Fibers made from shape memory alloys perform strain recovery during phase transformation of crystal structure. Controlled parameters such as heating time, holding temperature, and cooling time dominate the micro deformation of shape memory alloy fiber (SMAF). Mechanical contraction occurs at high temperature (austenitic phase), and strain-relief happens at low temperature (martensitic phase). But the rapid change of temperature causes unfinished or incomplete phase transformation, which induces residual strain within the SMAF. The accumulated defects shorten the specimen's life during cyclic loading and lower the limit of fatigue failure. This study uses digital image correlation to provide the in-situ response temperature-strain relations during the phase transformation and quantizes the residual strain within the SMAF. Experiments accurately control the holding temperature of SMAF in three conditions, which are (a) under, (b) around, and (c) beyond the phase transformation temperature of the specimen, and systematically analyzes the self-accommodation and strain-recovery of SMAF in the three experiments. The in-situ measurement of microscale deformation can help the end-user optimize the control parameters and increase the life and performance of SMAF.
The silicon thin film solar module (TFSM) is gaining popularity over crystalline silicon (c-Si) solar modules because of it's less energy consumption during production, only 1% amount of silicon is needed, superior low light performance and low temperature coefficient. The traditional silicon TFSM is all solar cells series connected configuration which can be easily achieved through laser scribing process; however, the all series connected configuration results in high module voltage (Vmpp ~ 96V) and non-optimized module output power due to the current limit issue. To reduce the PV system installation cost, it is necessary to have the low voltage TFSM comparable to cSi solar module. In this study, we present the development of 1.3x1.1m 2 parallel-and-series connected low voltage (Vmpp~32V) silicon TFSM, called Auria Solar C-series module (patent pending). The C-series module also passed the IEC 61646 and 61730 qualification tests by TÜV Rheinland certification. Through the analysis of the current limit issue of the silicon TFSM, we optimize the solar cell numbers to get the best module output power. The small dead zone width ~180um (from P1 edge to P3 edge) achieved via the precise laser scribing is also shown in this paper. The comparison of module performance between C-series module and traditional TFSM reveals that C-series module has 1.5% higher Pmpp output. The 900kWp system using the C-series module was installed in Verona, Italy; the PVsyst simulation shows high energy yield and 92.1% high performance ratio.
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