Dynamic Response of a Polyvinylidene Fluoride (PVDF) Sensor Embedded in a Metal Structure Using Ultrasonic Additive Manufacturing
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis study examined the dynamic response of a polyvinylidene fluoride (PVDF) piezoelectric sensor which is embedded into an aluminum coupon. Although authors conducted some tests, the current version cannot be published due to some important issues not being clarified.
1. The writing of the introduction was insufficient, and key innovations were not highlighted. It is necessary to highlight and clarify what problems existed in the previous work of using PVDF as a sensor. (In another word) Why authors need to carry out current study?
2. Why choose a sensor with such geometric size? How to choose the location to place the sensor?
3. Why is there a delay between the output voltage and strain in Figure 4?
4. Some experimental device/set up diagrams can be placed in a supporting document.
5. I don't quite understand the meaning/reason of last part experiment (the PLA clamp was replaced with two stainless steel nuts). What is the relationship between this part of the experiment and the PVDF sensor?
Author Response
See the enclosed document summarizing the changes made to the manuscript in response to the reviewers' concerns. The revised manuscript is uploaded separately.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript investigates the dynamic response (including the sensitivity, frequency bandwidth, and impact detection performance) of a Polyvinylidene fluoride sensors (PVDF) sensor embedded in an aluminum coupon using ultrasonic additive manufacturing (UAM). The embedded PVDF sensor's linearity with axial load applied to the coupon is also evaluated. The background, methods, results, and discussion are clearly presented. Given the interest in developing integrated sensors for monitoring material properties in structures/assemblies deployed in harsh environments, this manuscript will be of interest to the in situ sensors community, and to the readers of Actuators in general. I would, however, like the authors to address the following:
1. In the linearity test under axial loading, can the authors clarify how this work improves upon their previous work reported in (Ramanathan, A.K., Gingerich, M.B., Headings, L.M. and Dapino, M.J., 2022. Metal structures embedded with piezoelectric PVDF sensors using ultrasonic additive manufacturing. Manufacturing Letters, 31, pp.96-100.)?
2. How were the hammer impact tests performed on the suspended specimen? It is good to see that the authors performed multiple measurements for ensuring repeatability. Nevertheless, the procedure for the hammer impact tests will be helpful. Please clarify.
3. In the introduction, the authors provide several examples of prior work on embedded sensors (such as PZT ceramic patches in concrete). Please provide details of the techniques used in these prior studies for embedding sensors in a parent matrix material. It doesn't appear to be that all of the examples in the introduction used high temperature processing for sensor integration.
4. Please provide details of the UAM parameters for sensor integration. What is the normal force and ultrasonic frequency of vibration for welding the aluminum foils.
5. Please provide a broader perspective on how these findings can help further development of embedded PVDF sensors in metallic parts/ components. Are these expected to be dynamic strain sensors? Or passive NDE sensors?
Author Response
See the enclosed document summarizing the changes made to the manuscript in response to the reviewers' concerns. The revised manuscript is uploaded separately.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsPlease provide a manuscript with traces of revisions, as it is difficult for me to distinguish the author's modifications in the current version. The authors' response is too simple. Please provide a detailed description of the modifications made.
I previously suggested placing multiple images in supporting documents, please move Figs.3，6, 10 to supporting documents. Too many images in the main text make it difficult to grasp the key points.
Have you compared the situation of directly bonding（glue） the sensor to the aluminum coupon？
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
