The dynamic characteristics of the NC machine are the important technical indicators of NC machine performance, and the precision of existing machine's dynamic characteristics evaluation analysis that based on structural dynamics modeling and simulation is poor. For this problem, this paper presents NC machine dynamic characteristics evaluation methods based on Grey Correlation Analysis. This method, by measuring the vibration signal of feature points in NC machine and making 1/3 octave spectrum analysis for vibration signal, can obtain the characteristics data sequence of vibration signal. Through the grey correlation analysis method, calculate the relevancy between the characteristics data sequence of each vibration signal and that of ideal dynamic characteristics, and quantitatively evaluate the dynamic characteristics of machine tools according to the size of the grey correlation. Took three same type NC milling machines as study objects, designed the cutting vibration resistance experiments, used this paper's method for the evaluation analysis of the comprehensive dynamic characteristics of NC milling machine, and obtained the evaluation results which is in line with the actual dynamic characteristics of machine tools, and verified the evaluation method of comprehensive dynamic characteristics that proposed in this paper.

In allusion to the measurement and control system of the fracture traumatic cross-section stress, because of the manufacturing error and installation error of its mechanical components, the axial and radial force of the indicating value of the dynamometer exists at the same time, and the radial force will damage the fracture healing. According to the mechanical structure of the measurement and control system of fracture traumatic cross-section stress, analyzed the mechanics transmission, and established the mechanics transfer model of the stress measurement and control system. Based on the force method typical equations, acquired the unknown force and torque of the measurement and control system. Take the radial force of the indicating value of the fracture two-dimensional dynamometer into the mechanics transfer model expression, thus obtain the result of the fracture traumatic cross-section affected by the radial force that applied by the stress measurement and control system, and then adjust the size and direction of the radial force on the fracture trauma section applied by the stress measurement and control system, and reduce the negative effect of the radial force on fracture healing.