Needs["Graphics`PlotField`"];
l=100;
modell={u'[s]== v[s],
v'[s]==-2 u[s]- u[s]^3 -0.2 v[s],u[0]==u0, v[0]==v0};
p:=Module[{},loesung=NDSolve[modell,{u,v},{s,0,l}]; 
abb=ParametricPlot[Evaluate[{u[s],v[s]}/.loesung],{s,0,l},
DisplayFunction->Identity,
PlotPoints->50,PlotRange->All]
];
bild[1]=Table[{u0=z;v0=-2;p},{z,-2,2,2}];
bild[2]=Table[{u0=z;v0=2;p},{z,-2,2,2}];
bild[3]=Table[{u0=-2;v0=z;p},{z,-2,2,2}];
bild[4]=Table[{u0=2;v0=z;p},{z,-2,2,2}];
feld=PlotVectorField[{z2,-2 z1 -z1^3-0.2 z2},{z1,-3,3,0.5},{z2,-3,3,0.5},
DisplayFunction->Identity];
abb0=Show[Evaluate[Table[bild[i],{i,3,3}]],feld,
DisplayFunction->$DisplayFunction,
PlotRange->All,AxesLabel->{"x","y"},ImageSize->{400,300}];

'