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\!\(\*
ButtonBox["ClearSystemCache",
BaseStyle->"Link",
ButtonData->"paclet:ref/ClearSystemCache"]\)[] ;
sigx = 317;
e1 = 191000;
e2 = 9890;
m = 15;
b = 58;
f2tc = 61.62;
h1 = 0.165;
h2 = 4*h1;
ex = (h1*e1 + h2*e2)/(h1 + h2);
g12 = 7790;
g23 = g12/3;
H = 3*g12*g23/(h1*g23 + h2*g12)
α = Sqrt[((h1 + h2)*ex*H)/(h1*h2*e1*e2)];
sigx2b = (e2/ex)*sigx
sigx2b/f2tc
ep = (sigx2b/(sigx2b - f2tc))
l00 = 2*ArcCosh[ep]/α
p = 1 - Exp[-(F2t/b)^m]
f1 = D[p, F2t]
F = (e2*sigx/ex)*(1 - 1/Cosh[α*l0/2])
f2 = Abs[D[F, l0]]
l = 2;
f = l0/l^2
fc = f*f1*f2 /. F2t -> (e2*sigx/ex)*(1 - 1/Cosh[α*l0/2])
\!\(\*
ButtonBox["NIntegrate",
BaseStyle->"Link",
ButtonData->"paclet:ref/NIntegrate"]\) [fc, {l0, l, 2*l}, 
 Method -> {"GlobalAdaptive", 
   Method -> {"TrapezoidalRule", "Points" -> 3}, 
   "SingularityHandler" -> None}, PrecisionGoal -> 4]

Where the output for fc is

28.862 E^(-10.844 (1 - Sech[0.70973 l0])^15) l0 Abs[
  Sech[0.70973 l0] Tanh[0.70973 l0]] (1 - Sech[0.70973 l0])^14

l0 is the variable

but, NIntegrate fails to produce any results and simply shows

\!\(\*
ButtonBox["NIntegrate",
Appearance->Automatic,
BaseStyle->"Link",
ButtonData->"paclet:ref/NIntegrate",
Evaluator->Automatic,
Method->"Preemptive"]\)[
 28.862 E^(-10.844 (1 - Sech[0.70973 l0])^15)
   l0 Abs[Sech[0.70973 l0] Tanh[0.70973 l0]] (1 - 
    Sech[0.70973 l0])^14, {l0, 2, 4}, 
 Method -> {"GlobalAdaptive", 
   Method -> {"TrapezoidalRule", "Points" -> 3}, 
   "SingularityHandler" -> None}, PrecisionGoal -> 4]

Can anyone help me?

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closed as off-topic by Silvia, Artes, Oleksandr R., m_goldberg, Sjoerd C. de Vries Dec 25 '13 at 8:41

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – Silvia, Artes, Oleksandr R., m_goldberg, Sjoerd C. de Vries
If this question can be reworded to fit the rules in the help center, please edit the question.

1  
You should not copy the functions' names with a hyperlink (from the documentation I guess?)... With plainly typing the ClearSystemCache and NIntegrate words, I didn't seem any problem.. –  Silvia Dec 24 '13 at 22:17

1 Answer 1

sigx = 317; e1 = 191000; e2 = 9890; m = 15; b = 58; f2tc = 61.62;
h1 = 0.165; h2 = 4*h1; ex = (h1*e1 + h2*e2)/(h1 + h2); g12 = 7790;
g23 = g12/3; H = 3*g12*g23/(h1*g23 + h2*g12); 
α = Sqrt[((h1 + h2)*ex*H)/(h1*h2*e1*e2)];
sigx2b = (e2/ex)*sigx; sigx2b/f2tc; ep = (sigx2b/(sigx2b - f2tc));
l00 = 2*ArcCosh[ep]/α; p = 1 - Exp[-(F2t/b)^m];
f1 = D[p, F2t]; F = (e2*sigx/ex)*(1 - 1/Cosh[α*l0/2]);
f2 = Abs[D[F, l0]]; l = 2; f = l0/l^2;
fc = f*f1*f2 /. F2t -> (e2*sigx/ex)*(1 - 1/Cosh[α*l0/2]); 

NIntegrate[fc, {l0, l, 2*l}]
(*
  0.676373
*)
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