Flexural Deflection Prediction of Piezo-Composite Unimorph Actuator Using Material Orthotropy and Nonlinearity of Piezoelectric Material Layer
Round 1
Reviewer 1 Report
The article is well prepared and I believe that it can be published.
Only minor comments:
- The literature review in the introduction looks poor. It is advisable to expand it a bit.
- What are the reproducibility and measurement errors of nonlinear effects? What was the sample selection for experimental studies?
Author Response
We would like to thank for the valuable comments and suggestions. The paper cannot be as good as the current revision without these comments. The answers to the requests of reviewers are given below. We would like to response request by request.
Point 1: The literature review in the introduction looks poor. It is advisable to expand it a bit.
Response 1: As suggested, we added the following sentences and one related reference to introduction section as following.
“For a micro actuator application, Nguyen et al. [15] theoretically investigated the dynamics of piezo-actuated stick–slip micro-drives (PASSMDs), by exploiting micro-vibration and considering the dynamic contact status, which improved the performance of the is PASSMD about 15%.”
Point 2: What are the reproducibility and measurement errors of nonlinear effects? What was the sample selection for experimental studies?
Response 2: All tests were performed three times on each specimen with standard deviation error bar in Figure 8, which are shown by yellow highlighting in the page 7.
Reviewer 2 Report
Recommendation: minor revision
Commons to the Author:
The paper Coatings-761489 "Flexural deflection prediction of piezo-composite unimorph actuator using material orthotropy and nonlinearity of piezoelectric material layer" focused on the piezo-composite actuators. The piezo-composite actuator LIPCA-S2 and LIPCA-C3 specimens were manufactured and analyzed to investigate the actuated tip displacement of piezo-composite cantilevers. The actuated tip displacement of a piezo-composite cantilever could be predicted accurately using the proposed prediction model. The analysis and description are adequate for a publication. However, the following issues should be considered for the improvement of the manuscript.
- Two kinds of piezo-composite actuators were studied. The piezoelectric ceramic in each actuator was different, however, the material of CTS 3203-HD layer was not clarified. Furthermore, why did one actuator use polyimide film and the other use glass epoxy?
- Please explain the reason in details why the actuation displacement of a LIPCA-S2 cantilever could be predicted more accurately.
- Some of the images are not clear, for example, Figure 8. The color difference is not evident.
- The quality of English needs improvement, and there are some mistakes. The English grammar and sentence structure should be revised carefully so that the results of the study are clear to the readers.
Author Response
We would like to thank for the valuable comments and suggestions. The paper cannot be as good as the current revision without these comments. The answers to the requests of reviewers are given below. We would like to response request by request.
Point 1: Two kinds of piezo-composite actuators were studied. The piezoelectric ceramic in each actuator was different, however, the material of CTS 3203-HD layer was not clarified. Furthermore, why did one actuator use polyimide film and the other use glass epoxy?
Response 2: The material properties of material of CTS 3203-HD are shown in the third column of Table 1, which are highlighted in yellow color.
Point 2: Please explain the reason in details why the actuation displacement of a LIPCA-S2 cantilever could be predicted more accurately.
Response 2: Your request is explained in details in the pages 13 as following, which is shown by yellow highlighting.
“To reduce this large discrepancy between the predicted and measured data, variations in material properties with changes in the compression stress of a PMN-29PT piezoelectric single crystal were considered using the nonlinear prediction method. The core idea of the nonlinear prediction method is to use different d32 and E2 values, which are obtained from measured strains, for different compression stresses at each level of excitation voltage, as shown in Table 3. These values were derived from measured data in Figures 9 and 10. For a specific level of voltage, the internal compression stress level can be calculated using Equation (15) and the corresponding d32, d31, and E2 values can be obtained from Figures 9 and 10. The corresponding curvature change and tip displacement can be predicted for each electric field increment. The predicted total tip displacement of the nonlinear prediction model is equal to the sum of each individual tip displacement
We found that the actuation displacement of the LIPCA-S2 cantilever can be predicted more accurately by using the nonlinear prediction model with varied piezoelectric strain coefficients d32 and d31, and elastic moduli E2, even though there is still a considerable difference between the predicted and measured values. To reduce the prediction discrepancies at lower voltages, additional theories, such as the classical laminate plate theory that considers the change in the elastic modulus E2, d32, and d31 to determine the variation in the two-dimensional plane stresses (σxx, σyy, σxy), effects of longitudinal-transverse and regular interactions of the layers, and voltage actuation at the boundaries of a piezoelectric layer, will be considered in subsequent studies.”
Point 3: Some of the images are not clear, for example, Figure 8. The color difference is not evident.
Response 3: As requested, we have changed the line colors of Figure 8 more clearly
Point 4: The quality of English needs improvement, and there are some mistakes. The English grammar and sentence structure should be revised carefully so that the results of the study are clear to the readers.
Response 4: As requested, we will use MDPI English editing service to improve the English grammar and sentence even though the 1st draft was corrected by a professional native English speaker in our institute.
Reviewer 3 Report
The authors has studied LIPCA-S2 and LIPCA-C3 via a tip displacement performance during the actuation process based on electric excitation. This work may be of interest in another MDPI journal as this work does not fit into the scope of MDPI Coatings.
The authors should motivate why their manuscript should be publish in MDPI Coatings.
Some comments:
- Abstract show same information as described in the introduction. The authors should revise the abstract.
- The symbol K was not correct used in equations.
- Figure 8 show bad resolution and should be shown in same size.
- Please use correct unit in Figures. For example, MPa instead of Mpa
- The authors should better keep a nice overview because it's pretty cumbersome with lots of equations and figures.
Author Response
We would like to thank for the valuable comments and suggestions. The paper cannot be as good as the current revision without these comments. The answers to the requests of reviewers are given below. We would like to response request by request.
General comment: The authors should motivate why their manuscript should be publish in MDPI Coatings.
Response: Associate editor Bunny Zou contacted me on 16 October 2019, regarding a Special Issue entitled "Advances in Ferroelectric and Piezoelectric Thin Films: Synthesis, Properties and Applications", to be published in the journal Coatings.
That is the reason why we submitted our paper.
Point 1: Abstract show same information as described in the introduction. The authors should revise the abstract.
Response 1: As requested, we have eliminated the following sentence of abstract to avoid the same information.
“Research on piezo-composite actuators has been actively conducted over the past two decades as a response to strong demand for light, compact actuators to replace electro-magnetic motor actuators in micro robots, small flying drones, and compact missile systems.”
Point 2: The symbol K was not correct used in equations.
Response 2: As requested, we have eliminated the equations with symbol k.
Point 3: Figure 8 show bad resolution and should be shown in same size.
Response 3: As requested, we have improved the resolution of Figure 8 and changed the size.
Point 4: Please use correct unit in Figures. For example, MPa instead of Mpa
Response 4: As requested, we have corrected the unit in the Figure 8.
Point 5: The authors should better keep a nice overview because it's pretty cumbersome with lots of equations and figures.
Response 5: As requested, we have eliminated equations (10)-(16) since they are almost same with the equations of reference [6]
Round 2
Reviewer 3 Report
The authors have addressed very well on the comments and the manuscript is improved as well. It is suitable for the publication in Coatings.
