为了解决精密加工设备的微位移隔振问题,研制了一种以压电陶瓷为作动器的智能微位移主动隔振系统。在现有数据采集系统和激振器的基础上搭建了相应的实验平台,提出将模糊-比例积分微分(fuzzy-proportional integral derivative,简称Fuzz...为了解决精密加工设备的微位移隔振问题,研制了一种以压电陶瓷为作动器的智能微位移主动隔振系统。在现有数据采集系统和激振器的基础上搭建了相应的实验平台,提出将模糊-比例积分微分(fuzzy-proportional integral derivative,简称Fuzzy-PID)算法理论应用到微位移的主动隔振控制中,在实验室虚拟仪器工程平台(laboratory virtual instrumentation engineering workbench,简称LabVIEW)环境下开发了整个系统的算法控制程序,分别在扫频、随机和正弦激励信号下进行了微位移主动隔振实验。实验结果表明,受控后的振动位移大幅度降低,验证了该方法对微位移主动隔振的有效性。展开更多
It is important to reveal the performance of carbon/carbon composites subjected to complex loading, which can provide a basis for developing the failure laws of carbon/carbon composites. The uniaxial and biaxial compr...It is important to reveal the performance of carbon/carbon composites subjected to complex loading, which can provide a basis for developing the failure laws of carbon/carbon composites. The uniaxial and biaxial compressive performances of three-dimensional reinforced carbon/carbon composites (3D C/C) were investigated in this paper. The results showed that the compressive strength becomes larger when the loading direction parallels to the z-direction of 3D C/C. The uniaxial compression failure was mainly caused by fracture fiber bundles to form an overall shear fault in the z-direction. The failure mode was delamination of fiber bundle/matrix interface for the x- and y-direction samples. The biaxial compressive failure of x-y direction compressioncompression specimen was caused by the low interlaminar shear strength. In addition,for y-z and z-x direction compression-compression samples,the shear-type failure was formed on the surface of the specimen plumbing the loading direction. Overall,the weak-interface is still a main factor to influent the fracture mechanism of 3D C/C.展开更多
基金Sponsored by the National Security Basic Research Program of China (Grant No.61391)the National Natural Science Foundation of China (Grant No.91016029,10902030)
文摘It is important to reveal the performance of carbon/carbon composites subjected to complex loading, which can provide a basis for developing the failure laws of carbon/carbon composites. The uniaxial and biaxial compressive performances of three-dimensional reinforced carbon/carbon composites (3D C/C) were investigated in this paper. The results showed that the compressive strength becomes larger when the loading direction parallels to the z-direction of 3D C/C. The uniaxial compression failure was mainly caused by fracture fiber bundles to form an overall shear fault in the z-direction. The failure mode was delamination of fiber bundle/matrix interface for the x- and y-direction samples. The biaxial compressive failure of x-y direction compressioncompression specimen was caused by the low interlaminar shear strength. In addition,for y-z and z-x direction compression-compression samples,the shear-type failure was formed on the surface of the specimen plumbing the loading direction. Overall,the weak-interface is still a main factor to influent the fracture mechanism of 3D C/C.
