71 lines
2.2 KiB
Mathematica
71 lines
2.2 KiB
Mathematica
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function cycle = func_LifeMdl_StressStatistics(cycle)
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% Adds to "cycle" structure additional aging stress statistics.
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% Scalars:
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% cycle.Crate_rms,Crate_disrms,Crate_chgrms
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% Vectors: (using rainflow algorithm)
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% cycle.dsoc_i,ncyc_i,Crate_dis_i,Crate_chg_i,TavgK_i,socavg_i...
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%
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% Copyright Kandler Smith & Ying Shi, NREL 6/2013
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%{
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Input timeseries:
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cycle.t: time in days
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cycle.soc: soc in normal units, 0 to 1
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cycle.TdegC: temperature in celsius
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Outputs:
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cycle.dt: Time difference in days
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cycle.dEFC: Equvialent full cycles during this period
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cycle.TdegK: Time weighted average of temperature
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cycle.soc: Time weighted average of soc
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cycle.Ua: Time weighted average of Ua
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cycle.dod: Difference b/w max and min SOC
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cycle.Crate: Time weighted average of Crate in non-resting periods
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%}
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% dt
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dt = cycle.t(end) - cycle.t(1);
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% TdegK
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TdegK = trapz(cycle.t, cycle.TdegC + 273.15)/dt;
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% soc
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soc = trapz(cycle.t, cycle.soc)/dt;
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% Ua:
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x_a_eq = @(SOC) 8.5e-3 + SOC.*(7.8e-1 - 8.5e-3);
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Ua_eq = @(x_a) 0.6379 + 0.5416.*exp(-305.5309.*x_a) + 0.044.*tanh(-1.*(x_a-0.1958)./0.1088) - 0.1978.*tanh((x_a-1.0571)./0.0854) - 0.6875.*tanh((x_a+0.0117)./0.0529) - 0.0175.*tanh((x_a-0.5692)./0.0875);
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Ua = Ua_eq(x_a_eq(soc));
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% DOD
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dod = max(cycle.soc) - min(cycle.soc);
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% Crate
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Crate = diff(cycle.soc)./diff(cycle.t .* 24);
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% Crate is the average of the non-zero rates (Absolute value)
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% Any rate smaller than a 1000 hour chg/dischg rate is
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% considered to be negligible.
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Crate = abs(Crate);
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maskNonResting = Crate > 1e-3;
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if any(maskNonResting)
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Crate = Crate(maskNonResting);
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difft = diff(cycle.t);
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difft = difft(maskNonResting);
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tNonResting = cumsum(difft);
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Crate = trapz(tNonResting, Crate)/(tNonResting(end)-tNonResting(1));
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else
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Crate = 0;
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end
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% dEFC
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dEFC = sum(abs(diff(cycle.soc)))/2;
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% output the extracted stress statistics
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cycle = struct();
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cycle.dt = dt;
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cycle.dEFC = dEFC;
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cycle.TdegK = TdegK;
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cycle.soc = soc;
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cycle.Ua = Ua;
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cycle.dod = dod;
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cycle.Crate = Crate;
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end
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