检索结果-南通市图书馆

Propagation of Thermo-Elastic Waves at Several Typical Interfaces Based on the Theory of Dipolar Gradient Elasticity

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2018年第2期31卷 229-242页

作者： yueqiu li Peijun Wei Department of Mathematics Qiqihar University Department of Applied Mechanics University of Science and Technology Beijing

The reflection and transmission properties of thermo-elastic waves at five possible interfaces between two different strain gradient thermo-elastic solids are investigated based on the generalized thermo-elastic theory without energy dissipation （the GN theory）. First, the function of free energy density is postulated and the constitutive relations are defined. Then, the temperature field and the displacement field are obtained from the motion equation in the form of displacement and the thermal transport equation without energy dissipation in the strain gradient thermo-elastic solid. Finally, the five types of thermo-elastic interracial conditions are used to calculate the amplitude ratios of the reflection and transmission waves with respect to the incident wave. Further, the reflection and transmission coefficients in terms of energy flux ratio are calculated and the numerical results are validated by the energy conservation along the normal direction. It is found that there are five types of dispersive waves, namely the coupled longitudinal wave （the CP wave）, the coupled thermal wave （the CT wave）, the shear wave, and two evanescent waves （the coupled SP wave and SS wave）, that become the surface waves at an interface. The mechanical interfacial conditions mainly influence the coupled CP waves, SV waves, and surface waves, while the thermal interracial conditions mainly influence the coupled CT waves.

关键词： Gradient elasticity Thermo-elasticity Interfacial condition Reflection Transmission

Reflection and transmission of elastic waves at five types of possible interfaces between two dipolar gradient elastic half-spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第1期33卷 173-188页

作者： yueqiu li Peijun Wei Department of Mathematics Qiqihar University Department of Applied Mechanics University of Sciences and Technology Beijing

Reflection and transmission of an incident plane wave at five types of possible interfaces between two dipolar gradient elastic solids are studied in this paper. First, the explicit expressions of monopolar tractions and dipolar tractions are derived from the postulated function of strain energy density. Then, the displacements, the normal derivative of displacements, monopolar tractions, and dipolar tractions are used to create the nontraditional interface conditions. There are five types of possible interfaces based on all possible combinations of the displacements and the normal derivative of displacements. These interfacial conditions with consideration of microstructure effects are used to determine the amplitude ratio of the reflection and transmission waves with respect to the incident wave. Further, the energy ratios of the reflection and transmission waves with respect to the incident wave are calculated. Some numerical results of the reflection and transmission coefficients are given in terms of energy flux ratio for five types of possible interfaces. The influences of the five types of possible interfaces on the energy partition between the refection waves and the transmission waves are discussed, and the concept of double channels of energy transfer is first proposed to explain the different influences of five types of interfaces.

关键词： Gradient elasticity Interfacial condition Energy flux ratio Amplitude ratio Dipolar traction

Free vibration of thermo-elastic microplate based on spatiotemporal fractional-order derivatives with nonlocal characteristic length and time

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2023年第1期44卷 109-124页

作者： lingkang ZHAO Peijun WEI yueqiu li Department of Applied Mechanics University of Science and Technology BeijingBeijing 100083China Department of Mathematics Qiqihar UniversityQiqihar 161006Heilongjiang ProvinceChina

A fractional-order thermo-elastic model taking into account the small-scale effects of the thermo-elastic coupled behavior is developed to study the free vibration of a higher-order shear *** nonlocal strain gradient theory is modified with the introduction of the fractional-order derivatives and the nonlocal characteristic *** Fourier heat conduction is replaced by the non-Fourier heat conduction with the introduction of the fractional order and the memory characteristic *** calculations are performed to analyze the effects of the nonlocal strain gradient parameters,the spatiotemporal fractional order,the nonlocal characteristic length,and the memory characteristic time on the natural frequencies,the vibration attenuation,and the phase shift between the temperature field and the displacement *** numerical results show that the new thermo-elastic model with the spatiotemporal fractional order can provide more exquisite descriptions of the thermo-elastic behavior at a small scale.

关键词： orthotropic higher-order plate nonlocal strain gradient thermo-elastic coupling fractional-order derivative free vibration

Reflection and transmission of elastic waves through a couple-stress elastic slab sandwiched between two half-spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第6期33卷 1022-1039页

作者： Changda Wang Xuejun Chen Peijun Wei yueqiu li Department of Applied Mechanics University of Science and Technology Beijing Beijing 100083 China Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science University of Science and Technology Beijing Beijing 100083 China Department of Mathematics Qiqihar University Qiqihar 161006 China

The reflection and transmission of elastic waves through a couple-stress elastic slab that is sandwiched between two couple-stress elastic half-spaces are studied in this paper. Because of the couple-stress effects, there are three types of elastic waves in the couple-stress elastic solid, two of which are dispersive. The interface conditions between two couple-stress solids involve the surface couple and rotation apart from the surface traction and displacement. The nontraditional interface conditions between the slab and two solid half-spaces are used to obtain the linear algebraic equation sets from which the amplitude ratios of reflection and transmission waves to the incident wave can be determined. Then,the energy fluxes carried by the various reflection and transmission waves are calculated numerically and the normal energy flux conservation is used to validate the numerical results. The special case, couple-stress elastic slab sandwiched by the classical elastic half-spaces, is also studied and compared with the situation that the classical elastic slab sandwiched by the classical elastic half-spaces. Incident longitudinal wave(P wave) and incident transverse wave(SV wave) are both considered. The influences of the couplestress are mainly discussed based on the numerical *** is found that the couple-stress mainly influences the transverse modes of elastic waves.

关键词： Reflection/transmission Sandwiched slab Couple-stress Energy flux Multiple reflection/transmission

Relection of elastic waves at the elastically supported boundary of a couple stress elastic half-space

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2017年第2期30卷 154-164页

作者： Changda Wang Xuejun Chen Peijun Wei yueqiu li Department of Applied Mechanics Uniuersity of Science and Technology Beijing Beijing 100083 China Belting Key Laboratory for Magneto-Photoelectrical Composite and Interface Science University of Science and Technology Beijing Beijing 100083 China Department of Mathematics Qiqihar Uniuersity Qiqihar 161006 China

The relection elastic waves at the elastically supported boundary of a couple stress elastic half-space are studied in this paper. Different from the classical elastic solid, there are three kinds of elastic waves in the couple stress elastic solid, and two of them are dispersive. The boundary conditions of a couple stress elastic half-space include the couple stress vector and the rotation vector which disappear in the classical elastic solids. These boundary conditions are used to obtain a linear algebraic equation set, from which the amplitude ratios of relection waves to the incident wave can be determined. Then, the relection coeficients in terms of energy lux ratios are calculated numerically, and the normal energy lux conservation is used to validate the numerical results. Based on these numerical results,the inluences of the boundary parameters, which relect the mechanical behavior of elastic support, on the relection energy partition are discussed. Both the incident longitudinal wave（the P wave） and incident transverse wave（the SV wave） are considered.

关键词： Relection Elastic support Couple stress Dispersive waves Energy lux

在线全文

学校读者我要写书评

暂无评论

含磷苯并噁嗪UV-LED固化防火涂层

涂料工业 2024年第5期54卷 7-13页

作者：刘玖红李月秋辛本霞于青韩玉玺王忠卫山东科技大学材料科学与工程学院山东青岛266590

为了获得低吸水率的防火涂层,合成了含磷苯并噁嗪,并将其用于制备环氧丙烯酸酯涂料,以LED-385 nm为光源对涂料进行光固化,研究了涂层的防火性能、附着力、铅笔硬度、耐酸碱性和耐水性。为了降低防火涂层中含磷元素的用量,同时保持涂层... 详细信息

为了获得低吸水率的防火涂层,合成了含磷苯并噁嗪,并将其用于制备环氧丙烯酸酯涂料,以LED-385 nm为光源对涂料进行光固化,研究了涂层的防火性能、附着力、铅笔硬度、耐酸碱性和耐水性。为了降低防火涂层中含磷元素的用量,同时保持涂层的防火性能,在上述体系中引入了盐酸多巴胺,并在此基础上探索了磷氮协同作用对涂层性能的影响。结果表明:2种含磷苯并噁嗪衍生物(DPOBH和DOPOBH)中,DPOBH对涂层防火性能、附着力和硬度的提升作用优于DOPOBH。添加3.7%DPOBH的涂层(EA/DPOBH3.7)的UL-94为V-0等级,硬度为B,附着力为1级,酸质量损失率仅为0.40%,碱质量损失率为2.13%,吸水率仅为0.82%。添加0.5%盐酸多巴胺所得涂层(EA/DPOBH3.5-N0.5)的UL-94为V-0等级,硬度为2H,附着力为1级,耐酸碱性提升。综上可知,在含磷苯并噁嗪环氧丙烯酸酯光固化涂层中磷氮协同作用可有效提升环氧丙烯酸酯涂层的防火性能和耐酸碱性能,降低吸水率。

关键词：防火涂层环氧丙烯酸酯苯并噁嗪光固化磷氮协同作用

动物性食品中盐酸多西环素残留量荧光检测方法研究

在线全文

学校读者我要写书评

暂无评论

中国食品添加剂 2024年第8期35卷 20-27页

作者：李月秋田进禄徐天佑王燕张智邸科前河北大学基础医学院保定071000 唐山市丰南区卫生监督所丰南063300 新疆医科大学第一临床医学院乌鲁木齐830000

利用表面活性剂可以提高物质荧光强度这一原理以及固相萃取技术,建立荧光法检测动物性食品中盐酸多西环素残留量。讨论表面活性剂类型和加入量,反应温度、处理时间、加入顺序等条件对盐酸多西环素荧光强度的影响。设计了三因素三水平正... 详细信息

利用表面活性剂可以提高物质荧光强度这一原理以及固相萃取技术,建立荧光法检测动物性食品中盐酸多西环素残留量。讨论表面活性剂类型和加入量,反应温度、处理时间、加入顺序等条件对盐酸多西环素荧光强度的影响。设计了三因素三水平正交实验,优化样品前处理过程。选择Mcllvaine-Na2EDTA缓冲液作为提取剂,甲醇、乙酸乙酯(1∶9)混合液作为洗脱剂,涡旋萃取时间为2 min。在1 cm石英比色皿中,设定激发波长(λex)为378 nm,发射波长(λem)为438 nm,冰浴30 min后扫描测定。在7.14×10^(-4)~5.71×10^(-2)mg/mL时,盐酸多西环素的浓度和荧光强度线性关系较好(r=0.9995),检出限为74.99 ng/mL,加标回收率为79.93%~90.48%,相对标准偏差为0.34%~0.73%。该方法可用于定性定量检测动物性食品中盐酸多西环素残留量。

关键词：盐酸多西环素吐温-20 动物性食品固相萃取荧光分光光度法

同方期刊数据库

基于分数阶LS模型的多场耦合波的反射和透射

在线全文

学校读者我要写书评

暂无评论

高师理科学刊 2024年第5期44卷 50-55页

作者：边鑫禹王红岳田田韩旸魏蕴波李月秋齐齐哈尔大学理学院黑龙江齐齐哈尔161006

应用麦克斯韦电磁学理论引入洛伦兹力,反映外磁场对弹性波传播的影响,运用分数阶广义热弹性LS模型,反映热力耦合效应对弹性波传播的影响.通过色散方程,分析了外磁场和热力耦合效应对波动模式和色散特性的影响.应用连续性边界条件计算出... 详细信息

应用麦克斯韦电磁学理论引入洛伦兹力,反映外磁场对弹性波传播的影响,运用分数阶广义热弹性LS模型,反映热力耦合效应对弹性波传播的影响.通过色散方程,分析了外磁场和热力耦合效应对波动模式和色散特性的影响.应用连续性边界条件计算出各种反射波和透射波与入射波的能流比,并通过法向能量守恒验证了数值计算结果的可靠性.

关键词：分数阶热弹性 LS模型洛伦兹力反射透射

Propagation of thermoelastic waves across an interface with consideration of couple stress and second sound

在线全文

学校读者我要写书评

暂无评论

Propagation of thermoelastic waves across an interface with ...