共查询到20条相似文献,搜索用时 15 毫秒
1.
《Composite Interfaces》2013,20(4):283-300
This paper deals with the influence of adhesive properties on the interlaminar stress in externally FRP plated steel beams. The analysis provides efficient calculations for both shear and normal interfacial stresses in steel beams strengthened with composite plates, and accounts for various effects of Poisson's ratio and Young's modulus of adhesive. Such interfacial stresses play a fundamental role in the mechanics of plated beams, because they can produce a sudden and premature failure. The analysis is based on equilibrium and deformations compatibility approach developed by Tounsi [1]. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the steel beam and bonded plate. The paper concludes with a summary and recommendations for the design of the strengthened beam. 相似文献
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《Composite Interfaces》2013,20(7):561-571
In this paper an approximate analytical method is proposed to predict the distribution of interfacial stresses in FRP–RC hybrid beams. The theoretical results are compared, and show close agreement, with other rigorous theoretical analyses. A parametrical study is carried out to show the effects of some design variables, e.g. thickness of adhesive layer, thickness of FRP plate and the distance from support to cut-off end of bonded plates. 相似文献
3.
This paper reports an improved analytical solution for analysis the problem of interface stresses in functionally graded beam (FGB) strengthened with bonded hygrothermal aged composite plates. The material properties of the functionally graded beam are supposed to vary according to power law distribution of the volume fraction of the constituents through the beam thickness. The obtained results are compared with the existing solutions in the literature to verify the validity of the new analytical approach. It is found that the inhomogeneities play an important role in reducing the stress concentrations along bi-material interfaces. Finally, a parametric study was carried out to show the effects of the fiber volume fraction, the hygrothermal effect, and some design variables, e.g. thickness of adhesive layer and FRP plate on the magnitude of maximum shear and normal stress. 相似文献
4.
《Composite Interfaces》2013,20(7):587-614
The application of artificial neural network (ANN) to predict the shear capacity of reinforced concrete (RC) beams retrofitted in shear by means of side-bonded fiber-reinforced polymer (FRP) is investigated in this paper. An extensive literature review has been carried out. In addition, ten shear deficient RC beams with different carbon fiber-reinforced polymer (CFRP) configurations were tested and added as data to the collected data. It was aimed to build an efficient and practical ANN model with parameters which can easily be obtained without any calculation and/or experimental investigation. The results are compared with the design guideline equations that emerge as predictions of the FRP contribution using the trained neural networks: these are in good agreement with the experimental results and better than those calculated from the theoretical guideline equations. Based on ANN results, a parametric study has been carried out to study the importance of different influencing parameters on the FRP contribution. Thereafter, a new simple expression is proposed for determining the contribution of externally bonded side-bonded FRP. Accordingly, the suggested design formula is capable of predicting the experimental FRP satisfactorily so that it can be admitted as an alternative to the existing guideline equations within the range of parameters covered in the study. 相似文献
5.
Ismail Bensaid Bachir Kerboua Abdelmajid Cheikh Abdelhamid Hadjoui 《Composite Interfaces》2013,20(5):387-401
This paper presents an improved bi-material beam theory with adhesive interface and the new prestressed-fiber reinforced polymer (FRP) – model, which has been applied to the study the problem of interfacial stresses. This work explicitly considers the interfacial slip effect on the structural performance by including both the effect of adherend shear deformations and the fiber volume fraction of the prestressed laminates. This new method needs only one differential equation to determine both shear and normal interfacial stress, which is one aspect that has not been taken into account by the previous studies in the literature. A parametrical study is carried out to show the effects of some design variables, e.g., stiffness and thickness of adhesive layer and FRP plate. 相似文献
6.
《Composite Interfaces》2013,20(1):47-66
This study investigated the effectiveness of external strengthening technique. The experimental variables were the strengthening material and overlay materials using polymer mixtures. Beams considered in this study are the ones strengthened either with external steel plate or carbon fiber sheet (CFS) bonded to the overlay soffit or with reinforcing rebars in the overlay. An analytical method based on the nonlinear layered finite element method is used to simulate the load–deflection behavior of strengthened beam. The theoretically obtained load–deflection relationships and strains of the strengthened beams are compared to the corresponding experimental values. Efficiencies of the repairing techniques are evaluated by comparing the approximate measures on the cumulative slips. Parametric studies are then obtained using the developed model to investigate the effects of design variables on the overall flexural behavior of the strengthened beam. Simply supported beams under monotonically increasing symmetrical loads are considered exclusively. 相似文献
7.
This paper presents an analytical approach using higher order plate theories to determine wave reflections from and transmissions through a damaged region in a beam. The damaged region is either treated as two split beams or as an inhomogeneity. The reflection ratios and transmission ratios are found to depend strongly on the frequency of the incident flexural waves, as well as the size of the damage, which gives rise to strong stop/pass band behaviour. Using the spectral analysis method, the transient wave propagation in a beam with a part-through delamination is predicted and compared with experimental results, indicating a good agreement in the phases and amplitudes of both the reflected and transmitted waves. 相似文献
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为满足惯性约束聚变(ICF)系统中,对焦斑均匀辐照的条件,研究了连续位相板(CPP)面形特征对远场光斑质量的影响.从波动光学和几何光学两个不同的角度建立分析模型,并利用均方根梯度这一参数将其统一起来.利用所建立的分析模型,通过数值计算研究了CPP面形均方根梯度对低频畸变光束的匀滑效果.结果表明:随着CPP均方根梯度增大,匀滑后的远场焦斑半径增大;光束顶部不均匀性先很快减小,再缓慢降低,最后趋于不变,可见CPP对光束的匀滑效果明显;束匀滑过程对能量利用率的影响先几乎不变,然后逐渐减小.当CPP的相关长度不变,均方根梯度在0.2-0.8 wave/mm范围内时,光斑尺寸、光束顶部不均匀性及能量利用率都在较好的范围.
关键词:
连续位相板
均方根梯度
光束匀滑
聚焦光斑 相似文献
11.
S.Y. El-Zaiat 《Optics & Laser Technology》1997,29(2):63-65
The thickness and refractive index of a thick transparent plate are measured by using an unexpanded HeNe laser beam. The laser beam is incident at different angles onto the plate; and then two reflected beams; from the front and back surfaces; are received on a distant screen: the corresponding separations between them are measured. A theoretical relation between the refractive index; thickness; angle of incidence and separation is derived. This relation is experimentally verified and shows good agreement. The errors in the measured thickness and refractive index are analysed. The method is non-contact; non-destructive and low cost. 相似文献
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Hongxun Li Yimin Zhang Zhipeng Dong Jialiang Lv Chun Gu Peijun Yao Lixin Xu Rui Zhang Jingqin Su Wei Chen Yonggang Zhu Qiwen Zhan 《Annalen der Physik》2019,531(10)
An all‐fiber laser generating a cylindrical vector beam is proposed and demonstrated using a home‐made ring‐core Yb‐doped fiber (RC‐YDF). In the RC‐YDF, not only annular doping but also ring‐type beam pump is realized. This is believed to be the first report describing the realization of annular doping and ring‐type beam pump in active fiber simultaneously, which can enhance the efficiency for high‐order mode oscillation. This laser operates in the high‐order mode stably with a slope efficiency of as high as 55.7%. Cylindrical vector modes can be obtained easily through adjusting the polarization controller. This work may have great potential for providing high‐efficiency and high‐power cylindrical vector beam and vortex beam sources. 相似文献
14.
GaAlAs strip waveguides embedded in unbiased pn-junctions are employed for all-optical switching. The underlying physical mechanism is a combination of the photovoltaic effect and the conventional Franz-Keldysh effect, thus it is called the photo-induced Franz-Keldysh effect or photo-induced electroabsorption. Experimental as well as theoretical results are given and show good agreement. In the experiments the transmitted light power of a probe beam is switched by 3 dB due to an injected control beam at input light power levels of about 0.5 mW each. The dynamics of this all-optical switch is limited by RC time constants. 相似文献
15.
论述了基于视场补偿型Savart偏光镜的稳态大视场偏振干涉成像光谱仪的分光机理.依据电磁场边值条件,分析了光在视场补偿型Savart偏光镜中各晶体分界面上的透射情况,得出了透射率的理论计算公式.采用计算机模拟,分析了在半波片为不同材料时,透射率随入射波长、视场角及半波片厚度的变化关系.研究表明,视场补偿型Savart偏光镜具有大视场、高通量、高探测灵敏度的显著特点.此研究可为新型干涉成像光谱技术的研究和新型偏振干涉成像光谱仪的设计、研制提供重要的理论指导.
关键词:
偏振干涉成像光谱仪
视场补偿型Savart偏光镜
透射率
电磁场边值条件 相似文献
16.
In order to analyze and simulate the impact collapse or seismic response of the reinforced concrete(RC)structures,a combined fiber beam model is proposed by dividing the cross section of RC beam into concrete fiber and steel fiber.The stress-strain relationship of concrete fiber is based on a model proposed by concrete codes for concrete structures.The stress-strain behavior of steel fiber is based on a model suggested by others.These constitutive models are implemented into a general finite element program ABAQUS through the user defined subroutines to provide effective computational tools for the inelastic analysis of RC frame structures.The fiber model proposed in this paper is validated by comparing with experiment data of the RC column under cyclical lateral loading.The damage evolution of a three-dimension frame subjected to impact loading is also investigated. 相似文献
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Biswajit Chakraborty 《Optik》2005,116(1):10-14
When a polarized polychromatic beam passes through a birefringent medium, the constituent spectral components suffer different change of state of polarization. As a result when the beam passes through an analyzer, the intensity of the resultant beam changes depending on the orientation of the analyzer, state of polarization of the input beam, spectral and spatial intensity distribution of the source and the polarizing properties of the birefringent medium. In the present study the intensity variation of the resulting beam passing through a quarter-wave retarder plate is observed theoretically with the variation of the azimuthal angle of the analyzer for monochromatic and polychromatic source of light. A simple experiment is conducted to observe the intensity variation for an incandescent lamp and HeNe laser as polychromatic and monochromatic source of light passing through a birefringent polymer-based quarter-wave retarder plate. The experimentally obtained values are compared with theoretical values and a good agreement is observed. 相似文献
19.
Amirov V. Kh. Akhmetov T. D. Gorbovskiy A. I. Deychuli P. P. Ivanov A. A. Kapitonov V. A. Shikhovtsev I. V. 《Physics of Atomic Nuclei》2023,85(1):S50-S60
Physics of Atomic Nuclei - The receiver calorimeter (RC) is one of the main elements of the beam path of an atomic beam injector with ballistic focusing. A water-cooled RC developed for an injector... 相似文献
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Gabor波带片是一种理想的单级聚焦光学元件,但制备困难.本文采用聚焦离子束直写技术成功制备出30环、20扇区的二值化Beynon-Gabor波带片,其有效面积半径为700μm,第一环半径90μm.利用各向异性腐蚀液对硅基底进行开孔,实现了Beynon-Gabor波带片二值化、自支撑、镂空的结构特征.在波长为355 nm的激光下测试其光学性能,结果表明所制备的Beynon-Gabor波带片主光轴上只存在1级衍射叠加后的焦点,不存在高级衍射焦点,具有优异的单级聚焦性能. 相似文献