共查询到20条相似文献,搜索用时 93 毫秒
1.
采用压电陶瓷元件进行智能板振动控制 总被引:9,自引:1,他引:8
将分布的压电传感器/驱动器运用于智能板结构的主动减振控制中,分布的压电传感器能感知结构的局部应变状态,并通过控制回路反馈给驱动元件,构成闭环控制。建立了智能板闭环控制的分析模型,揭示在应变率反馈下,主动控制的机理是增加了结构的阻尼。用两对压电陶瓷元件仿真了柔性板的闭环控制,获得了令人满意的结果。 相似文献
2.
提出了一种通过测量动态应变实现工程中低频振动监测的方法.在对动态应变压电传感特性进行理论分析的基础上,对压电传感元件在不同激振频率下(0.1~40.0Hz)的动态响应进行了实验研究,实验给出了较好的测量精度.结果表明,压电传感元件灵敏度高、频响范围宽、响应时间快,符合工程中低频振动测量的要求. 相似文献
3.
4.
5.
分析了叉指形电极(IDEs)1-3型压电纤维复合材料传感元件的结构特点和电场特性,构建了压电纤维传感元件的本构方程,并建立了IDEs1-3型压电纤维传感元件的有限元模型,探索了IDEs关键尺寸和压电纤维直径及间隔对传感元件传感性能的影响.结果表明:该传感元件X向产生的电位移大小约为Y向产生电位移大小的3倍,正交异性更加明显,能清楚区分不同方向的应力波;选择合适的纤维间隔,减小电极中心距、电极面宽度和纤维直径能有效的改善传感元件的传感性能. 相似文献
6.
7.
基于阻抗技术的压电元件自损伤检测- 总被引:1,自引:0,他引:1
为了保证结构健康监测系统的有效运行,基于压电阻抗技术原理,提出了一种压电传感、驱动元件自损伤检测方法.通过研究压电元件等效电容值(压电元件导纳虚部数值)的变化,判别压电元件是否破损及其与主体结构之间是否剥离,并在悬臂梁结构上进行压电元件自损伤检测试验.结果表明,相比压电元件完好的情况,各频率下压电元件电纳值随脱粘部分面积的增加而上升,随破裂部分面积的增加而下降,并且损伤程度和等效电容变化量成比例关系,与理论分析结果吻合较好. 相似文献
8.
基于设计和工程实用性的需要,建立了含金属芯压电纤维压电传感器的理论模型。根据本构关系方程,推导出悬臂杆结构含金属芯压电纤维受轴向力和轴向应变后产生电荷的解析表达式;分别计算了不同半径比、含钨芯和铂金芯的压电纤维受到固定轴向力和固定轴向应变时产生的电荷值,分析了金属芯性能和半径比对产生电荷的影响。试验比较了不同长度和半径的压电纤维的准静态和动态应变传感性能,测试了等强度梁的固有振动频率。试验结果表明,该传感器具有较高的准静态和动态应变传感灵敏度,最高达0.163nC/με;具有较好的冲击振动传感性能。 相似文献
9.
10.
Cymbal型压电复合换能器的数学模型 总被引:2,自引:0,他引:2
研究了Cymbal换能器的工作机理。利用压电方程和弹性力学公式,推导了Cymbal换能器的径向和轴向谐振频率,给出了轴向位移与径向位移之间的数学关系式。部分实验数据与理论计算结果表明,Cymbal换能器的轴向有效压电应变常数是相同规格压电元件的40倍,在压电式微位移驱动器或超声换能器技术领域具有一定的应用前景。 相似文献
11.
Usik Lee 《Journal of Mechanical Science and Technology》1998,12(2):233-243
This paper considers smeared continuum damage mechanics based on the equivalent elliptical crack representation of a local
damage. This approach provides a means of utilizing the crack energies derived in fracture mechanics, and of identifying the
local damage state from local stress and strain information. The strain energy equivalence principle is used to derive the
effective continuum elastic properties of a damaged solid in terms of the undamaged elastic properties and a scalar damage
variable. The scalar damage variable is used to develop a consistent damage evolution equation. The combination of representing
local damage as an equivalent elliptical crack, the determination of effective elastic properties using a strain energy equivalence
principle, and a consistent damage evolution equation yields a simple, yet powerful local approach for continuum damage analysis 相似文献
12.
采用INSTRON准静态压缩实验机和分离式霍普金森压杆装置对铸造固溶态AM80镁合金不同应变速率下的压缩变形行为进行了研究,应变速率分别为0.0001s-1、800s-1、1050s-1、1600s-1、1850s-1和2100s-1。结果表明:当应变速率ε˙≤1850s-1时,实验用AM80镁合金的流变应力随应变速率的增大而增大,表现出明显的正应变速率敏感性;当应变速率增至2100s-1时,由于局部温升效应,合金产生了明显的动态软化,导致流变应力反而略有减小。采用Johnson-Cook材料模型对实验用AM80镁合金在不同应变速率下的变形行为进行描述,并取材料应变速率强化参数为应变速率的函数。对比结果表明,所建立的本构方程与实验结果基本吻合。此外,由于力学本构忽略了由形变引起的温升软化,基于ABAQUS的仿真结果在较低应变速率(800s-1)和高应变速率(1850s-1)的中低应变下与实验结果吻合得较好;而在高应变速率(1850s-1)的较高应变条件下,仿真结果与实验结果差异较大。 相似文献
13.
Screen HR Lee DA Bader DL Shelton JC 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2004,218(2):109-119
During physiological loading, a tendon is subjected to tensile strains in the region of up to 6 per cent. These strains are reportedly transmitted to cells, potentially initiating specific mechanotransduction pathways. The present study examines the local strain fields within tendon fascicles subjected to tensile strain in order to determine the mechanisms responsible for fascicle extension. A hierarchical approach to the analysis was adopted, involving micro and macro examination. Micro examination was carried out using a custom-designed rig, to enable the analysis of local tissue strains in isolated fascicles, using the cell nuclei as strain markers. In macro examination, a video camera was used to record images of the fascicles during mechanical testing, highlighting the point of crimp straightening and macro failure. Results revealed that local tensile strains within a collagen fibre were consistently smaller than the applied strain and showed no further increase once fibres were aligned. By contrast, between-group displacements, a measure of fibre sliding, continued to increase beyond crimp straightening, reaching a mean value of 3.9 per cent of the applied displacement at 8 per cent strain. Macro analysis displayed crimp straightening at a mean load of 1 N and sample failure occurred through the slow unravelling of the collagen fibres. Fibre sliding appears to provide the major mechanism enabling tendon fascicle extension within the rat-tail tendon. This process will necessarily affect local and cellular strains and consequently mechanotransduction pathways. 相似文献
14.
G. KHODABAKHSHI D. WALKER A. SCUTT L. WAY R.M. COWIE D.R. HOSE 《Journal of microscopy》2013,249(3):195-205
Tendons are tough fibrous tissues that facilitate skeletal movement by transferring muscular force to bone. Studies into the effects of mechanical stress on tendons have shown that these can either accelerate healing or cause tendon injuries depending on the load applied. It is known that local strain magnitude and direction play an important role in tendon remodelling and also failure, and different techniques to study strain distribution have been proposed. Image registration and processing techniques are among the recently employed methods. In this study, a novel three‐dimensional image processing technique using the Sheffield Image Registration Toolkit is introduced to study local strain and displacement distribution in tendon. The results show that the local normal strain values in the loading axis are smaller than the global applied load, and fibre sliding was detected as a dominant mechanism for transferring the applied load within tendon. However, results from different samples suggest three distinct modes of deformation during loading, as some show only parallel sliding of fibres in respect to the loading axis, whereas others are twisted or deflected in directions transverse to the loading axis. The proposed 3D image registration method is essential for analysing this out‐of‐plane movement, which cannot be detected using a standard 2D method. 相似文献
15.
《Measurement》2014
Structure multi-parameters measurement, such as strain, displacement, corrosion and temperature, is of the utmost importance for structural health monitoring. Meanwhile uncoupling method of temperature and strain has still a technical problem in structure sensing measurement. In this paper, we proposed a method for simultaneous measurement of strain and temperature using a hybrid local and distributed optical fiber sensing system. The principle of the method is investigated and then validated by the theoretical simulation experiments and tensile tests in laboratory. Furthermore, one experiment for internal force measurement of a smart stranded wire, under the interaction of temperature and strain, is also conducted in lab. The experimental results show that the strain and temperature can be well measured simultaneously by using one multi-signal optical fiber sensor. 相似文献
16.
This work presents a novel approach of nondestructive detection of damage in plate structures by using experimental modal analysis (EMA) and modal strain energy method (MSEM). An aluminum alloy 6061 thin plate with a surface crack is investigated in this study. EMA is conducted on the plate to obtain the mode shapes before and after damage. The modal displacements of each mode shape are then used to compute the modal strain energy. For all measured mode shapes, a damage index is defined by using the ratio of modal strain energies of the plate before and after damage. In fact, small damage causes very little change in system response, but it is an essential early warning of structure damage. As the second-order derivatives, modal strain energy is much more sensitive to the small change of structural response than frequencies and mode shapes. It is therefore feasible to approach the small damage by using a damage index defined by fractional MSE of the structure before and after damage. In this study, a scanning damage index (SDI) is developed by moving damage indices obtained from the local area throughout the structure as if a scanning sensor is used to inspect the structure. The damage indices in overlap areas are added up and the summation may intensify the signals of damage in the plate. Limited by the numbers of measured point, a differential quadrature method is employed to calculate the partial differential terms in strain energy formula. Experimental results show that SDI well identifies a surface crack location by using only few measured mode shapes of the aluminum plate. This novel approach provides a flexible, cost-effective, and nondestructive damage evaluation in either local or global structure. Its applicability to different types of structures and different sizes of damage is to be experimentally validated in the future work. 相似文献
17.
18.
19.
Kim DG Brunski IB Nicolella DP 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2005,219(2):119-128
This study employed an optical strain measurement method, called microdisplacements by machine vision photogrammetry (DISMAP), to measure both the global and local strain fields in microtensile specimens of cortical bone subjected to controlled uniaxial tension. The variation of local maximum principal strains was measured within the gauge region of samples as a function of applied tensile stress during testing. High gradients of local strain appeared around microstructural features in stressed bone even while the global strain for the entire gauge region showed a strong linear correlation with increasing tensile stress (r2 = 0.98, p < 0.0001). The highest local strain around microstructural features in bone was 11.5-79.5 times higher than the global strain. 相似文献
20.
用LY12CZ和30CrMnSiNi2A两种材料制成中间有类椭圆孔的试件,对战斗机随机谱载下的寿命试验结果,分别用局部应力应变法和裂纹扩展的方法对裂纹形成寿命进行计算,并讨论上述两种方法的优缺点。用相对Miner法则修正的局部应力应变法能较好地估算随机语载下的寿命也指出损伤的线性累积不是很合理,大过载及载荷顺序等参数在局部应力应变法中对寿命的影响不是直接的,在裂纹扩展的方法中能较好解决这些问题。一般用裂纹扩展方法计算的寿命比局部应力应变法更符合试验的结果。 相似文献