## 4 Summary and Conclusions  
A reliability methodology for application to new mechanical systems was presented. It contained: (1) a parametric ALT scheme created on product BX lifetime, (2) a load inspection for ALT, (3) ALTs with the design alterations, and (4) an estimation of whether the system design(s) fulfilled the target BX lifetime. We thus proposed a generalized stress model and sample size formulation. As an example, a new refrigerator drawer system subjected to repetitive food loading was discussed.  
* For the original drawer design, when the accelerated loads were performed, the left/right rail rollers were taken away and the center support rail was deformed because of the insufficient strength. The drawer structure might be altered by extending the roller support in the guide rail as well as attaching up-strengthened ribs on the center support.
* In the first ALT, the box cover in the drawer system fractured at the junction of the drawer cover and its body structure. It was corrected by making the enforced ribs and executing fillets thicker. As the approximated stress concentrations at the intersection areas of drawer decreased from 23.0 to 14.0 MPa using the FEM analysis, we also verified the appropriateness of new design for fatigue.
* In the second ALT, rollers in the center support were broken away and the guide rails fractured. To improve them, the center support rail extended the roller rib. The guide rail also was altered through: (1) adding the reinforced rib; (2) enhancing the corner rounding.
* With these altered designs, in the third ALT, there were no reliability issues. The altered drawer system was guaranteed to satisfy the lifetime need--B1 life 10 years. By examining problematic field products, load analysis, and parametric ALTs with design modifications, the mechanical system, such as in the drawer, was successful in having a lengthy lifetime.
* By figuring out the design problems for returned products, we could design and perform parametric ALTs. After reproducing the design failures, we might modify them. Finally, we checked if the product achieved the lifetime target. In the process, we utilized the (generalized) stress model and sample size equation.  
This structured reliability method can be applied to other mechanical products such as airplanes, automobiles, and construction machinery. To make use of this systematic method, designers might recognize why products fail during their lifetime. If there are design flaws in the structure which are subjected to repeated loads, the system will be unsuccessful before its anticipated lifetime. After identifying the load features of a mechanical system, engineers may perform the parametric ALT until the needed mission cycles. Ultimately, parametric ALT can be utilized to recognize the design problems of a mechanical product and alter them.  
[PERSON] performed the idea developing, methodology, analysis and experiment, and wrote down the original document. [PERSON] inspected the study and writing for the draft manuscript. [PERSON] corrected the document. All authors have understood and agreed to the published edition of the document. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data supplied in this research can be attained on request from the corresponding author.  
The authors declare no conflict of interest.