As standard concepts for precision positioning within a machine reach their limits with increasing measurement volumes,inverse concepts are a promising approach for addressing this problem.The inverse principle entail...As standard concepts for precision positioning within a machine reach their limits with increasing measurement volumes,inverse concepts are a promising approach for addressing this problem.The inverse principle entails other limitations,as for high-precision positioning of a sensor head within a large measurement volume,three four-beam interferometers are required in order to measure all necessary translations and rotations of the sensor head and reconstruct the topography of the reference system consisting of fixed mirrors in the x-,y-,and z-directions.We present the principle of a passive heterodyne laser interferometer with consequently separated beam paths for the individual heterodyne frequencies.The beam path design is illustrated and described,as well as the design of the signal-processing and evaluation algorithm,which is implemented using a System-On-a-Chip with an integrated FPGA,CPU,and A/D converters.A streamlined bench-top optical assembly was set up and measurements were carried out to investigate the remaining non-linearities.Additionally,reference measurements with a commercial homodyne interferometer were executed.展开更多
Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane...Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula, and it includes almost all the present non-linear strength theories, which can be used in just one material. The shape of failure function of the GNST is a smooth curve between the SMP criterion and the Mises criterion on the π-plane, and an exponential curve on the meridian plane. Through the transformed stress space based on the GNST, the combination of the GNST and various constitutive models using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state. Keywords generalized non-linear strength theory (GNST) - transformed stress - constitutive model - application展开更多
基金funded by the Deutsche Forschungsgemeinschaft(DFG)under contract 279458870.
文摘As standard concepts for precision positioning within a machine reach their limits with increasing measurement volumes,inverse concepts are a promising approach for addressing this problem.The inverse principle entails other limitations,as for high-precision positioning of a sensor head within a large measurement volume,three four-beam interferometers are required in order to measure all necessary translations and rotations of the sensor head and reconstruct the topography of the reference system consisting of fixed mirrors in the x-,y-,and z-directions.We present the principle of a passive heterodyne laser interferometer with consequently separated beam paths for the individual heterodyne frequencies.The beam path design is illustrated and described,as well as the design of the signal-processing and evaluation algorithm,which is implemented using a System-On-a-Chip with an integrated FPGA,CPU,and A/D converters.A streamlined bench-top optical assembly was set up and measurements were carried out to investigate the remaining non-linearities.Additionally,reference measurements with a commercial homodyne interferometer were executed.
基金the National Natural Science Foundation of China ( Grant No. 10272010) the Ministry of Science and Technology of China (Grant No. 2002CCC00200).
文摘Based on the test data of frictional materials and previous research achievements in this field, a generalized non-linear strength theory (GNST) is proposed. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula, and it includes almost all the present non-linear strength theories, which can be used in just one material. The shape of failure function of the GNST is a smooth curve between the SMP criterion and the Mises criterion on the π-plane, and an exponential curve on the meridian plane. Through the transformed stress space based on the GNST, the combination of the GNST and various constitutive models using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state. Keywords generalized non-linear strength theory (GNST) - transformed stress - constitutive model - application
