It is well recognized that the cutter run-out appearing in the milling process will cause an uneven redistribution of the instantaneous uncut chip thickness through the cutter flutes and thereby will generate an irregular distribution of the cutting forces in different tooth periods. This work aims to develop a new approach able to identify the cutter radial run-out and cutting-force coefficients in the flat end milling. It is shown that the total cutting forces can be considered as the sum of a nominal component that is independent of the run-out plus a perturbation component induced by the run-out. Mathematical formulations of both components are developed, accounting for the cutting geometry and the radial run-out parameters. Firstly, to calibrate the cutting-force coefficients, a generic procedure is proposed using the instantaneous value of the nominal component instead of the average value. Secondly, considering the fact that the perturbation component of the cutting force depends non-linearly upon the run-out parameters, the identification of run-out parameters is carried out by solving the linearized equation. In the identification procedure, some key techniques such as the calculation of the immersion boundary at any cutting instant and the reasonable selection of the depth of cut are discussed in detail. Finally, based on simulation and experimental results, the validity of the identification approach is demonstrated.
This paper is focused on the microstructure modelling and evaluation of effective elastic properties of three-dimensional multiphase and multilayer braided composite. Regarding the multiscale characteristics of the composite, the microstructure modelling is carried out sequentially from fibre to tow scale. The geometrical configuration of the microstructure is first analysed, and mathematical relations among different geometrical parameters are derived on each scale. Second, effective elastic properties are obtained based on the sequential homogenisation from fibre to tow scale. A strain energy based method is proposed to evaluate effective elastic properties with specific boundary conditions imposed on the microstructure. Numerical results obtained by the proposed method and the microstructure model show a good agreement with the results measured experimentally.
Three methods are presented for calibrating the instantaneous cutting force coefficient (ICFC) and the cutter runout parameters in peripheral milling. In the first method, ICFC and the runout parameters are calibrated separately. First, the nominal cutting force components extracted from the measured force data are used to calibrate the ICFC, and then the runout parameters are obtained by optimally selecting those producing the minimum squared difference between the measured and predicted cutting forces. The second method calibrates the cutting force coefficients and the runout parameters simultaneously by choosing those that best maintain the cutting force coefficients constant. The third method was previously proposed by the current authors. Comparisons between the calibrated results from different tests and different methods are made to validate the consistency of the presented methods. Experiments are also conducted for comparison purposes.
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