Systematic Methods to Increase the Lifetime of Mechanical Products Such as Refrigerators by Employing Parametric Accelerated Life Testing

Round 1

Reviewer 1 Report

 

Comments from Reviewer

Manuscript ID: applsci-1808816-peer-review-v1.pdf

Title: Systematic methods to increase the lifetime of mechanical product such as refrigerator by employing parametric accelerated life testing

The current form's presentation of methods and scientific results is satisfactory for publication in the Apllied Sciences journal. I think this paper is not suitable for publication in its current form, given it is a high-standard journal. The drawbacks to be addressed can be specified as follows:

1.                  Fig. 1. The problem of capital letters at the beginning of a word, see e.g. “Generator & control”, “Heat exchanger”, etc.

2.                  Fig. 1. Wear-out or Wearout?

3.                  Line 135. Positioning a total Parametric ALT procedure ---> Positioning a Total Parametric ALT Procedure.

4.                  Line 555. Red symbol?

 

Sincerely,

The reviewer.

Author Response

Dear Sirs:

Thank you for your review of our paper.  Below is a response to the review.

Comment 1.                 

1) Fig. 1. The problem of capital letters at the beginning of a word, see e.g. “Generator & control”, “Heat exchanger”, etc.

2) Fig. 1. Wear-out or Wearout?

3) Line 135. Positioning a total Parametric ALT procedure ---> Positioning a Total Parametric ALT Procedure.

4) Line 555. Red symbol?

Response:   As you recommended, we modified them. Please check it.

Sincerely,

The authors

Reviewer 2 Report

See the attached document.

Comments for author File: Comments.pdf

Author Response

Dear Sirs:

Thank you for your review of our paper.  Below is a response to the review.

Comment 1. Woo, S., & O'Neal, D. L. (2019). Reliability design and case study of mechanical system like a hinge kit system in refrigerator subjected to repetitive stresses. Engineering Failure Analysis, 99, 319-329. I see a lot of similarities between the two works while this work not cited in this article.

Response:   For a long time, we have studied the methodology of parametric ALT. In the meantime, we developed detailed methodology, compared with that of Woo, S., & O'Neal, D. L. (2019) cited in [33] also. That is, in the generalized time-to failure formulation we added some equations as follows:

1) the detail derivation of reliability (Equations (1) – (4)),

2) the derivation of a series of potential barriers that hinder the movement of the charged impurities from Schrodinger wave (Equations (6)-(12)),

3) transport processes (Equation (13)),

4) for example, solid-state diffusion of impurities dopped in silicon (Equations (14)-(16)).

And for this methodology we also suggested another case-study: lifetime of a localized Ice-maker including Auger Motor with Gear System in a Domestic Refrigerator.

Comment 2. The authors mention that they use the parametric accelerated life testing, and I didn’t see the mathematical work for the parametric model and the effect of the acceleration on this model

Response:   In general, various life-stress models can be utilized to explain the mathematical work for the parametric model such as Electromigration, Contact Failure, Bond-pad Corrosion, Rolling contact fatigue, etc.

Instead, we suggested the general stress model (Equations 18 & 19) and the acceleration on this model (Equation 20) based on transport phenomena. To show the effectiveness of this model, we provided the case study (see section 2.4).

Comment 3. Figure 2 shows that the failure rate of the lifetime model has the Bathtub shape, while the best model for fitting this type of failure rate is the Weibull lifetime distribution, so why the authors didn’t use it.

Response:   As you mentioned, Figure 2 has the Bathtub shape. However, we know that the shape parameter of Weibull distribution in Bathtub curve is different, dependent on the regions of: 1) first, there is initially a decreasing failure rate (b<1), 2) a constant failure rate (b=1), and then an increasing failure rate ((b>1). So, because bathtub shape follows Weibull lifetime, we can use this model to derive the sample size equation (see equation (22) & Appendix A)

And we also modified Figure 2 that was added with shape parameters, dependent on the regions of bathtub curve.

Comment 4. Could the authors propose a real-life example of lifetimes for the purpose of illustration?

Response:   As you recommend, we added the Equations (43) & (44) to calculate the lifetime and failure rate and the results and briefly suggested the result in the end of results and discussion.

Additionally, we modified Figure 1 & 9.

Sincerely,

The authors

Author Response File: Author Response.pdf