Abstract:Nitinol, a shape-memory alloy (SMA), is gaining popularity for use in various applications. Machining of these SMAs poses a challenge during conventional machining. Henceforth, in the current study, the wire-electric discharge process has been attempted to machine nickel-titanium (Ni55.8Ti) super-elastic SMA. Furthermore, to render the process viable for industry, a systematic approach comprising response surface methodology (RSM) and a heat-transfer search (HTS) algorithm has been strategized for optimization of process parameters. Pulse-on time, pulse-off time and current were considered as input process parameters, whereas material removal rate (MRR), surface roughness, and micro-hardness were considered as output responses. Residual plots were generated to check the robustness of analysis of variance (ANOVA) results and generated mathematical models. A multi-objective HTS algorithm was executed for generating 2-D and 3-D Pareto optimal points indicating the non-dominant feasible solutions. The proposed combined approach proved to be highly effective in predicting and optimizing the wire electrical discharge machining (WEDM) process parameters. Validation trials were carried out and the error between measured and predicted values was negligible. To ensure the existence of a shape-memory effect even after machining, a differential scanning calorimetry (DSC) test was carried out. The optimized parameters were found to machine the alloy appropriately with the intact shape memory effect.Keywords: shape memory alloy; superelastic nitinol; WEDM; heat transfer search algorithm; DSC test; shape memory effect
proceedings of the nitinol heat engine conference pdf download
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Nitinol is a kind of wire that has a memory. If you heat it, it tries to return to the shape it remembers. [Latheman666] recently posted a video (see below) of a Nitinol engine that uses a temperature differential to generate motion.
Yes, and yes, in fact that was one of the early proposed applications as just the heat gradient between the ambient air and ground water could drive the engine so that the water it pumped for irrigation also powered it.
Water is heated to 90 degrees Celsius with help of conventional heating process and then the heating source is removed. Water is then poured in a flask and NiTinol engine is placed over the flask. The temperature on cool side is room temperate which was found to be 32 degrees Celsius during the experiment.
help of laser tachometer. Laser tachometer used for measuring speed of NiTinol engine in RPM. As the time passes, temperature of water bath goes on decreasing due to heat loss to surrounding. Variation in speed of the engine is measured with the help of laser tachometer.
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