Real time digital recording and numerical reconstruction of a temporal digital hologram sequence have become feasible in recent years.They provide a new measurement method which enjoys the valuable advantages of being full-field,noncontact and high precision.In this paper,a combined method of temporal digital hologram sequence and windowed Fourier transform is proposed to measure the kinematic parameters of random vibration.A series of holograms are recorded by CCD camera and the original phase can be reconstructed by Fresnel reconstruction algorithm.The three-dimensional windowed Fourier transform is used to filter noise in phase and extract the instantaneous kinematic parameters of the specimen,such as the displacement,velocity and acceleration.An experiment is conducted on a chloroprene rubber latex membrane.Results demonstrate that the proposed method determines the vibration parameters precisely and enjoys many merits.
Chong Yang,1,2 and Hong Miao 1,1) Key Laboratory of Mechanical Behavior and Design of Materials (CAS) Department of Modern Mechanics,University of Science and Technology of China,Anhui 230027,China 2) Institute of Structural Mechanics Chinese Academy of Engineering Physics,Sichuan 621900,China
A three-nested-deformation model is proposed to describe crack-tip fields in rubber-like materials with large deformation.The model is inspired by the distribution of the measured in-plane and out-of-plane deformation.The inplane displacement of crack-tip fields under both Mode I and mixed-mode(Mode I-II) fracture conditions is measured by using the digital Moire' method.The deformation characteristics and experimental sector division mode are investigated by comparing the measured displacement fields under different fracture modes.The out-of-plane displacement field near the crack tip is measured using the three-dimensional digital speckle correlation method.
Xia XiaoHai-Peng SongYi-Lan KangXiao-Lei LiXiao-Hua TanHao-Yun Tan
One-dimensional nanostructured materials are often used as beams in many applications such as ultrahigh-frequency resonators and ultrasensitive sensors.Compared with usual macroscopic beams,nanobeams have much higher surface/volume ratios so that their surface energies may play a significant role.Besides,they often bear large deflections due to their typically large slenderness ratios and larger elastic ranges.There is,however,lack of a theory that takes into account of both the above two features owned by nanobeams.In this paper,we present such a theory and give applied examples to show that surface energy and large deflection may individually or jointly have notable effects.
Dujuan Zeng Quanshui Zheng 1(Department of Engineering Mechanics,Tsinghua University,Beijing 100084,China)
