边界条件对附于软基体上压电薄膜的局部屈曲的影响

本文研究了附于预拉伸弹性软基体上的压电薄膜的局部屈曲行为,弹性软基体和刚性支座之间为滑动边界。通过比较弹性软基体和刚性支座之间为固支情况下附于基体上压电薄膜的局部屈曲行为,讨论边界条件对于压电薄膜的局部屈曲的影响。     

共振式压电驱动器分析及实验研究

推导了压电陶瓷等效刚度和驱动力的表达式.考虑胶层及预压弹簧的影响,将压电陶瓷简化为等效驱动力作用下的弹簧,设计了共振式压电驱动器.建立了共振式电驱动器的动力学模型,并进行了共振式压电驱动器原理性实验验证.实验与理论分析结果误差在10％以内,结果表明等效弹簧模型在低频范围内能够较为准确地模拟压电陶瓷的动力学特性.共振式压电驱动器可以显著放大压电陶瓷的位移,克服压电陶瓷输出位移小的缺点,有较为广阔的用途.     

压电材料中的表面电极

讨论了压电介质表面存在电极时的电学混合边值模型,应用复变函数中解析延拓方法和Reimann-Hilbert等理论,得到在电极作用下产生的应力应变场和电场分布,从而得到混合边值问题的全场解,并研究了压电体存在表面电极时的特性与强度问题。     

声表面波波速快速求解策略

针对有效介电常数与边界条件系数行列式值这两种常用求解方法存在的求解速度、精度及通用性等问题,提出了采用混合法;利用材料对称性和介质的连续性,选用合适的动态搜索步长及区间等策略,实现准确快速求解波速．为声表面波问题的快速求解及三维空间的切型优化提供参考．     

主动隔振平台的低频微振动测量研究

阐述了气垫式隔振平台的主动隔振关键技术之一的低频微振动测量问题,着重分析了压电传感器在低频、微幅测量的条件下电荷变换单元的电路参数,并介绍了实际研究结果及其在主动隔振系统中的使用效果．     

光折变铌酸锂晶体电光、压电效应研究

该文讨论了在外加电场与晶体光轴方向有一定夹角β时光折变铌酸锂晶体的电光和压电效应．并在此基础上研究了光栅衍射效率为0时,外加电场与夹角β和光束偏振之间的关系,从而达到探求最小外加电场实现光开关功能．     

基于时间反演法的螺栓健康监测研究

针对实际工程结构中容易出现的螺栓联接松动问题进行了研究。采用Greenwood和Williamson模型和时间反演原理对聚焦信号幅值与螺栓预紧力的关系进行理论推导,得出两者成单调增函数关系;并据此提出一种基于时间反演法的螺栓健康监测方法。建立实验装置,进行实验研究。实验结果表明,聚焦信号幅值与螺栓预紧力的关系曲线近似于对数函数关系;接触界面粗糙度越大,聚焦信号幅值越快趋于稳定;时间反演法具有良好的自适应聚焦效果,能有效提高信号信噪比,在螺栓健康监测方面具有很好的应用前景。     

多孔氧化铝陶瓷内高温流体的流动及传热特性

通过仿真模拟的方法研究了模拟烟气、水蒸气及含尘烟气三类高温流体在多孔氧化铝陶瓷材料内的流动及传热特性。结果表明:随孔隙率增大,流体平均流速加快,流体进出口温降逐渐减小。三类流体中,水蒸气流速最大,在最大孔隙率下其流速达到66.64 m/s;烟气温降最显著,当孔隙率为0.3时,其进出口温差达到最大值85.6 K。随压差的增大,流体流速加快,其中受粉煤灰颗粒影响的含尘烟气流速增幅较小,流速仅从0.23 m/s增至0.93 m/s;另一方面,压差增大导致流体与壁面的热传导减少,模型内流体温降减小。含尘烟气流体扰动较大,当增大孔隙率和压差时,流速呈线性增长;尽管粉煤灰颗粒的存在强化了传热,但流体分子间的相互作用使得含尘烟气温度变化显著。     

Dielectric,piezoelectric, and ferroelectric properties of lanthanum-modified PZTFN ceramics

Specimens of Pb_1?1.5xLa_x(Zr_0.53Ti_0.47)_1?y?zFe_yNb_zO₃(x = 0, 0.004, 0.008, 0.012, and 0.016, y = z = 0.01) (PZTFN) ceramics were synthesized by a semi-wet route. In the present study, the effect of La doping was investigated on the structural, microstructural, dielectric, piezoelectric, and ferroelectric properties of the ceramics. The results show that, the tetragonal (space group P4mm) and rhombohedral (space group R3c) phases are observed to coexist in the sample at x = 0.012. Microstructural investigations of all the samples reveal that La doping inhibits grain growth. Doping of La into PZTFN improves the dielectric, ferroelectric, and piezoelectric properties of the ceramics. The hysteresis loops of all specimens exhibit nonlinear behavior. The dielectric, piezoelectric and ferroelectric properties show a maximum response at x ≥ 0.012, which corresponds to the morphotropic phase boundary (MPB).     

Effects of sintering atmosphere on the physical and mechanical properties of modified BOF slag glass

This study proposes an efficient way to utilize all the chemical components of the basic oxygen furnace (BOF) slag to prepare high value-added glass-ceramics. A molten modified BOF slag was converted from the melting BOF slag by reducing it and separating out iron component in it, and the modified BOF slag was then quenched in water to form glasses with different basicities. The glasses were subsequently sintered in the temperature range of 600–1000℃ in air or nitrogen atmosphere for 1 h. The effects of different atmospheres on the physical and mechanical properties of sintered samples were studied by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and by conducting experiment on evaluating the sintering shrinkage, water absorption and bulk density. It is found that the kinetics of the sintering process is significantly affected by sintering atmosphere. In particular, compared with sintering in air atmosphere, sintering in N₂ atmosphere promotes the synergistic growth of pyroxene and melilite crystalline phases, which can contribute to better mechanical properties and denser microstructure.