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In the present work, we propose an adaptive topology optimization (TO) method under suitably graded truncated hierarchical B-spline refinement and coarsening (SGTHB-TO). A series of algorithms have been devised to implement admissible adaptivity of SGTHB-TO by resorting to the definitions of suitably graded isogeometric hierarchical meshes. We apply the proposed SGTHB-TO method to two-dimensional and three-dimensional TO problems of compliance and compliant mechanism. According to the numerical results, SGTHB-TOs with or without admissible restriction share similar optimization processes, except that numerical artifact, such as edge blurring and islanding gray regions occurring in SGTHB-TO without admissible restriction, can be eliminated by SGTHB-TO with admissible parameter equaling to 2. Besides, the convergence rate can be largely accelerated by imposing an admissible constraint on SGTHB-TO for TO problems with geometric nonlinearity existing in the design domain, which is attributed to the improved numerical accuracy by the admissible adaptive discretization scheme of isogeometric analysis (IGA). Therefore, the SGTHB-TO method with the admissible parameter equaling to 2 is a more effective adaptive TO method than SGTHB-TO without considering admissible restriction, in terms of both numerical stability and convergence rate.

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In high-precision machining, it is very important to obtain operational modal parameters of machine tools to ensure the quality of machined parts. More specifically, the prediction of free chatter boundary is a critical requirement for improving productivity, which requires accurate dynamic parameters under operational conditions. Operational modal analysis is an effective method to estimate dynamic parameters of the tested system. However, for machine tools, the direct application of the operational modal analysis method is not feasible. In measured responses, periodic components are very preponderant during cutting, which is mainly caused by the periodic cutting force. In order to overcome this issue and to extract operational modal parameters of machine tools, the method of time-synchronous-subtraction based on the principle of time-synchronization-averaging is proposed. The correctness of the proposed approach is demonstrated by a simulation experiment, and the feasibility is verified through a milling experiment. The results show that the time-synchronous-subtraction method can well eliminate harmonics in the vibration response under the real cutting condition. The method is not only accurate but also simple in calculation.

-In order to simultaneously obtain the comprehensive performance and mechanical characteristics of spindle parts of CNC machine tools, In this paper, through analyzing the testing technology of spindle parts performance, we designed a testing platform. It considers multiple types of spindle parts and can be used for actual production. The platform can achieve online realtime measurement and analysis of the stiffness, rotary accuracy, temperature, noise and vibration of spindle parts, also realize testing and analysis of the integration of data acquisition, processing, and evaluation.