共查询到18条相似文献，搜索用时 46 毫秒
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本文建立了一个层间弱粘贴复合材料层板热弹性脱层模型.该模型建立在两个描述层间弱粘贴的基本假设基础上.层间位移不连续由层间粘贴的物理关系来描述,表现为层间位移跳跃值与层间残余横向应力的关系;层间温度不连续由层间传热薄层来描述,并据此给出一个计算层间温度跳跃值的计算公式,表现为温度跳跃值与层间横向张开量之间的关系.在此假设基础上,根据平衡方程和静态传热方程导出了正交柱面弯曲层板热弹性脱层解.算例显示了层间弱粘贴对层板热弹性响应的影响. 相似文献
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本文通过将两块非对称铺层的矩形层板交叉铺设同时引入切口设计,提出了一种新型十字形多稳态复合材料层板,通过该切口设计解决了共固化成型引起的层板结构胶接区域内刚度增强进而导致层板失去多稳态特性的问题。建立了含切口十字形多稳态复合材料层板的有限元模型,并通过热压罐成型工艺制备了试验件,仿真和试验结果验证了本文切口设计的可行性。最后研究了胶接面积、切口角度和矩形纵横比对十字形多稳态层板稳定构型的影响规律。结果表明：胶接面积与第一稳态的面外最大位移呈线性关系,切口角度对层板第二稳态构型具有显著影响,而层板纵横比也对第一稳态起重要作用。
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为探明双稳态复合材料层合结构在复杂环境条件下的应用,对双稳态复合材料层合结构的黏弹性行为进行了研究。首先,将纤维简化为弹性材料,考虑基底材料的黏弹性行为。然后,根据纤维和基底的材料属性,通过理论分析得到了双稳态复合材料层合结构的黏弹性材料属性;根据经典层合板理论、最小应变能原理和Maxwell黏弹性模型建立了双稳态复合材料层合结构的黏弹性模型,通过理论分析得到其第二稳态主曲率与扭曲率随加载时间和温度的变化关系。同时,利用有限元软件ABAQUS及其子程序UMAT建立了相应的有限元模型,研究了加载时间和温度对层合结构第二稳态性能的影响。理论与模拟结果均表明:层合结构第二稳态主曲率随加载时间的延长和温度的升高而增大;扭曲率随加载时间的延长而减小,一般情况下随温度的升高而增大,但在加载时间较长且温度较高时,可能会出现扭曲率随温度升高而减小的情况。理论计算结果与有限元模拟结果的比较显示两者吻合较好,可以通过有限元模拟对双稳态复合材料层合结构的黏弹性行为进行研究。 相似文献
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用基于Mindlin 板理论的有限元方法进行了带脱层损伤的复合材料层板的屈曲载荷分析。为了获得物理上可能的屈曲模态, 即避免上下脱层的相互贯穿, 在接触区域引入一些假想弹簧, 并给出了这些假想弹簧刚度系数的计算公式和接触计算的迭代格式, 通过这些弹簧对原始刚度矩阵进行修正可以有效地求解屈曲载荷特征值分析中的接触问题。数值计算结果表明了本算法的有效性和引入接触分析对这类屈曲分析的重要性。同时, 还对脱层的大小、形状、位置和脱层的纤维铺层方向对屈曲载荷的影响进行了研究。 相似文献
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采用更为合理的分散度系数表达式改进了玻/碳层间混杂复合材料板断裂应变混杂效应系数公式,结合该混杂效应系数公式与复合材料强度混合定律,提出了层间混杂复合材料单向板的拉伸强度预报方法。将该混杂效应系数公式引入复合材料多向板渐近损伤有限元分析模型,修正了低延伸率纤维单层板的拉伸强度值,在此基础上提出了层间混杂复合材料多向板拉伸强度预报方法,并讨论了刚度退化方案。结果表明,模型预报值与实验均吻合较好,尤其考虑混杂效应的预报值与实验情况更加接近;基体退化系数大的刚度退化方案与实验更为吻合。 相似文献
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由形状记忆合金纤维、普通纤维、基体构成的混杂复合材料是一类用途广泛的智能材料结构系统。阻尼性能研究是结构被动振动控制的一项重要研究内容。本文采用混杂复合材料阻尼预测的细观力学理论计算SMA纤维混杂复合材料单层的阻尼特性。首先计算包含普通纤维和基体材料的复合材料介质的阻尼性能,其次计算由横观各向同性介质和SMA纤维构成的混杂材料的阻尼性能。通过计算实例分析SMA纤维混杂复合材料单层的正轴阻尼特性及其偏轴阻尼的特性随SMA纤维体积含量、纤维铺设角等参数改变的规律。 相似文献
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设计并制备了一种共形承载一体化的埋微带天线蜂窝夹层结构。利用有限元方法分析了该结构的力学性能, 与三点弯曲实验比较, 获得较好的一致性。研究了蜂窝层厚度等参数对电性能和力学性能的影响。结果表明, 蜂窝层厚度为8~14 mm时, 共形承载天线不仅具有高增益和低损耗, 还具有较好的力学性能。 相似文献
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双模数复合材料层板分析中的一种新方法——有限层元素法 总被引：1，自引：0，他引：1
一种分析双模数复合材料层板的新方法——有限层元素法在本文中提出,与文献[1]提出的有限层法相比,精度有明显提高。与其它文献中的已有解比较,吻合较好。 相似文献
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提出了一种新型的小型化频率可重构天线,通过两个开关二极管控制天线的频率,实现频率的重构.天线结构新颖简单,采用宽缝隙天线上加载开关,且开关易于操作控制.当开关闭合时,天线的实测结果谐振频率在5.34 GHz,反射系数为-23.4 dB,相对带宽为70%,实现了超宽带.当开关断开时,天线的实测结果谐振频率为2.4 GHz... 相似文献
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Siti Rahena Isa Muzammil Jusoh Thennarasan Sabapathy Jamel Nebhen Muhammad Ramlee Kamarudin Mohamed Nasrun Osman Qammer Hussain Abbasi Hasliza A. Rahim Mohd Najib Mohd Yasin Ping Jack Soh 《计算机、材料和连续体（英文）》2022,70(2):2699-2725
New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements. This paper presents a comprehensive review of reconfigurable antennas, specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation (5G) New Radio frequency bands. They represent the key of antenna technology for materializing a high rate transmission, increased spectral and energy efficiency, reduced interference, and improved the beam steering and beam shaping, thereby land a great promise for planar antennas to boost the mid-band 5G. This review begins with an overview of the underlying principals in reconfiguring radiation patterns, followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features. The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement. A variety of design configurations have also been critically studied for their compatibilities to be operated in the mid-band communication systems. The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beam shaping antennas where the operation modes and purposes are clearly investigated. The review also revealed that for mid-band 5G communication, the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance. 相似文献
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Shakir Ullah Sadiq Ullah Inzamam Ahmad Wasi Ur Rehman Khan Toufeeq Ahmad Usman Habib Mahmoud A. Albreem Mohammed H. Alsharif Peerapong Uthansakul 《计算机、材料和连续体（英文）》2021,68(3):3015-3031
In this paper, the design and experimental evaluation of a hexagonal-shaped coplanar waveguide (CPW)-feed frequency reconfigurable antenna is presented using flame retardant (FR)-4 substrate with size of 37 × 35 × 1.6 mm3. The antenna is made tunable to three different modes through the status of two pin diodes to operate in four distinct frequency bands, i.e., 2.45 GHz wireless fidelity (Wi-Fi) in MODE 1, 3.3 GHz (5G sub-6 GHz band) in MODE 2, 2.1 GHz (3G Long Term Evolution (LTE)-advanced) and 3.50 GHz Worldwide Interoperability for Microwave Access (WiMAX) in MODE 3. The optimization through simulation modeling shows that the proposed antenna can provide adequate gain (1.44~2.2 dB), sufficient bandwidth (200~920 MHz) and high radiation efficiency (80%~95%) in the four resonating frequency bands. Voltage standing wave ratio (VSWR) < 1.5 is achieved for all bands with properly matched characteristics of the antenna. To validate the simulation results, fabrication of the proposed optimized design is performed, and experimental analysis is found to be in a considerable amount of agreement. Due to its reasonably small size and support of multiple frequency bands operation, the proposed antenna can support portable devices for handheld 5G and Wireless LAN (WLAN) applications. 相似文献
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Interfacial stresses, electric fields, and electric displacements of a piezoelectric unsymmetrical bi-layer orthotropic laminate are presented. A state space equation for orthotropic piezoelectric material is derived from three-dimensional piezoelectric elasticity directly. With the application of the transfer matrix and recursive solution approach, a strong solution for the unsymmetrical piezoelectric generalized plane strain bi-layer laminated structure is sought after considering all elastic and piezoelectric constants of materials. Electromechanical boundary layer effect is identified quantitatively at free edges. To facilitate the discussion on the results, the corresponding calculations from finite element models are compared with those of the strong solution. 相似文献
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Wasi Ur Rehman Khan Muhammad Fawad Khan Muhammad Irfan Sadiq Ullah Naveed Mufti Usman Ali Rizwan Ullah Fazal Muhammad Saifur Rahman Faisal Althobiani Mohammed Alshareef Mohammad E. Gommosani 《计算机、材料和连续体（英文）》2023,74(2):2517-2530
A compact, reconfigurable antenna supporting multiple wireless services with a minimum number of switches is found lacking in literature and the same became the focus and outcome of this work. It was achieved by designing a Th-Shaped frequency reconfigurable multi-band microstrip planar antenna, based on use of a single switch within the radiating structure of the antenna. Three frequency bands (i.e., 2007–2501 MHz, 3660–3983 MHz and 9341–1046 MHz) can be operated with the switch in the ON switch state. In the OFF state of the switch, the antenna operates within the 2577–3280 MHz and 9379–1033 MHz Bands. The proposed antenna shows an acceptable input impedance match with Voltage Standing Wave Ratio (VSWR) less than 1.2. The peak radiation efficiency of the antenna is 82%. A reasonable gain is obtained from 1.22 to 3.31 dB within the operating bands is achieved. The proposed antenna supports Universal Mobile Telecommunication System (UMTS)-1920 to 2170 MHz, Worldwide Interoperability and Microwave Access (WiMAX)/Wireless Broadband/(Long Term Evolution) LTE2500–2500 to 2690 MHz, Fifth Generation (5G)-2500/3500 MHz, Wireless Fidelity (Wi-Fi)/ Bluetooth-2400 to 2480 MHz, and Satellite communication applications in X-Band-8000 to 12000 MHz. The overall planar dimension of the proposed antenna is 40 × 20 mm2. The antenna was designed, along with the parametric study, using Electromagnetic (EM) simulation tool. The antenna prototype is fabricated for experimental validation with the simulated results. The proposed antenna is low profile, tunable, lightweight, cheap to fabricate and highly efficient and hence is deemed suitable for use in modern wireless communication electronic devices. 相似文献