength concrete. Meanwhile, the smaller the coarse aggregate size, the higher the flexural strength. Fracture energy and characteristic length increase with increasing coarse aggregate size in both normal and high strength concretes. 展开更多
关键词 Aggregate size stress-crack opening relation Fracture energy Bending test
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EFFECT OF DENTIN TUBULES ON THE MECHANICAL PROPERTIES OF DENTIN. PART Ⅰ: STRESS-STRAIN RELATIONS AND STRENGTH CRITERION 被引量:2
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作者 霍波 郑泉水 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1999年第4期355-365,共11页
As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be tre... As known, there is a large number of dentin tubules in dentin. These tubules have varying radii and are shaped into radially parallel pattern. The anisotropy of microstructure of dentin shows that dentin should be treated as a ma- terial of varying transverse isotropy. In this Part, the elastic stress-strain relations and the quadratic strength criterion are established in the form of having varying transverse isotropy, in the framework of micromechanics to take into account of the effect of the microstructures-dentin tubules. Simplified forms for isotropic and ho- mogeneous cases, as well as the corresponding plane stress form of the stress-strain relations are also given. These theoretical models are very well supported by the experiments shown later in the continued paper (Part Ⅱ). 展开更多
关键词 DENTIN dentin tubules ANISOTROPY INHOMOGENEITY stress-strain relations strength criterion
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Exploring Work-Related Stress and Coping Strategies among Omani Nurses Working in Tertiary Governmental Hospitals at Muscat: A Cross-Sectional Study
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作者 Safiya Al-Yaqoubi 《Open Journal of Nursing》 2023年第6期368-385,共18页
Introduction: Work-related stress has become a global issue in the nursing workplace, with about 9.20% - 68.0% of nurses globally experiencing stress. Conversely, work-related stress ranges between 20% and 40% in nurs... Introduction: Work-related stress has become a global issue in the nursing workplace, with about 9.20% - 68.0% of nurses globally experiencing stress. Conversely, work-related stress ranges between 20% and 40% in nursing. Other researchers noted that 35.1% of nurses globally experienced elevated stress levels. Stress can damage well-being and lead to coping, which can, directly and indirectly, improve well-being through a perceived state. Nurses need coping mechanisms to manage their stress levels and maintain stability. Coping mechanisms can vary greatly depending on a nurse’s culture and background. Numerous findings indicate that managing stress is more critical than the cause of stress and that the more successful a stress-management approach, the less damage stress brings. Objective: In response to this, it is necessary to explore Omani nurses’ stress level and their coping strategies working in tertiary governmental hospitals in Muscat. Methods: The sample size for this study was 383 Omani nurses, with a 100% response rate. This study used a descriptive cross-sectional design from 15 October 2020 to 30 November 2020. Samples were selected through proportionate population sampling (PPS) from the five selected tertiary hospitals. Data were collected by self-administered questionnaires using a perceived stress scale and Ways of Coping. A simple random sample within a stratum (each hospital admitting ward) was done to identify the study participants. The sample size for this study was 383 Omani nurses, with a 100% response rate. Results: About 83.3% of participants had a moderate perceived level of stress with an overall mean perceived stress level of 18.46 ± 4.52. The most common sources of perceived stress are feeling nervous and “stressed” in the last month (2.30 ± 0.95). According to the ways of coping strategies, nurses seemed to be resorting to more “planful problem” (mean = 11.04) and least was seeking social support (mean = 9.67). Conclusion: This study highlighted the work-related stress level of staff nurses, explored their ways of coping and determined the relationship between work-related stress levels and methods of coping. The key finding of this study was that the frequency of stress reported by nurses was high enough to suggest that their stress levels were significant, given the demanding nature of their profession that requires maximum attention. Additionally, nurses seemed to resort to more planful problem-solving mechanisms to deal with their stressful situations than other coping strategies. 展开更多
关键词 stress Level Work-related stress Coping Strategies
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Rotation invariant constitutive relation for Reynolds stress structure parameter
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作者 Jinglei XU Zhengguang TU Ning HU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第4期517-522,共6页
A new Reynolds stress constitutive formula is constructed using the first- order statistics of turbulent fluctuations instead of the mean strain rate. It includes zero empirical coefficients. The formula is validated ... A new Reynolds stress constitutive formula is constructed using the first- order statistics of turbulent fluctuations instead of the mean strain rate. It includes zero empirical coefficients. The formula is validated with the direct numerical simulation (DNS) data of turbulent channel flow at Reτ=180. The Reynolds stresses given by the proposed formula agree very well with the DNS results. The good agreement persists even after the multi-angle rotation of the coordinate system, indicating the rotation in- variance of the formula. The autocorrelation of the fluctuating velocity rather than the mean strain rate is close to the essence of the Reynolds stress. 展开更多
关键词 direct numerical simulation (DNS) channel flow Reynolds stress consti-tutive relation
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Effect of hydrostatic stress on yield function and plastic constitutive relations
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作者 盖秉政 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2001年第4期328-333,共6页
A new yield function taking effect of hydrostatic stress into account is presented through establishing and solving the functional equation satisfied by the yield function, and its characteristic is simple in form and... A new yield function taking effect of hydrostatic stress into account is presented through establishing and solving the functional equation satisfied by the yield function, and its characteristic is simple in form and strong in generality. In order to reveal its availability, a comparison is made between the results obtained with it and the experimental results of grey cast iron has be done, both seem to be in good agreement. At the same time, taking the yield function obtained here as a potential function, a new associative plastic constitutive equation taking effect of hydrostatic stress into account is built, and the plastic volume change ratio of plastic deformation is given. 展开更多
关键词 hydrostatic stress yield function plastic constitutive relations
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The relationship between psychological distress with salivary <i>α</i>-amylase and stress related symptoms among breast cancer survivors 被引量:1
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作者 H. W. Yong H. Zailina +3 位作者 J. O. Zubaidah M. Saidi H. Y. Yong M. S. Zalilah 《Health》 2013年第4期811-816,共6页
Background and Aims: This study examined the stress levels, the stressors and biomarker such as Alpha (α)-Amylase enzyme which is secreted under distress conditions. The aim was to determine the relationship between ... Background and Aims: This study examined the stress levels, the stressors and biomarker such as Alpha (α)-Amylase enzyme which is secreted under distress conditions. The aim was to determine the relationship between these three variables. Methods: The study respondents were made up of cancer outpatients from 3 hospitals namely the Hospital Kuala Lumpur, Seberang Jaya and Johor Baru, Pantai Ipoh and Putrajaya. The Personal Stress Inventory (PSI) questionnaire was used to identify stressors, while the Hospital Anxiety and Depression Scale (HADS) were used to determine the psychological distress levels. The Salimentary Oral Swab (SOS) Technique was used to collect the saliva and then the Salivary α-Amylase Assay Kit was used to analyse for α amylase. Results: The majority of respondents were stressed due to their sensitive emotion and nervousness in their daily lives (68.7%), they had poor memory and short attention spans of carrying out job tasks (67.3%) as well as they were emotionally depressed (65.3%). Their poor memory and short attention span (p = 0.037), heavy work load and poor task delivery (p = 0.008) were predictors for distress using HADS. The salivary α-amylase concentration was significantly related to the stress levels (p = 0.002). Conclusion: Breast cancer respondents with musculoskeletal system related symptoms, with heavy work load and poor task delivery, as well as had poor memory and short attention span were at higher risk of experiencing psychological distress. The salivary α-amylase which had significant relationships with psychological distress was therefore, a potential biological indicator for distress, while the musculoskeletal system related symptoms from the PSI questionnaire were predictors for distress. 展开更多
关键词 Breast Cancer Survivors SALIVARY Α-AMYLASE stress-related Symptoms Distress
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ANALYSIS OF THE LOCALIZATION OF DAMAGE AND THE COMPLETE STRESS-STRAIN RELATION FOR MESOSCOPIC HETEROGENEOUS BRITTLE ROCK SUBJECTED TO COMPRESSIVE LOADS
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作者 周小平 张永兴 +1 位作者 哈秋聆 王建华 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2004年第9期1039-1046,共8页
A micromechanics-based model is established. The model takes the interaction among sliding cracks into account, and it is able to quantify the effect of various parameters on the localization condition of damage and d... A micromechanics-based model is established. The model takes the interaction among sliding cracks into account, and it is able to quantify the effect of various parameters on the localization condition of damage and deformation for brittle rock subjected to compressive loads. The closed-form explicit expression for the complete stress-strain relation of rock containing microcracks subjected to compressive loads was obtained. It is showed that the complete stress-strain relation includes linear elasticity,nonlinear hardening,rapid stress drop and strain softening.The behavior of rapid stress drop and strain softening is due to localization of deformation and damage. Theoretical predictions have shown to be consistent with the experimental results. 展开更多
关键词 compressive load mesoscopic heterogeneous rock complete stress-strain relation localization of damage and deformation
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ANALYSIS OF THE LOCALIZATION OF DAMAGE AND THE COMPLETE (STRESS-STRAIN) RELATION FOR MESOSCOPIC HETEROGENEOUS ROCK UNDER UNIAXIAL TENSILE LOADING
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作者 周小平 王建华 +1 位作者 张永兴 哈秋聆 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2004年第9期1031-1038,共8页
The mechanical behavior of rock under uniaxial tensile loading is different from that of rock under compressive loads. A micromechanics-based model was proposed for mesoscopic heterogeneous brittle rock undergoing irr... The mechanical behavior of rock under uniaxial tensile loading is different from that of rock under compressive loads. A micromechanics-based model was proposed for mesoscopic heterogeneous brittle rock undergoing irreversible changes of their microscopic structures due to microcrack growth. The complete stress-strain relation including linear elasticity, nonlinear hardening,rapid stress drop and strain softening was obtained. The influence of all microcracks with different sizes and orientations were introduced into the constitutive relation by using the probability density function describing the distribution of orientations and the probability density function describing the distribution of sizes. The influence of Weibull distribution describing the distribution of orientations and Rayleigh function describing the distribution of sizes on the constitutive relation were researched. Theoretical predictions have shown to be consistent with the experimental results. 展开更多
关键词 uniaxial tensile loading mesoscopic heterogeneous rock localization of damage and deformation complete stress-strain relation
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Non-uniform,axisymmetric misfit strain:in thin films bonded on plate substrates/substrate systems:the relation between non-uniform film stresses and system curvatures
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作者 Yonggang Huang D. Ngo A. J. Rosakis 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2005年第4期362-370,共9页
Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate... Current methodologies used for the inference of thin film stress through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. By considering a circular thin film/substrate system subject to non-uniform, but axisymmetric misfit strain distributions in the thin film, we derived relations between the film stresses and the misfit strain, and between the plate system's curvatures and the misfit strain. These relations feature a “local” part which involves a direct dependence of the stress or curvature components on the misfit strain at the same point, and a “non-local” part which reflects the effect of misfit strain of other points on the location of scrutiny. Most notably, we also derived relations between the polar components of the film stress and those of system curvatures which allow for the experimental inference of such stresses from full-field curvature measurements in the presence of arbitrary radial non-uniformities. These relations also feature a “non-local” dependence on curvatures making a full-field measurement a necessity. Finally, it is shown that the interfacial shear tractions between the film and the substrate are proportional to the radial gradients of the first curvature invariant and can also be inferred experimentally. 展开更多
关键词 Non-uniform misfit strain Non-uniform wafer curvatures stress-curvature relations Non-local effects Interfacial shears
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THE GENERAL STRESS STRAIN RELATION OF SOILS INVOLVING THE ROTATION OF PRINCIPAL STRESS AXES
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作者 刘元雪 郑颖人 陈正汉 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1998年第5期437-444,共8页
In the light of matrix theory, the character of stress increment which causes the rotation of principal stress axes is analysed and the general stress increment is decomposed into two parts: coaxial part and rotationa... In the light of matrix theory, the character of stress increment which causes the rotation of principal stress axes is analysed and the general stress increment is decomposed into two parts: coaxial part and rotational part. Based on these, the complex three dimensional (3-D) problem involving the rotation of principal stress axes is simplified to the combination of the 3-D coaxial model and the theory about pure rotation of principal stress axes that is only around one principal stress axes. The difficulty of analysis is reduced significantly. The concrete calculating method of general 3-D problem is provided and other applications are also presented. 展开更多
关键词 matrix theory principal stress axes rotation decomposition of stress increment stress strain relation SOILS
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Water Relations on Alhagi sparsifolia in the Southern Fringe of Taklamakan Desert 被引量:23
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作者 李向义 张希明 +5 位作者 曾凡江 Andrea FOETZKI Frank M .THOMAS 李小明 Michael RUNGE 何兴元 《Acta Botanica Sinica》 CSCD 2002年第10期1219-1224,共6页
Water relations of Alhagi sparsifolia Shap. at the transition zone between oases and sandy desert were studied in the southern fringe of Taklamakan Desert. Results showed that A. sparsifolia maintained the positive tu... Water relations of Alhagi sparsifolia Shap. at the transition zone between oases and sandy desert were studied in the southern fringe of Taklamakan Desert. Results showed that A. sparsifolia maintained the positive turgor during the summer. The steady high predawn water potential (psi(P)) indicated A. sparsifolia had sufficient hydration and water supply in growing season. In July, water deficit caused by drought stress had no effect on the transpiration of A. sparsifolia. Therefore, drought stress is not a main factor affecting the survival of plants. The physiological adaptation to drought of A. sparsifolia was shown mainly at the leaf level by significant difference (DeltaII) and relative water content (RWC) between the osmotic pressure at full turgor and at turgor loss, by occurring of osmotic adjustment, by high percentage of dry mass-related water content ( WCsat), by RWC at turgor loss point ( RWCp) in stable level and low RWC of the saturated symplast (RWCsym). However, the morphological features of transpiring surface reduction and deep root system seem to be the main way for the plant to adapt to the extreme drought environment. Result also suggests that one time of irregular irrigation in summer will not be helpful to recover water status of A. sparsifolia in location where the water table is very low. 展开更多
关键词 Alhagi sparsifolia water relation drought stress water potential PV parameters irrigation effect
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A GENERAL CONSTITUTIVE RELATION FOR FATIGUE CRACK GROWTH ANALYSIS OF METAL STRUCTURES 被引量:27
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作者 W.C. Cui and X.P. HuangSchool of Naval Architecture & Ocean Engineering, Shanghai Jiaotong University, Shanghai 200030, China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2003年第5期342-354,共13页
Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capabilit... Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capability to explain various special phenomena observed in tests. A modified constitutive relation recently proposed by McEvily and his co-workers showed very promising capability. This modified constitutive relation is further generalized by (1) introducing an unstable fracture condition; (2) defining a virtual strength to replace the yield stress; and (3) defining an overload and underload parameter. The performances of this general constitutive relation for fatigue crack growth is extensively studied and it is found that this general constitutive relation is able to explain various phenomena observed with particular strong capability on load sequence effect. 展开更多
关键词 metal fatigue S-N curve crack growth rate general constitutive relation mean stress effect load sequence effect
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Effect of Relative Stress on Post-Peak Uniaxial Compression Fracture Energy of Concrete 被引量:4
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作者 王学滨 PANYi-shan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2003年第4期89-92,共4页
Fracture energy in strain softening regime was investigated analytically by considering microstructures interaction and interplay.Based on gradient-dependent plasticity, the thickness of localized band was determined ... Fracture energy in strain softening regime was investigated analytically by considering microstructures interaction and interplay.Based on gradient-dependent plasticity, the thickness of localized band was determined completely and strictly by characteristic length in relation to average grain diameter.After obtaining the plastic shear displacement of the band,the formula on axial response of concrete was proposed and the analytical post-peak fracture energy was deduced.A comparison between present theoretical results and earlier experimental results was carried out and the analytical result is reasonable and has a plausible foundation as considering the localized failure theoretically.Decreasing the relative stress leads to increasing the fracture energy non-linearly.The larger the shear elastic modulus and shear softening modulus,the lower the post-peak fracture energy.A larger fracture energy is caused by a larger thickness of shear band or a larger characteristic length of concrete material.If the inclination angle of the shear band and the compressive strength are not concerned with structural size of specimen,the post-peak fracture energy is size independent. 展开更多
关键词 fracture energy relative stress gradient-dependent plasticity thickness of shear band uniaxial compression characteristic length
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Method of Numerical Modeling for Constitutive Relations of Clay 被引量:1
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作者 周葆春 王靖涛 卫军 《Journal of China University of Geosciences》 SCIE CSCD 2006年第4期355-360,共6页
In order to study the method of numerical modeling for constitutive relations of clay, on the basis of the principle of interaction between plastic volumetric strain and plastic generalized shear strain, the two const... In order to study the method of numerical modeling for constitutive relations of clay, on the basis of the principle of interaction between plastic volumetric strain and plastic generalized shear strain, the two constitutive functionals that include the function of stress path were used as the basic framework of the constitutive model, which are able to demonstrate the dependence of stress path. The two partial differential cross terms appear in the expression of stress-strain increment relation, which are used to demonstrate the interaction between plastic volumetric strain and plastic generalized shear strain. The elasoplastic constitutive models of clay under two kinds of stress paths, CTC and TC, have been constracted using the triaxtal test results. The three basic characteristics of deformation of soils, pressure sensitivity, dilatancy, and dependence of stress path, are well explained using these two models. Using visualization, the three-dimensional surfaces of shear and volume strains in the whole stress field under stress paths of CTC and TC are given. In addition, the two families of shear and volmetric yield Ioei under CTC and TC paths are plotted respectively. By comparing the results of deformation under these two stress paths, it has been found that, there are obvious differences in the strain peaks, the shapes of strain surfaces, and the trends of variation of volumetric yield loci, however both families of shear yield loci are similar. These results demonstrate that the influences of stress path on the constitutive relations of clay are considerably large and not negligible. The nmericul modeling method that can sufficiently reflect the dependence of stress path is superior to the traditional one. 展开更多
关键词 nmerical modeling CLAY constitutive relations stress path.
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Molecular Cloning and Characterization of Three Novel Genes Related to Fatty Acid Degradation and Their Responses to Abiotic Stresses in Gossypium hirsutum L. 被引量:1
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作者 DONG Jia WEI Li-bin +1 位作者 HU Yan GUO Wang-zhen 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2013年第4期582-588,共7页
Fatty acid metabolism is responsible not only for oilseed metabolism but also for plant responses to abiotic stresses. In this study, three novel genes related to fatty acid degradation designated GhACX, Gh4CL, and Gh... Fatty acid metabolism is responsible not only for oilseed metabolism but also for plant responses to abiotic stresses. In this study, three novel genes related to fatty acid degradation designated GhACX, Gh4CL, and GhMFP, respectively, were isolated from Gossypium hirsutum acc. TM-1. The phylogenetic analysis revealed that amino acid sequences of GhACXand GhMFP have the highest homology with those from Vitis vinifera, and Gh4CL has a closer genetic relationship with that from Camellia sinensis. Tissue- and organ-specific analysis showed that the three genes expressed widely in all the tested tissues, including ovules and fiber at different developing stages, with expressed preferentially in some organs. Among them, GhACX showed the most abundant transcripts in seeds at 25 d post anthesis (DPA), however, GhMFP and Gh4CL have the strongest expression level in ovules on the day of anthesis. Based on real-time quantitative RT-PCR, the three genes were differentially regulated when induced under wounding, methyl jasmonate (MeJA), cold, and abscisic acid (ABA) treatments. The characterization and expression pattern of three novel fatty acid degradation related genes will aid both to understand the roles of fatty acid degradation related genes as precursor in stress stimuli and to elucidate the physiological function in cotton oilseed metabolism. 展开更多
关键词 genes related to fatty acid degradation molecular cloning expression analysis abiotic stress cotton( Gossypium hirsutum L.)
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Study of experiment method for triaxial frost heaving constitutive relation of frozen soil 被引量:1
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作者 Bing Sun 《Research in Cold and Arid Regions》 2010年第3期230-234,共5页
A new experiment method is introduced to study the relations between frost heaving strain and stress of soil or fracture rock under different moisture contents, temperatures and stress states. Based on experiments, a ... A new experiment method is introduced to study the relations between frost heaving strain and stress of soil or fracture rock under different moisture contents, temperatures and stress states. Based on experiments, a new triaxial frost heaving stress-strain relation is presented aiming at tunnel in cold regions. The experimental equipments are strain-controlled and low temperature buildup, and different restrained conditions are controlled by changing the stiffness of a test-force-ring. Then the frost heaving strain and stress of soil or fracture rock can be obtained under different restrained conditions, and the frost heaving stress-strain relation can be got by regression analysis of some feature points. Experiments of saturated sandy soil conducted by this method show that the triaxial frost heaving stress-strain relation could be expressed by logarithmic curves, and the frost heaving stress changes linearly with the logarithm of the frost heaving strain. The stronger the constraint, the smaller the frost heaving strain and the larger the frost heaving stresses. The frost heaving stresses would tend to a limit value with increasing the constraint intensity. The larger the confining pressure, the larger the frost heaving strain and stress. 展开更多
关键词 triaxial frost heaving stress-strain relation frost heaving stress tunnel in cold region fracture rocks
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SOME IDENTITY RELATIONS BETWEEN PLANE PROBLEMS FOR VISCO-AND ELASTICITY
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作者 杨骁 程昌钧 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1997年第12期0-0,0-0+0-0+0-0+0,共9页
In this paper.the boundary value problems of plane problems with a simply-ormultiply-connected domain for isotropic linear visca-elosticity are first established byterms of Airy stress function F(Xu t). Secondly some ... In this paper.the boundary value problems of plane problems with a simply-ormultiply-connected domain for isotropic linear visca-elosticity are first established byterms of Airy stress function F(Xu t). Secondly some identity relations betweendisplacements and stresses for plane problems of sisco-and elasticity are discussed indetait and some meaningful conclusions are obtained As an example the deformationresponse for viscoelastic plate with a small circular hote at the center is analyzed undera uniasial uniform extension. 展开更多
关键词 VISCOELASTICITY plane problem Airy stress function identity relation integral constitutive relation
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