Developing a hardware in-the-loop simulator for a backpack energy harvester

Abstract

Excessive vibration, such as chatter, is a common problem in machining processes. Meanwhile, numerous hard, brittle metals have been shown to form segmented chips, also known as sawtooth chips, during machining. In the literature, a cyclic cutting force has been demonstrated where segmented chips are formed, with the force cycle corresponding to the formation of segments. Segmented chip formation has been shown to be linked to high vibration levels in turning and milling processes. Additionally, it has been proposed that the amplitude of chatter vibrations can be limited by interference between the tool flank and wavy workpiece surface, a phenomenon known as tool flank process damping.In this contribution, a model is proposed to predict the amplitude of forced vibration arising due to the formation of segmented chips during turning. The amplitude of vibration was calculated as a function of cutting parameters. It was demonstrated that the model can be extended to account for the effect of tool flank process damping. For validation, titanium Ti6Al4V alloy was turned using a flexible toolholder, with surface speed ranging from 10 to 160m/min, feedrate from 0.1 to 0.7mm/rev and width of cut from 0.35 to 4mm.In the experimental validation, 25 of 68 test cuts exhibited high amplitude vibration. In 16 of these cases, the main cause was concluded to be chip segmentation, which can be predicted by the model. The model is thus considered of practical value to machinists.

Optimum resistance analysis and experimental verification of nonlinear piezoelectric energy harvesting from human motions

“…Currently, there are a variety of transduction mechanisms based on piezoelectric [7][8][9], electromagnetic [10,11], or thermoelectric [12] effects for converting human kinetic energy and motion to usable electric energy. Among them, piezoelectric vibration energy harvesting has been considered to be a promising method to harness natural body movements to power wearable electrical devices such as healthcare watches, pacemakers, and mobile phones, due to its high energy density and easily miniaturized fabrication [13].…”

Harvesting Inertial Energy and Powering Wearable Devices: A Review

“…The load mass oscillates up and down due to the inertial excitation and spring, Transferring motion to the generator. [ 111,112 ] The trajectory of the frame and the mass can be seen in Figure 8c, and since the frame is attached to the body, its trajectory is identical to that of the COM, while the mass moves relatively to the frame. The energy‐harvesting backpack can be seen as a mechanical system, as shown in Figure 8d.…”

Energy harvesting from human motion and bridge vibrations: An evaluation of current nonlinear energy harvesting solutions

“…To acquire a time history of the acceleration due to walking motion, a direct current (DC) accelerometer was placed on several participants who were then asked to walk on a tread mill. This data was gathered as part of the work shown in (Papatheou and Sims (2012)) and (Papatheou et al (2012)). For information about the test procedure, see (Papatheou et al (2012)).…”