Thank you very much.
During the experiments, different chatter frequencies occurred at different spindle speeds, which could be assigned to different modes. This effect is reflected in the calculated stability limit, as the limit results from the superposition of the lobes of several modes. Furthermore, due to the strong speed dependence, modes can become relevant which do not appear dominant in measurements at the non-rotating spindle.
A very interesting presentation!
The concept of identification from the FRF assumes causality, so that the response results only from hammer excitation. However, if the spindle is rotating, there will be other (non-measurable) sources of excitation. What influence does this have on the estimation of the modal parameters from the FRF?
Thank you for your comment!
The FRF is calculated based on the ratio of the measured displacement and the force impulse introduced and measured by the impact hammer. Forces caused by other sources of excitation, which were not introduced by the hammer, would be neglected in this scenario as they were not measured directly. Since the modal parameter values were approximated based on the FRF, this effect, if significant, may result in discrepancies between the estimated and the actual dynamic compliance.
Great outlooks, Mr. Woeste! Maybe effect of tool wear on chatter will be investigated beside that spindle speed. Thus, the system can be tested from end to end a tool life.
Thank you very much!
You are right. The consideration of tool wear is an interesting aspect, as it can significantly influence the resulting process dynamics due to, e.g., substantial damping effects.
For instance, the calculation of stability diagrams taking such effects into account is a considerable challenge. This requires more complex cutting force models, which continue to be an important subject of research.
Nice work. The chatter occur at one mode. Why do you investigate up to 7 modes?
Thank you very much.
During the experiments, different chatter frequencies occurred at different spindle speeds, which could be assigned to different modes. This effect is reflected in the calculated stability limit, as the limit results from the superposition of the lobes of several modes. Furthermore, due to the strong speed dependence, modes can become relevant which do not appear dominant in measurements at the non-rotating spindle.
A very interesting presentation!
The concept of identification from the FRF assumes causality, so that the response results only from hammer excitation. However, if the spindle is rotating, there will be other (non-measurable) sources of excitation. What influence does this have on the estimation of the modal parameters from the FRF?
Thank you for your comment!
The FRF is calculated based on the ratio of the measured displacement and the force impulse introduced and measured by the impact hammer. Forces caused by other sources of excitation, which were not introduced by the hammer, would be neglected in this scenario as they were not measured directly. Since the modal parameter values were approximated based on the FRF, this effect, if significant, may result in discrepancies between the estimated and the actual dynamic compliance.
Great outlooks, Mr. Woeste! Maybe effect of tool wear on chatter will be investigated beside that spindle speed. Thus, the system can be tested from end to end a tool life.
Thank you very much!
You are right. The consideration of tool wear is an interesting aspect, as it can significantly influence the resulting process dynamics due to, e.g., substantial damping effects.
For instance, the calculation of stability diagrams taking such effects into account is a considerable challenge. This requires more complex cutting force models, which continue to be an important subject of research.