DESIGN UNDER UNCERTAINTY FOR A PIEZOELECTRIC ENERGY HARVESTER TO POWER A TIRE PRESSURE MONITORING SYSTEM

In this paper we perform reliability analysis for a piezoelectric energy harvester to power the tire pressure monitoring sensor (TPMS) under various uncertainty. Reliability based design optimization (RBDO) is applied to improve the performance of the system. Wasted vibrational energy in a vehicle's rotating tire can be exploited to enable a self-powered TPMS. Piezoelectric type energy harvesters (EHs) are frequently used to collect vibrational energy and power such devices. While exposed to a high impact loading condition in a tire, the harvester experiences increasing strains which is under a higher risk of mechanical failure. Therefore, there is a need for a design to enhance the harvester's fatigue life as well as maintaining the required power generation. Multiple design optimization studies found to consider the design update by traditional deterministic design optimization (DDO) which does not show reliable performance as it is unable to account for various uncertainty factors including manufacturing tolerances, environmental effects, and material properties. In this study, we consider uncertainty issue by using reliability-based design optimization under presence of various source of uncertainties. The RBDO problem is defined to satisfy power requirement and durability concerns as the constraints while considering design limitations such as compactness and weight. The time varying response of the EH such as generated power, dynamic strain, and stresses are measured by a transient analysis. Sequential Quadratic Programming (SQP) algorithm is used for both DDO and RBDO, and the design results are compared. The RBDO results demonstrate that the reliability of EH is increased by 26% with scarifying the objective function for 2.5% compared to DDO.