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A generalized 4-unknown refined theory for bending and free vibration analysis of laminated composite and sandwich plates and shells 层合复合材料和夹层板壳弯曲和自由振动分析的广义4未知精化理论
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-08-01 DOI: 10.12989/CAC.2020.26.2.185
O. Allam, K. Draiche, A. A. Bousahla, F. Bourada, A. Tounsi, K. H. Benrahou, S. R. Mahmoud, E. A. Bedia, A. Tounsi
This research is devoted to investigate the bending and free vibration behaviour of laminated composite/sandwich plates and shells, by applying an analytical model based on a generalized and simple refined higher-order shear deformation theory (RHSDT) with four independent unknown variables. The kinematics of the proposed theoretical model is defined by an undetermined integral component and uses the hyperbolic shape function to include the effects of the transverse shear stresses through the plate/shell thickness; hence a shear correction factor is not required. The governing differential equations and associated boundary conditions are derived by employing the principle of virtual work and solved via Navier-type analytical procedure. To verify the validity and applicability of the present refined theory, some numerical results related to displacements, stresses and fundamental frequencies of simply supported laminated composite/sandwich plates and shells are presented and compared with those obtained by other shear deformation models considered in this paper. From the analysis, it can be concluded that the kinematics based on the undetermined integral component is very efficient, and its use leads to reach higher accuracy than conventional models in the study of laminated plates and shells.
本文采用基于广义简单精化高阶剪切变形理论(RHSDT)的四变量解析模型,研究了层合复合材料/夹层板壳的弯曲和自由振动特性。提出的理论模型的运动学由待定积分分量定义,并使用双曲形状函数包括横向剪切应力通过板/壳厚度的影响;因此不需要剪切校正系数。利用虚功原理推导了控制微分方程和相关边界条件,并采用纳维耶解析法求解。为了验证该改进理论的有效性和适用性,给出了简支叠合/夹层板壳的位移、应力和基频的数值结果,并与本文考虑的其他剪切变形模型的结果进行了比较。分析表明,基于待定积分分量的运动学分析是非常有效的,在层合板壳研究中,它的使用可以达到比传统模型更高的精度。
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引用次数: 91
Shear strength of match-cast-free dry joint in precast girders 预制梁无配浇干缝抗剪强度研究
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-08-01 DOI: 10.12989/CAC.2020.26.2.161
Haibo Jiang, Jiahui Feng, Jie Xiao, Mingzhu Chen, Weibin Liang
Shear keys in precast concrete segmental bridges (PCSBs) are usually match-casting which is very labour intensive. In this research, an innovative match-casting-free construction was proposed by leaving small gap between the convex and the concave castellated shear keys in the joints of PCSBs. Specimen experiment, shear strength analysis and numerical simulation were conducted, investigating the loading performance of this new type of dry joints, the gap dry joints. Compared with matchcasting joint specimens, it has been found from experiment that shear capacity of gap joint specimens significantly decreased ranging from 17.75% to 42.43% due to only partially constrained and contacted in case of gap dry joints. Through numerical simulation, the effects of bottom contacting location, the heights of the gap and the shear key base were analyzed to investigate strength reduction and methods to enhance shear capacity of gap joint specimens. Numerical results proved that shear capacity of gap dry joints under full contact condition was higher than that under partial contact. In addition, left contact destroyed the integrity of shear keys, resulting in significant strength reduction. Larger shear key base remarkably increased shear capacity of the gap joint. Experimental tests indicated that AASHTO provision underestimated shear capacity of the match-casting dry joint specimens, while the numerical results for the gap dry joint showed that AASHTO provision underestimated shear capacity of full contact specimens, but overestimated that of left contact specimens.
预制混凝土节段桥的剪力键通常采用匹配浇筑,劳动强度大。在本研究中,提出了一种创新的无配铸结构,即在pcb板接头的凸形和凹形剪切键之间留下很小的间隙。通过试件试验、抗剪强度分析和数值模拟,研究了这种新型干缝的加载性能。试验发现,与匹配浇筑节理试件相比,在裂隙干缝情况下,由于仅局部约束和接触,裂隙节理试件的抗剪承载力显著降低,降幅在17.75% ~ 42.43%之间。通过数值模拟,分析了底部接触位置、缝隙高度和剪切键基对接缝试件强度降低的影响,探讨了提高接缝试件抗剪能力的方法。数值结果表明,裂隙干接头在完全接触条件下的抗剪能力高于部分接触条件下的抗剪能力。此外,左接触破坏了剪切键的完整性,导致强度显著降低。较大的剪切键基显著提高了缝节点的抗剪能力。试验结果表明,AASHTO对匹配浇筑干节理试件的抗剪承载力存在低估,而对间隙干节理的数值计算结果表明,AASHTO对完全接触试件的抗剪承载力存在低估,对左侧接触试件的抗剪承载力存在高估。
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引用次数: 5
On static bending of multilayered carbon nanotube-reinforced composite plates 多层碳纳米管增强复合材料板的静态弯曲研究
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-08-01 DOI: 10.12989/CAC.2020.26.2.137
A. Daikh, Ismail Bensaid, Attia Bachiri, M. Houari, A. Tounsi, T. Merzouki
In this paper, the bending behavior of single-walled carbon nanotube-reinforced composite (CNTRC) laminated plates is studied using various shear deformation plate theories. Several types of reinforcement material distributions, a uniform distribution (UD) and three functionally graded distributions (FG), are inspected. A generalized higher-order deformation plate theory is utilized to derive the field equations of the CNTRC laminated plates where an analytical technique based on Navier's series is utilized to solve the static problem for simply-supported boundary conditions. A detailed numerical analysis is carried out to examine the influence of carbon nanotube volume fraction, laminated composite structure, side-to-thickness, and aspect ratios on stresses and deflection of the CNTRC laminated plates.
本文采用各种剪切变形板理论研究了单壁碳纳米管增强复合材料(CNTRC)层合板的弯曲性能。考察了几种类型的增强材料分布,即均匀分布(UD)和三种功能梯度分布(FG)。利用广义高阶变形板理论推导了CNTRC层合板的场方程,并利用基于Navier级数的解析技术求解了简支边界条件下的静力问题。研究了碳纳米管体积分数、层合材料结构、侧厚和长径比对CNTRC层合板应力和挠度的影响。
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引用次数: 7
A model to characterize the effect of particle size of fly ash on the mechanical properties of concrete by the grey multiple linear regression 建立了粉煤灰粒径对混凝土力学性能影响的灰色多元线性回归模型
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-08-01 DOI: 10.12989/CAC.2020.26.2.175
Yunpeng Cui, Jun Liu, Licheng Wang, Run-qing Liu, B. Pang
Fly ash has become an important component of concrete as supplementary cementitious material with the development of concrete technology. To make use of fly ash efficiently, four types of fly ash with particle size distributions that are in conformity with four functions, namely, S.Tsivilis, Andersen, Normal and F distribution, respectively, were prepared. The four particle size distributions as functions of the strength and pore structure of concrete were thereafter constructed and investigated. The results showed that the compressive and flexural strength of concrete with the fly ash that conforming to S.Tsivilis, Normal, F distribution increased by 5-10 MPa and 1-2 MPa, respectively, compared to the reference sample at 28 d. The pore structure of the concrete was improved, in which the total porosity of concrete decreased by 2-5% at 28 d. With regarding to the fly ash with Andersen distribution, it was however not conducive to the strength development of concrete. Regression model based on the grey multiple linear regression theory was proved to be efficient to predict the strength of concrete, according to the characteristic parameters of particle size and pore structure of the fly ash.
随着混凝土技术的发展,粉煤灰作为补充胶凝材料已成为混凝土的重要组成部分。为了高效利用粉煤灰,制备了四种粒径分布分别符合S.Tsivilis分布、Andersen分布、Normal分布和F分布四种函数的粉煤灰。随后,构建并研究了四种粒径分布作为混凝土强度和孔隙结构的函数。结果表明,在28 d时,符合S.Tsivilis、Normal、F分布的粉煤灰的混凝土抗压强度和抗弯强度分别比参考试样提高了5 ~ 10 MPa和1 ~ 2 MPa,改善了混凝土的孔隙结构,28 d时混凝土的总孔隙率降低了2 ~ 5%,但对于符合Andersen分布的粉煤灰,则不利于混凝土的强度发展。基于灰色多元线性回归理论的回归模型,根据粉煤灰的粒径和孔隙结构等特征参数,可以有效地预测混凝土的强度。
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引用次数: 4
Free vibration of sandwich micro-beam with porous foam core,GPL layers and piezo-magneto-electric facesheets via NSGT 多孔泡沫芯、GPL层和压电磁电面板夹层微梁的NSGT自由振动
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-07-01 DOI: 10.12989/CAC.2020.26.1.075
M. Mohammadimehr, S. Firouzeh, Mahsa Pahlavanzadeh, Yaser Heidari, M. Irani-Rahaghi
The aim of this research is to investigate free vibration of a novel five layer Timoshenko microbeam which consists of a transversely flexible porous core made of Al-foam, two graphen platelets (GPL) nanocomposite reinforced layers to enhance the mechanical behavior of the structure as well as two piezo-magneto-electric face sheets layers. This microbeam is subjected to a thermal load and resting on Pasternak's foundation. To accomplish the analysis, constitutive equations of each layer are derived by means of nonlocal strain gradient theory (NSGT) to capture size dependent effects. Then, the Hamilton's principle is employed to obtain the equations of motion for five layer Timoshenko microbeam. They are subsequently solved analytically by applying Navier's method so that discretized governing equations are determined in form of dynamic matrix giving the possibility to gain the natural frequencies of the Timoshenko microbeam. Eventually, after a validation study, the numerical results are presented to study and discuss the influences of various parameters such as nonlocal parameter, strain gradient parameter, aspect ratio, porosity, various volume fraction and distributions of graphene platelets, temperature change and elastic foundation coefficients on natural frequencies of the sandwich microbeam.
本研究的目的是研究一种新型的五层Timoshenko微梁的自由振动,该微梁由一个由泡沫铝制成的横向柔性多孔核心,两个石墨烯片(GPL)纳米复合材料增强层组成,以增强结构的力学性能,以及两个压电磁电面片层。该微梁承受热负荷,并在帕斯捷尔纳克的基础上休息。为了完成分析,利用非局部应变梯度理论(NSGT)推导了各层的本构方程,以捕捉尺寸相关效应。然后,利用Hamilton原理得到了五层Timoshenko微梁的运动方程。随后应用Navier的方法对其进行解析求解,从而以动态矩阵的形式确定离散化的控制方程,从而有可能获得Timoshenko微梁的固有频率。最后,通过验证研究,给出了数值结果,研究和讨论了非局部参数、应变梯度参数、长径比、孔隙率、石墨烯薄片的不同体积分数和分布、温度变化和弹性基础系数等参数对夹层微梁固有频率的影响。
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引用次数: 3
Research on damage of 3D random aggregate concrete modelunder ultrasonic dynamic loading 超声动荷载作用下三维随机骨料混凝土模型损伤研究
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-07-01 DOI: 10.12989/CAC.2020.26.1.011
Lixiao Wang, Qidong Chen, Xin Liu, Bin-bin Zhang, Shen Yichen
Concrete are the most widely used manmade materials for infrastructure construction across the world. These constructions gradually aged and damaged due to long-term use. However, there does not exist an efficient concrete recycling method with low energy consumption. In this study, concrete was regarded as a heterogeneous material composed of coarse aggregate and cement mortar. And the failure mode of concrete under ultrasonic dynamic loading was investigated by finite element (FE) analysis. Simultaneously, a 3D random aggregate concrete model was programmed by APDL and imported into ABAQUS software, and the damage plastic constitutive model was applied to each phase to study the damage law of concrete under dynamic loading. Meanwhile, the dynamic damage process of concrete was numerically simulated, which observed ultrasonic propagating and the concrete crushing behavior. Finally, the FE simulation considering the influence of different aggregate volume and aggregate size was carried out to illustrate the damage level of concrete.
混凝土是世界范围内基础设施建设中应用最广泛的人造材料。这些建筑由于长期使用而逐渐老化和损坏。然而,目前还没有一种高效、低能耗的混凝土回收方法。在本研究中,混凝土被视为一种由粗骨料和水泥砂浆组成的非均质材料。采用有限元法研究了超声动载作用下混凝土的破坏模式。同时,利用APDL编程建立三维随机骨料混凝土模型,导入ABAQUS软件,将损伤塑性本构模型应用于各阶段,研究混凝土在动载作用下的损伤规律。同时,对混凝土的动态损伤过程进行了数值模拟,观察了超声波的传播和混凝土的破碎行为。最后,进行了考虑不同骨料体积和骨料粒径影响的有限元模拟,以说明混凝土的损伤程度。
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引用次数: 0
Minimum cost design of RCMRFs based on consistent approximation method 基于一致逼近法的rcmrf最小成本设计
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-07-01 DOI: 10.12989/CAC.2020.26.1.001
A. Habibi, Mobin Shahryari, H. Rostami
In this paper, a procedure for automated optimized design of reinforced concrete frames has been presented. The procedure consists of formulation and solution of the design problem in the form of an optimization problem. The minimization of total cost of R/C frame has been taken as the objective of optimization problem. In this research, consistent approximation method is applied to explicitly formulate constraints and objective function in terms of the design variables. In the presented method, the primary optimization problem is replaced with a sequence of explicit sub-problems. Each sub-problem is efficiently solved using the Sequential Quadratic Programming (SQP) method. The proposed method is demonstrated through a four-story frame and an eight-story frame, and the optimum results are compared with those in the available literature. It is shown that the proposed method can be easily applied to obtain rational, reliable, economical and practical designs for Reinforced Concrete Moment Resisting Frames (RCMRFs) while it is converged after a few analyses.
本文提出了一种钢筋混凝土框架自动优化设计方法。该过程包括以优化问题的形式对设计问题进行表述和求解。以R/C车架总成本最小为优化问题的目标。在本研究中,采用一致逼近法明确地表达了设计变量的约束条件和目标函数。在该方法中,主要的优化问题被一系列显式的子问题所取代。利用序列二次规划(Sequential Quadratic Programming, SQP)方法有效地求解了各子问题。通过一个四层框架和一个八层框架对所提出的方法进行了验证,并将优化结果与现有文献进行了比较。结果表明,本文所提出的方法可以很容易地应用于钢筋混凝土抗弯矩框架的合理、可靠、经济和实用的设计,但经过一些分析,其结果是收敛的。
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引用次数: 0
Vibration analysis of porous nanocomposite viscoelastic plate reinforced by FG-SWCNTs based on a nonlocal strain gradient theory 基于非局部应变梯度理论的FG-SWCNTs增强多孔纳米复合粘弹性板振动分析
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-07-01 DOI: 10.12989/CAC.2020.26.1.031
P. Khazaei, M. Mohammadimehr
This paper investigates the size dependent effect on the vibration analysis of a porous nanocomposite viscoelastic plate reinforced by functionally graded-single walled carbon nanotubes (FG-SWCNTs) by considering nonlocal strain gradient theory. Therefore, using energy method and Hamilton's principle, the equations of motion are derived. In this article, the effects of nonlocal parameter, aspect ratio, strain gradient parameter, volume fraction of carbon nanotubes (CNTs), damping coefficient, porosity coefficient, and temperature change on the natural frequency are perused. The innovation of this paper is to compare the effectiveness of each mentioned parameters individually on the free vibrations of this plate and to represent the appropriate value for each parameter to achieve an ideal nanocomposite plate that minimizes vibration. The results are verified with those referenced in the paper. The results illustrate that the effect of damping coefficient on the increase of natural frequency is significantly higher than the other parameters effect, and the effects of the strain gradient parameter and nonlocal parameter on the natural frequency increase are less than damping coefficient effect, respectively. Furthermore, the results indicate that the natural frequency decreases with a rise in the nonlocal parameter, aspect ratio and temperature change. Also, the natural frequency increases with a rise in the strain gradient parameter and CNTs volume fraction. This study can be used for optimizing the industrial and medical designs, such as automotive industry, aerospace engineering and water purification system, by considering ideal properties for the nanocomposite plate.
考虑非局部应变梯度理论,研究了单壁功能梯度碳纳米管(FG-SWCNTs)增强多孔纳米复合材料粘弹性板的尺寸依赖效应。因此,利用能量法和哈密顿原理,推导了运动方程。本文研究了非局部参数、长径比、应变梯度参数、碳纳米管体积分数、阻尼系数、孔隙率系数和温度变化对固有频率的影响。本文的创新之处在于分别比较上述各参数对该板的自由振动的影响,并表示每个参数的适当值,以实现振动最小化的理想纳米复合材料板。所得结果与文献资料相吻合。结果表明,阻尼系数对固有频率增加的影响显著高于其他参数的影响,应变梯度参数和非局部参数对固有频率增加的影响分别小于阻尼系数的影响。结果表明,随着非局部参数、宽高比和温度变化的增加,固有频率降低。固有频率随应变梯度参数和CNTs体积分数的增加而增加。通过考虑纳米复合材料板的理想性能,本研究可用于优化工业和医疗设计,如汽车工业、航空航天工程和水净化系统。
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引用次数: 2
Prediction of the critical buckling load of SWCNT reinforcedconcrete cylindrical shell embedded in an elastic foundation 弹性地基中swcnts钢筋混凝土圆柱壳的临界屈曲荷载预测
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-07-01 DOI: 10.12989/CAC.2020.26.1.053
A. Timesli
Concrete is the most widely used substance in construction industry, so it's been required to improve its quality using new technologies. Nowadays, nanotechnology offers new frontiers for improving construction materials. In this paper, we study the stability analysis of the Single Walled Carbon Nanotubes (SWCNT) reinforced concrete cylindrical shell embedded in elastic foundation using the Donnell cylindrical shell theory. In this regard, we propose a new explicit analytical formula of the critical buckling load which takes into account the distribution of SWCNT reinforcement through the thickness of the concrete shell using the U, X, O and V forms and the elastic foundation using Winkler and Pasternak models. The rule of mixture is used to calculate the effective properties of the reinforced concrete cylindrical shell. The influence of diverse parameters on the stability behavior of the reinforced concrete shell is also discussed.
混凝土是建筑工业中应用最广泛的材料,因此对其质量的提高提出了新的要求。如今,纳米技术为改善建筑材料提供了新的领域。本文利用Donnell圆柱壳理论对单壁碳纳米管(SWCNT)钢筋混凝土圆柱壳嵌入弹性地基的稳定性进行了研究。在这方面,我们提出了一个新的临界屈曲载荷的显式分析公式,该公式考虑了碳纳米管钢筋通过混凝土外壳厚度的分布(采用U, X, O和V型)和弹性基础(采用Winkler和Pasternak模型)。采用混合规则计算钢筋混凝土圆柱壳的有效性能。讨论了不同参数对钢筋混凝土壳稳定性能的影响。
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引用次数: 12
Post-buckling analysis of geometrically imperfect nanoparticle reinforced annular sector plates under radial compression 几何缺陷纳米颗粒增强环形扇形板径向压缩后屈曲分析
IF 4.1 4区 工程技术 Q1 Engineering Pub Date : 2020-07-01 DOI: 10.12989/CAC.2020.26.1.021
S. Mirjavadi, Masoud Forsat, Saeed Mollaee, M. Barati, B. Afshari, A. Hamouda
Buckling and post-buckling behaviors of geometrically imperfect annular sector plates made from nanoparticle reinforced composites have been investigated. Two types of nanoparticles are considered including graphene oxide powders (GOPs) and silicone oxide (SiO2). Nanoparticles are considered to have uniform and functionally graded distributions within the matrix and the material properties are derived using Halpin-Tsai procedure. Annular sector plate is formulated based upon thin shell theory considering geometric nonlinearity and imperfectness. After solving the governing equations via Galerkin's technique, it is showed that the post-buckling curves of annular sector plates rely on the geometric imperfection, nanoparticle type, amount of nanoparticles, sector inner/outer radius and sector open angle.
研究了由纳米颗粒增强复合材料制成的几何缺陷环形扇形板的屈曲和后屈曲行为。考虑了两种类型的纳米颗粒,包括氧化石墨烯粉末(GOPs)和氧化硅(SiO2)。纳米颗粒被认为在基体中具有均匀和功能梯度分布,并使用Halpin-Tsai程序推导了材料的性质。环形扇形板是基于考虑几何非线性和缺陷的薄壳理论设计的。利用伽辽金方法求解了控制方程,结果表明环形扇形板的后屈曲曲线与几何缺陷、纳米颗粒类型、纳米颗粒数量、扇形内外半径和扇形开口角有关。
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引用次数: 3
期刊
Computers and Concrete
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